INTRODUCTION

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For 16 years (2008-2024), the original Coincident Pure Reference (PR), and the later "Extreme" models, were the finest speakers I had ever heard, and my top "References". The PR replaced my previous 10+ year "Reference", the Ars Acoustica System Max. These two speakers are very similar in their basic design philosophy, though their execution is quite different, mainly due to a decade's worth of improvements in (dynamic) driver technology. The PR is also unusually practical: It is highly flexible in the choice of both the amplifiers and the size of the listening room.

Since I obviously don't change my personal speaker references very often, I felt it was necessary, at the time, to discuss my basic philosophy on speakers. Accordingly, this lengthy file will include the long-term history, and evolution, of my personal speaker references, plus the specific and detailed reasons why the Coincident Pure Reference had achieved its "Reference" status back in 2008.

Important Note- The first 9 Parts of the below essay/review were about the "Original" Pure Reference, which came out in late 2007. The "Extreme" version came out in late 2009 (Part Ten). It subsequently became my new "Reference". In spring 2010, I "doubled-up" the Extremes, and this became my new "Reference" (Part Eleven). The Mk. II version of the Extreme came out in 2017 (Part Twelve), and the entire process was repeated.

I've personally owned (let alone my former store) countless speakers in the last 36 years. However, most came and went quickly, and it is only the speakers below that were my true primary speakers (or "References"). The dates are as good as my memory can provide:

1972 to 1974- Original Quad ESL-57 Electrostatics (stock)

1974 to 1976- KLH Nine Electrostatics Doubled-Up (Two speakers per channel - side by side in a "V" shape)

1977 to 1982- Original Quads (Modified) with RTR ESR-15 Electrostatic Tweeters, and later with various subwoofers

1982 to 1985- Strathearn Ribbons (3 stacked as a line source) with various (sub)woofers

1986 to 1989- Martin-Logan Original CLS (Modified) with Entec subwoofers

1989 to 1996- Wilson WATT (Modified) with (stacked) Entec and (later) Tympani (sub)woofers

1997 to 2008- Ars Acoustica System Max (with their own subwoofers)

Details and Explanations:
1. I went back to the Quads in late 1977 because the (otherwise superior) KLH Nines had buzzing wood frames and unreliable transformers.
2. The Quad's front and back protective grilles were removed, the speaker raised 18" and the crossover capacitor was replaced.
3. The CLS had a 9" taller frame, shorter internal wiring and improved passive parts.
4. The WATT's two drivers and internal crossover were all replaced.
5. The years 1976/8, 1985/6 and 1996/7 were all transitional, with no direct exchange of references.

At a quick glance, these six speakers appear to be very different from each other, but there is a basic design philosophy with two critical commonalties.

1. Since 1979, the use of subwoofers (to get the last octave and to also bi-amp and clean up the midrange).
2. The subwoofers withstanding, all of the speakers were either one or two ways.

In practice then, my reference speakers were all, at least in design theory, relatively full-range and cohesive.
When using more common terms, the goals of my two design priorities were very simple:
1. I wanted to hear all (full-range) of the music, and
2. I wanted to hear this music from (ideally) only one source* (driver).

*Analogy- Even the most highly skilled "Duo" can't exactly imitate a "Soloist".

Accordingly, it is now easy to understand why I have avoided, and even ignored, so many different speakers, from so many different companies (including earlier Coincident models), no matter how excited other audiophiles felt about them. From my perspective, if the speakers didn't conform to my two basic design requirements, they were effectively irrelevant, because I knew, from decades of direct experience, that they could never satisfy me, no matter what other sonic strengths they possessed.

Of course, these six reference speakers also share actual performance attributes, especially compared to their many competitors:

1. They are all fast and detailed, particularly the electrostatics and ribbons in the midrange.
2. They are all clean, with low distortion, particularly at low and medium volume levels.
3. They are all relatively neutral, particularly the Quad, Wilson and Ars, though all of them have some colorations.
4. They all have a low "sound-floor", with the Ars being the best of the bunch in this area.
5. They all have a "live" and "immediate" sound.

They also have some noticeable problems, many of them which are shared:
1. None of them can play "really loud" (or "blasting"), and the Quad is particularly limited in this area.
2. The imaging capabilities are mixed, with only the Strathearn, Wilson and Ars being really good in this area.
3. Related to #1, they all compress the loudest dynamic swings, especially compared to the better horns.
4. The subwoofers were difficult to integrate, especially with the dipoles, but I was (very) successful with the Wilson and Ars.

Still, looking back over more than 35 years, I feel I made the right choices at the time, considering what was available. I heard and tried out so many speakers; in my homes, in my store, at audio shows and in other audiophiles homes. I even had "hybrids" that I configured myself, but none of these innumerable speakers could satisfy me, in the long-term, as well as my above "references".

When assessing my personal "Evolution", the most recent (dynamic) speakers had fewer noticeable problems; In general, while they retained almost all of the strengths of the earlier references; They were a little more neutral; with a lower sound-floor; with a larger soundstage along with superior image focus; had better subwoofer integration; and the ARS finally had the (important and critical) capability of being amplified with the finest, low-power SET models. In practical terms; they drew less attention to themselves.

So now the Coincident Pure Reference joins this ultra-tiny group, and these are the reasons why...

The PR is a simple two-way speaker, with a (built-in) subwoofer. It is the most highly evolved example I've heard of this very specific genre of speakers.

Why and how: The PR's parts, and its execution, elevate its performance to "outstanding". This is in stark contrast to the numerous other speakers which also share its basic design, and yet mainly remain "mediocre", with the usual exceptions of "better or worse".

As for the details, I will begin by focusing on the two basic design fundamentals discussed above. First will be "Cohesiveness", which is, by far, the more difficult of the two to achieve.

The PR's single midrange driver obviously eliminates the main problem of "hearing two different sources". However, there are still other (potentially serious) design problems to avoid, and most speakers fail at solving them. These design challenges are:
1. The midrange to tweeter transition,
2. The midrange to (sub)woofer transition,
3. The more subtle problems of various, audible changes within the midrange itself (to be discussed later in Part 2).

I spent many hours, particularly in Toronto, listening specifically for transitional problems. I used every musical (LP) test and hurdle I could think of (strings, voices, woodwinds, piano, organ etc.). I eventually came to the conclusion, later verified by what I heard in my own system, that the Pure Reference is superior or equal to the finest speakers I've heard at each of these two transitions.

The three best speakers I've heard at handling the critical midrange/tweeter transition are the original Quad (for its time), the Morrison(s) and the Avantgarde Duo. Meanwhile, the Coincident Total Victory II (TVII) and the Ars Acoustica System Max are the two best I've heard with the midrange to subwoofer transition (which is one of the reasons why the Ars was my reference for so many years). The Pure Reference equals each of these five speakers in their respective transitional strength. This accomplishment, excelling in both (or all) transitions, is unprecedented in my experience. To be more specific...

The PR noticeably beat out the Ars in the critical midrange/tweeter transition. This superiority was most noticeable with violins and sopranos. While the Ars is still excellent at this transition, the PR is as close to a single-driver as any two-way I've heard. The TVII, for its part, has two transitions in the midrange, which automatically disqualifies it.

Next, both the Quad* and the (stock) Duo have serious problems* with their midrange/(sub)woofer transition, the Morrison less so. The Duo may work well with their Basshorns, but this solution entails both a huge monetary expenditure and highly unusual room requirements. As for the Quad, I know of no one who has successfully mated a subwoofer with it, including myself, and I spent years at it. The Morrison goes pretty deep, and it's also fast, but it's also dynamically limited, presenting a unique matching challenge. (*As do all the other dipole/dynamic woofer combinations I've heard.)

Ironically, the better the performance of a particular speaker in the midrange (especially in "speed"), the greater the challenge it is to match that same quality in the bass (which will then help "hide" the transition). That is why some speakers, like the Quad, are so fiendishly difficult to optimally transition with a subwoofer.

In short then, the PR sounds more like a full-range one-way speaker ("The Ideal") than any full-range two-way dynamic speaker I've ever heard, at any price (with the Morrison coming in second).

In fact, the only speakers that have any advantages in "transitions" are a few dipoles with no transitions. Examples are the largest Sound Labs and Acoustats, or custom "hybrids", such as the Martin-Logan CLS*/Tympani woofer combination. However, as far as I know, none of these speakers is truly full-range, in the traditional, flat to 20 Hz sense of that term. Worse, virtually none of them are flat to 20 Khz either. (*The Quad can also work with the Tympani, but there are severe dynamic discontinuites.)

This then brings us to the second design fundamental; "Full-Range".

The second design fundamental is being "full-range". This has not been a serious design challenge for many years, actually decades now. It's mainly a matter of cost and proper execution, particularly for achieving the bass part of the equation (20 Hz). To again be specific:

The Pure Reference goes as deep as any speaker I've heard (the quality of the PR's bass will be discussed later). The only speaker I'm aware of (but haven't heard) that can go truly and noticeably lower is the Eminent Technology Model 17 Subwoofer, which can not transition to a midrange driver. This makes it of academic interest only within this context.

As for the high frequencies, the Pure Reference is flat to beyond 20 Khz, and it sounds like it. It takes a true super-tweeter (usually the finest ribbons), or the Acapella Ion Tweeter, to sound even more extended. Unfortunately, I have not heard any speaker using any of those advanced tweeters that did not have noticeable transition problems. To summarize the above then, and by strict definition;
The Pure Reference is the most cohesive of the truly full-range (20 Hz to 20 KHz) speakers that I've heard.

And now it's time to discuss all the standard and familiar performance requirements, and their related engineering challenges. They must be met, and overcome, before a speaker can be honestly described as "an outstanding reproducer".

Important Perspective- I may have given a misleading impression of my audio priorities, which must be dispelled:

Despite my intense focus on "Cohesiveness" and "Full-Range" in both "My Personal Speaker References" and the discussion above, these two parameters were not what I listened for when I first heard the Pure References in Toronto in October 2007. Before I get into the actual performance details, I must explain exactly what happened that first evening...

When arriving at Israel Blume's home, I thought I would be listening to the Total Reference, his new "flagship", which I had never heard. To my great surprise, I saw a different speaker, which Blume had never told me about (or even hinted at). So, for the next 6 hours or so, I listened to this "mystery speaker". Blume played CDs for the first 30 minutes as the system warmed up. After that, he only played records, many of which were at my specific request. At that time, transitions never entered my mind. Instead, as I always do at first, I focused on "the basics": Neutrality, sound-floor, dynamics, immediacy, purity, image size and overall (gut) naturalness etc.

I soon had an extra reason for doing so: A strong sense that I was hearing a speaker which had a combination of sonics strengths I had never experienced before. I had to know, ASAP, whether my gut feeling was correct or not, which is why I was almost manic that evening in my musical requests. By the end of the night, I had satisfied myself that I had indeed heard something truly "special". Then, in the following days, along with confirmation, I made an intense focus (30 hours) on what most people would consider subtleties, but experienced audiophiles know that it's those important details (like obscure legal details in contracts) that will make (or kill) the final deal.

So, after reversing my traditional order of focus within this essay, I want to finally concentrate on "The Audio Basics", and methodically compare the Pure Reference's performance to the best speakers I've ever heard, category by category. First up isn't much of a surprise...

Neutrality of Character- The Pure Reference is as neutral as any speaker I've ever heard (and more neutral than any I've heard using a wood box). Is it "the most neutral"? Maybe, but I honestly can't say that without hearing all the other most neutral speakers at the same time. For perspective, these are the other most neutral speakers I've ever heard (all of them now discontinued!): The KLH-9, (Original) Quad, the Ars Acoustica System Max, the Eminent Technology LFT-3, Coincident Victory II and Total Victory II. Plus, there are invariably other speakers just as neutral that I can't think of at this time. (Such as the Original Apogee, but the amplification is ultra-critical.)

All these speakers have this in common; Because of their minimal (cabinet and driver) resonances, which are the "keys" to neutrality, they have a "character" which is difficult to describe, especially in words, for it is relatively subtle. Most attempts are useless or even ludicrous ("chocolate"). Accordingly, I will not attempt to do so, other than stating that the PR comes as close as any speaker I've heard to having no character to even describe. While I do hear a slight emphasis in part of the upper bass, it is too subtle and elusive to "characterize", because it can change, for better or worse, depending on the amplifier, crossover adjustments and room placement. Further...

I believe "neutrality" is somewhat different than other sonic attributes, not only due to its vital importance, but because the issue of "relativity" is less relevant here. By this I mean that when a component is described as "neutral" (without serious resonances), it's more "absolute" than simply saying that it's "detailed". This is because we don't know how much detail is actually potentially available to reproduce. However, "neutral is neutral", and once a component honestly achieves that distinction, it's inconsistent to challenge this later, even if higher performance levels are eventually attained. The proof I offer is that even some vintage components, originally described as "neutral", are usually still considered the same way today.

Finally, I "sense" (and only sense) that the PR may have fewer "mini-deviations", from perfect neutrality, than the other speakers. This is different than the broad variations usually associated with this term, which are also much easier to hear. It will take time and/or measurements to find some real proof of this sense, one way or the other. My thinking is mainly based on the superior performance of the ceramic drivers that are used in the PR. They may have fewer deviations than the drivers in other (dynamic) speakers, so even if a speaker, such as the Ars Acoustica System Max, has even less noticeable cabinet resonances than the PR, the System Max should still have slightly more noticeable overall deviations. I realize this may be all quite subtle, but still noticeable, so it must be at least mentioned.

Immediacy- The Pure Reference is the most immediate dynamic speaker I've heard. Just as important, and rare in my experience, the PR is equally immediate throughout virtually the entire frequency range. However, the most immediate speakers I've ever heard, with no qualifiers, are the Martin Logan CLS, the (1990s) Audiostatics and the Avantgarde Duo. I don't have any of these speakers available for a direct comparison, but I've heard the first two extensively, and based on my memory of them, the PR is not as immediate as either electrostatic, but it does come extremely close to matching the (horn based) Duo. In fact, I'm not sure I can make a confident distinction between them based on memory.

While the gap is noticeable between the PR and the two electrostatics, it is not "dramatic". This is because I believe the gut reaction of most audiophiles, hearing the PR for the first time, will be the same as mine: "This speaker is immediate"*. In fact, the PR comes closer to sounding like a good electrostastic (in their strengths) than any dynamic speaker I've ever heard. So, while the PR may be, or is, at the highest level of immediacy within its dynamic speaker group, and it should obviously be considered a "strong suit", I feel it still does not quite match the best of the entire speaker universe.

Further- One of my associates has owned the CLS for years now, and he even recently replaced the panels. He visited me for a couple of days in mid-February 2008, on his annual visit. We spent many hours listening to the PR. I played some records he specifically requested, which he had recently heard on his own speakers. The "big question" to him: How close is the Pure Reference to the CLS in the areas of "Immediacy and Speed"? His answer: "Very, very close."

*Examples-
Martin Codax-Cantigas De Amigo-Criswick-HARMONIA MUNDI HM 1060
BRAINSTORM (SOUNDTRACK)-HORNER-TER 1074/VARESE SARABANDE STV 81197

Cleanness and Purity- The results here are similar to "Immediacy" above, though not quite the same. The Pure Reference is very clean and pure. It is equal, or superior overall, to any dynamic speaker I've ever heard (though the Ars Acoustica is close, and maybe even better at some bass frequencies).

Still, I don't think the PR matches the best electrostatics at low to medium volume levels. However, the PR is noticeable superior to these electrostatics at higher volume levels and in the deep bass. This also means its "sense of purity" doesn't (noticeably) change as the volume or frequency changes. So I give the edge in overall purity to the PR when compared to the electrostatics. This doesn't complete the purity picture though...

When you compare the Pure Reference to the Avantgarde Duo (stock), the Duo will have a slight edge at extremely high (and even dangerous) volume levels (and maybe lower levels), but the PR will have an even more noticeable advantage in the entire bass range (below 200 Hz), and at all volume levels. So I once again give the overall edge to the PR. Still, there are a few even more imposing "challengers"...

There are the large dipoles, mentioned earlier, the big Acoustats and Sound Labs, plus the (rare) Original Apogees. They are not quite as ultra-pure as the CLS, Stax or Audiostatic at low to medium volumes, but they are cleaner at higher volume levels, and also in the mid and deep bass. I would say they have an edge over their two smaller rivals, but are they the equal of the Pure Reference? I would say it's too close to call without direct comparisons, because all of these speakers have basically the same important strengths across the board, and virtually no noticeable weaknesses, in this area.

In short, the Pure Reference is as clean and pure as any speaker I've heard, when all volume levels and all audio frequencies are taken into consideration .

Speed and Outer Details- Once again, this parameter is similar to "Immediacy" and "Purity", with the same two names as my "References"; The Martin-Logan CLS and the Audiostatics (now you know why these two speakers are among the very few in my Reference File). As above, the Pure Reference comes close, but does not quite match their performance in these areas. The PR is fast alright, faster overall than any dynamic speaker I've heard, and even "feels" like an electrostatic in its lack of obvious slurring, but those two fastest electrostatics still have a sense of instantaneous reaction that I've never heard equalled by any other speaker, even including the original Apogee.

This "starting" and "stopping" advantage also allows them to maximize the reproduction of outer detail. In practical terms, it is this ability that enables the speaker to be "intelligible", which, in turn, allows the listener to hear each individual note (or word) without an artificial smear. The PR is superb here for sure, but it's not "the best".

Many audiophiles have a problem making a distinction between a component's ability to reproduce "outer detail" and "low-level information" ("inner detail"), which I discuss below. They think it is the same thing. It isn't. If a component can reproduce outer detail, but not inner detail, that component will sound "sterile" and "analytical". Many transistor amplifiers have this problem. To make a visual analogy...

It's like the difference between looking at a forest in Summer, and the same forest in Winter. Yes, the analytical component, with only outer detail, will allow you to see more of the trees in Winter, but that's only because the leaves and foliage are all dead and gone. That's a heavy price to pay, which is why many audiophiles prefer tube electronics, and other components which minimize this problem.

High Frequency Reproduction- The finest tweeter I've ever heard is the Acapella Ion TW 1S, but it can only go down to 5K, and even then only under certain circumstances. Still, from around 10K and above, it is "the best", and approaching "perfection". For the more traditional (and practical) frequencies, 3K and above, the best tweeters I've heard are all ribbons. Examples are the outstanding ribbon tweeters in the Coincident (Total) Victory (II) as well as the Magnepan Tympani series.

So what about the Pure Reference's tweeter? It's the best dome tweeter I've ever heard. It's superb** in every area; speed, purity, smoothness, extension, lack of homogenization and (vitally important to me) it has an ultra-low sound-floor. However, it obviously doesn't match the Acapella within their shared frequency range.

The remaining question I have is when comparing the PR's tweeter to the finest ribbons I've heard. I feel, at this time, that the ribbon in the Victory II has a slight advantage over it. I would like to make a direct comparison between them one day. However, this speculative tweeter "shootout" can never be anything more than an "academic exercise", because no matter what the results of this comparison are, it is very important to keep this critical perspective...

At this highest level of audio performance, matching the tweeter to the midrange (and vice-versa) is usually even more important to the final sonic results (and much more difficult to achieve) than the isolated and independent reproduction of the two drivers themselves. In other words, if a superior ribbon tweeter replaced the dome tweeter currently in the PR, the overall results would most likely be a serious disappointment (See Part 1). Why? There would be a discontinuity between the two drivers that would be even more noticeable than the slight deterioration in the high frequencies.

This is why simply designing a speaker with the best available woofer, midrange and tweeter (if that's even technically possible) would not automatically create the best overall performer.* Further, evaluating a speaker by only focusing on the "lows, mids and highs", independently of each other, is also dangerously incomplete and usually highly misleading.

*For an analogy, imagine a relay race with one team having the four fastest runners, but one of them almost always drops the baton. I would instead place my bet on another team, which will not be as fast individually, but will practice perfecting the handoffs, so none of them ever drops the baton.

**Examples-
RAN-TAKEMITSU-FANTASY FSP-21004 (the most intense flute-like sound I've ever heard)
LA SPAGNA- ATRIVM MVSICAE DE MADRID/GREGORIO PANIAGUA- BIS LP-163/64

Low Frequency Reproduction- Even though we are only focusing on the (3 octave) frequencies between 20 Hz to around 160 Hz (deep, mid and upper bass), there's still no one speaker I've heard that is unqualifiedly "the best". (And if we consider the ultra-deep bass, below 20 Hz, only one speaker, the Eminent Technology Rotary subwoofer, is even viable.) These are my bass references (prior to the arrival of the Pure Reference):

Mid-bass and Upper-bass (40 to 160 Hz)- The Original Apogee (with the Tympani IV bass panel receiving a well deserved "Honorable Mention")

Deep Bass (20 to 40 Hz)- Concentric Speaker Technology Super Sub

Complete Bass Range (20 to 160 Hz)- Ars Acoustica Gravitas Subwoofer (By default, since the other two speakers can not reproduce the entire bass range)

Explanations:
1. The Apogee would be "the best", without qualifications, except that it doesn't reach into the the low/mid 20s. The Tympani IV "dies" even earlier, at around 30 Hz. They are both outstanding in the same areas; Impact, definition, immediacy, control and linearity.
2. The Concentric has superb weight, detail, control and power, but the quality deteriorates above 50 Hz.
3. The Gravitas has all-around excellence. It can't play "real loud", and it doesn't have the definition or impact of the two big dipoles, but it's still excellent in those two areas.

Both the Apogee and Tympani have the same problems, with the Tympani's being more obvious. Because they require a lot of power/current (which means complex/inferior amps) and they also don't go "real low", there have a certain "dry quality", which doesn't allow the size, scale and decays of the recording space to be heard or sensed (especially at low volumes). This weakness will be inconsequential to many listeners, but to lovers of acoustical music (such as myself), this may be a serious problem. I prefer the Ars, overall, because its problems are more "relative", and not as noticeable in the long-run. Now, what about the Pure Reference's bass...

It is very similar in quality to the Ars Acoustica, though I feel the PR has a very slight edge. Further, the PR has more weight, impact and sense of scale, and it even goes down a touch lower. This means, in effect, it is as at least as good, or better, than the Ars in every bass parameter. However, the PR requires more care to optimize than the Ars, because of its single cabinet and larger woofers.

Accordingly, the PR is now my new "reference" for low frequencies, even though it is not "the best" in every way. So while the PR will never match the Apogee in its greatest strengths, it will come closer than any other dynamic woofer system I've heard, and at any price.

Also, please remember the perspective I provided earlier for the "High Frequencies": The cohesiveness of the bass to the midrange is still more important than the bass frequency performance in isolation. It is the same case here, though not nearly as difficult to achieve.

Finally, I have one highly subjective (and extremely difficult) test that has never failed me in evaluating the bass reproduction of speakers.
The Test: Can the speaker's bass "Frighten Me"*? (Or "Threaten", in contrast to just "overwhelm".)
If it can, that means the speaker is not only going truly deep, but also with power and with control**. It takes all three qualities to pass this test.
The results: The Pure Reference passes this test.

