REFERENCE COMPONENTS-VINTAGE AUDIO

These are components that were manufactured from the middle 1950’s to the late 1970’s, which is a quarter of a century. They are still sonically competitive with most current models. Most of these older components listed below are incredible bargains when considering their relative performance, build quality and price, especially to those of modern components.

When it comes to electronics, you will only find power amplifiers and tuners listed here. All vintage preamplifiers that I know of are now obsolete compared to the top models made in the last 30 or so years, no matter how extensively they are modified*.

Only three speaker designs of the distant past can hold up to today’s models in my opinion, the original Quad Electrostatic, the KLH Model Nine Electrostatic and the post 1970s Klipschorn. Other speaker models from that "golden era" may have some excellent and unique qualities, but they are otherwise too flawed to compete with recent designs and are for serious enthusiasts only.

As for turntables, I used to believe they all were to be avoided, but I have since profoundly changed my mind**. A number of readers just love the EMT and Garrard 301/401 idler-drive turntables if they're optimized, but none of us has ever heard them in anywhere close to that condition.

*The only two exceptions to this blanket statement are the dedicated use of the phono-stages within some of the better vintage preamplifiers, or if the preamplifiers are, literally, totally gutted.

**The Reference Lenco was an important and unexpected development, and, accordingly, I wrote an extensive essay/review of it in May/June 2010: The Lenco L 75 Reference Turntable. Also included in this new dedicated file are my early and recent correspondence with idler-drive (and rim-drive) enthusiasts, which were also originally located in the Reference Turntable file.

I recently received a depressing letter from a reader who purchased a VTL Ultimate* preamplifier, on my advice, only to see it break down after a few months, with the required repairs too expensive to be economical, at least for this reader, who is in the tube elctronics business no less. So readers, please...

When you are buying an audio component used, especially an older tube unit from an unknown source, make certain there is some previous "feedback" or some resource if there are problems. Either that, or make sure the price you pay is low enough to allow you to still spend something to bring it up to top "stock" performance. (Modifications can come later.) Ideally, you should hear the component in your own system, and check it out personally, BEFORE the purchase. Fortunately, the nightmare this upset reader experienced is relatively rare, at least in our audio world, but always be careful before you make your commitment.

*This preamplifier is generally reliable, so I'm not trying to make an "example" out of it, but the reader informed me that the (VTL) factory won't be of any help (with schematics or parts lists), so be extra careful with it.

A reader sent me a letter advising me to post some common sense "cautions" when purchasing "vintage components". I should have done this years ago myself. Here's his list, which is more thorough than what I would have posted on my own. Any reader, who thinks he can add something to this list, is strongly encouraged to share their thoughts. With some minor editing, here it is:

"1. Do NOT plug in ANY piece of vintage tube equipment, EVEN if the owner says he's had it running recently. Old capacitors can not take the shock of throwing line current through them, if they have not been used on a regular basis.

2. ONLY test vintage tube equipment if you have a variac, or similar variable power supply to SLOWLY apply current to said piece of vintage tube equipment. This will allow the capacitors to slowly reform, and prevent things from just plain blowing up in your face!

3. ALL vintage tube equipment should, at the very least, have the selenium rectifiers replaced with modern silicon diode equivalents, if you plan on using the amp again.

4. Ideally, replace all power supply caps, and strap new caps under cans if the cans are shot. This will make for a much more reliable and stable power supply.

5. Old audio couplers are most likely leaky and sound very bad. Modern caps again will greatly improve sound quality.

6.* Lastly, all above listed recommendations WILL degrade the value of vintage equipment. ONLY do the recommendations if you do not care about preserving a "museum piece", but want to have the safest and best sounding vintage equipment possible. If you do not want to alter the original components, then DO NOT use said piece. Just have it on display like an antique."

*Personal Note- For those audiophiles who want to retain "the value", while also enjoying "the safest and best sounding vintage" components, I advise taking some detailed pictures of the component before any modifications are made, and also retaining all the original parts. Then the component can always be put back into its original condition for top resale value.

These amplifiers generally approach the performance of the "modern" designs I've placed in Class C and even Class B, but only if they are modified and care is taken to optimize their strengths (and minimize their weaknesses) within a system. They all require some modifications; improvements to their passive parts and maybe replacement of the electrolytic power supply capacitors and speaker binding posts to allow the use of modern cables.