*The exact opposite (or complete failure) of this test is bass that is "comical" (or "flatulent"). Think of a graceless, ponderous image with the accompanying sound of a tuba, Sousa Horn or contrabassoon. This is a complete contrast from "threatening".

**Examples-
STRUNZ&FARAH-MISTERIO-BURABAMPO (SIDE TWO)-WATER LILY WLA-CS-08
OREGON-ECM 1258 (SIDE ONE)
EVIL DEAD-VARESE SARABANDE 81199 (SIDE TWO)

Separation of Instruments (and Lack of Homogenization)- This area is directly related to "speed and outer detail" previously discussed above. Further, it is also seriously effected by two other performance parameters; "imaging" (coming later) and "volume changes". So "excellence" in this one area thus requires excellence in all three areas at the same time. It should be no surprise then why I consider this parameter to be so important in evaluating overall performance and also why it's so difficult to master.

It's critical importance for appreciating music is a "no brainer". It's obvious that hearing all the musicians, and all the notes, all the time, no matter what else is happening, must be one of the highest priorities for audiophiles and music lovers. Contrast this ideal to the alternative, unfortunately the norm, of a musical "soup", where all the musicians, and all their unique relationships, are compromised.

There are plenty of speakers that can achieve one or even two scores of "excellence" (look above for examples), but it's very rare to find a speaker excelling in all three. The Ars Acoustica System Max is one of them, though only barely, because it is marginal in both "speed" and "volume changes". Another successful speaker is the MBL 101. I don't like the MBL for other reasons, but this important area is its "strong suit", probably the best I've heard, and the main reason for many audiophiles' admiration of the design. Some of the Wilson speakers are also contenders, similar to the Ars. So, why aren't there more speakers who score the "Separation Trifecta"?

The problem is combining speed and imaging (phase accuracy), which are relatively easy to achieve at lower volumes, with the almost directly contradictory achievement of clean (and unchanging) high loudness capability. The same drivers that excel at low volumes almost always become strained at high volumes, with the result being a noticeable homogenization. To experience this phenomena, just listen to a well recorded orchestral work with both varying soft and loud passages. Most speakers begin to homogenize at a certain volume point. Still, what about all those (usually large and expensive) speakers that use multiple drivers, and can play really loud?

It's true that most of these speakers don't change for the worse with higher volume levels, but this "advantage" usually comes with a highly ironic price: Their INability to adequately separate the instruments (and notes) at lower (normal) volume levels. So the fact that they don't noticeably change with volume is ultimately irrelevant, since they were "failures" at separation (and detail retrieval) before the loudness test even began. (This is the cost of complex designs.)

So now we must evaluate how the Pure Reference performs in this almost impossible to master parameter.

I'm happy to report that the Pure Reference excels in "Separation", and at both low and high volume levels. It's very similar to the Ars, but it's even more detailed and it changes even less at higher volumes. In fact, I haven't heard any deterioration at high volumes, either in Toronto or in my room in Florida. I play pretty loud at times, though I always try to keep it "realistic". When the PR is compared to the MBL, it's a mixed bag. The MBL is equivalent in detail and loudness capability to the PR, but has more potential for "imaging" if it can be set-up correctly. The problem is that "if", because the MBL is only at "its best" in certain large rooms. Otherwise it's no better that the PR, and could be even worse.

In short, both speakers are outstanding, but there can be no clear-cut winner because the MBL's performance is room dependent. Bottom Line- While the MBL can achieve the highest possible score, the PR will score as high, or higher, in most rooms.

Image Size and Focus- My standard for this category has been the same for more than 30 years; The Morrison Speaker (originally the Hegeman). It is a two-way omni-directional, with a large, yet totally natural, image size, and with amazing focus. The image size has since been matched by a number of other speakers (such as the Ars Acoustica and some line sources), but while the Morrison's focus has been approached over the years, it has never been equalled in my experience. I haven't heard any of the contemporary versions of this speaker for something like 15 years now, but I am very familiar with the 1980s versions, because I was a Morrison dealer for a number of years (He sells direct now).

I heard the Morrisons in every listening room of my store and apartment, plus in numerous customers homes. They weren't easy to set-up, and they imaged at their very best only in a large room, which created a dilemma, because they couldn't really play that loud. Still, they are my reference, and I would say the closest I've heard any speakers matching them, overall, are the (second place) MBL and the above mentioned Ars Acoustica. So how does the Pure Reference fit in to this picture?

The PR, at a minimum, equals the Morrison, and any other speaker I've heard, in image size. In fact, it may even have a unique advantage in this regard. Not because it is bigger than the others "at its best", but because it is truly big even in a medium size room with a low ceiling. When I heard the Pure Reference in Toronto, the room had a lower than average ceiling height. Despite this, I still heard a "huge sound", something I've never experienced before in a room with a low ceiling, and I've literally heard hundreds of good systems in rooms with a similar disadvantage. Compared to the Ars Acoustica, in my own present room, the image size is very similar, but I believe the "sense of scale" (meaning image height in this instance) slightly favors the PR. In short, image size is about as good as it gets with the Pure Reference. What about focus though?

Unfortunately, the Pure Reference does not equal the Morrisons in focus. Actually, I don't even think it is possible for any speaker to equal the Morrisons, unless its design is basically replicated. In short, I believe a properly designed omni-directional will have an advantage in focus compared to every other type of speaker design, no matter how well it is executed. Because of this, it is understandable that, for some audiophiles, an omni will be the only type of speaker they can live with, regardless of any other considerations.

Now, what about the PR versus the Ars Acoustica in focus, which is also a virtual "point source"? They are similar once again. However, the Ars still has an easily noticeable advantage. In fact, this is the one area which I definitely prefer (and miss) the Ars compared to the PR. The Pure Reference then is definitely "excellent", or at least "very good", in image focus, but it's not equal to "the (or second) best".

Tonal Consistency- This is a new category for me, which I don't think I've ever discussed in the past, and I may have difficulty in trying to describe it. In fact, it took the Pure Reference's unique capabilities in this category for me to even think about it, and later coin the term*. Tonal Consistency is more than just being "smooth" (meaning having a linear frequency response) or "neutral". I believe TC is a combination of being both linear and harmonically complete (without distortion) at the same time, and, even more, all of the time.

TC is more than the different notes sounding like they're all being treated "equally", so no single note is emphasized or de-emphasized. "Tonal Consistency" only exists when the notes are coming from the exact same (and unique) instrument, with the same exact harmonic signature, no matter which note, and no matter how loud that note is played. It's a "consistency" of dynamic emphasis and the unique harmonic structure of a particular musical instrument. Accordingly, it is highly difficult to accomplish, particularly for a speaker. Though, when it's accomplished, the speaker sounds disarmingly, and effortlessly, "natural".

Since this is a new category, I'm not absolutely certain what my "references" are, but I would say that, once again, the Ars Acoustica System Max is most likely the best I've heard in the past, with maybe the Original Apogee -if optimized- an "Honorable Mention". (Another good reason why the Ars was my personal speaker for more than a decade.) The Pure Reference appears to already match the Ars in this category, and is probably even superior, though that judgment will require a direct comparison. I write "superior" because I sense that the PR is even more revealing of the time/tonal distortions which are noticeable with (the numerous) records that are not exactly center pressed. I realize this isn't a purely objective (measurable) test, but when a component reveals more about a recording, for better or worse*, I believe that aspect of its performance is relevant.
Bottom Line- The Pure Reference is at least as good as any speaker I've heard in this critically important category, if not superior.

*Upon hearing the frequency modulation problems of LPs more clearly with the PR, I naturally became curious about why this was so. Eventually, the concept of "Tonal Consistency" came to me. It has always been there, just not as obvious.

Further- I will have more to write about this category, because of its vital importance to the reproduction of music. I'm still in the process of thinking my way through this subject.

Naturalness- In effect, I've already partially discussed this category within "Tonal Consistency". However, its musical importance, and its ubiquitous (and historical) presence within all serious audio evaluations, impels me to discuss it on its own. First the (or my) definition of "naturalness"; A combination of neutrality (linearity) and harmonic completeness. Either one of them, on their own, will not reach the final goal.
(Examples: If the sound is simply "neutral", missing some of the natural harmonics, the component will sound "analytical" and/or "lean". Alternatively, if you have only the harmonics, without the neutrality, you will get a "colored" sound, with an almost infinite choice of "colors". The former is true of many transistor designs, while the latter is true of many tube designs.)

My references will be no surprise; The Ars Acoustica System Max, Original Quad, Coincident Victory II and Total Victory II. The KLH-9 and Eminent Technology, discussed above, are also exceptional, but their amplifier requirements somewhat compromise the "harmonic completeness" part of the equation. This is a category where a lot of good speakers come close, but it's difficult to get an excellent score in both requirements. So what about the Pure Reference? Based on its "Tonal Consistency" performance, the answer is also predictable:

The Pure Reference is as natural* as any speaker I've ever heard, and maybe even more so. This is because it is natural in an unusually wide frequency range, 20 Hz to 30 KHz, and at both soft and loud volumes. This accomplishment is easily noticeable when you hear the PR, and may even be the first (disarming) attribute I heard during my initial audition with them.

*Example- Saudades-Water Lily WLA-CS-16

Inner Detail- Since I've already discussed "Outer Detail" above, it is obvious that I am making an important distinction between outer and inner detail. This is because there is no guarantee that accomplishing the former will automatically grant you the latter. Outer detail is mainly related to "speed", and, in particular, the ability of the component (in this case a speaker) to stop as quickly as the signal itself stops. The component's ability to "stop" the first note from extending on (artificially), allows the second (or subsequent) note(s) to be heard independently, and without interference. It should be no surprise then that speakers such as the Martin-Logan CLS or Audiostatic, both electrostatics with ultra-light diaphragms, enabling them to start and stop on a proverbial dime, excel in reproducing outer detail. However, inner detail requires another attribute. This is the (even rarer) ability to reproduce low-level information, because inner detail is, by nature, relatively soft in volume.

So while both the CLS and Audiostatic are still "very good" at reproducing inner detail, they are not "outstanding". What is? My long-time reference for inner detail is the Ars Acoustica System Max, which has the advantage of an ultra-low sound-floor, along with very good speed. To make a visual analogy, the Ars fills in "the coloring book" noticeably better than the fore mentioned speakers, though the "outlines" are not quite as precise. For another analogy, think of a piece of clothing, the outer boundaries (the edges) are the "outer detail", while the texture of the actual cloth is the "inner detail".

This brings us the Pure Reference. After break-in, I can state that its sound-floor is competitive with the Ars, while it has superior speed. Accordingly, the PR is my new "champion" when it comes to reproducing inner detail.

Transparency- This is an audio attribute that was initially observed by (Stereophile founder) J. Gordon Holt in the 1960s. Later, around 20 years ago now, Harry Pearson became almost obsessed with it (see TAS Issues 35/36). For some reason, it is not discussed as much today, being partially displaced by an assortment of worthless, "feel good" and highly ambiguous "magic words", such as "musicality" and "involving". This is too bad, because the existence of transparency, while much easier to accomplish now than in the past, is still highly important if the listener wants to fully appreciate the music.

I define transparency, in music reproduction, the same as I do in its most common visual context; being able to hear (or "see") into the performance. In the most simple and practical terms then, this means the listener is able to hear what's going on all the way to the far back of the recording studio (or the concert hall). Until 20 years ago or so, this was a rather unusual experience, and highly difficult to achieve, especially for speakers. However, superior drivers, components, crossovers and cabinets, plus better time alignment, has made this accomplishment much more common. In fact, the true test these days is not simply hearing "all the way back" (that's considered too easy now), but "what (how much) can you hear back there"?

So what are my speaker transparency "standards"? No surprise here, the Morrison and the Ars Acoustica once again. Now there are, without question, a pretty good number of other speakers (such as the Quad, Audiostatic and CLS) that will equal them in accomplishing "normal" transparency (defined above), but these two speakers give you an added "bonus"; they also allow you to hear the relatively subtle details of what's going on "back there". Of these two, I prefer the Ars overall, because while it is not quite as focused as the Morrison (nothing else I've heard is either), its ultra low sound-floor picks up more musical information and original space of the recording. As for the Pure Reference...

The PR is closer in performance to the Ars Acoustica, but more extreme. I would say the PR gives up a little on focus to the Ars, but, in return, it gives you even more musical information, plus it has the added advantage of greater accuracy of the music that is reproduced. So, while there is no clear-cut "Transparency Winner", I feel that the Pure Reference is not only competitive to the finest speakers I've heard in this category, but preferable overall.

Dynamic Response or Scale (Soft and Loud)- A few years ago, I wrote (in My Audio Philosophy) that "the weakest element in audio was the inability to reproduce lifelike dynamics". I feel this is still true today. Any casual brush with live music, long enough to experience its intensity, will provide overwhelming evidence in support of this statement. Of course, much of the overall loss is already within the software, but amplifiers and speakers share a lot of the blame as well. We're focusing on speakers here, but I feel I should reiterate one general observation with amplifiers; Rated RMS power has virtually no relationship with reproducing dynamic swings, though it does have a correlation with peak volume levels, which is very different.

Unanimity in audio is very rare, but there is an exception: Horn speakers are the most realistic reproducers of lifelike dynamics. This is particularly true in the midrange. In the frequency extremes, especially the bass, horns are generally no better than the competition. Conversely, electrostatics are usually the worst speakers in this category (especially in the bass), which is the main reason why they are avoided by many audiophiles. I'm not a horn expert, or enthusiast (outside of the Avantgarde Duo), but I have heard plenty of them over the years. My two standards for dynamics are the Duo (mids and highs only) and the (legendary) Klipschorn (full-range). There are probably a few more I've heard that match them, but I'm not certain enough to mention them.

Further, there are also a few outstanding dynamic speakers that basically equal my horn standards at very low to moderate levels, such as the Ars Acoustica System Max. What elevates these horn references is that they have minimal dynamic compression at all volume levels. This (relatively) effortless quality is the main reason why people can go "crazy" over good horns. They can induce a strong feeling of exhilaration with the right music, which is as difficult to forget, or ignore, as any other peak emotional experience. For some, it may even become "addicting".

My personal dynamic test is whether a speaker can "startle" or simply "surprise" me (even subtlety). To do so requires the ability to instantly change the volume, softer or louder, before the listener's mind is ready for it. It is here that large speakers (and most large amplifiers) fail, because of their complexity, which causes a form of "dynamic inertia". Yes, they can play "really loud", but this loud volume level is "telegraphed", and like pro boxing, it's the punch you don't see coming that has the greatest effect (in this instance, on the listener). So where does the Pure Reference fit into this difficult category?

With the exception of the finest horns in the midrange, the Pure Reference is as uncompressed as any speaker I've ever heard. Just as important, it is uncompressed full-range*, and in this instance, that means all the way down to 20 Hz. This separates the PR from almost all horns, which tend to lose some dynamic strength in the lower frequencies. Compared to the Ars Acoustica, it matches the Ars' outstanding performance at low to medium volume levels, but the PR extends this dynamic capability to very loud volume levels (fff), and at both frequency extremes.

In short, the Pure Reference is competitive (if not superior) in dynamic response, full-range, and at all volume levels, with any speaker I've heard, and that includes the finest horns.

*This is something I have never experienced before. You can call it "Dynamic Consistency". I feel this is more important than simply having the best dynamics in a frequency range, even the vital midrange.

The Pure Reference now has around 500 hours on it (June 2008), though less on the (sub)woofers. The improvements become subtle after around 300 hours, but are still noticeable: The sound-floor drops; the dynamic range expands and the tiny "resonances" become even less noticeable. I believe 500 hours basically finishes the process. Israel Blume, the designer, agrees with this assessment.

Sound-floor, "Completeness" and Low-level Information- Since the inception of this website, I've been emphasizing the critical importance of this performance category. This focus included detailed descriptions of how the performance in this area so critically effects the ultimate reproduction of music (see My Philosophy and Reference Components).

I would have discussed this category much earlier, but the sound-floor is usually one of the last performance areas where you will notice an improvement as the component is breaking-in, and this has proved to be the case here also. I've heard enough already, and with verification by a recently visiting associate, that I can state this now:

The Pure Reference has the lowest sound-floor of any speaker I have yet heard. It is even superior to my previous and long-time sound-floor "champion", the Ars Acoustica System Max, though not by a "dramatic" margin. The fact that it is even "noticeable" is significant enough for me. For those readers who would like a definition of "sound-floor" (which many audiophiles refer to as "noise-floor"), I will repeat what I wrote in Reference Components. The sound-floor is:

Put in another manner, it can be described as:

Analogy- It is the audio component's (or system's) direct equivalent of the listener's ability to sense or hear "soft sounds".

Now, what does all this mean in real-life listening to recorded music?

It's the low sound-floor of a component (and complete system of course) that allows you to hear the natural harmonics, body, decays, space, ambience and subtle dynamic shifts of the original recording. It also reduces the tendency for musical homogenization. Another benefit is that the component, in this case a speaker, doesn't change (by "dying") when the music becomes softer in volume. This weakness, so common in speakers, forces the listener to play extra (unnaturally) loud if he wants the music to always sound "alive". Listening at a natural volume even enhances the dynamic excitement of the music, because of the extra contrast when going from truly soft to truly loud. Playing "loud" and then "extra loud" is a poor and unsatisfying substitute for natural contrasts.

The Pure Reference, by virtue of its outstandingly low sound-floor, reproduces more low-level musical information than any speaker I've heard, while also allowing a natural volume level to be used, without any compromise of the recorded dynamic contrasts.

We've now reached the end. I've saved this for last because I feel it is the single most important category, and it's also the Pure Reference's "Trump Card". The Final Category...

Individuation!- As I've grown older and more experienced, it is my increasing conviction that a component's ability to Individualize each instrument (including voices), and the recording space, is its most difficult, musically rewarding and ultimate challenge. If the ultimate goal of listening to (recorded) music is a human-to-human, emotional, intellectual, spiritual and artistic "connection", I don't see how anything can be more important than individualizing each musician as a unique and distinct artist, along with their own "space". Further, by definition and simple logic, the unavoidable rule is that every weakness of a component (and system), either of omission or commission, will compromise that desired individuality. Some examples...

Every coloration masks some of the inherent sound (aesthetic) of, and adds an artificial quality to, a unique instrument. Every dynamic compression, no matter how subtle, diminishes some of the musician's original emphasis and emotion. Every subtraction of the natural harmonics and decays makes the musician and space sound more "generic". Any loss of transparency removes at least part of the complete musical picture (performance). Accordingly, when a component lacks the capability of individuation, what the listener will experience is inevitable...

The musician(s) will lose (some of) their one-of-a-kind individuality which makes them "special". In effect, the musicians are "seen" (heard) in the same manner that a person of prejudice sees people of a certain (ethnic/racial/religious etc.) group; as basically all the same, and absent the individual characteristics which would identify them as unique human beings. Instead, they are seen as "generic" ("All the violins sound exactly the same to me!"), existing only in the limited, cookie-cutter version of that person's mind-world.

The inferior component, then, lacks the ability to adequately differentiate the instruments (or voices) that are similar. For another analogy: An ordinary person may not be able to distinguish a piece of pure, shining glass from a real diamond. However, a true jewelry expert (like an outstanding component) can look at a diamond, and not only confirm that it's real and give you its exact value, but can even tell you where it was mined.

The Pure Reference absolutely excels in the ability to individualize musicians* and their recording space. It is, without a doubt, the best I've heard in this all encompassing category. It is also the main reason why I feel it is the finest speaker I've ever heard. The finest I heard before the PR was the Ars Acoustica System Max, and I've heard numerous speakers since I purchased them more than 10 years ago, a rare few of them excellent in this category. The Pure Reference is both a qualitative and quantitative improvement over the Ars, reproducing a little more of the unique character of the musicians, and retaining more of that enhanced quality at higher volume levels and at the frequency extremes.

Every other speaker I've heard either compresses, colors, distorts, veils, rolls-off and/or subtracts more noticeably than both the Ars and PR. In fact, in most instances, the other speakers I've heard, even the finest, compromise the level of individuation in multiple ways, so the performance gap between them is pronounced. Most audiophiles, and especially mainstream "reviewers", don't dwell/focus on this serious problem. This is probably because most audiophiles have never had the experience of hearing a system where this problem is mainly "overcome" (in only the relative sense of that word of course, because this is audio).

Someday, inevitably, some speaker, of unknown origin, will further improve on the Pure Reference's unprecedented "Individuation" capability. Maybe this speaker already exists as this is written, but I know I haven't heard it myself.

*If the word "musician" is too personal to accept scientifically or technically, than replace that word with "notes". It's the concept of individuation that is important, not the focus on the object or subject.

As I mentioned in the Introduction of this extended essay, the Pure Reference is "unusually flexible" when it comes to both amplifier and listening room requirements. If anything, I've come to believe that this was an understatement.

During the time I've heard the Pure Reference in my own system, it has been mainly bi-amped, using the Coincident Frankenstein amplifier on the midrange/tweeter, and the Coincident Dragon amplifier on the subwoofers. However, I've also heard the Frankenstein drive the PR full-range, but only on a digital source (MHZS CD66-Modified).

Previous to this, when I initially auditioned the Pure Reference in Toronto, I heard them full-range with the VAIC/KR VV52B amplifiers, for over 40 hours, both on a phono (VPI HR-X "Special Edition"/Dynavector XV-1S) and a digital source (Oracle 2500 MKII). These are the only amplifiers I've heard with the Pure Reference, and I've yet to hear the Dragon playing the PR full-range.

I've also had one other important and surprising observation. For some unknown reason, the Pure Reference plays louder (around 2dB) than the Total Victory II, or the Victory II, when everything is exactly the same (including the volume control's position), despite the fact the the PR is 3dB less efficient on paper.

Israel Blume, of Coincident, has also experienced this same phenomena in his own system, which I confirmed during my Toronto trip, but he still has no technical explanation for it. I thought, at the time, that this was some sort of fluke response confined to Blume's system, but the PR is also more efficient than the Victory II in my own system. Whatever the reason, this is good news, because it means that the (94dB) PR is even easier to drive than the (97dB) Victory series.

Based on all these experiences, I feel that the Pure Reference can be driven, full-range, by virtually any (SET) amplifier. The only possible exceptions are a true "flea power" (less power than a 300B or 50 output tube); like an amplifier using a 45 output tube. Amplifiers using 2A3 tubes should be viable, but they are probably right at the "tipping point", so a definitive answer will require an actual audition. Of course, I'm assuming that the listening room isn't "gigantic" and the loudness levels are "natural". As for transistor models, I can't think of even one of them that won't drive the PR, and with ease.

Now, to put things in clear perspective, I want to elaborate on "driven full-range". By this I mean that the amplifier(s) will have no problems with virtually any music, with the only exceptions being those (far less than 1% of) recordings that are simply ultra-demanding. These recordings will usually have both sustained (organ) and percussive bass playing simultaneously. Other than that, there shouldn't be any noticeable problems, and I can even provide a specific reason for this confidence, which I experienced myself in Toronto.

Near the end of my multiple listening sessions, I made a request to hear a Mobile Fidelity LP (510): Holst's The Planets, and specifically the first movement on Side Two- "Saturn". This cut starts off very softly, then slowly becomes very loud and finally ends with ("killer") sustained organ notes. These particular organ notes have proven to be the "Achilles' Heal" of many otherwise excellent subwoofers, including the largest (and most powerful ever) Entec subwoofers. Years ago...

During the early 1990s, I had two pairs of the Entec SW-2s, which were stacked on top of cement blocks (an 8' tower!). This means there were two amplifiers, and 6 woofers per channel. Even this all-out combination couldn't handle those organ note(s). Not even close. The Entecs distorted to such a scary degree, that I thought they were going to be damaged. And now we were going to hear the Vaic VV52B SET driving the Pure Reference on the exact same cut. The results...

The Vaic handled the organ notes with no problems. It went deep, and with both power and control. I wouldn't say this was "the best" I've ever heard with this section, but it was still excellent. Needless to say, at no other time did I ever hear the Vaic amplifier have any problem with the Pure Reference, no matter what LP or CD was played, and many of them were very demanding. According to Blume, it takes the Reference Recording (RR-11) of Symphony Fantastique (Side 3/4), or a Japanese Kodo Drum CD, for the Vaic (or the Frankenstein) to demonstrate any type of stress.

In my own system, the results have been the same. While I don't have very many CDs in my collection, I do have a number of large orchestral and soundtrack (synthesizer) recordings, and the Frankenstein, full-range, has handled all of them with relative ease. It has even shaken my walls at times. So...

Considering that my room is pretty large (27L X 19W X 10H), and Blume's room is also good sized (at least in width), I feel it is fair to say that virtually any good SET amplifier should be more than sufficient for most audiophiles, in most rooms, including those listeners with diverse musical demands. For those audiophiles who require absolute assurance, and no possible compromises, then biamping, or using a push-pull amplifier full-range, will be necessary.

Finally, I feel it should be emphasized, because of its importance, that all of these amplifiers, including the transistor models, will usually be heard "at their best" with the PR. This is because of the ultra-easy load of the Pure Reference, and not just its high efficiency. This is an ideal situation where all that matters is the quality of the amplifier, because the quantity (in watts and/or current) is basically irrelevant.

I've heard the Pure Reference in two rooms, my own in Florida, which is pretty large (see above), and in Toronto, where the room was around "average" in length, slightly below average in height, and far above average in width. The PR sounded outstanding in both rooms, though what particularly impressed me was the size and scale of the soundstage in the Toronto room, despite its relatively low ceiling height.

Over the years, I've been in countless rooms with low ceilings (less than 8 feet), usually in basements, but this was the first (and only) time I experienced a large and spacious soundstage in one of them. The sense of height amazed me, as though the ceiling had almost disappeared. Hearing side and back walls "disappear" is a routine occurrence with good systems, but not the ceiling in my experience.

When performing my normal setup in my own listening room, and also when I was in Toronto, I listened to the PRs at varying distances. I needed to know what happens up close and far away, and everything in between. This was mainly to optimize my own setup (which I will discuss in Part Five), but I also wanted to know if there was a problem someone else couldn't avoid, because they lacked my flexibility in speaker placement. Bottom Line- I couldn't find any distance that was "problematic", short of being literally on top of the speakers.

Based on these experiences, I would say that the Pure Reference will work well in virtually any room imaginable. The only exception would be something just too small, say less than around 150 sq. ft., where the subwoofers would most likely simply overpower the room. To hear the PR at "its best", would require, I believe, a room of around 300 sq. ft. or larger (20 X 15). Of course, "taste" has a place here, because some listeners enjoy a more intimate sonic presentation, which is easier to achieve in a relatively small room.

I must stress that when the Pure Reference isn't in "the ideal room", which few people actually have, its superior performance will not only still be evident, but it's likely that its sonic advantages will be even more noticeable. This is because most speakers are even more compromised when they're not totally optimized. This is exactly what I meant by the Pure Reference's "unusual flexibility": It suffers less compromise than any speaker I've heard when the listening room is not fully optimized, and I believe this rule also applies to amplifiers.

Because the Pure Reference is able to retain its "sonic integrity" at lower-than-life volume levels, this means it may be played in both close proximities and/or at unusual times, that could otherwise cause problems with sensitive family members and/or intolerant neighbors.

The most difficult part of positioning the Pure Reference is handling its 190 lb weight. Since the speakers in my listening room are on a thick carpet, I was able to slide them into the optimized position (and then later install the "Extender Feet").

I found the most critical aspect was the "toe-in", or how the PR is "aimed" at the listener. The last two speakers I owned, the Wilson WATT and the Ars Acoustica, were both aimed at my outer shoulders (as was the Victory II) for optimization. In other words, the tweeter, if it was the barrel of a rifle, would be aimed at the outer part of my shoulder; right tweeter to right shoulder etc. So, I naturally thought that after 3 successive optimizations, using the same formula, I had discovered some sort of set-up "rule". Well, I didn't.

To my surprise and annoyance, the Pure Reference was too "intense" or just too bright when it was positioned exactly where the Ars Acoustica was, including the same toe-in. Moving it back helped a little, but it was still "wrong". I could have contacted Coincident, but I consider that "cheating" as long as there are other options, and it can also create a form of lazy bias as well. So I tried something else;

I moved my head back and forth a foot or so, which mimicked the effect of changing the toe-in. Based on what I heard, I realized that my toe-in "Rule" was false, so I started changing the angle. I ended up with the "Inside" panel of the PR aimed at the outside of my shoulder*. The tonal balance of the speaker dramatically changed for the better, and so did the size of the soundstage. Everything now sounded "natural", and while the exact center listening position provided the best possible sound, which is always the case, sitting outside of the center still gave very satisfactory results. Satisfied, I called Israel Blume of Coincident, and discovered his speakers were angled-in exactly the same as mine!

*Stand behind the PR and align your eye with the inside of the cabinet. It should be aiming at the tip of your (friend's) outer shoulder, or a marker where your own shoulder would normally be.

Next, it was now a matter of positioning the PR the correct distance from the back wall, while always keeping the "aim" exactly the same.

I started off around 4.5' from the back wall (measured from the rear of the PR, which is 2' deep). I went back almost two feet, and then started moving the PR forward again. I was trying to optimize the "Image Size" (especially the depth of field and "layering"), while also retaining the PR's sense of "Immediacy"*, simultaneously. I found that around 3.5' from the back wall was the best choice (so the front of the PR is 5.5' into the room), but a few inches either way didn't make much of a difference. My room is around 27' deep, and in Toronto, where the room was 15' deep, the PR was 2' from the back wall.

*The deep bass is almost always the third parameter in the speaker positioning equation. Totally optimizing both deep bass and soundstage size and depth is virtually impossible, because the former normally requires close proximity to room boundaries (corners), while the latter requires just the opposite. In this instance, the PR's ultra-tight bass tuning ensured that the deep bass didn't change along with the position. Thus, this was not a factor during this process.

The next part was routine.

The Pure Reference has mirror-imaged subwoofers, so the speakers had to be switched to find the position where the room's standing waves were the least noticeable. In my case, I was very fortunate, both positions, woofers inside or outside, sounded virtually the same, so I kept the woofers to the outside. I did so because then they wouldn't face directly at the tube amplifiers. According to Blume, when both positions sound the same, which doesn't happen too often, that means the room has only very minor standing wave problems (to avoid).

Lastly, after everything is completed as described, the (supplied) Extender Feet are attached to the speakers (4 per cabinet). This is an absolute requirement* if the speakers are to be heard at their best. The PR is so much more cleaner and focused, and the bass is so much tighter and controlled, that I had to actually change the (low pass) frequency of my subwoofer crossover after they were installed.

Very Important- You must not install the Extender Feet until the very end, because the speakers can no longer be moved after they're installed, without actually lifting (or "walking") them. I've "walked" them on my own, but even then you're risking serious back problems if you are momentarily careless with their 190 lb weight. Also, unless you are in really good shape, installing the Extender Feet is a two-person job, because the speakers must be first placed on the floor (gently), and then lifted back up and placed back into the correct position.

*The Extender Feet also greatly reduce the chance of the PR ever being tipped over, which could obviously have catastrophic consequences.

I've used speakers with front inclines (the Wilson Watts and Ars Acoustica) for the last 20 years, 1988-2007. During that time, I have received excellent results with them (especially in Image Focus), so I decided to experiment with the Pure Reference as well. I first tipped the speakers back, but raising the front two Extender Feet. That gave me almost an inch, and then I later used a metapolymer plate, 1" thick, underneath those same two front feet, giving me 2" total. I heard positive results, better focus and driver integration. In general, the closer the speakers are to the listener, the more noticeable the improvement. Just be careful to retain the speaker's stability during this process.

I've already made dozens of sonic comparisons above, but they were all focused on individual performance categories. Now it's time to compare the "overall" performance of the Pure Reference with its closest competitors. Unfortunately, as soon as the "overall" perspective comes into play, virtually every speaker I've ever heard is immediately eliminated from contention, because whatever strengths they possess, their weakness are simply too noticeable to qualify. (An Analogy- This is also why so few athletes can seriously compete in the Olympic Decathlon, no matter how talented they are otherwise.)

Of all the speakers I've heard, "at their best", and with no qualifiers, I would have to say that the Ars Acoustica System Max and the Coincident Total Victory II (TVII)* (both discontinued) are the closest overall performers to the Pure Reference. Other speakers will be discussed also, but they will have various qualifiers and caveats, some of them very serious. (*Or the Coincident Victory II with a proper subwoofer.)

PR VS. ARS- The PR is very similar to the Ars in basic design philosophy. Both are essentially two-ways (like a Mini-Monitor) with their own subwoofer. The Ars, like the earlier designed Wilson WATT/Puppy, has separate cabinets for the satellite and the subs, while the PR is an all in one box, though it has separate internal enclosures to avoid sonic interference. The Ars uses dense polymers, which are even stronger than those used in the WATT, while the PR uses about as heavy a MDF cabinet as is theoretically possible, which is why it is 190 lbs. I give a slight advantage to the Ars in the cabinet(s) department, because, ultimately, it feels even "deader" than the PR. However, everything else is in the PR's favor, the drivers in particular, and the sonic results demonstrate this superiority.

Fundamentally, the Pure Reference is an enhanced version of the Ars; being more extended, cleaner, faster, more cohesive in the mids/highs, more dynamic, more immediate and transparent, with greater volume capability and even easier to drive (especially full-range with one amplifier). They're both very neutral and have an ultra-low sound-floor, which makes them very similar in their "basic sound" or (lack of) character. If the Ars has any sonic advantage, I would have to say it is still slightly better in image focus, but I haven't totally dialed in the PR yet, so that may change.

PR VS. TVII- I find the comparison of the PR to the TVII to be even more interesting. They share no drivers in common, though the cabinets are quite similar, with the PR being a little larger. The PR has 4 drivers per channel, while the TVII uses 9, and that epitomizes the differences between them. The TVII is slightly more extended on the top, while the PR is slightly more extended at the bottom, but the PR's advantage here is more noticeable (and important). However, the serious differences between them are:

1. The PR has only two drivers between 150 Hz and 20K, while the TVII uses 5 and, just as important...
2. The PR's two drivers are as similar in design and material as is currently possible, while the TVII's drivers consist of 3 very different types.

Basically, most of the differences between the PR and TVII are relatively minor (and much less noticeable than the ARS), especially when it comes to speed and purity etc. They are uncannily similar at times. However, the PR not only improves on the TVII's "weak suit" of multiple midrange sources, as does the ARS or any excellent two-way, but it goes further, much further. The Pure Reference's superior (and unprecedented) midrange/tweeter "transition" and uniform (lack of) character are the closest to a true (and ideal) one-way that I've ever heard. So, the PR not only has a large superiority over the (inherently disadvantaged 3-way) TVII, it also has a noticeable superiority over the best 2-ways as well. This, alone, makes the PR truly "special".

In short, even if you combined the best qualities of the Ars and TVII into one "super" speaker, which is how one could superficially describe the PR, the Pure Reference would still be noticeably superior to that theoretical speaker. So the performance gap between the PR, and these two (otherwise outstanding) speakers, is actually large enough to allow other speakers to fit in between them.

There are now quite a number of speakers that use the ceramic drivers from Accuton. A number of them will be discussed in the "Price Comparisons" section just below. I was also able to actually hear some of these models when I was at the 2004 CES in Las Vegas. I, and an associate who was with me during the show, still have some relevant memories of at least two of them; the Kharma Midi-Grand Ceramique and the Lumenwhite Whitelight. (I also made notes of our impressions at the time, which I subsequently posted in my "Show Report".)

We were impressed with both speakers, considering show conditions, though the Lumenwhite only performed really well on the last day of the show. At the time, neither of us knew very much about ceramic drivers, though they obviously looked a little different than those using the standard paper and other materials. The main difference appeared to be the prices for these speakers, which were among the most expensive we had ever seen for their respective size and driver complement.

The Kharma had some good qualities, see below for details, but lacked both deep bass and dynamic impact, despite the fact that it was driven by very powerful, and expensive, Tenor Hybrid mono amplifiers. The Pure Reference, even with the relatively low powered SET Frankenstein amp, sounds like a dynamic powerhouse by comparison. The Lumenwhite (room) was better than the Kharma overall, but then it did have a serious analog front end and probably better (tube and SET) electronics. It also didn't go real low or have intense dynamic capabilities, and this time they had no excuse in either the source or the amplification. So while I liked much of what I heard, I didn't feel they fully competed with my system at the time (Ars Acoustica/Golden Tube 300B), let alone the even noticeably superior Pure Reference and Frankenstein amplifier combination.

Now, what about other speakers, those with outstanding qualities, but also with the "caveats" and "qualifiers". These will now be discussed, and it must be emphasized that, at this point, cost is not a qualifier. We will be focusing on performance (even when it's purely speculative), and it will be broad enough to even include speakers that are "theoretical" (meaning that I'm not sure they even exist!).

First, when using the qualified with the least amount of speculation and risk, I would say of all the speakers I've yet heard, the closest sonic competitor to the PR would have to be the Avantgarde Duo with Basshorns (BH). Assuming you had the proper room, I would choose them as an "alternative" to the Pure Reference. The "qualifier" here is that I haven't heard the BH myself, but I feel enough veteran and highly critical audiophiles (including some readers) have been impressed enough with them that I would take the sonic leap of faith.

The Duo has a slight advantage in dynamic force (its greatest strength), and maybe even purity. (For many, this unique horn projection will alone prove decisive.) Both speakers are very immediate. However, I (would) still prefer the PR overall, because I feel it is more neutral, disappears better, goes lower in the bass and is even more cohesive. Further, the fact that the BH has its own built-in transistor amplifier is also a downside for me. I strongly believe that tube amplification is a requirement at this (highest) level of music reproduction.

The Duo's advantage in sensitivity is real, but it's irrelevant in most cases, because the PR is highly sensitive itself, already plays much louder than I (and most audiophiles) require, and there's no ultra-low power amplifier, that I currently know of, which is superior to the finest (300B based) amplifiers I've heard.

The PR has another important practical advantage over the Duo, and that is in Listening Room Flexibility. I have a truly large room. At most, only 2% of the listening rooms I've seen are as large (or larger). Still, I am unable to use the Duo/BH combination, unless I want to go through windows to access my bedrooms, den and bathrooms. My former listening room in Toronto, similar in size to my Florida room, would have been ideal with the Duo/BH. What's the difference? The Toronto room was totally dedicated to audio, and had corners without entrances. In practical terms then, to hear the Duo/BH at "its best", will require a room that maybe only 1 out of 100 audiophiles have available to them.

Next come the "theoretical" speakers. First up is another horn "design", which is really an all-out DIY project. It is only for the most serious, patient and experienced audiophiles. I'm referring here to the horn projects discussed at Romy "The Cat's" website (www.goodsoundclub.com.). These DIY projects include dedicated, custom built amplifiers for each frequency range. This is as "avantgarde" and extreme as you can take audio. I would get involved myself if I was younger (and richer) and had more space. This is only for people who really love and appreciate what horn speakers can uniquely do, and are prepared to optimize them at any cost; in time and money.

Finally, there is the "dream speaker" I've mentioned in the past, but have never seen (even in pictures), let alone actually heard. Maybe it's just a rumor, but I want to be as complete as possible in this essay, so it must be mentioned. I'm referring to the new Apogee, "built" in Australia, and based on the Original Apogee (the 1980s speaker with so much potential, and yet so frustrating, because of its almost impossible load). However, this new company has claimed that they have totally solved the loading problem. In fact, they even claim their new version has 100 dB sensitivity! This is obviously the most extreme change imaginable; going from being almost impossible to drive, to even a SET amplifier being able to drive it! Is it real?

I don't know. If anything, "it sounds too good to be true", but if it is, and everything else about the new version is the same (or better) than the Original Apogee, than I can't think of another speaker that could equal its performance, including the PR. It would possess, in theory, a combination of speed, purity, cohesiveness, neutrality, impact, immediacy, dynamic range, extension, image size and completeness that would be unprecedented. Unfortunately, this ("Super") Apogee is supposed to cost $ 100,000 a pair, but even then, for the first time in my life, I would finally agree that a component costing that much was actually worth it. For now though, the Pure Reference is the closest equivalent I know to this theoretical "super speaker", including the easy drive capability.

So that's every relevant comparison I can think of, even in my imagination, literally. There are, of course, many other speakers I could have brought up which are excellent performers. Some of them are mentioned above (Quad, CLS, MBL, Morrison, Sound Labs etc.), but their sonic problems are even more noticeable than those I chose to discuss, so it would be only an academic exercise.

I almost always make some form of relevant price comparisons, especially if any of the closest competitors are either considerably less, or more, expensive. In this instance, I'm going to be far more encompassing, because this is the only the second time, in the history of this website, that I've made a reference of any (currently available) component which has a "list price" of $ 20,000 (or more).

This obviously raises the issue of "value" to the discussion, which always has at least some elements of "relativity" and personal impression to it. However, for the perspective of this essay, I'm removing (and ignoring) the subjective element of "value" (which is impossible to calculate and much too easy to abuse). Here, we are only going to focus on the ratio of the best estimated manufacturing cost to the actual retail price. This is a purely objective approach to "value", which is almost always avoided by mainstream audio reviewers, despite its critic relevance to their readers and potential purchasers.

I'm going to break the comparisons down into two separate groups. The first group consists of four speakers, three from a single manufacturer, all using midrange drivers that are very similar to that used in the Pure Reference, though they're not exactly the same. These critical drivers all come from the same manufacturer (Accuton).

The second group, consisting of three speakers, doesn't use any drivers that are similar to those in the Pure Reference. These speakers are still included because they're either "famous", or (currently) "Hot", and are generally well-known and "respected" by many serious audiophiles. All of these speakers are still available new as this is written, and they have also been recently reviewed by one, or more, magazines of the mainstream audio press. (Predictably, all the "reviews" were "raves".)

Before we begin, let's refresh ourselves as to what drivers are used in the Pure Reference. The PR uses two (very expensive) ceramic drivers from Accuton; a 6.5" midrange and a 1.2" dome tweeter. Neither one of them is "stock". The major, and most important, differences are that these "custom" drivers are much more sensitive (94 dB) and also have a "totally flat" impedance. There are also two very expensive, and heavy duty, 12" woofers, which I've held in my own hands. Each woofer costs almost as much as the ceramic midrange. The cabinet is also extremely well-made and braced (190 lbs). The internal wiring, and crossover parts, are all as good as it gets. (I would go the Coincident website for the actual details and verification of this brief, paraphrased summary.) The Pure Reference's "List Price" is $ 22,000 (a pair).

Since the primary sonic contribution of the PR comes from the Accuton ceramic midrange driver, I chose the Kharma speaker company to mainly represent the first group of 4 speakers, since they use a very similar driver in a number of varying designs. Here are the details:

Kharma Ceramique 3.2
Two Way using Focal Titanium Tweeter and Accuton ceramic 6.5" mid/woofer.
Price : $21,000
70 lbs.

Comparison- This speaker is the closest in price to the Pure Reference. It also has a very similar version of the Accuton midrange driver. Other than that, they could hardly be more different. The 3.2 uses a Focal tweeter, while the PR uses the matching Accuton tweeter, which is far more expensive. Most importantly, the 3.2 uses its Accuton driver as both its midrange and its "woofer", while the PR's has two separate 12" woofers. Finally, the Ceramique cabinet is much smaller and, at 70 lbs, is 120 lbs lighter.

Here's the relevant part of what TAS (Harley/Valin) wrote about the 3.2: "Best Sound at Home Entertainment 2002 Show" (Issue 137, Aug/Sept 2002, Pages 33-34)

"...First place, however, goes to the Kharma Ceramique 3.2... This... stereo system had the most realistic sound of any at the show. Dynamic, detailed, superbly transparent, incomparably rich in color, gorgeous in the treble and midband... its only weakness... was a slight roll in the very deep bass (sub-40Hz), which, nevertheless, didn't keep the Kharmas from roaring like an orchestra in full voice on the last movement of the Rachmaninoff Third Piano Concerto..."

Personal Notes- I wasn't there, but I know, with a certainty which can only come from the laws of physics, that one observation by TAS is total nonsense; "its only weakness...was a slight roll in the very deep bass...". Reality- The single 6.5" Accuton driver has basically no "deep bass". In fact, it "drops like a stone" below 70 Hz, its resonance point, which means that even the 3.2's mid-bass is severely rolled-off. Actual frequency measurements confirm this, and nothing TAS says can change that fact. (So, we've now actually reached the pathetic point where the mainstream reviewers can't even concede that a 6.5" driver has serious problems when it's futilely attempting to accurately reproduce deep bass.)

The Focal tweeter, while quite good if it's modified (such as in the Ars Acoustica System Max), has a number of its own problems. Then there's the transition between the two drivers. They can never be as seamless as the PR, where both drivers are made by the same manufacturer, using the same materials, and specifically designed to work as a matched pair.

Bottom Line- If someone is truly impressed with the Ceramique 3.2, think of how they will react to a speaker, at almost the same price, with:
1. The matching ceramic tweeter to go with the midrange,
2. Two very high quality 12" woofers, that extend the bass down to a real 20 Hz (and which also relieve the midrange driver from the bass modulations)
3. 120 lbs greater total mass
4. A load so benign that it can be even driven with low power SET amplifiers

Kharma Grand Ceramique Midi 1.0
Three way using Accuton ceramic midrange, Focal titanium tweeter and one 11" woofer.
Price: $40,800
170 lbs.

Comparison- This speaker is much closer in design to the Pure Reference. While it has the exact same Accuton midrange and Focal tweeter used by the 3.2, there is one major difference between them. The Midi also has a real woofer this time, which should extend the bass into the last octave. The Midi's weight is also pretty close to the PR, being only around 20 lbs lighter. (Since the approximate weight of the PR's extra woofer is also around 20 lbs, this is a non-issue.) It was reviewed a few years ago by Michael Fremer (still available on the Stereophile website for free). Needless to say, it was another "rave".