The main difference between these "vintage" amps and more modern amplifiers, is that they (the vintage) usually have less power and current (plus a lower damping factor), so they are at their best normally with high-impedance and high-sensitivity speakers.

DYNACO STEREO ST-70 & ST-35, MARK II, III & IV- These are the best known and most popular amplifiers ever made, and deservedly so. They are perfect as entry-level components and more. They also can be modified, are very reliable and always hold their value. Their sonic worth is enhanced today because an increasing number of speakers have been designed and optimized to work with them (high sensitivity and high impedance models). These amplifiers offer outstanding performance value for the money with these suitable speakers.

Their other amplifiers are not references, and that includes the grossly overrated and overpriced (and unreliable) MK.VI (which I owned for years, and actually built myself from the kit).

HEATHKIT W-3M, 4M, 5M & 6A- These amplifiers were underrated for years by audiophiles fascinated by more high profile names. They are all mono and best bought in matched pairs because Heathkit made continual minor changes to them.

These, and the other vintage amplifiers, should all be updated with better capacitors. In some cases the filter capacitors must be entirely replaced. The 6M amplifier has had serious problems with biasing, which is why it is not a reference (unless you're a technician). The Heathkit amps only serious weakness is poor bass reproduction.

EICO HF-14, 22, 30, 35, 50 & 60- These amplifiers, all mono, have a similar story to the Heathkits’ above. They are all are "industrial" looking, but still very well built. To find out more about all their amplifiers, check out Vacuum Tube Valley and search the Internet.

AUDIO RESEARCH CORP. (ARC) D-51, D-75, D-76, D-79 & D-150- These amplifiers all come from the generation succeeding all of the amps above, but they are now more than 30 years old themselves, so they can finally be considered vintage without compromising the term.

They are more dynamically exciting at high volumes than the other vintage amplifiers and they also have more power. They are very well built. Their one downside is that their circuits are more complex, which may make them sound more mechanical, drier and (sometimes) less natural. On the other hand, they are generally cleaner, more neutral and have less of an "old tube" sound than some of the other vintage amps (especially if those other tube models are not modified). All these models are stereo. Despite being more recent, they still should be modified.

QUAD II- A superb little amplifier with between 15 to 20 watts. Only desirable if it's purchased at a reasonable price; at most $ 800 U.S. Otherwise get the Dynaco Mk. IVs or the Heathkits that use the KT-66/6L6 tubes. The recent, updated version of this amplifier is absurdly overpriced.

LUXMAN MB-3045- An excellent sounding amplifier. Beautifully built, but rare. Sound quality is similar to the Quad II, but it has more power. Very desirable. 1970s vintage.

Caveat- A number of owners have had "reliability problems" with these amplifiers. Since they have a straight forward design and are well built, I initially felt that it was mainly "user abuse", rather than an inherent flaw. However, there have been too many negative reports to blame solely on the owners. Also, their output tubes are somewhat rare and difficult to replace. Potential buyers should test the amplifiers first, or have some form of recourse if they are or become "problematic".

STROMBERG-CARLSON AP-428- These amplifiers are from the 1950s and are rather rare these days. They are mono and similar to the Heathkit WM-5. They have regulation for the input tubes, a larger output transformer and much better bass than the Heathkits.

STROMBERG-CARLSON AP 55 MONO BLOCKS- This is probably the finest vintage pentode amplifier I've ever heard. It uses four 6L6 outputs tubes, a 6SN7 input tube (see below!), a 6N7 driver, plus three 5Y3 rectifiers. It was also highly modified:

1. Better coupling caps and resistors
2. Power Supply caps changed to all polypropylene
3. Volume pot removed
4. Speaker binding posts/RCA female replaced with modern equivalents
5. Internal wiring replaced with modern interconnect cable
6. IEC jack installed for utilizing a modern power cord
7. "Roll-off" circuit removed.

The amplifiers, driving the Coincident Total Victory II, which are both highly sensitive and an easy high-impedance load, were unusually clean, dynamic, transparent, immediate and captured both the frequency extremes. They had virtually none of the typical "tube sound" of most vintage tube amps; slow, overly warm, loose and weak bass, rolled-off highs etc.