I heard this speaker a few years back, with Tenor (hybrid) amplifiers in a good sized room, and the sound was impressive (for "audio show sound"). It was relatively natural, clean, fast and there was a large, focused soundstage. The most noticeable problem was the severe roll-off in the deep bass, in spite of the 11" woofer, tremendous available power and a much larger cabinet. (This is more direct evidence why the TAS write-up on the Ceramique 3.2 is total rubbish. If the Midi can't reproduce truly low bass, how can their model without the 11" woofer do so?) The Midi has relatively high sensitivity, but the impedance varies and it's even low at times. This makes it an easier than average load overall, but it's still not suitable for any SET amplifiers.

So what do you get for the Midi's extra $ 18,800 cost (the price difference between the Midi and the PR)? You get one less woofer, an inferior tweeter, a more difficult load, which means you will lose the option of using a SET amplifier, and a highly noticeable roll-off in the deep bass. The Midi does have a more beautiful looking cabinet though. I found it stunning myself.

Bottom Line- The Midi is almost twice the price of the Pure Reference. I wouldn't be able to explain how any serious audiophile could ever prefer it to the PR, unless what he sees is even more important than what he hears, which actually isn't that unusual these days.

Kharma Grand Ceramique 1.0
Three way using Accuton ceramic midrange, Focal titanium tweeter and two 11" woofers.
Price: $56,500
240 lbs

Comparison- This is the Kharma speaker which is the most similar to the Pure Reference in design. In fact, they're almost design clones of each other. The ceramic midrange and Focal tweeter are exactly the same as those used in the Midi (and 3.2) above. The only serious differences between this and the Midi is now there are two woofers (just like the PR), and of course the cabinet is a little larger. In fact, this speaker weighs even (50 lbs) more than the Pure Reference. The sensitivity and load are almost exactly the same as the Midi. Once again though, the cabinet is beautifully finished. As for reviews...

Positive Feedback (David Robinson) gave it a rave review (Issue 13- available on-line), plus it received a "Brutus Award". Robinson wasn't shy about his complete admiration for this speaker: "This was simply the very finest sound that I've ever heard in 15 years in my listening room. No exceptions...Of no other loudspeaker have I ever been able to offer such unqualified praise in all my years of reviewing."

One can only imagine Robinson's reaction to a similar speaker with an even better tweeter, made from the same material as the midrange (and with greater extension). Then add even better woofers, with deeper extension in the bass (the two frequency extreme rolloffs were the only faults Robinson could find). Then there's the PR's greater sensitivity and easier load on the amplifier. And all of this for 60% less than the price of the Grand Ceramique.

Bottom Line- Outside of slightly deeper bass and greater power handling capability, this speaker is an exact duplicate of the Midi. However, there is now a $ 34,500 price difference between it and the Pure Reference. So, what do you get for this extra investment? Inferior drivers and a more difficult load, with the offset of a heavier and more impressive looking cabinet.

Further- Is there a speaker which is even closer in design to the Pure Reference than the above Kharmas? Yes actually, the Avalon Acoustics Isis, which has almost the same midrange driver, along with somewhat similar (Eton) woofers, but it uses the (ultra expensive) Accuton diamond tweeter. The Isis costs $ 62,000 (almost 3 times the price of the PR). Still, I feel the Isis is a much better (relative) value than the Grand Ceramique 1.0 above. (Probably due to the Kharma line being imported from Europe.)

The Isis costs exactly $ 40,000 more than the PR. For this you get the diamond tweeter and a more attractive and slightly heavier cabinet. However, you lose a little low frequency extension. Most importantly, you also lose the ability to drive the speaker with a SET amplifier, since the Isis has a considerably more difficult load than the PR (or even any of the above Kharmas). For those familiar with the unique performance capabilities of the finest SET amplifiers, this constitutes a major disadvantage.

The second group of three speakers come from three different manufacturers. Two of them should be well-known to everyone. The other one is a relative newcomer, but all of them have recently received a lot of hype in the mainstream audio press (Stereophile & TAS). First up is, by far, the most famous and established of them all:

Wilson WATT/Puppy 8 (WP8)
Three way using Focal tweeter, 7" Dynaudio midrange and two 8" Dynaudio woofers
Price: $27,900
170 lbs

I owned an earlier version of this speaker (WATT only), and heavily modified it. It was my "Reference" for almost 10 years (see "My References" above). However, I used various subwoofers with the WATT. (The Puppy, which has a severe roll-off below 40 Hz, has never been even remotely close to being a true subwoofer.) The WP combination has received countless raves over the years. Check out the June 2007, Stereophile (Wes Phillips) review, which is on their website. It's a rave of course: "While acknowledging that it's not perfect*...it captures the excitement of live music as do few loudspeakers I've heard."

*Phillips also reviewed the WP5 in November 1995, again gratuitously using the word "perfect". He also refused to mention even one specific criticism of the WP5. (See Reviewing the Reviewers for the details.) In the WP8 review, he finally describes all the problems he heard with the WP5 back in 1995. Maybe Phillips feels this will now change the historical record, but it won't. Phillips was apparently too terrified to mention these criticisms when they actually mattered, to both his trusting readers and to Wilson Audio. Instead, until now, they only existed in his fantasy world, where he is still the fearless audio critic and communicator. If Phillips is betting that no one would remember his past, he lost.

So, how does the WP8 compare to the Pure Reference in the price/value category?

Comparison- I would give the WATT/Puppy 8 a slight edge over the PR when it comes to the cabinets. While they are considerably smaller, somewhat lighter, and far less complex internally, I still feel they have an advantage because of the very expensive meta polymers being used. (The WP8 cabinets are still not as dead as the Ars Acoustica System Max, which are entirely molded.) Other than the cabinets though, there is no comparison between the two speakers.

The WATT uses the Focal tweeter (which they modify), also used by the Kharma speakers above. It can be excellent, but it's far less expensive than the Accuton ceramic tweeter in the PR. The WATT's Dynaudio midrange, while also of good quality and relatively expensive, is still a fraction of the cost of the Accuton ceramic midrange. Ditto the Puppy's two Dynaudio 8" woofers. They're good for sure, and not cheap, but they cost only a fraction of the price of the heavy-duty 12" woofers used in the PR. Further, the internal wiring and the crossover parts used in the Pure Reference also appear to be higher quality and more expensive.

Bottom Line- The WATT/Puppy 8 costs $ 5,900 more than the Pure Reference. What do you get for this extra money? You get a somewhat more expensive (and shiny) cabinet, but you also get four dynamic drivers, internal wiring and crossover parts that, in total, cost far less than those used inside the PR.

Finally, despite the ridiculous suggestion by Phillips that a 2 watt amplifier can actually drive the WP8, the truth is exactly the opposite. It takes considerable power and current to adequately drive the WP8 (or the earlier versions). This is because the impedance looks like a mountain range, and even goes down "to 2.2 ohms at 77 Hz". This is another serious disadvantage for the WP8.

Magico Mini MK II (with stand)
Two way using Scanspeak Ring Radiator ("Revelator") tweeter and 7" titanium composite mid/woofer.
Price: $29,900
80 lbs (Stand 120 lbs)

This is the speaker that TAS (Jonathan Valin in particular) is really "pushing" these days (I used that word deliberately). In fact, I've never seen TAS, in their entire 35 year history, gush over any components like the Magico Mini line. (I wonder what Harry Pearson's reaction could be to this development.) The original review came out in November 2006 (Issue 163), and there's since been another review on the MK. II (Issue 179). The price of the Magico Mini has gone from $ 22,000 up to almost $ 30,000, which includes the matching stands. So it now costs $ 2,000 more than the Wilson WATT/Puppy 8, and $ 7,900 more than the Pure Reference.

Here's what Valin recently wrote about the MK II version of the Magico Mini: "If someone...had told me that the Mini’s fabulous midrange could be improved upon to this extent, I wouldn’t have believed him. But hearing is believing. Is the Mini II a 'perfect' speaker. Of course not..." Is it me, or do these reviewers appear to really like to bring up the word (and the concept of) "perfect"? As far as I'm concerned, shamelessly using a word like "perfect", as a tease, with loudspeakers no less, is an insult to the intelligence of audiophiles.

So, how does the Magico Mini MKII compare to the Pure Reference in the price/value category? Let's start with their cabinets.

Comparison- The Magico's cabinet is superbly made, but most of the total weight is in the stand (120 lbs), and not the actual speaker (80 lbs). While it does cost more to "shape" (and finish) the Mini, the Pure Reference is much larger and much more complicated internally. In short, the Pure Reference appears to have a decided advantage in cabinet value. Both speakers also use internal cables and crossover parts of the highest quality, so they are comparable here. However, the most serious differences between them are in their respective dynamic drivers.

The Magico's tweeter, the Scanspeak Revelator, is an excellent performer, used in many speakers (including some Coincident Eclipse models). It costs more than the popular Focal mentioned above, but it's still a fraction of the price of the ceramic tweeter in the PR. The Magico's midrange is an unusual design, rare and expensive, but it's still much less costly than the Accuton ceramic midrange used in the PR. The Mini has no dedicated woofers, compared to the two (highly expensive) 12" woofers in the PR.

Bottom Line- The Magico Mini costs $ 7,900 more than the Pure Reference. For this you get a cabinet of somewhat lesser value, though more nicely shaped and finished, plus internal parts which are comparable. After this, there is absolutely no comparison. The Magico's tweeter and midrange are of high quality, but still a fraction of the cost of those in the PR. Much worse, you also lose both of the high quality woofers included in the PR. In fact, the Magico is severely rolled-off in the bass. Ironically, the Magico doesn't appear to even equal the "cost value" of the WP8, which has been criticized itself for not being a good value.

Finally, but still highly important for many, the Magico Mini is a very difficult load, so it can not be used by any SET amplifiers. In fact, Valin himself recommended amplifiers of at least 200 watts per channel.

Peak Consult El Diablo
Three way using 1" Scan-Speak Tweeter, 5" AT Midrange, Two 9" AT Woofers
Price: $75,000
188 lbs

This speaker comes from Denmark. It was reviewed in Stereophile (May 2007), by Michael Fremer*. The Diablo, and its sister, the Empress, both made "Class A". The Empress was even the "Joint 2005 Loudspeaker of the Year". Fremer wrote: "I spent three months with the Diablos and found them to be among the most capable and musically engaging speakers I've yet auditioned...the Diablo is very expensive at $65,000/pair*. Although its value will be in the eye, ear, and wallet of the beholder...". Fremer also avoided making a direct comparison, or stating a clear preference, between the Diablos and his personal Wilson MAXX 2 speakers.

*The Diablo was distributed by Signals SuperFi at the time of the review. This is the same company that imports the Continuum turntable. They sold a Continuum to Fremer at "parts cost" (a discount of 80 to 90% off the retail price). Signals SuperFi later stopped importing the Peak Consult line, and Stereophile immediately removed the Class A recommendations. The Diablo's price, since the review, was later raised from $ 65,000 to $ 75,000.

Comparison- The price value comparison of the Diablo to the Pure Reference is similar to what we have already seen before. The respective cabinets are very competitive, in complexity, total size and weight, though the Diablo has a more polished finish. Peak also claims that the crossover parts have "been chosen for its sonic and musical behaviour, with no consideration for cost". They don't mention any specific brand names, but we'll give Peak Consult the benefit of the doubt, and call this a "draw". This brings us back, once again, to the speaker drivers...

Both speakers have 4 drivers, each doing the same exact task (2 woofers, a midrange and a tweeter), but that's were the similarity ends. The Diablo's Scan-Speak tweeter is well-known for it performance, and it costs more than the Focal, but, to repeat myself, it's only a fraction of the cost of the Accuton ceramic tweeter. The Audiotechnology midrange and woofers have the same story. These are, by reputation, high quality and relatively expensive drivers, but they cost far less than the Accuton ceramic midrange and the heavy-duty 12" woofers inside the PR. This matters even in the objective measurements, because both of the Diablos's frequency extremes are rolled-off by comparison with the PR. Finally, the Diablo's load is around average, so SET amplifiers are not usable with it.

Bottom Line- The Diablo costs $ 53,000 more than the Pure Reference. This is more than 3 times the price of the PR, and while its (more attractive) cabinet and crossover parts are comparable, the Diablo's speaker drivers, though undeniably of high quality, cost far less than those used in the PR. The Diablo, in direct contrast to the PR, also can't be used with SET amplifiers. Sadly, the Diablo may be the single worst speaker in this "value" survey, in spite of Fremer's blindness to that obvious reality. Even if you totally ignore the Pure Reference comparison, the Diablo actually costs $ 13,000 more than the Avalon Acoustics Isis, which also has far more expensive drivers.

I will start off with the most relevant statement first ("The Bottom Line"): I don't know of another speaker which has the combination of such highly expensive drivers, high quality cabinet structure and all-out internal parts, that costs less than the Pure Reference. (I also don't know of a speaker that equals its performance for less money either, though that is a separate issue.) That said, there is, of course, more to the issue of "value" than just the selling price/manufacturing cost ratio, as important as I feel that is.

While I don't know of any speaker selling for less (or even more) than the Pure Reference that equals its overall performance, this certainly doesn't mean that it will be a typical audiophile's first choice when it comes to "performance for the money". There are numerous speakers, many mentioned above, that equal (or slightly exceed) it in different performance parameters. Even though the Pure Reference will exceed all of these speakers in overall performance (in many instances by a large margin), and further assuming this "margin" will be heard and appreciated by the listener, this still does not mean that the extra cost of the Pure Reference will appear justifiable to them.

This is because the speakers I've already compared the PR with in performance above, plus others, such as from Magnepan, Vandersteen, Legacy, Gallo and VMPS, as well as some DIY projects, have been able to satisfy countless audiophiles over the years, despite their more noticeable sonic faults. Further, these speakers are also known to provide "cost value" along with their "sonic value". It's obvious that only listeners themselves can decide whether the superior performance of the Pure Reference is worth the extra investment.

The critical perspective I'm trying to convey here is simple: Yes, the Pure Reference is an expensive speaker. However, it not only provides noticeably superior performance to any less expensive speaker (I've heard), it is also an outstanding value, considering its manufacturing costs. This is true when the PR is compared to not only more expensive speakers, but, much more importantly, even when it's compared to less expensive speakers. This achievement of "universal cost value" is very rare today, mainly because of recent audio marketing trends, but the Pure Reference is that rare exception to this unfortunate trend.

This essay has taken me four months to write. This was necessary because I had three goals:
1. To help readers understand exactly why I finally changed my personal speaker reference after more than 10 years;
2. To also provide a basic "template" on how I evaluate the finest speakers, which I hope may be useful to others;
3. To clearly disclose my personal perspective on what I feel are the most important elements of music reproduction, and with practical examples.

This third goal required discussing my personal speaker history in depth. Ironically, it took this examination of my own past to discover, for myself, what was really most important to me. What I had only conjectured in the past, was finally confirmed when I saw it all for myself, in black and white. So, between this observation, and all the subsequent challenges required in the multiple sonic comparisons I made, this essay ended up being an exercise of "self-discovery", something I would never have predicted when it was started.

And, after all that has been written above about the Pure Reference's sonic performance, I feel it is possible, and necessary, to condense the entirety of it into two simple sentences, which are both personal observations and opinions:

1. The Pure Reference does more things "right" than any other speaker I've heard (it's the most "complete" or "natural").
2. The Pure Reference does less things "wrong" than any other speaker I've heard (it's the most "accurate").

It is critical to keep in mind that achieving Observation #1 does not mean achieving Observation #2 is a given. In fact, it can be just the opposite, because optimizing (either) one of them may require a "trade-off", thus compromising the other. Achieving both of them, simultaneously, is a rare and difficult accomplishment, but the Pure Reference has done it. This makes it not only a benchmark for audiophiles and/or music lovers, but also a potential "tool" for audio engineers.

Even from the perspective of the purely "practical", the Pure Reference has a number of important advantages:
1. It can be optimally used with virtually any existing amplifier, including the finest SET models.
2. It can be optimally used in virtually any listening room.
3. Its total parts costs (drivers, cabinet, crossover) are only matched by competitors selling for more than twice its selling price.

Because of both its unprecedented performance, and its unusual "practicality", I purchased a pair of Pure References for my own use. Unlike many audiophiles, particularly mainstream "reviewers", I rarely change components, especially speakers. It now takes something extraordinary for me to replace what I have. Something that I can't live without after hearing it. The Pure Reference is that "Extraordinary Something".

I've now lived with the Pure Reference for more than a year and, with the exception of a few minor edits, I have not made any changes or additions to my lengthy review (above) of this speaker. I've decided it's time to do so because there have been both a technical change in the way the speakers are used in my system and I also believe I have some important and edifying personal observations to share.

On the technical side, in the last year I have changed my speaker cables, 300B output tubes and the Jadis JP-80's volume controls. In each instance there was a noticeable improvement in the system's performance. However, the most important sonic improvement came when I began playing the Pure Reference full-range with the Coincident Frankenstein 300B amplifiers. In short, I removed both the Behringer Digital Crossover and the Coincident Dragon 211PP amplifiers from my system (along with all their associated cables).

I made this change with a considerable amount of trepidation, because not only would I lose 90% of the available power for the subwoofers, I would also now have to rely completely on my preamplifier's bass level and extension, which hadn't proved sufficient since it was gutted from six tubes to two tubes back in 1993 (consistent with my "minimalist audio philosophy"). Fortunately, my fears proved, so far, to be groundless...

As I wrote in August 2008, to my surprise, I've received outstanding results with the Frankenstein playing the Pure Reference full-range. Not only is the sound more cohesive, there is also more bass detail, a larger image, better focus and a lower sound-floor (with all the associated benefits). The overall improvement is such that I can't go back to biamping (using an electronic crossover). I'm even going to experiment with different turntable settings and cables because of the more revealing nature of the system.

Now I did help matters somewhat by increasing the input impedance of the amplifiers as well as the preamplifier's volume pots (from 250K to 500K). Any sonic problems? So far I have detected none with certainty, but I believe there will be some ultra-demanding records (or CDs) that, at certain times, can challenge the Frankenstein beyond its capabilities (especially in my large room). This belief has been confirmed by Israel Blume, who designed both the amplifier and the speaker. However, 1% or so of my records don't trump the other 99%, and even those 1% will still sound better, most of the time, with the Frankenstein playing solo.

June 2009 Update- I recently conducted an audition of the Ars Acoustica monitors, in my own listening room, for the person who ended up purchasing them from me. Based on this audition, I concluded that the Ars had a larger advantage in "Image Focus", compared to the Pure Reference, than what I had written in my initial review. I have since updated the review to reflect this reassessment.

Future Plans- I still plan to bi-amp the Pure References with the Dragons, but this time going direct, and without the Behringer Digital Crossover. Based on prior listening sessions, I believe almost all of the sonic problems I (indirectly) heard, and described above, came from the Behringer (between its two digital/analog conversions and its solid-state analog stage). It may be possible to get "the best of all worlds", or at least the minimum possible amount of compromises, with the combination of the Frankenstein and Dragon (on the subwoofers), though it will obviously come with a monetary price.

I also want to make clear that while the Behringer, or any other electronic crossover, will no longer be used in my current system, they can still be useful, and even necessary, in other systems. It all depends on what is required: slopes, levels, equalization etc. In general, the more complex the requirements, the more likely an electronic crossover will be necessary. The Pure Reference's utter simplicity makes such a component not only unnecessary, but also the cause of a serious deterioration in its performance.

The "Extreme" is simply the "Original" Pure Reference, with the exact same drivers and crossovers, but in two separate cabinets (a mini-monitor and a subwoofer), instead of one large floorstander. With the monitor sitting directly on top of the subwoofer (at the front), the Extreme is around 12" shorter, though its subwoofer takes up around 50% more floor space, because it is 4" wider. The price for the Extreme is $ 26,000, compared to $ 22,000 for the Original.

The big questions are how the Extreme compares* to the Original, and whether the $ 4,000 price differential is worth it (since the Original will still be available)?
Now, as to its performance...

*Both speakers were auditioned with the exact same components, and they also had identical positioning. Further, a number of my visiting associates heard these speakers and verified my observations.

The Extreme is superior to the Original in a number of areas, equal in others and inferior in none. A typical "neighbor", or "brother-in-law", would not be able to distinguish one speaker from the other, but any experienced audiophile should easily hear the differences. In every instance, but one, the sonic differences between them are minor, meaning they are "noticeable", but not "obvious", unless you are an exceptionally discerning listener, or are intimately familiar with their sonics (as a normal long-time owner should be). I will deal with these minor improvements first.

The Extreme is a little cleaner, more immediate and faster than the Original. In short, the Extreme sounds even more like a top electrostatic, such as the Martin-Logan CLS (in its greatest strengths), than before. While its overall tonal balance, perspective and neutrality are the same as the Original, the Extreme does have a small reduction of those tiny frequency aberrations which are unavoidable in every speaker design. These deviations are too subtle to even describe, but they still signal you that a mechanical device is reproducing the musical instrument, rather than it being the real thing.

As for the frequency extremes, the highs are the same, though the bass appears to be just a touch more extended, and with a little more weight and body to it. The quality of the bass is also slightly improved, being, once again, a little more articulate, controlled and defined (see Addendum 2 below). The quality of the highs is also better, but it's even more subtle. This time, a very tiny resonance, only barely (and occasionally) audible with very specific frequencies (flutes, violins and sopranos), has now been effectively eliminated. (Since a very similar resonance was slightly more noticeable with the Ars Acoustica System Max, I wasn't able to isolate the cause of the residual problem when I first heard it being reduced with the Original Pure Reference.)

I saved the best for last, because there is one area that the Extreme is significantly superior to the Original: Image Focus. In my review of the Original Pure Reference (PR), I mentioned that my ultimate references for image focus were the Morrison & MBL, which are omni-directionals. Just behind them was the Ars Acoustica, which is the speaker that the PR replaced. The PR, as good as it was, still noticeably lagged behind all of them. This is no longer the case. Now the Extreme is in the same league as the Ars Acoustica. (I lived with the Ars for 10+ years, and just heard it again in June 2009, so I have high confidence in my memory.)

There is one small difference between them that I have picked up, and it's actually in the Extreme's favor. The Extreme is slightly better focused at the lateral extremes (to the left of the left speaker and to the right of the right speaker) than the Ars. In fact, the Extreme is about as good as I've ever heard, even including the Morrison/MBL, at the outer edges of the overall soundstage. (The Morrison/MBL are still the undisputed "champs" in the large middle.) I don't believe the soundstage itself is any larger, but it is better "organized", so it may appear bigger because it is more convincingly "seen" and "understood".
This brings us to the second "big question":

This question can only be answered by how much you value the various improvements. In my own case, the improved image focus alone makes it worth the extra money, with the rest being "icing on the cake". The bottom line for me is simple: I can't go back to the PR.

However, other audiophiles, who don't value "imaging", may have a very different perspective. In fact, unless you truly value imaging, I would most likely pass on the Extreme, unless either:
1. You just must have that last degree of purity, speed and detail etc., discussed above, or
2. The added flexibility of having two separate cabinets is important to you, especially if you want to "double up" the speakers one day, and/or place the subwoofers elsewhere in your room, while optimizing the position of the monitors on their own.

Then there is one last question: What if you already own the Original PR? Should you spend something like $ 10,000 to trade up? For me, I don't feel it's worth it, unless you are an imaging "enthusiast", meaning someone who is actually bothered by the PR's imaging performance, but otherwise satisfied. Other than that, the differences I've described are simply too minor to justify that kind of money.

The Extreme is a welcome improvement over the Original Pure Reference. If I was asked to make an analogy, I would say that most of their differences are the equivalent of "turning a page or two", while the Image Focus improvement is the equivalent of an entire "new chapter". In the final analysis, the Pure Reference, in its Extreme form, is another step closer to the music, and a step further away from the "mechanics".

The advantages of separate cabinets should be obvious to anyone, at least in theory. Those advantages are why all of my reference speakers had them for the 3 decades before the arrival of the (Original) Pure Reference. Further, and at my request, Coincident owner, Israel Blume, also the designer of the Extreme, has sent me the specific details which should help explain the reasons for the sonic differences mentioned above. Here is Blume's letter (my bold):

"I would like to discuss briefly why the Extreme will sound better, since many may wonder why the 2 cabinets make a difference.

The benefits are:

1. Separation of the enclosures reduces vibrations and enhances cabinet rigidity. Sonically this translates to greater purity and transient precision;

2. Monitor- The connection from the woofer to the binding post eschews any wire at all. The crossover inductor is a direct, hardwired connection to the driver and the binding posts.
The PR requires a 5 ft cable to connect the crossover to the binding posts.
The wire connecting the tweeter to the binding post has been reduced from 5 ft in the PR to 4" in the Extreme.
The small Monitor enclosure (just large enough to house the 2 drivers) reduces diffraction affects dramatically, which results in a more open soundstage with greater focus.

3. SubWoofer- The wider stance (13" vs 9" for the PR) results in greater physical stability, which reduces micro movement of the enclosure. Furthermore, the extra width places the back of the side firing woofers 4" further away from the enclosure wall. This reduces reflections back to the woofer, which slightly reduces non linear cone motion at very high SPLs."

Based on my experiences with the Original Pure Reference, the Extreme will require around 300 hours of play for full break-in. This was eventually verified when I also reached 300 hours with the Extreme.

As with the Original PR, I have changed the incline of the speaker, so that the tweeter is a little further from the listener than the midrange driver. I found this change improves the driver integration, making it sound even more seamless at its crossover point. This must be done in a manner which does not compromise the stability of the speaker. The sonic advantages of doing so are most noticeable if the listener is relatively close to the speaker (8 to 12 feet), which means that at a listening distance of 20' or so, there may not be much (if any) of a noticeable improvement.

As for separating the cabinets, I originally used (4 small pieces of) "Blu Tac" between the monitor and subwoofer, which Israel Blume uses himself and suggested to me, but now I use a rubber like compound. I also have a 1" metapolymer plate sandwiched between the two cabinets.

Finally, I have been using the Coincident Frankenstein M300B Mk. II exclusively with the Extreme, full range, as I had with the Original PR for the last 8 months (to respect the principle of "continuity"). Accordingly, my impressions of their comparative bass performance are based completely with this one amplifier. I must note that the Frankenstein's bass reproduction, as amazing as it is for its low power rating (8 watts), does not equal what I heard with the Coincident Dragon 211PP with the Original PR. The Dragon had greater extension, weight, control, impact and authority. However, it may take relatively demanding music to demonstrate some of these qualities. I must assume that those same improvements will also be noticeable when the Dragon is used with the Extreme's subwoofer, but I don't plan to use this combination until the Extreme is fully broken-in.

This latest update only concerns the monitor part of the Extreme.

As I mentioned above, I used the (supplied) "extender feet" to slope back the original speaker, with the goal of having the tweeter positioned further behind the midrange, for better time alignment (and focus). I later did the same with the Extreme monitor. Now, it turns out, Coincident has a new version of the PR Extreme monitor which is sloped back (one inch less depth between the bottom and the top), and I've had a chance to audition these sloped monitors in my own system. (In every other manner, they are exactly the same.)

The result is a very small improvement in image focus. However, you must remember that my monitors were already sloped back somewhat in the first place (by raising the front of the speakers with the extender feet), so there should be a slightly greater improvement in other systems. Further to this, the "should" requires more explanation...

Creating a slope, for time alignment, artificially (as I did earlier), or with the actual construction of the speaker itself (as with this new sloped PR monitor), will provide an improvement in image focus, though mainly at close distances; 12 feet or closer. However, the further the speaker is located from the listener, the less noticeable the improvement in focus will be. In fact, I doubt there will be any improvement at around 20 feet or more.

In short, the closer you are to the monitors, the more noticeable the improvement with the sloped version, but I also need to make this perspective clear; Unless one is sitting very close (8 feet or less), the overall improvement with the sloped monitors will usually be noticeable, though subtle. So, for most listeners, this change will be considered a refinement, which is always welcome, and only rarely will it be a "big deal".

In December 2009, I discussed the new "Extreme" version of the original Coincident Pure Reference (PR), which consists of two cabinets (monitor and subwoofer), instead of one. Within this relatively short post, I also mentioned that one of the advantages of having separate cabinets was the ability to "double up" the speakers (immediately or sometime in the future). Well, I now have such a system in my home, and with enough listening hours and break-in to make a report I am confident in.

"Doubling Up" is simply getting a second pair of the Pure Reference Extremes (PRE), and then deciding how to place them in your room. If the monitor is currently sitting on top of the subwoofer, but you now want to stack the subs, then you will have to move the original subwoofer back and then place the second sub directly on top of it. However, if your room is large enough, you may want to place the second subwoofer besides the first sub (with the woofers facing in a different direction). If you do decide to stack the subwoofers (which I did), then...

The original monitor, now without its "stand", will have to be placed on a custom made stand (which is available from Coincident) and the second monitor placed directly on top of it (but upside down only), so that the two tweeters are in close proximity to each other. Blu-tak should be used between the second monitor and the lower monitor and the lower monitor and the stand, which will make them feel like one solid piece (instead of three). Then comes the really difficult task of stacking the subs.

The subwoofers are 175 lbs each, so almost everyone will require some help*. The initial subwoofers should be well placed first, with their Extender Feet re-secured after they are moved. Damping material must also be used between the two subwoofers. I used a condensed artificial rubber, though Blu-tak is also acceptable. Importantly, all the speakers (monitors and subwoofers) are wired together in parallel.

Speaker positioning- I originally placed the stacked monitors exactly where the single monitors were located. However, I ended up making two critically important adjustments over (one year's) time.

First- While the single monitor was aimed at the outside of the listener's shoulder (right monitor/right shoulder), the stacked monitors ONLY sounded their best when they were aimed straight ahead. This change was probably necessitated by the different radiation pattern of the Doubles.

Second- The listening distance was also changed: In 2010, my listening position was 12 feet from the speakers (stacked monitors). In 2011, this was changed, in two separate increments, to first 11 ft. and then eventually to 10.5 ft. (including moving my listening couch forward).

*I received the gracious assistance of Jean Nantais (Lenco).

With everything now broken-in, and with verification from several objective, competent and experienced listeners, I am confident that my observations and descriptions below are accurate. First of all, there are no sonic* "downsides", which I admit initially surprised me, since I was concerned about a possible negative interaction between the two tweeters*, even though they are in close proximity to each other (because the second monitor is upside down). Every difference we did hear was for the better, and there is a critically important "bonus", which I will save for last. Here are the specific improvements when using the "Doubles":

*There is a practical downside though. The "sweet spot" has been narrowed down to really only one listening position. This is due to the combing effects of the two tweeters, which can be minimized at only one position.

Greater Efficiency- To be exact as possible; 3db more, which places the doubles at 97db for 1 watt. Further, and most importantly, the efficiency in actual practice matches the above specification, which doesn't always happen with speakers, for various reasons.

Greater Purity- This is audible at all times, but it's especially noticeable at higher volume levels. This makes perfect sense, since all the drivers are now working at 50% when matching the same volume levels of one pair of the PRE. Just as important, the amplifiers are also using only half power to match the same volume level, so they are also producing less distortion. In practice then, there are two theoretical reasons why the speaker should sound purer, and they do. I obviously can't distinguish between the two of them while listening. I can only report the final results and make my best effort to explain them.

Superior Immediacy and Presence- This is somewhat subtle, but still noticeable (most of the time). It may have something to do with the greater purity described above. It's not a "big deal", but it's still real.

More Natural "Substance"- I purposely did not use the normal word "body", because this would obviously infer that the PRE is "lean", which it definitely is not. In this instance, the existing "body" feels like it has more solidity and weight*, though without any sense of "heaviness". I've seen the word "density" used by others, but I prefer the word "substance" to describe what I am hearing. This is because I also feel there is actually more harmonic and low-level information being reproduced as well. Even further, the individual images are also somewhat larger (see below). So, I feel I have to use a new word (for me) to describe this combination of improvements.

I also would like to stress that this added "substance" is completely natural, meaning it is reflective of live music and sound, and is in no manner "euphonic" (which I consider a distortion, however pleasing it is to some).

*From a different perspective, it is easier to physically "feel" the musicians' presence, just as you would feel something actually in your room.

Superior Bass- The Doubles go (a little) deeper, and with more noticeable weight and impact. This should not be a surprise, considering they also have double the air-moving capability of a single pair. The quality of the bass is also better, but the improvement, in this instance, is relatively subtle.

Larger Images (and Sense of Scale)- The depth and width of the "soundstage" are about the same as the PRE, but the individual images are larger, mainly in height. I believe that this change also effects the sense of extra "substance" discussed above. It also provides a larger, though still natural, "sense of scale" with many recordings. Despite the larger image size, there is no compromise in the image focus or any added homogenization. In fact, the Doubles also have...

Superior Separation- There is a slightly greater sense of separation of the instruments and singers, at all volume levels, though it's most easily noticeable at higher volumes. This may be another byproduct of the Doubles' greater purity, itself caused by the 3db higher sensitivity.

Superior Dynamic Gradations and Contrasts- This is a further improvement over an already strong suit. The dynamic capabilities of the Doubles are simply breathtaking, even at lower volumes, where the sense of dynamic "tension" is critical, especially for acoustical music. At higher volumes, the Doubles are completely effortless, even with low powered amplifiers. Only the finest horn systems can compete with them overall.

And finally the "trump card", which is the primary reason why I am so enthusiastic about these speakers, and have decided to keep them. This is one of those situations where the whole becomes greater than sum of the parts...

Besides myself, 4 other experienced listeners, with widely different backgrounds, have now heard the PRE Doubles in my home. Naturally, we've all had a subjective response to them. However, there are two surprises when it comes to these "responses";

(1) They were all the same and
(2) In each instance, they were unprecedented for the individual listener.

I rarely focus on the typical subjective responses of audiophiles, to a particular component or a system. This is because it is now much too common, easy and tempting to enter weasel territory (it's "involving" or "not involving"). This circumstance is quite different. Not only were the responses unanimous and unprecedented (for all five of us), but their very nature was also both risky and encompassing. Here are the important details:

Jean (Lenco) Nantais was the first of us to "go public". Nantais had already heard a single pair of PRE for two days, but this was the first night he and I heard the Doubles, having just assembled them earlier that afternoon. After a couple of hours of listening, we had now heard a variety of music; soft and loud, simple and complex, delicate and crude, large and small. While I was changing records (our only source that evening), Nantais said something to me that I was feeling myself, but was still not able to put into words yet (and I was also somewhat embarrassed by this same feeling).

To paraphrase Nantais; "This is the first time I've ever heard an audio system with no limits. It does everything". After hearing Nantais' words, I was silent for a while. Finally, I told him that I agreed with him. I told Nantais that these speakers gave me a feeling of confidence that there was nothing they could not do, and that this was the first time I've ever experienced this, in my own system, or anywhere else. Further, while it obviously took the entire system to achieve this highest level of performance, it could only be the speakers that were able to finally put it "over the top". Let me explain...

From my experience, there are now (and have been in the past) many "big speakers" that can play loud (cleanly), sound "big" and go low and high, but not without easily noticeable problems, especially at lower volume levels. However, the PRE Doubles can equal these "big speakers" in their mentioned strengths, while avoiding their (once thought unavoidable) problems. This reality became increasingly clear to me that evening, especially after I had heard a few particularly challenging records, now forgotten unfortunately*, that were reproduced in a manner which I had never experienced in the past.

Then, in quick order, came the confirmation from three other listeners. A week or so after Nantais left, I had two more visitors (who are brothers), both of whom had heard my system in the past (one of them had worked in an audio store for a few years), and were no longer easily impressed. After a few hours of listening that evening, both of them were literally speechless for a while, and then they both repeated what Nantais had first said, and almost word for word: "This system can do it all!" I informed them that the turntable guy (Nantais) had said the same thing, and they weren't surprised, since they both felt that it was an obvious conclusion.

Then, a week later, my final visitor came. He was the toughest critic of the bunch, by far. He had been an executive of a classical recording company in the past, in the LP/CD business for decades and someone who had been to the most famous concert halls all over the world. He was also very familiar with all of my audio systems of the last 25 years, including the original Pure Reference and the PRE, which he heard in my home.

Well, lightning struck again, and after hearing the fabulous Kodaly LP reissue**, and choosing his words carefully, he told me he had never experienced anything like this in his life, including all of my previous systems, no matter how good he felt they were at the time. He used similar words to the others; "it does it all" and "there's nothing it can't do" and "I don't hear any problems at all, no matter what." He couldn't have been more impressed and moved by what he heard.

Finally, to clarify any potential "issues" concerning the above; outside of the two brothers, none of these listeners knew any of the others, except me of course. More importantly, I said, and did, absolutely nothing to elicit or encourage any type of positive response, let alone what I actually heard. The bottom line- These personal responses were completely spontaneous, which is why I believe they are so powerful and meaningful. This is the only reason why I am even reporting them in the first place.

*They were probably the records I described in my Lenco Reference Review/Essay

**Decca SXL 6136 "Music of Kodaly" Hary Janos Suite ("Battle of Napoleon") Speakers Corner

The "Doubles" version of the Pure Reference Extreme is unquestionably the finest loudspeaker system I have ever heard. The performance gap between the Doubles and other speakers I've heard, with the sole exception of the PRE itself, is obviously now even larger than I've described in the past, and that includes all of the speakers I auditioned at the 2004 CES, at any price. So, while the cost of the Doubles is "high" ($ 50,000), its overall performance level is also unique, and any potential competitors that I'm aware of, which use similar drivers and all-out cabinets, will cost considerably more ($100K+).

In short, in the dynamic speaker universe, its flaws are exceedingly minor, barely noticeable and basically "nitpicks" in relative terms. Even the most critical listeners will be completely satisfied with this speaker, no matter what other dynamic speaker they've heard in the past, at any price. The only exceptions being those audiophiles who prefer a completely different sonic presentation; meaning either dipoles (ribbons or electrostatics) or omni-directionals. In fact, I believe it will take a radically different technology to noticeably outperform this speaker (something like the Apogee Definitives, which cost $100K+).

It also has other important advantages...

Unlike any of its potential competitors, the Doubles can be purchased in "stages" (one pair at a time), which makes the single PRE even more attractive on its own, because of its increased flexibility. This is the only reason why I was able to purchase them myself, since I already owned a pair of the PRE. The Doubles also have placement advantages, since the subwoofers and monitors are not attached to each other. This can be critical in the goal of optimizing its performance as well as fitting them in unusual rooms and satisfying personal requirements.

Even more important, the Doubles can be easily driven, full-range, including the deep bass, with a good 300B SET amplifier. Personally, I'm so satisfied with the results I'm receiving with the Coincident Frankenstein 300B, that I haven't bi-amped* the Doubles even once, and I play them at pretty high volumes at times, in a relatively large room. This combination is only seriously compromised at the most ear shattering listening levels (105 db+), or when playing the most challenging recordings. For those audiophiles who regularly listen at those levels or higher (I'm not one of them), I would instead suggest using a more powerful amplifier of very high quality (Coincident Dragon, ASL Hurricane, Canary 339, Altec 1570 or DeHavilland 845 etc). The speakers themselves can play, cleanly, at levels which can be ear damaging, but abusing this capability would be foolish, and a tragedy for the listener.

In the final analysis...

I realize that many readers will consider such a large ($50K) investment in any component, even a speaker system, to be "crazy". I would have felt this way myself not too long ago, mainly because none of the speakers I heard at such prices (or even much higher) was superior, overall, to a few speakers I heard that cost far less ($20K or under). More importantly, none of the mega-priced speakers ($50K to $250K+) I heard was capable of "doing it all". This entire paradigm/dilemma has changed with the PRE Doubles.

The Doubles definitely "do it all". This is why I made such a "big deal" about all of those personal responses above, and they're the main reason why the Doubles are my ultimate speaker "Reference". Even if and when something proves to be superior to them in the future, it will not change the fact that they were the first speaker which "crossed the Rubicon" in my experience. It will also not change the fact that their performance is so satisfying and encompassing, that our typical and unavoidable audiophile "concerns", conscious and unconscious, slowly become just a memory. Depending on your perspective, this could be liberating or frightening, or maybe even both.

*Based on all my experiences with the PRE, I am still convinced that the Doubles will sound their very best only when they're bi-amped. While most source material will still sound basically the same, bi-amping will be a noticeable improvement in many instances, and, with the most challenging recordings (Shostakovich Symphony 11, Second Movement), there will be a dramatic improvement. (9/10)

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Here are pictures of the Double Extremes in my listening room. The top three pictures were taken in Spring 2010, while the bottom three pictures were taken in Spring 2013 (when they were also bi-amped, aimed straight ahead and moved forward, along with my listening couch):

An Important Development...

The (2017) Mk. II update of the Coincident Pure Reference Extreme (PRE) speakers is a serious and important improvement over the original model (which I've owned for almost a decade). In fact, the overall extent, scale and scope of the sonic improvements, provided by the Mk. II, are unusually large, and hence requires more than just a simple and cursory description.

Accordingly, the review/essay of the PRE MK. II below is my best attempt to provide a thorough, useful and relevant perspective of these new models for both an original PRE owner, and for all current loudspeaker enthusiasts as well.

The "original" Pure Reference (a single enclosure, now long discontinued) joined my system in late 2007. The "Extreme" (two enclosure) version of the Pure Reference, which I had incessantly lobbied for, replaced the original model in late 2009.

Later on, in Spring 2010, I "doubled up" the Extremes, by stacking a second pair of the PRE on top of the first pair. Finally, in Spring 2017, I added a pair of Acapella ION Super Tweeters. Each of these three changes, all of which provided serious sonic benefits, are well documented, described and discussed, above or below, in this PRE file.

All during the 8 years of the PRE's existence (2009-17), a number of minor changes were made to the speakers. However, none of these changes were truly significant enough, even cumulatively, to actually cause a change to the model designation. Finally though, in Fall 2017, it happened. Coincident made an announcement that a new version of the (two-enclosure) Extreme was now available. It was designated by the manufacturer as the PRE "MK. II".

Important - I highly advise reading at least some of my earlier articles above, and below, to fully understand and appreciate this current review, which is, in reality, just an (important) "Addendum" to the original essay/review. (Example; The original PRE review (above) discusses my entire personal loudspeaker history, going back to 1972, amongst many other subjects and issues addressed about speakers etc.)

According to a phone conversation I had with Israel Blume, owner and designer of Coincident, and later confirmed on the Coincident website, there are several changes to the original PRE (which he feels are of "significant proportions").

1. The new Coincident Statement cabling will be used internally.
2. The Accuton ceramic midrange and tweeter are the latest improved versions.
3. The crossover components are also improved, along with some slight adjustments for further improvements.

The subwoofer also has a new inductor and the new internal Statement cabling. The selling price of the new Mk. II is $ 29,995 for a pair, which is $ 3,000 more than the final $ 27,000 price of the original Extreme. Blume claims that his costs for all of the various Mk. II updates are "substantial".

It must also be disclosed that the PRE II, both the subwoofers and the monitors, were compromised in route by the shipper (UPS). I was able to repair (and even improve) the subwoofers on my own (with the assistance of a neighbor), but the PRE II monitors had to be shipped back to the manufacturer, since the work required greater skill and I also wanted to be absolutely certain that they would be performing at their highest potential level. Thankfully, the monitors arrived back quickly, and even improved as well, so it's another satisfying "lemons into lemonade" audio experience.

I received the PRE II in February 2018. During the first listening period, between February and March 2018, I was only able to play the PRE II for less than 100 hours before I sent them back to the manufacturer. However, even then, we were still very impressed with them. When they returned, a long stretch of bad weather severely reduced my playing time, so it ended up taking more than 6 months for the PRE II to fully break-in.

I performed my most challenging listening tests and experiments when they reached 370+ hours. That number is the total hours of play from the time they were built. It even includes the hours they were initially used as demos by the manufacturer. While they were breaking-in, I could hear the PRE II improve over time, though most (and all) of the (significant) improvements were experienced in the first 200 hours. I felt the PRE II generally "plateaued" in performance once they were over 300 hours, and any changes I have observed after that were definitely subtle.

My very first sonic impression of the PRE II, of any type, was that it was "more immediate". Further, in an interesting confirmation, an "associate" visited me around two weeks later, and that was also his first impression, at least verbally. As per my usual auditioning protocol, his statement was purely spontaneous, and conveyed without any prior request or description from me.

However, this was just the beginning, because the PRE II has many other important sonic improvements when compared to the original PRE...

Transparency, Precision, Speed and Detail - The PRE II has greater transparency, enabling much more musical information to be heard, and discerned, in the back of the recording space (which now sounds, by comparison, "illuminated"). It is also faster, more precise and more detailed than the original PRE, and the improvements in these general areas were actually large enough, in at least in one instance, to be observed in another room.

Homogeneity and Separation - The PRE II is less homogeneous than the original PRE, which was aleady excellent in this regard. Using different, though directly related, audiophile terms; the PRE II is superior in separating the instruments and vocalists, both in the front and the back of the soundstage/recording venue.

Sound-Floor - The PRE II also has a lower sound-floor than the outstanding PRE, so more of the numerous subtle sounds of the recording, which expose and reproduce the "individuality" of the musicians, instruments and recording space, are now audible. This is so important because, with a higher sound-floor, this information would be otherwise forever lost. To be clear, the PRE II has the lowest sound-floor I've ever experienced (with the original PRE now in second place).

Dynamic Acceleration and Shifts - In a related area to the above, the PRE II is also a little more "dynamic", with more convincing "shifts" and an even less "mechanical" sound than before. It is important to note that this was another attribute in which the original PRE was already exceptional to begin with.

Bass and Cohesion - Maybe the single most important sonic improvement was in bass/midrange cohesion, which I (and especially my associates) have long felt was the original PRE's most easily noticeable "weakness". This particular improvement requires a detailed explanation...

The bass of the PRE II is significantly more detailed, tight and controlled than the original model. The new subwoofer is also a better sonic match with the PRE II's new midrange driver. This occurs despite the fact that the new midrange driver is itself now faster than before. This could only mean that the subwoofer improvement is even larger, or at least more noticeable, than the corresponding improvement in the midrange, because the critical sonic/performance gap between them has been greatly diminished.

In fact, the bass/midrange transition (and/or "cohesion") of the PRE II is at least as good, and maybe even superior, to any other speaker I've ever heard using dynamic drivers. Further, though not nearly as easily noticeable, the PRE II's midrange/tweeter cohesion is also improved, which is a surprising sonic bonus, since the original PRE was already the best I had ever heard in that regard.

To summarize and clarify this critically important subject: The PRE II is, by far, and without a doubt, the most cohesive multi-driver dynamic speaker I've ever heard or, in other words, the PRE II is the multi-driver system which comes the closest to sounding like a single-driver system.

Finally, I recently went back to my original review of the PRE, and I would say that while it still holds up very well, despite all the system changes and experiences since then, the one prior evaluation I now regret is that I over emphasized the strength and accuracy of the subwoofer/midrange transition. The PRE's bass/midrange transition was, and is still, excellent, but it was not as good as I described back then.

Soundstage and Focus - The PRE II's soundstage is slightly larger than the original PRE, though it's not as large, nor does it have the "scale", as the original PRE when it was "Doubled-Up". (I would estimate that the PRE II has around 20% of the PRE's "Doubled-Up" soundstage enhancement.) Much more important; the PRE II has substantially improved focus, and its "sense of space" is also noticeably improved. The end result = The various musical recordings reproduced with the PRE II are more intelligible and organized.

Purity and Cleanness - The PRE was already noted for its purity, but the PRE II is slightly improved even in this regard. I can now only compare the PRE II's cleanness to electrostatic speakers, and even then only at their finest.

Naturalness - The overall tonal balance of the two models is nearly identical but, even so, the PRE II still sounds more natural. I believe this is because of the combination, and the accumulation, of its greater purity, a lower sound-floor and even fewer micro-deviations in its frequency response.

The most obvious similarity between the two models is their appearance; they are virtually identical, though I will attempt to find a subtle difference which would make it easy (if not definitive) to distinguish them from each other. Also, as I mentioned above, the "overall tonal balance" is basically identical and, if there is a difference, too subtle for me to describe, at least for now.

The frequency range of the two speakers is also very similar, though I feel that the PRE II is slightly more extended, and open, in the extreme highs. Also critically important from a practical viewpoint; the PRE II is just as sensitive and easy to drive as the original PRE, which means that no technical compromise has been made to achieve the superior sonic results.

Finally, to be clear as possible, the PRE II does not have even one disadvantage, even insignificant, when it's compared to the original PRE; in sonics, aesthetics or drive capability. (Though, of course, the selling price has risen.)

I listen to the PRE/PRE II using the monitors "solo" (with the subs off) most of the time, and it's possible that other PRE owners share this proclivity to some degree, so it may be important for those listeners to learn that the PRE II monitors go a little lower in the bass. Accordingly, the PRE II monitors now sound more "full-range" on their own, though this is, obviously, a relatively minor advantage when compared to all of their other sonic improvements.

Further, it required around 300 hours of play before the PRE II monitors broke-in sufficiently to observe the improved bass extension. In fact, they actually sounded leaner in the first 100 hours or so of play.

In my initial review of a decade ago (see above), I compared the original PRE to the best speakers I had heard in the (generally accepted) most important sonic categories. Those performance evaluations will now be updated for obvious reasons, but my previous sonic "References" will not be changed, due to the fact that I haven't had the opportunity to hear, with my own ears, any improved standards during this period.

I have already sufficiently discussed several sonic categories above, so I will try to avoid repeating myself, but others require greater detail and perspective:

Immediacy and Purity - The PRE II is superior to any dynamic system I've heard in both of these categories, and it's extremely close to the finest electrostatics ever made (Martin-Logan, Audiostatics, Stax etc).

Soundstage and Focus - The PRE II is now "competitive" with, and only slightly bettered by, the finest omni-directional speakers in focus, such as the Morrison and MBL. In other words, the PRE II no longer has a noticeable disadvantage in this category, as did the original PRE. Further, its soundstage is as good as the finest I've heard. Bottom Line - With the exception of slightly inferior focus compared to the finest omnis, the PRE II is at least equal, and almost always superior, to any speaker I've heard.

High-Frequency Reproduction - The PRE II is improved in this area; in purity, speed and extension, but it's obviously not in the league of the best tweeter ever available; the Acapella Ion Super Tweeter. The PRE II has the finest dome tweeter I've yet heard, but I don't believe it is the very best available of its type either. However, none of the superior dome tweeters I'm aware of possess the core strength of the PRE II's tweeter, which is its unprecedented ability to provide a near perfect cohesive match with its corresponding midrange driver. This capability is much more important, in its effect on overall sonic performance, than just simply improved speed and extension.

Bass Reproduction - As I explained above, I overestimated the quality of the bass of the original PRE in my initial review. However, my evaluation error was relatively small, so it took a number of changes (improvements) in my system, over a 10 year period, to finally expose it. So, how does the PRE II's (improved) bass reproduction compare to the best I've heard, with my perspective of today? Actually, it ends up being in almost the exact same position as was the original PRE: The best, overall, I've heard. Why?

Further Explanation: The Original Apogee Speaker, now almost 40 years old, is still my ultimate bass frequency "Reference", since it is unsurpassed in all these important areas: Impact, definition, immediacy, control and linearity. The Apogee's only weakness is that it doesn't extend down to a useful 20 Hz. If it did, it would be "the best" period, even after all these decades, and without any qualification (except it is extremely difficult to drive). Of all the speakers I've yet heard, the PRE II comes the closest to the Apogee in its strengths, while simultaneously still extending down to a solid 20 Hz.

Tonal Consistency, Naturalness, Inner Detail, Transparency - The PRE was already equal to anything I've heard in all these areas, and the PRE II has even improved on those high standards.

Dynamic Response or Scale (Soft and Loud) - The best horns (Avantgarde Duo/Trio) still have an advantage in dynamic acceleration in the midrange and highs. However, the PRE II is dynamically consistent in the full-frequency spectrum, unlike horns, which almost always have dynamic response problems at lower frequencies. The PRE II is the most "dynamic" speaker I've heard full-range. I further believe that only the top Avantgarde models, and even then only with their "Basshorns", will outperform them in this category.

Sound-floor, "Completeness" and Low-level Information - The PRE II is the finest speaker I've heard in these related categories, period. (The original PRE was the best.)

"Individuation" - Is the vitally important (and rarest to achieve) ability to individualize each and every musical instrument, voice, recording space, LP/CD, and even each separate cut of a LP/CD. It is actually the end result of the cumulative ability to excel in each of the other categories already discussed above. The PRE was already the finest I've heard in this category and the PRE II is even better.

For some readers, it may be possible that a "numbers only" experiment will further clarify my sonic assessment of the PRE II. Why? Numbers are the most precise descriptive method possible if the goal is to objectively evaluate the performance of the PRE II in relation to all the other speaker I've heard. However, there must be a prior understanding that the numbers will also be completely consistent with my subjective (word) descriptions and evaluations, previously posted above.

First, the (completely arbitrary) parameters: Imagine 10 individual "Performance Categories" and a scale of "1 to 100" in each Performance Category, with "1" being "Atrocious" (or the worst performer imaginable) and "100" being "The Best Possible Performance" (at our current level of technology). This would mean that the highest total score possible (in theory, but not in reality) would be "1,000" (10 X 100).

Some Examples: Using this system, while also being consistent with my previous posts, the Morrison speakers would score the highest possible "100" in an "Imaging and Focus" category, and the original Apogee would also score a 100 in a "Mid-Bass Impact" category. So, using these categories and scales, where does the PRE II stand in comparison with all the speakers I've heard?

I have no idea what the PRE II's actual exact final score would be out of a possible 1,000, and I don't want to even take a guess at it. However, the combination of my experience with the PRE II, along with intellectual consistency, inevitably leads me to two strong convictions:

1. The PRE II will have the highest total score of any speaker I've ever heard (it will be the closest to 1,000), and from a more subtle (and contrarian) perspective, though maybe even more important to some ultra-critical listeners...

2. The PRE II's lowest individual score, of the 10 categories, will be higher than any other speaker's corresponding lowest score.

This is an important achievement, and much more than just a back-handed compliment. It means that the PRE II's most noticeable "Weakest-Sonic-Link" (whatever it is) will be less "noticeable" than any other speaker's "Weakest-Sonic-Link". In actual practice then, the PRE II is the speaker that is the least likely I know of to be "annoying" to an ultra-critical listener.

There are three (major) upgrade options for the current owners of the original PRE. I have been fortunate to have experienced all three options in my own system over the last decade.
Here they are in the exact chronological order they were implemented by me:

Option 1. "Doubling-Up" the PRE by purchasing a second pair and then placing that pair on top of the original pair (both monitors and subwoofers).

Option 2. Adding the Acapella Ion Super Tweeters to the PRE (while rolling off the PRE's own tweeters at the same crossover frequency).

Option 3. Upgrading the PRE to the PRE II by sending them back to the manufacturer.

I have had extensive experience with all 3 options. Further, I can confidently state that each of the 3 options has large and, importantly, unique sonic attributes and advantages, which are not matched, or addressed, by the others. Accordingly, there can never be one "right choice" for everyone.

To simplify the three Options' respective sonic advantages, and the resulting audiophile dilemma:
Option #1 has an unmatched and thrilling sense of scale, size and weight, plus a deeply satisfying quality of "effortlessness", and even (3 db) greater sensitivity.
Option #2 is unmatched in openness and high-frequency purity, speed and extension.
Option #3 has the most midrange immediacy, best focus, superior reproduction of the bass frequencies and the most cohesive bass/midrange and midrange/tweeter transitions.

In short, no one option of the three will sound superior, overall, to other two options with all the vastly different types and genres of musical recordings, let alone their varying quality. This means that each of these three options, along with their sonic benefits, will also have inherent sonic compromises, which all serious audiophiles loathe.
So, if this will help, I will now answer "the big question": What would I do myself, if I was (theoretically) forced* to make only a single choice of the three available options?

After considerable thought, and even discussion, I would choose Option #3; upgrading to the PRE II. Why? In the end, it was actually simple for me: For most of the wide variety of music I play, and for the vast majority of time within these recordings, the PRE II will outperform the other two options. In fact, I actually slighlty prefer, overall, the PRE II (Option #3) to Option #1 and Option #2 combined.

What about Option #2? Not a chance. At best, the sonic advantages of the Ion Super Tweeters (with the PRE) would only be showcased and thus preferable, overall, to the PRE II, with some relatively rare recordings.

What about Option #1? This will be the really excruciatingly tough choice for many audiophiles. There is no doubt in my mind that on many recordings (Mahler, large symphonic works, rock concerts, some electronic music etc), the PRE "Doubles" will be more thrilling and satisfying overall than the (single pair) PRE II. Further, the "Doubles" have the extremely rare ability to "overwhelm" you, and this can be an exhilarating experience for many audiophiles. In fact, once experienced, being overwhelmed can be almost (literally) addicting.

However, for me (and I suspect a majority of serious music listeners), only a small minority of my large collection of recordings can take specific advantage of "The Doubles" sonic strengths in size, weight and scale. And further, I believe even those special recordings will still sound superior with the PRE II most of the time. It will usually only be in those "big moments" of the recording when "The Doubles" will really shine.

Still, I realize that Option #1 ("Doubling-Up") will be the best choice for those audiophiles who place the highest sonic priority on size, weight and scale, and/or whose dominant musical tastes (and corresponding music collections) favor the recordings that can take advantage of the unique strengths of "The Doubles". For these audiophiles, "The Doubles" will be their no-brainer first choice and their only logical and satisfying option.

*I, very fortunately, do not have to make this awful (and even cruel) choice. I already own the Acapella Ion Super Tweeters and I also plan to eventually purchase a second pair of the PRE II, allowing me to then double them up. (Yes, it is actually "cruel" after you have heard all three options in your own system!)

The Coincident Pure Reference Extreme Mk. II is an significant improvement over the original PRE model. This review explains the critically important "why" and "how" details of the PRE II sonic improvements. Further...

The PRE II is the least compromised commercial speaker system I have yet experienced, of any type and at any price. To be clear, with the majority of my recordings (both analogue and digital), and during the majority of the time, I prefer the PRE II to my previous "Ultimate Reference": The "Double PRE", even with the Acapella Ion Super Tweeters. Also important, the PRE II is just as easy to drive (SET friendly) as the original PRE.

Finally, I always make an effort to avoid repeating myself, but I am not able to improve on the conclusion of my original PRE review (links above and below), so here it is, with some minor updates and edits:

"...I feel it is possible, and necessary, to condense the entirety of this review into two simple sentences, which are both personal observations and opinions:

1. The Pure Reference Extreme Mk. II does more things 'right' than any other speaker I've heard (it's the most 'complete' or 'natural').

2. The Pure Reference Extreme Mk. II also does less things 'wrong' than any other speaker I've heard (it's the most 'accurate')."

As outstanding performers as they are "stock", and as dominating as I feel they are at their current price range, it is still important to note that the PRE II is also not a "dead-end" purchase. This is a significant factor for those serious (and even obsessed) audiophiles, like myself, who are always looking for further improvements, or the "next step", in the near and/or far future, no matter how currently satisfied they are with their system. The details...

The PRE II can still be noticeably improved with the Acapella Ion Super Tweeters. I already know this for a fact, from my direct experience (see below), and I've further had four veteran listeners observe these specific super tweeter improvements for confirmation. It's true that these particular ion super tweeters will be expensive, and they will also be a hassle to optimize, but when any system, such as the PRE II, is already at the highest level of audio reproduction, further serious improvements are rarely easy and economical.

Then there's another improvement, which I have not heard yet. This improvement will most likely be even more easily noticeable than the super tweeters, and even more important in the reproduction of music. Unfortunately, it will also be much more expensive to implement. Of course, I'm referring to a second pair of the PRE II, which will be stacked on top of the first pair (as I did with the original PRE).

A "Double PRE II Super-System", as I have just described, already exists. It is currently being enjoyed by Israel Blume, the owner of Coincident, and also the fortunate guests (and customers) who have the opportunity to visit him. To relay our relevant conversations: Blume is convinced that "doubling" the PRE II makes an even larger and consequential sonic difference/improvement than doubling the original PRE and, of course, he has heard both respective "doublings" extensively, since he has actually lived with them. Accordingly, then...

My Obvious PRE II Future - I will eventually join Blume's (presently) exclusive "PRE II Doubles Club", though I don't know when this will occur. I do promise that when (not if) this happens, I will report back with all the pertinent details.

I installed the Acapella super tweeters two times; first at around 100 hours of play and later at around 400 hours of play, when I felt the PRE II was basically fully broken-in. I used the same 5K crossover point as before, and once again positioned the super tweeters on the top of the subwoofers, with similar isolation platforms.

In both instances, the sonic improvements were heard immediately, and the ion tweeters were an even better cohesive match than before. However, the degree of improvement was not quite as large, or as easily noticeable, as it was with the original PRE. I assume this is because the new PRE II tweeter has superior high-frequency performance, which thus slightly reduces the previous sonic performance gap between them. This then inevitably brings us to...

"The Big Question": Are the Acapella Ion Super Tweeters still worth it with the PRE II? Yes!

I used numerous records and CDs, over many months, to make my sonic evaluation of the PRE II. I also kept some detailed notes on a few of my most critically important reference LPs, which were evaluated only after the PRE II was completely broken-in. I always keep my listening notes completely private, since they are my initial, unfiltered and spontaneous "gut feelings and thoughts".

However, I have decided to experiment in this review and share my private notes with the public for the first time. Why? I believe it's possible that some readers may gain further insight into my evaluation and thinking process, as well as enhance their interpretation of this PRE II review.

The notes were all written down during the actual auditions, and without any edits. I realize that these notes may be confusing and/or difficult to understand for some readers, since they are without any context and/or perspective, with atrocious grammar, and also written in figurative "shorthand", but they should all be consistent with the edited descriptions of the PRE II posted above. So, the readers of this section can now decide whether an act of self-indulgence, and being actually helpful, are mutually exclusive, or not...

Medieval Xmas Music/Nonesuch - echoes and decays are incredible! - separation of chorus!

Sing We Noel/Nonesuch - 1st Cut- "Continuousness" analogue strength

Lucia Hwong/House Sleeping Beauties/Private - "sense of space", In general - like (ZYX) UNI 1 Vs. UNI II - Greater Precision and focus and Immediacy - Less diffuse than "doubles"

Arabo-Andalusia/Harmonia Mundi - always an improvement, sometimes top to bottom, sometimes just focus - bass! - Lower, softer listening levels never so realistic and satisfying

Thibaut/Harmonia Mundi - difference between lps/cuts easier than ever to hear

China/Vangelis/Polydor - focus during movement - 1st cut!

Pfitzner/Songs with Orchestra/EMI Germany - still missing size and scale and weight compared to "doubles"

Other Random Listening Notes - Without Specific LPs - Most cohesive 3-way I've heard - bass decays ultra-defined, with impact and power - "illumination", like a light turned on in the back - both "big picture" and tiny details are "there" and obvious - the more "legato", the greater the sonic differences between analogue and digital - never felt more "transported to LIVE" - Analogue vs Digital: analogue still has advantage in "continuous presence", PRE II makes this more obvious.

Bonus! - Direct Quotes from my (most Ultra-Critical) "Associate" - "amazing change"; "a major achievement"; "Better in every way"; "Faster and more open"; "largest improvement in midrange, plus bass transition"; "tweeter improvement is much smaller, and not as important".

These are the current prices, direct from the manufacturer, in United States Dollars, as of April 2019.

Price Brand New- Pure Reference Extreme Mk. II - $ 29,999 - includes freight.

Trade in-

Pure Reference Extreme - Mint Condition - $ 16,500 - plus all freight.

Upgrades-

PRE to PRE MK. II- $ 11,999 /pr - plus all freight.

Monitors Only - $ 7,500 /pr - plus freight.

Subwoofers Only - $ 6,000 /pr - plus freight.

An Important Project finally completed...

Finally, after a more than 3.5 year gap, I once again have a completely optimized speaker system, without any serious compromises. The back story first...

I last had a no-compromise system back in October 2017. At that time, I had a Double-pair of the Original Pure Reference Extremes (PRE). Even better, this already outstanding speaker system was augmented with the Acapella Ion Super Tweeters. At the time, I couldn't imagine being more satisfied with any system. However, the inevitable happened: I received the fateful phone call from Israel Blume, the Designer/Owner of Coincident, who informed me that a Mk. II version of the PRE was now available, and it had substantially superior performance when compared to the original models I owned. I was excited of course with this news, though I now had two pairs of speakers to sell and replace.

I sold, and replaced, the first original pair with the current Mk. II Model, in Fall 2017 and early 2018 respectively. It was soon apparent that while the Mk. II was an overall better performer, even as a single pair, than the original PRE Doubles, they still lacked some of the important strengths of the Doubles. This was my Reference speaker system until early January 2021, when I received the second pair of PRE II Monitors alone (without the matching subwoofers). Then, finally, on May 26th, the second pair of subwoofers were mounted (with the assistance of a friend), which completed the entire update process. While there is obviously still some break-in required (see below) to hear this system at its very best (mainly the subwoofers), I believe I've heard the system enough hours, and with a thorough enough variety of music, to write a review I feel confident with.

Not surprisingly, the improvements I noticed when doubling the original PRE speakers in 2010 (My Review of the Original PRE Doubled-Up), and the updated Mk. II models, were very similar to each other, though there was one significant difference between them (see below). There were also two listening protocol changes; I heard (in the first few months) the Original PRE Doubles with a number of other experienced audiophiles, while (due to the pandemic) I've only heard the Mk. II Doubles alone (so far). I also heard the Mk. II Doubles in two separate stages (the monitors first and the subwoofers later), unlike the Originals. (It is also important to note that I removed the Ion Super Tweeters for most of the evaluation, to eliminate an irrelevant and potentially misleading factor and also avoid confusion.)

So, while attempting not to repeat myself, I will update all the improvements I noted back in 2010 with the Original PRE Doubles:

Greater Efficiency- This is completely automatic of course, and inherent due to the laws of electronics. To be precise, the efficiency is 3db higher, which places the Mk. II Doubles at around 97db for 1 watt, which is the same as the Original PRE Doubles. Nothing else to report here.

Greater Purity- Just as above, this is also an inherent improvement, as I wrote more than a decade ago now: "since all the drivers are now working at 50% when matching the same volume levels of one pair of the PRE Mk II. Just as important, the amplifiers are also using only half power to match the same volume level, so they are also producing less distortion." Also as before, this important improvement can be heard at all volume levels.

Superior Immediacy and Presence- This improvement was somewhat subtle, as with the Original PRE Doubles, but with the Mk. II it is more noticeable this time, though still not dramatic. Once again, it may not be a "big deal", but it's still real.

More Natural "Substance"- I had difficulty describing this improvement 11 years ago, so I will simply repeat myself for now, though I will have something to add to this at the end:

I purposely did not use the normal word "body", because this would obviously infer that the PRE is "lean", which it definitely is not. In this instance, the existing "body" feels like it has more solidity and weight*, though without any sense of "heaviness". I've seen the word "density" used by others, but I prefer the word "substance" to describe what I am hearing. This is because I also feel there is actually more harmonic and low-level information being reproduced as well. Even further, the individual images are also somewhat larger (see below). So, I feel I have to use a new word (for me) to describe this combination of improvements.

I also must stress that this added "substance" is completely natural, meaning it is reflective of live music and sound, and is in no manner "euphonic" (which I consider a distortion, however pleasing it is to some audiophiles).

*From a different perspective, it is easier to physically "feel" the musicians' presence, just as you would feel and sense something actually in your room.

Superior Bass- Virtually the same improvement I observed 11 years ago. The bass is now "(a little) deeper, and with more noticeable weight and impact...The quality of the bass is also better, but the improvement, in this instance, is relatively subtle." From a purely subjective perspective; The deep bass of the Mk. II Doubles has an ability to sound (literally) "ominous and scary" in a manner that a single pair of the PRE Mk. II lacks. For certain musical compositions, this is a critical factor for them to be fully appreciated and enjoyed.

Superior Dynamic Gradations and Contrasts- This is a further improvement over an already strong suit. The dynamic capabilities of the Doubles are simply breathtaking, even at lower volumes, where the sense of dynamic "tension" is critical, especially for acoustical music. At higher volumes, the Doubles are completely effortless, even with low powered amplifiers. Only the finest horn systems can compete with them overall.

Larger Images (and Sense of Scale)- Once again, the improvement is similar to the Original PRE Doubles: "The depth and width of the soundstage are about the same, ...but the individual images are larger, mainly in height... It also provides a larger, though still natural, "sense of scale" with many recordings".

Separation of Instruments- The separation of instruments is slightly superior (like the Original PRE Doubles), though it is mainly observed only at higher volume levels and with complex material. However, the image focus of the PRE II Doubles is slightly compromised at medium to lower volume levels. This is the only sonic downside I was able to observe with the Doubles.
Further: The issue of image focus is somewhat complex, and thus requires a more thorough explanation...

Image Focus- As it turned out, the image focus was also compromised with the Original PRE Doubles (when directly compared to a single pair), though I wasn't able to report it initially in Spring 2010. Why? We observed the problem instantly, and immediately changed the speaker/listening position, mistakenly believing this issue was now mitigated (so no report). However, once I (and my associates) were able to observe the image focus degradation with greater clarity (later that same year), we moved the speaker/listening positioning a second time (more radically) to minimize the problem, though it was never close to being eliminated. My PRE II Doubles experience with image focus is somewhat different:

1. The image focus degradation is much less noticeable than with the Original PRE.
2. Accordingly (and consistently), the "cure" (re-positioning the speaker/listening position) was much easier and less radical.
3. The original PRE Doubles had only one true "sweet spot" listening position, due to the combing effects of the two tweeters, which could only be seriously minimized at one position. However, the Mk. II Doubles still sound superb even when outside the optimum listening position.
4. Most important: As I reported three years ago (2018), the image focus of the PRE II is far superior to the Original PRE. How much so, exactly? The PRE II Doubles, while slightly compromised compared to a single PRE II, are still noticeably superior in image focus to even a single pair of the Original PRE!

To summarize and clarify the subject of image focus: With the exception of a single pair of the PRE II (and the speakers which equal it), and the omni-Morrison/MBL (which outperform all other speaker designs), the "compromised" PRE II Doubles are still competitive with all other speakers I've heard in image focus. Finally, if I had to quantify the performance of these specific models, by using numbers alone, though they obviously can not be exact or literal, this would be my best estimation:

10/10 - Morrison/MBL (no implication of "perfection", simply the best designs I've experienced so far)
9.5 - PRE Mk. II (and its rare equals, such as the Ars Acoustica System Max)
9 - PRE Mk. II Doubles
8.5 - PRE Original
7.5 - PRE Original Doubles

Room Size Compatibility- There is an important practical difference between the PRE Mk. II and the PRE Mk. II Doubles. As I mentioned in the 2018 review, the PRE Mk. II has a serious practical advantage when directly compared to most other speakers, large or small: The PRE Mk. II is almost universally compatible with different listening rooms, from Tiny all the way to Large. However, because of its sheer size, and the large surface area of its multiple drivers, the Doubles are NOT close to being "universal". The Doubles, in contrast, are only compatible with Medium to Huge listening rooms. (See more about this subject below in "Options".)

My conclusion is straightforward, and consistent, with the above review: I already Doubled-up the original PRE speakers back in 2010, and achieved outstanding results (reported in detail at the time). Thus, it is no surprise that the current results with the PRE Mk. II Doubles are also outstanding. The above review of the PRE Mk. II Doubles provides all of the supporting and confirming details as to why I arrived at such a highly positive evaluation. However, I believe my purely personal and subjective response may also be important to many readers. Accordingly, while I truly dislike repeating myself, in this instance I believe it is instructive for us to again go back to the 2010 review of the Original PRE Doubles, and specifically to a relevant conversation I had with Jean Nantais (Lenco Reference) during the very first night we heard them. This is what I wrote at the time...

Now, is there anything I can add to the above in 2021? Yes. The PRE Mk. II Doubles perform at such a high level that an accurate subjective description of their full capabilities may even appear to be contradictory at times, so let me use some analogies. The Doubles are like a combination of the skills and abilities of both a flyweight and heavyweight boxing champion, simultaneously, or both a Bolshoi ballerina and an Olympic shot putter, simultaneously. In short, to repeat, and summarize, the various subjective quotes in the Original PRE Double review; "It does it all", period.

Further, and most important, I believe the majority of current (and future) owners of the PRE Mk. II can also experience highly satisfactory results when they invest in the PRE II Doubles. However, their existing system must be ready for the "creation" of such a highly-revealing instrument. This means the capability of bi-amping, outstanding sources, good quality AC, etc. The PRE Mk. II Doubles will reveal virtually everything, including, unfortunately, every system weakness, so be well prepared.

Finally, it must be conceded that my own situation is rather fortunate, especially considering that my current listening room is the same as it was in 2010. So, a "majority" definitely does not mean everyone, and this brings us to...

We must now broaden our perspective (from just me) and thus closely consider the upgrade options available for all the current, and prospective, owners of the PRE Mk. II. (I have already discussed the upgrade options for the owners of the Original PRE, see this link: PRE II Review, with Upgrade Options for the Original PRE.) Each PRE II owner will have their own unique set of circumstances, dependent on their budget, room size, aesthetics and sonic priorities.

So, we first start with the very few available options for upgrading the PRE Mk. II: (Explanation- There are not many upgrade options for the simple reason that the PRE Mk. II is already superlative on its own.)

1. Doubling-Up with a 2nd pair of PRE II.
2. Acapella Ion Super Tweeters (assuming they are optimized, see review).
3. Extra pair of PRE II Monitors Only.

Fortunately, I've had extensive experience with all three options, which brings us to the first "big question": What upgrade option makes the largest overall impact on performance? That's a no-brainer. In ideal conditions (like mine), it is, without question, Doubling-Up (Option #1). In fact, no other option is remotely close. However, it will not be that simple for many serious audiophiles. So, it is at this time that the critical issues of room size, sonic priorities and budget become relevant factors which we must discuss.

Let's start with "room size compatibility", which I already specifically mentioned above, though not in detail until now...

Based on my experiences with the PRE (II) Doubles (and many other very large speaker systems), I'm convinced that they always sound their best in relatively "large rooms". In fact, not only does their performance slowly degrade (and they eventually lose almost all their sonic advantages) in smaller rooms, they can actually sound inferior (to be kind) if the room is too small.

So, the next inevitable "big question" arises: Is there some sort of room size "cut-off point" for the PRE II Doubles, where their sonic advantages would begin to be seriously compromised if the room was any smaller? I believe there is, and my best estimate would be around 15' X 20" (or around 300 sq. feet). Now while it may be possible to use the PRE Doubles in an even slightly smaller room, that room (and, to a large extent, even the medium room) would have to be otherwise ideal (structurally solid, high ceilings and with minimum standing waves).

The Bottom Line - While you will not hear the PRE Mk. II Doubles "at their best" in such medium-sized rooms (around 300 sq. ft., which are typical for most homes), I believe their various sonic advantages will still be significant in nature, especially in totality, and well worth the investment. However, many audiophiles don't have access to even medium-sized rooms, so we are still not through with the important issue of room size (which indicates just how critical it is for the optimization of, or for the least compromised, sonic performance). This brings us to...

Upgrade Option #2 - Acapella Ion Super Tweeters - In addition to costing "only" 40% of the retail price of the PRE II, the Ion super tweeters have one other practical advantage, their sonic improvement is the same no matter what the room size; from tiny to humongous (again, assuming they are optimized). In other words; As the various performance advantages of the PRE (II) Doubles increasingly decline as the listening room size decreases, the point is eventually reached (though only in tiny and small rooms) where the Ion Super Tweeters actually become the preferable option (even when ignoring cost, see below). However, there is even a third option, which may be preferable in tiny/small rooms, though it will cost somewhat more than the Ion Super Tweeters. This is...

Upgrade Option #3 - PRE Mk. II Monitors Only - I listened to this (half-way) system for more than 4.75 months earlier this year (2021). Though it took a while for the Double Monitors to break-in and fully optimize (see below), their many sonic advantages were observed almost immediately (see above). However, it is also true that only after the second pair of subwoofers were installed that the full "sense of scale", all the natural "substance" and the total and effortless overpowering capability of the Doubles was experienced ("it does it all"). Even the image height was compromised by using the double monitors by themselves.

Still, for many audiophiles, the performance advantages of the Double Monitors will be preferable to the Ion Super Tweeters upgrade. This choice will depend on the audiophile's sonic priorities and, frankly, their ability to still hear (ultra)high-frequencies. The Double Monitors have one other potentially practical financial advantage; If a larger room eventually becomes available, specifically one which can also accommodate the Double Subwoofers, then only the subwoofers have to be purchased at that time to complete the "Doubles", thus splitting the total cost into two installments.

Break-In - Almost all of the initial break-in was with CD/SACD sources. I was first able to observe a small sonic improvement with the 2nd pair of monitors at around 20 hours, and with many other incremental improvements to around 250 hours or so, even though the 1st pair of monitors was well broken-in. I felt, at the time, that the system had finally plateaued. However, to my surprise, I still observed further improvements, though admittedly subtle, even to approximately 500+ hours. The sonic improvements, at that point, were either the exposure of (previously lost) very soft sounds (space, decays etc) or superior dynamic gradations. Conclusion - I don't believe I've ever experienced another speaker system, of any type, which still noticeably improves even after so many hours of play.

Acapella Ion Super Tweeters - The super tweeters from Acapella were removed from the system when I first installed the second pair of Monitors. They were re-installed just before the second pair of subwoofers were received (and later mounted). The listening results were basically the same as I had with the PRE Mk. II...

1. The Ion super tweeters work (blend) even better with the PRE Mk. II Doubles (when compared with the Original PRE Doubles).
2. The sonic improvements with the Ion tweeters were slightly less pronounced. I believe this is because the PRE II tweeters have slightly improved, which, in turn, reduces their relative performance gap. However, I must stress that this reduction of the "relative performance gap" is subtle.
The Bottom Line - The Acapella Ion Super Tweeters are still well worth their investment.

Musical Examples - I played literally hundreds of analogue and digital recordings, but I have decided to discuss only three of them. Further, these 3 chosen recordings are relatively extreme in nature, and much different than my usual choices. In fact, two of the recordings are mono (from the 1950s) and the third recording is digital (from the 1980s). Why choose to focus on recordings that are mostly considered light-years from "demonstration quality"? Because I believe a different approach is required to illuminate the unique ability of the PRE II Doubles to reproduce all forms of music, even when the recordings are supposedly useless, if not invulnerable, to advancements in the audiophile arts. Here they are:

1. Verdi - Falstaff/Act III/Scene 1 -"Ehi! Taverniere!" - Toscanini/Valdengo - Mono CD- Recorded April 1950 - Toscanini Complete RCA Collection - Volume 57/CD 2/#13 - Giuseppe Valdengo ("Falstaff"), a baritone, sounds like he "is in the room". The sheer immediacy of this cut, as reproduced by the PRE Mk. II Monitors Doubled, is incredible, especially for a 70+ year old recording. Further, I played this CD in March 2021, when the PRE II Monitors weren't even fully broken-in yet! I am certain it would sound even better now.

2. Debussy - Images for Piano - Gieseking - Mono CD/LP - Recorded August 1953 - Walter Gieseking had an unique ability to create a full sonority, even (and especially) at the softest volumes, which is required to faithfully play Debussy's piano compositions. This is why his Debussy recordings are still so valued today. The PRE II Doubles excelled in reproducing this sonority, both on CD and LP. Reproducing sonority, especially at soft volumes, is critical for an audio system to sound natural, alive and complete.

3. Mahler - Symphony No. 2 "Resurrection" - Bernstein - Digital LP/Album - Recorded April 1987 - Giant size and overwhelming sonics, with virtually no typical digital artifacts, even at the softest and highest volume levels.

Final Thought - A truly great system must do "justice" to both the Mahler and the Debussy recordings, as they represent the two extremes of music. In my evaluation, the PRE Mk. II Doubles are fully capable of providing this highest level, and widest range, of musical justice.

Sometime in Spring 2021, I stumbled upon a website that was new to me, "Audiophile Style", which contained a thread, from May 2018, titled "why does consumer audio suck" (a link to the thread is below). Most interesting to me was a comment on page 14 of that thread, from a member using the moniker of "mansr". When another member brought up the concept of the "sound-floor" (a term I coined many years ago), "mansr" replied, on May 16; "Out here in the real world we call that sensitivity or something like that."

Wow, I thought! Did this mean all the years, thought and effort I gave to this concept of the "sound-floor" (even though, in the end, it appeared so evident and simplistic) was only because I was utterly blind to its obvious description and simple cause? No. Sure, I wish audio was so simple, where a single measurement provided such an important qualifier, and a profound amount of relevant performance information.

Unfortunately, member "mansr" most likely did not even understand the basic concept of the "sound-floor" (see link below), and thus inevitably ended up grossly over-simplifying it. However, there is actually a diamond in the manure pile of the "mansr" post (See below). First though, we must completely contradict and discredit the "Sensitivity = Sound-floor Theory" ("SSFT") of "mansr". Fortunately, this is so easy that it can be accomplished with some elementary examples which even novice audiophiles can understand and appreciate...

1. If the SSFT was actually reality (a proven fact), then all speakers with the exact same sensitivity would also have exactly the same sound-floor, which, of course, is absurd (AKA "reductio ad absurdum"). In actuality, the SSFT contradicts the experiences of millions of serious listeners (let alone speaker designers), every day and in every venue, and has done so for decades, but it gets worse.

The SSFT is also inconsistent with the results of millions of successful speaker modifications (inferior passive parts replaced by superior capacitors and resistors, of the same value, and even wire), also conducted over decades. Many, if not most, of these modifications were accomplished by DIY enthusiasts (such as myself), while the others were by the designers and manufacturers of commercial and professional loudspeakers (such as the Coincident PRE Mk. II).

2. Then there are electronics, such as power amplifiers, which are also modified on a regular basis. (I am focusing on modifications, here and above, because there is usually no change in "Sensitivity", which is critical to my argument.) Once again, literally countless audiophiles, over many decades (including myself, thousands of times), have replaced the inferior stock resistors, capacitors and wiring, with superior equivalents of the same values (so the sensitivity remained the same), and then experienced a noticeable reduction of the sound-floor, thus allowing more soft sounds to be heard. I'm still not through yet.

3. Unfortunately for the SSFT, there's a lot more contradictory evidence that's also ubiquitous in nature, but we'll finish with just one more common example. Let's now move on from speakers and passive parts, and consider simple "tube-rolling". How many millions of owners of tube electronics have routinely replaced their existing tubes with others of the same gain (AKA the same sensitivity) and experienced a noticeable, and sometime dramatic, improvement in sound quality, including a lower sound-floor?
The Bottom Line and Indisputable Conclusion - SSFT is Dead Wrong or Case Closed.

Finally, what about that "diamond in the manure pile" I mentioned above? Does the "mansr" post provide any contribution to audio reality? I believe so...

While the SSFT of "mansr" does not reflect reality, I now believe that sensitivity still has at least some relationship with the sound-floor. In fact, in a fortuitous coincidence, it is my experiences with the PRE (Mk. II) Doubles which provided the direct evidence which is the basis of my new theory concerning the relationship of sensitivity and the sound-floor. My new theory is also elementary:

This theory is based on my experiences with doubling-up both the Original PRE and the PRE Mk. II. In both instances, doubling-up the speakers increased their sensitivity (by 3db) and simultaneously lowered their sound-floor. And, of critical importance, in both instances everything else was equal. In fact, the speakers had to be equal for the doubling-up to be successful (or even attempted) in the first place. This insight conveniently brings us to the final important and relevant subject, which I believe must be addressed at this point.

First, from my distant audio past...

While breaking-in the PRE II Doubles and writing this review, I couldn't resist reminiscing about the other times I had doubled-up speakers in years long past. While it's impossible for me to remember every instance in the last 50+ years, I do remember the first two times I doubled-up my speakers; the KLH Model 9 (a 6' tall electrostatic, placed side-by-side in a "V" shape) in 1974, and the Original Large Advent (stacked) a few years later. In neither of these two instances was doubling-up my own idea. The Double KLH 9 was the brainstorm of (the late) J. Gordon Holt (Stereophile), and the Double Large Advent was the idea of (the late) Harry Pearson (in TAS' Inaugural Issue #1).

So, how did these two experiments work out for me? The doubling-up was a success in both instances, and while I was quite satisfied with the results, neither system lasted long. I had the Double KLH 9 for 2+ years, and I would have kept them even longer, but they had mechanical (buzzing frames) and transformer problems. (They were also very difficult to properly amplify.) Meanwhile, the Advents*, though also satisfying and problem-free, sadly lacked the unique sonic qualities I was used to from my previous electrostatics experiences, which I couldn't live without at the time, so I went back to the Original Quad Electrostatics (which I owned before the KLH 9), augmented by the RTR ESR-15 electrostatic tweeters.

*I had 3 iterations of the Large Advents: The Original Pair, a Double Pair and a Double Pair augmented with RTR ESR-15 Electrostatic Tweeters. I sold the Double Pair to pay for the Quad ESL, while keeping the RTR tweeters.

While I fantasized owning a pair of stacked Quad ESL at various times during my audio career, I never did. However, I have heard stacked Quads several times (in homes and at audio shows), the first being at the home of Israel Blume (Coincident) back in 1981 (he built the stands himself). I was very impressed at the time. Later that year I opened my audio store in Toronto and, for a number of reasons (clumsy customers, mounting issues & other problems), I never pursued the many opportunities I had to double-up other applicable speakers.

While I believe that dwelling on past regrets is usually self-destructive, and useless as well, I can still state now, and with certitude, that I would experiment with doubling-up speakers to a much great extent if I could go back in time. Since every experience I've had with doubling-up speakers has had positive results overall (though I believe some luck is involved here), I feel this particular regret is both rational, and excusable, at this point in time. However, this discussion is also meant to be about the present...

So, is doubling-up something to seriously consider today? And, if so, what are the best prospects? I believe doubling-up is definitely viable today. However, there are still some pitfalls, so any audiophile who contemplates such a project must be prepared to seriously and thoroughly research the subject before they begin.

First, we must rule out all the speaker designs which are not prospects, mainly due to their size and shape. This is easy; all planars (including hybrids), plus all medium to large floor-standing loudspeakers. I realize that this eliminates a countless number of speakers. So, where does that leave us? Mostly, if not exclusively, monitors (such as the PRE (II) Monitors), but don't be concerned by this extreme discrimination. There are still plenty of qualified monitors around to choose from, including current models and some of the better models from the past (which can be purchased used, and usually at huge discounts). Next, we must discriminate again, this time amongst the large universe of monitors, but fortune, and experience, is here to assist us.

To find the best currently available "qualified monitors" for doubling-up, the least riskiest method is to analyze an already proven performer, the PRE (II) Monitors, and discover what makes them so desirable, in particular. Upon review, the PRE Monitors possess four specific and essential qualities:

1. The PRE Monitors have a flat top. This makes it possible for the monitors to be securely attached to each other, and then stacked. (The top monitor is placed upside down on top of the bottom monitor, so the tweeters are in the closest possible proximity. See picture below.)
2. The PRE Monitor tweeters are both centered and close to the top of the cabinet. This is the only method to minimize (though not eliminate) the unavoidable "combing" effect of two tweeters, which compromises image focus (see above).
3. The PRE Monitors have a benign impedance, allowing them to excel with even SET amplifiers. Speakers with low impedances, and/or with sharp dips and spikes, should usually be avoided, since those same impedance problems will magnify when they're played in parallel.
4. The PRE Monitor sound quality is excellent on its own. However, as with all monitors, there will be a lack of mid/deep bass reproduction. Subwoofers can address the bass issue (see below).

The next critical requirement are the speaker stands. They must be extremely stable (and usually spiked), so they will not fall over easily. This is especially important if there is regular activity in the listening room from the unappreciative, and/or the uncaring (clumsy family members and friends, kids and pets). Needless to say, the speakers and the stands have to be well attached to each other in a highly secure manner as well (I use blu-tac myself).

There are other important issues; The speakers will normally be wired in parallel, which halves their impedance (example: from 8 to 4). This means that the existing amplifier must be able to handle the future lower load, or be replaced. The 4 (2 X 2) monitors must be exactly the same for the best results, with a minimum of the drivers and the crossover points being exact. (This strict requirement was the reason I could never mix the PRE and PRE II Monitors, which had different drivers, and even cabinet shapes, for the 2+ years when both pairs were available.)

Do I have any favorite doubling-up prospects myself, which I would love to hear? Yes, there are two monitors that have intrigued me for some time now, and both of them are "classics" from the distant past which I am well familiar with.

1. Rogers LS3/5a - This is a truly classic speaker which influenced the entire audio industry, and spawned literally thousands of imitators. Fortunately, all that is required is to find two pairs that are exactly the same vintage, and in good working condition of course. This search may not be easy, but patience should be rewarded in the long run, since the design was popular for decades.

Further good news, the (BBC) LS3/5a design was also used by other reputable speaker manufacturers, such as Harbeth, Spendor, Chartwell and KEF (see the link to a 2001 LS3/5a "shootout" below). This means that there are multiple alternatives, though I would generally choose the models with the heaviest cabinets and in the best condition. The LS3/5a impedance (from all the manufacturers) is unusually high, from 11 to 15 ohms, which makes it very practical for both transistor and tube amplifiers when it is halved down to 5.5 to 7.5 ohms.

2. Wilson WATT (any versions) - Another design that revolutionized the speaker industry (the WATT had the first truly dead speaker cabinet in audio history). However, unlike the LS3/5a option, the Wilson WATT is a truly serious project, which will require considerably more funds, planning and effort to accomplish, but the sonic rewards will also be commiserate. This is the general plan I am suggesting (and I promise you that I would do it myself if I was still in the audio business):

1. Purchase two pairs of WATTS, of any vintage (usually the oldest, because they're the cheapest), at the lowest price. Make certain the cabinets are in excellent condition and the drivers are the exact same size. Nothing else matters, including the condition of the drivers, which won't be used.
2. Remove all the drivers and crossover parts, effectively gutting the speakers. (They may still have some value in the used parts market.)
3. Research, and purchase, the finest midrange and tweeter. They must be matched in efficiency, impedance, respective crossover ranges and, most importantly, can be securely attached to the existing openings.
4. Research to find the optimum crossover point, and then purchase the finest respective crossover parts (capacitors and inductors) for a 1st order crossover.
5. Replace the speaker binding posts and consider what acoustical material, if any, or any extra deadening material, if any, you will place within the cabinet.
6. Find an appropriate and secure stand which can easily handle the size and weight of a pair of WATTS. (The stand, from Entec, that came with the WATT II is excellent. I'm still using it. See picture below.)
7. Assemble the four speakers and mount them properly and securely to the stand (a two person job).

Once again, doubling-up the WATT was not my idea. It was originally created by (the late) David Wilson, founder and designer of Wilson Audio.

Finally, what about the subwoofers? They will be required for true full-range sonics. Look for quality and compatibility over loudness capability. Also, two pairs of subwoofers, stacked or separated, may also work well, though they must all be the same model.

Relevant Links:

Coincident Speaker Website with Further Information on the PRE Mk. II

My Review of the Acapella Ion Super Tweeters

My Audio System

"Audiophile Style" Website Thread and Relevant Post on "Sound-Floor and Sensitivity"

My Description of the "Sound-Floor"

LS3/5a "Shootout" from 2001

The Coincident Pure Reference Extreme Mk. II "Doubles" are pictured below. Attentive readers, when looking closely, will notice two thin wires (red and black) attached to the amplifier's speaker outputs, extending to the stand below, and then attached to three film capacitors. These 3 capacitors (in parallel) form a 1st order filter, which rolls-off the PRE II Monitors above 5k. Without this low-pass filter, the PRE II Monitors, and the Acapella Ion Super Tweeters, would both operate, at full volume, above 5K, thus resulting in confused sound (see the Acapella review, link above).

I actually made these comparisons some time ago, and there were no surprises, just a confirmation of past results and observations. I decided to delay writing about this subject until I heard one final important comparison, with an associate present. I wanted to place all the relevant information, on this one subject, within only one post, which would prevent future confusion and wasted time. Here is what I/we heard, virtually none of which should surprise anyone:

1. When played full-range, the Frankenstein amplifiers were preferable overall, most of the time, and only demonstrated their shortcomings, in an obvious manner, on the most challenging of records, which required very high volumes and/or demanding bass notes. They excelled in purity, transparency, naturalness, ultra-low sound-floor and a lack of an "electronic character".

2. The Dragon amplifiers, while outstanding performers, were only superior in attaining ultimate volume levels, and in the bass frequencies, though the latter improvement was usually subtle, and only obvious on music with serious bass challenges. The only surprise we ever experienced, though it was heard before, was that the Dragons were not superior in dynamic intensity (except when the Frankenstein was over extended), even though this quality is one of their greatest strengths.

3. The best sound we heard, without a doubt, was when the (Coincident Pure Reference Extreme Doubled, or CPRED) speakers were bi-amplified, with the Frankenstein on the monitors and the Dragon on the subwoofers.

In the end, choosing between the amplifiers, assuming the speakers are the Pure Reference, or something similar, comes down to "quality versus quantity". If the listener requires the Dragon's extra power for a variety of reasons; an unusually large room, high listening levels, and extra challenging music, plus "peace of mind" that the amplifiers will never "give up" under any circumstances, then I would get the Dragons. Otherwise, the Frankensteins are to be preferred.

It must be kept in mind that the Dragons cost more and that they will also easily drive almost any speaker made, while the less costly Frankensteins are really "specialists", but are unmatched, in my experience, with the right speaker. For the best of both worlds (with the CPRED or any Pure Reference for that matter), which unfortunately comes with a monetary price, we must now discuss bi-amping.

There are several sonic advantages that are gained when bi-amping. The most easily heard improvement, even by a non audiophile, is in the bass, if and when a challenging recording is played (Shostakovich Symphony 11, Second Movement). However, while this improvement can be definitely described as "dramatic" at times, it is also a relatively rare event, constituting maybe 10% of my recordings. In truth, most of the time, the improvement in the bass is subtle, and many times hardly even audible. This is because the CPRED is an extremely easy load, and the Frankenstein has exceptional bass reproduction, especially for a 300B SET amplifier.

Fortunately, there are other improvements, which are both more common and much more satisfying (to me anyway) in the long run, even though they are less obvious than hearing overwhelming bass impact etc. They are caused by the Frankenstein amps now driving the monitors alone, and no longer having to also drive the subwoofers.

While never "dramatic", the monitors sound cleaner, faster, more transparent, detailed, immediate and effortless, less homogenous and even more cohesive and intelligible. These improvements are noticeable with almost all recordings and at all volume levels, and cumulatively, once heard, are such that it would be "painful" to have to go back and live without them. These results are not surprising, since they were also heard with the original (single box) Pure Reference, and (going back in time) the Ars Acoustica System Max for that matter.

Finally, the Dragons provide one other improvement that many audiophiles may find very important, even though it is not obvious at first. In comparison to the Frankenstein, on many recordings, the Dragon has somewhat more "weight". This is not surprising, but at the same time there is also a sense that some instruments have grown closer to their "real life" size. This is especially noticeable with instruments such as a double bass and large drums. How a listener responds to this change is obviously personal, but for me, it can be quite thrilling at times, and also helps make the final sound even that much more realistic.

The "bottom line" of the totality of our observations is simple: Bi-amping has its (monetary and other) costs, but with a speaker such as the Pure Reference, or others with similar accuracy and resolution, it is absolutely indispensible to achieve all their potential performance.

The Sum of the Parts...

During the first few months of 2011 I made several noticeable improvements to my system:

1. Adding the Coincident Statement Line Stage
2. The Lenco Spring (Replacement) Modification
3. Bi-amping the Coincident Pure Reference Extreme Speakers
4. Repositioning the Coincident Pure Reference Extreme Speakers (see above for details)

The accumulated improvement of these four changes has been dramatic in a number of important ways. In fact, at this time, I am experiencing a level of performance noticeably beyond anything I've ever heard in the past, including any of my previous systems, in private homes or at audio shows, regardless of the price, scale and ambition of the components and/or systems.

However, this short article was not written to "crow" or celebrate. Instead, I would like to discuss just one element of the performance. It epitomizes what has been achieved. It is also the easiest to explain and the least likely to have been predicted, which thus makes it the largest surprise for me (and maybe others). I also believe it sets a precedent of sorts, at least in my experience, which is the primary reason I feel I must share it.

The specific improvement I am referring to is the area of "speed and articulation". Further, I believe only an actual example will illustrate what I am observing, and will also provide a "reference point" (or "control") for others. While I heard this improvement with virtually every LP I played, one record in particular made it so obvious that it was simply impossible to ignore. This LP is the well known Praetorious Tanzmusik on Archive 198166 (I played the 180 gram Alto Reissue).

Listening to the first four or five cuts (dances) on Side One of this LP are all that is necessary to understand the accomplishment. The instrument to focus on is (their ancient version of) the flute. It is one of the major instruments in the ensemble and the flutist is able to repeatedly play (what appear to be) 64th notes, which come and go like lightning. (Of course, the recording engineer, along with the mastering engineer, should also receive some kudos.)

To make things clear, I've never heard these particular notes as precisely articulated, as they are at present, on any system I've played this record (or the original pressing), and I've heard this recording numerous times, on many systems, for more than 25 years. Until now, I had no idea there were even 64th notes on this recording in the first place, since they were always "smeared", to one degree or another, in the past. Further, as satisfying as this is, there is a serious implication and a much more important issue to be addressed...

What must be emphasized at this point is that I'm hearing this outstanding level of performance on a system that, by "conventional/mainstream audio wisdom", should not be able to accomplish it. My current system consists of a phono source, which then uses tubes in the phono stage, line stage and the power amplifiers, and dynamic drivers in the speakers. However, such an outstanding level of articulation is supposed to be the exclusive domain of digital (SACD) sources, and even then only using hyper-speed transistor electronics (like Spectral) and electrostatic speakers (like Martin-Logan). This "theory", which I previously believed in myself, has proven to be false. This unexpected equivalence is, to me, for once, a real "breakthrough".

The implications of this achievement are serious and must not be understated: This now means that choosing the route of "analog and tubes" does NOT also mean that "second-rate" articulation must be an inevitable consequence of that choice. It may be difficult, and somewhat expensive, to reach the high level of performance I'm now experiencing, but it can be done! That fact is the most important point of this article.

Important Note - For the entire review of the Acapella super tweeters, use this link: THE REFERENCE SPEAKERS - CLASS A

I purchased and received the Acapella tweeters in June 2015. I could only afford them because I received a once-in-a-lifetime "sweetheart deal" from a distributor (who I've known for 40+ years now), basically the OEM price. I could provide a number of common "excuses" for the unusually lengthy delay in auditioning the tweeters, but the main reason was that I strongly felt I required some assistance, not only for positioning and basic set-up, but also to ensure a thorough and competent evaluation, which I could then post with confidence. Unfortunately, one by one, my associates cancelled their plans to visit me for various reasons until, finally, Jean Nantais (of Lenco fame) visited me as planned in April, 2017, and eagerly agreed to help me with the experiments.

The reason why I felt I required assistance with the Acapella TW 1S was simple; The tweeter was much heavier and bulkier than I imagined, even though I had seen pictures of it and had read the relevant specifications (it includes a built-in amplifier and crossover). However, once I actually handled it, I knew immediately it was impossible for it to safely fit on top of the Pure Reference Monitors (my obvious first choice, which proved to be a fantasy). Considering my "options" at length, I realized there weren't any. There was only one real option...

Short of building custom stands for them (which would take up space I didn't have, even ignoring the extra cost), all I could do was place the tweeters on the tops of the Pure Reference Subwoofers!? Yes, the resulting issues and questions with this "solution" are both obvious and inevitable: 1. Will the vibrations from the subwoofers compromise the tweeters? 2. Will the extra height of the subwoofers, and their backward position in relation to the monitors, compromise the cohesiveness of the signal and music? Only actual auditioning would answer these important questions, as you will find out below.

Meanwhile, I had the first basic logistical question to answer: Would I risk placing the tweeters, all by myself, on top of the subwoofers? For me, it required a ladder and extremely steady arms and hands. One serious slip had multiple consequences: A broken tweeter for certain, plus most likely either a broken amplifier (Frankenstein 300B) or a broken speaker (Pure Reference Monitor), since both of them are directly below the subwoofers. In a worse case scenario, maybe all three components broken at the same time. Even a slight slip meant the top of the subwoofer would be seriously scratched. I felt that while such a catastrophe had maybe only a 5% chance at most of actually occurring, that 5% was still too much of a chance for me to take. Thus 22 frustrating months went by.

Jean Nantais (JN) and I spent 4 days and (late) nights experimenting with these tweeters. We positioned, removed and re-positioned the tweeters multiple times, taking turns lifting them into position. I did all the crossover work, including the important calculations, along with the capacitor choices and soldering (see pictures below). Jean, in turn, helped me to acoustically isolate the tweeters from the subwoofers, properly angle them for optimum cohesion and also make certain that they would never slide off the subs.

Further, some basic information: The tweeters have an RCA input, since they have their own dedicated tube amplifier. The volume control is external (in the rear), but the crossover is inside the unit, requiring a side panel to be removed. Changing the crossover frequency requires inserting specific capacitors into tiny slots (see picture below). The Acapella crossover is 12 db/octave (second order). The stock crossover frequency is 8500 Hz. The tweeters turn on automatically, in stages, when they sense a moderate level signal (like many contemporary subwoofers), and they also shut off automatically when they sense no signal for around 15 minutes.

Finally, the actual results...

Nantais and I didn't get to the Acapella super tweeters for a few days. His last visit was three years ago (2014), so we decided to first re-optimize the (Reference Lenco) turntable and the phono system. By the time we finished the phono optimization, we had improved sonics along with the added bonus that JN had re-familiarized himself with my system and could now easily notice slight differences.

As it turned out, our first experiment, conducted initially in the afternoon and then later in the evening, actually consisted of two separate and independent "stages". The most important experiences and insights, specifically about the Acapella (positive and negative), as well as about super tweeters in general, were acquired during these two first stages. The two remaining experiments, discussed below, were also illuminating, but they are more accurately described as refinements in comparison to the "big picture" results of the first experiment.

First Stage- After the tweeters "snapped on" and the system warmed up, the first stage commenced with JN and I listening intensively. Frankly, neither of us was impressed, initially or even after an extended period of time. In fact, we both soon began to wonder, eventually out loud to each other, whether the system had actually gone backwards with the addition of the super tweeters. Yes, we could easily hear the extra high frequency extension and speed, but everything else was somewhat "confused" and imprecise. Overall, this was a major disappointment. So we obviously asked ourselves, what could be the cause of the problems?

It could not be subwoofer related, because they weren't even turned on at this point (it was still in the afternoon and I rarely turn them on during the day). Further, the music we played wasn't even that challenging. Fortunately, I had anticipated exactly this kind of result and had planned for it. I asked Nantais to leave the room, to reduce any bias on his part, and made a single change to the system: I now rolled-off the monitors above 8500 Hz, the exact same crossover frequency as the Acapellas, using a capacitor network going from hot to negative (see picture).

The Details- Before JN's visit, I had opened up the Acapella cabinet to learn the stock crossover frequency. I then researched the monitor's impedance (two of them in parallel), used the standard crossover frequency formula, and built a high quality (all film and foil) capacitor network to roll-off the monitor at the same frequency as the Acapella. I used wires with alligator clips, allowing me to use the caps, or remove them, in seconds. (I asked JN to come back after an appropriate period of time, which wouldn't tip him off, and we began the "second stage" of our listening session.)

Second Stage- We both noticed a dramatic improvement almost immediately. While the sound still had the extension and speed we heard before, it was now also highly precise and intelligible, instead of being diffuse and congested. The sound was also cleaner, with greater instrumental separation, as well as improved focus. The soundstage was better defined, with a much clearer sense of the recording space, and the decays lasted longer and in a realistic manner. It was like hearing one natural voice again, instead of two artificial voices arguing and interfering with each other.

So we had found "the critical key" for a successful implementation of the super tweeters, and through direct experience; The monitors had to be rolled-off as well, at the same frequency, or they would noticeably interfere with the super tweeters in a disastrous fashion. In short, the high-pass super tweeter crossover frequency had to match the crossover frequency of the low-pass (monitor's) tweeter. If this was not done, there would be "sonic chaos" in the entire frequency range in which the two tweeters simultaneously played. In this case, between 8.5K and 20K+ Hz.

We next experimented with the volume of the super tweeters, matching them with the monitors' tweeters and, after being satisfied with the results, we shut the system down for the afternoon. Later that same evening, we turned the system back on, this time including the subwoofers. We first went through the afternoon play list, but eventually played some highly demanding music as well. We listened closely for any sonic problems that we may have missed in the afternoon session, expected and unexpected, especially now that the subwoofers were engaged and the potential problems they brought along.

Here is what we also discovered through these initial day and evening experiments:

1. The subwoofer vibrations did not cause any noticeable problems, and we listened specifically for them. This was verified many times by playing the same recordings with the subs off and on, and was verified again when my second friend visited me a few weeks later. This result was not surprising when you think about it. The Coincident subwoofer has outstanding cabinet structural integrity (175 lbs each). Better, its top plate is extremely thick, and the tweeter is located at its deadest part, the front joint. The Acapella is even further acoustically isolated with damping material.

2. There was also no noticeable problems caused by the location of the super tweeters, with its extra height and distance from the monitor's tweeters. The focus and separation were outstanding, even better than before. There was absolutely no "fun house mirror" effect, that can be noticed with out-of-phase reproduction. However, it did take careful positioning and the angling down of the super tweeters to achieve the optimum level of performance. We first used paperback books, though we eventually used Nantais' much more elegant and functional "little isolation platform".

3. JN and I also listened to the monitors rolled-off above 8.5k, and with the super tweeters turned off as well. The end result was now a "mellow and sweet" speaker, but surprisingly satisfying, mainly because most of the high frequencies were still present. I can understand why someone would prefer this type of sound, especially with poor recordings (digital and analogue), even though it is not true "hi-fi". Actually, I once had plenty of customers who preferred speakers with a "forgiving" sound. JN had the last word, he said "it sounds just like a vintage speaker".

4. We even listened to the Acapella super tweeters on their own (to break them in without having to turn on the entire system). We were surprised yet again. This time we couldn't get over how much of a positive effect the super tweeters were making considering how little actual sound we observed coming directly from them on their own. In fact, at certain times it almost sounded like virtually nothing was turned on and playing.

5. Finally, we also heard another benefit from rolling-off the monitors' tweeters: The listening "sweet spot" had expanded from just one seat in the middle, to all three seats. While this obviously wasn't important to me when listening by myself, which is 90+% of the time, it is important when I have guests. Since I had lost the two side seats when going to double monitors per side (which meant two tweeters per side), I can only surmise that the roll-off decreased the interference caused by the two Coincident tweeters operating simultaneously in the highest frequencies.

Our first night's listening sessions lasted until very late in the evening. I was exhausted, but still excited, especially considering how we had overcame the disappointing initial results. I also had another reason for my excitement. I was acutely aware that the crossover capacitors in the Acapella were basically "junk" (and that is being kind), which meant that there was plenty of room for improvement (the double-edge sword), so I was really looking forward to our next day's experiments.

The next morning I did an inventory of my small value (.02 uf or smaller) capacitors, new or used. All of them were either Teflon or polystyrene (2nd best to Teflon in my experience). Most of them were in the picofarad range. I soon discovered that I was not able to exactly match the 8.5K crossover frequency of the internal stock capacitors, but I came pretty close, 8K. I didn't believe such a small (Hz) difference, by itself, would be noticeable. I also discovered that the capacitor insertion openings were too small for the V-Cap Teflons, so I used the REL cap Teflon caps instead. I also, of course, lowered the roll-off crossover frequency of the monitors to 8K as well, so there would be no overlap in the system frequency range.

The system was powered up and we listened once more to the same (now by default) reference recordings from the previous day. Once again, we almost immediately heard an easily noticeable improvement. However, we also agreed that it was definitely smaller, in both scale and importance, compared to the critical improvement we experienced the previous day. The sound was even purer than before and there was also a greater sense of the original recording space, which is an important element if the goal is to "take down your guard" and help you believe what you are hearing is "alive" and "real".

I was quite happy with our efforts at this point. I also wondered whether anyone else had ever changed the Acapella's internal crossover caps to the best available, or was I the first? There is no record of this capacitor upgrade happening that I can find and, to put it simply, if you don't use the best capacitors, then you will never hear the full capabilities of the Acapella ion tweeters. Meanwhile, we now had to make another decision, this time concerning the crossover frequency.

The only option I ever considered was attempting to lower it, but how low? I knew we should try 5K eventually, which is the lowest frequency limit of the Acapella (without any sonic compromises). My first inclination was to change the frequency in two separate stages: first from the current 8K to 6.5K, and then go from 6.5K down to 5K. However, after discussing this scenario with Jean, and contemplating all the extra work that was required to build four crossover networks and installing/uninstalling them, plus the added changes necessary to roll-off the monitors also at different frequencies as well, we decided to go to 5K immediately, and skip the 6.5K interim step (which became "Plan B").

It was a long and tedious job to change the crossovers of both the Acapella tweeters, plus the Coincident monitors (see picture). We had no idea what to expect, since it could be incredible, or a disaster in a worst case scenario (a cohesive, a spectral and/or a phase total mismatch). As it turned out, it was a complete success. There was another improvement, definitely larger than the second experiment, though still not quite as important as the first (Second Stage). Overall, this was a very satisfying change. In fact, when I considered the overall cumulative improvement in performance, starting from no Acapella tweeters, I had reached the (crossing the Rubicon) point where I could now genuinely state, with conviction, that "I couldn't live without them". This was no longer simply a nice refinement, what we were listening to now was effectively a new speaker, which was also literally true. The details...

The mid and extreme highs were still the same, meaning the added extension and purity didn't change. However, the lower highs and upper midrange did change, and all for the better, which had a large impact in many areas. There was first a greater overall feeling of immediacy and presence. Most instruments were now faster, cleaner and more precise. This was especially noticeable with the percussion family, but it was also true with any instrument operating in the higher frequency ranges. These improvements included all voices, and especially sopranos. The sense of space and natural decays were also once more enhanced. Further, the musicians playing at the back of the soundstage were now better clarified.

Overall, this improvement was major in scale. It was only less important than the "Experiment One-Second Stage" because that one change critically removed the monitor's tweeters' interference, thus enabling all the benefits of the ion super tweeter to be heard in the first place.

While both Jean and I were excited with the results of the new Teflon 5K crossover point, we decided that after all these different changes, we should go back to the very beginning, and once again audition my audio system without the Acapella tweeters playing. We did this for two reasons; first to allow us to hear, and appreciate, the entire extent of the sonic improvements and, as a bonus, it would also make it easier for us to make any adjustment, if required, to the volume level of the super tweeters in relation to the monitors.

This was a difficult task, and required a second person for verification (another reason why the audition delay was necessary). Changing the volume level of these super tweeters is similar to a VTA change (or even using "tone controls" in many decades past). We ended up using only a few discs, all of them CDs. CD was our best option in this instance because we needed a source that could be played multiple times quickly and without any sonic change (potentially caused by vinyl deformation and/or volume). We ended up choosing high quality recordings using jazz horns and woodwinds, plus piano and some ancient music as well. In the end, the jazz instruments were the most revealing and important, and in particular one CD: Blue Sun - Mark Isham - Columbia CK 67227.

Our Methodology- As discussed above, to first establish a reference we could trust, we went back to the Coincident Pure Reference Extreme playing strictly on its own. To our surprise, it sounded much better than we expected, which could only mean that the Coincident tweeters are truly superb. (They are still the finest dynamic dome tweeters I've ever heard overall.) We played the reference CDs until we were ultra-familiar with them, and then we went back to the Acapella ion super tweeters and played the same CDs all over again.

The ultimate goal was for the sound to be both as accurate and realistic as possible (yes, they are closely related). We quickly discovered that with improper settings the system could sound either "forgiving" or "aggressive". (Both are equally wrong, but the former is popular and desirable to many pseudo-audiophiles, while the latter is almost universally avoided.) In general, the "most accurate and realistic sound" offers; the greatest diversity, the least predictability and the smallest noticeable (and least describable) character. From a purely practical perspective, the end result should sound as if the original tweeters have simply been improved, and with no sense that there are two different tweeters with two different characters. The good news- after a couple of intense hours of back-and-forth, with increasingly smaller incremental volume changes, we achieved all of our goals.

A few days after Jean Nantais left, another audiophile friend visited me for a couple of days (he would also visit me a second time around a month later, which was also important and described below). I'm glad he did, because his opinion of the ion super tweeters was more critical than either Jean's or mine. It's not that he heard something that we did not, but rather the weight he placed on what he heard. This requires a detailed explanation:

Unlike Jean and I, my friend had mixed feelings when first auditioning my system with the new tweeters. He observed and enjoyed all the sonic benefits of the tweeters operating at 5K as described above, as we had. He was also quite surprised, as again we were earlier, that the unusual positioning of the super tweeters didn't cause any noticeable problems, even when he was directly listening for them (in fact, he had even warned me earlier about them). However, he still felt that a different sonic downside came along with all the benefits.

My friend argued that the ion tweeters had enhanced the perceived speed of the system in the midrange. This enhancement, in turn, increased the already existing speed differential between the midrange and the bass, which is, of course, inevitable when using different bass and midrange drivers. In other words, the inherent midrange/bass driver dichotomy had crossed his personal threshold, meaning it was now an active problem that he could no longer ignore. He described it as "disjointed".

His specific example was the contrasting left and right hands performing on a solo piano. He felt that while the two hands will always sound somewhat different, as they had in the past, this difference was now more noticeable with the new tweeters. Worse, it had reached that critical point where it now bothered him. My friend also emphasized that this particular problem was only audible with "simple music", where a single instrument was individually exposed. By contrast, he felt it was completely inaudible if the music was "complex", with continually changing volume levels, frequencies and instruments. I generally agreed with him concerning the simple/complex music issue, but I had a different subjective response to the midrange/bass issue on simple music. I felt the change was relatively subtle, and ultimately a trifle compared to all the benefits of using the Acapella super tweeter.

My Friend's Second Visit- This was a month or so later, and my audio system had changed again during this short period (details forthcoming), and this particular change had improved the bass reproduction. In fact, the improvement was significant enough, in my friend's estimation, to change his perspective. In short, he now felt that the midrange/bass problem, while still noticeable, was once again small enough to be easily ignored, and so he left a happy man.

Relevant Links:

Acapella Manufacturer

Further information on the Acapella

Note- The foam is being used to dampen the capacitors' micro-movements, which could be the cause an audible distortion.

THE REFERENCE SPEAKERS

THE REFERENCE COMPONENTS

AUDIO CRITIQUE

THE RECENT FILE

The Supreme Recordings

My Audio System

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