CAVEAT- The input tube, a 6SN7, is highly critical to the performance of this amplifier. In fact, I've never heard, in more than 30 years of comparisons, one tube make such a huge difference in sound quality. We used two high quality 6SN7 NOS tubes; GE and Sylvania. The Sylvania was far superior, to the point where the amplifier was, literally, totally transformed; meaning it actually sounded like a different amplifier. My two fellow listeners agreed with this assessment.

AP 55 Vs. Hurricanes- While I was not able to make a direct comparison myself at the time, my associate told me that he prefers the Stromberg-Carlson amplifiers, after the above listed modifications, overall, to even the latest ASL Hurricane. In his own (paraphrased) words; "the Hurricane still has minimal advantages in power and impact with the Victories, but the AP 55 is more natural, transparent and less electronic sounding. The high frequencies are also more extended on the AP 55." He believes the sonic advantages were due to "the simpler circuit, fewer output tubes, custom made output transformers and all tube rectification" of the Stromberg-Carlson amps.

AP 55 Vs. Coincident MP 300B- This time I made the comparison myself. Prologue- I've heard the Coincident amplifiers a number of times now, at great lengths and with both equipment and software I am intimately familiar with. The last time I heard them, in October 2003, they were simply superb, though they had problems in the bass, due to (according to the importer, Israel Blume) their (then) stock 300B output tubes. This time I heard them with the (now stock) Electro Harmonic Gold Grid 300B. There's no question they're a noticeable improvement over the former 300Bs. The bass is better defined, deeper, cleaner and with more impact and punch. There may be other improvements in the mids and highs, as Blume claims, but I couldn't confirm them in these limited circumstances.

After a proper (30 minute) warmup, it soon became obvious that the MP 300B was to the AP 55 as the AP 55 was to the (described and remembered) Hurricane. In short, the MP 300B was cleaner, more transparent, more immediate, and less electronic than the AP 55. In turn, the AP 55 was still a little better in the bass and dynamically. This was all easily noticeable, but a particular comparison of two records demonstrated the sonic superiority of the MP 300B in a manner I've never experienced before. (To read about this, go to the Amplifiers File, and check out the Coincident MP 300B essay.)

MICHAELSON AND AUSTIN TVA-1- This amplifier came out more than 30 years ago. It is stereo, large, well built and heavy (80 lbs). It uses two KT-88 output tubes per channel and has a rating of 75 watts per channel.

It has a number of strengths; it is clean, powerful, natural, very dynamic and has excellent bass, with both impact and control. This amplifier has more "guts" than many 200 watt per channel amplifiers I've since heard, and it will work with an unusually large variety of speakers. It is a little "crude" sounding compared to some of the best contemporary designs.

This amplifier has always had an excellent reputation, and it's somewhat rare, so the used price is still virtually the same as when it was new. This steady demand, and its ultra rare price stability, confirms to me what I have long felt about the TVA-1: It is a "Classic".

Further- A reader sent me some information which may help the owners of this very fine amplifier optimize its performance. With some minor editing:

"I own the M & A TVA-1. It is as you describe: very dynamic, fabulous bass and enough valve musicality to make it very satisfying. In my humble opinion, music ain’t music without appropriate drive, impact and slam. For the money I paid - $1000AUD, the TVA-1 was a great buy.

I might add that the 12AX7 input valves are absolutely critical in the TVA-1 circuit. With 1950’s Mullard 17mm long plate ECC83’s in the input, and similar Mullard’s as drivers + GEC KT88’s, the TVA-1 is very special, and much of the “crudeness” to which you refer is eliminated.

With new production valves as input and drivers, the sound is bright and forward. The same applies for the KT88’s. Unfortunately, the cost of my NOS valves is more than I paid for the amp! Ah, but who cares. I have great music and that’s what counts." (7/04)

Personal Note- While I do have a lot of experience with the TVA-1 (in my former store during the 1980s), I only experimented with the output tubes and never with the input tubes. Accordingly, it's possible that successful input "tube rolling" may provide superior sonic performance, as this reader claims.

I have long preferred good vintage tuners above the tuners manufactured today, or from the recent past. They are less expensive, better built and usually sound much more natural. You just have to find them, which is easier than ever considering where this is being read. (The finest tuners made today are probably the expensive tube models from Magnum-Dynalab.)

Also, I must point out that some of the finest sound I've ever heard was from a local FM station broadcasting live (or even taped) concerts. Unfortunately, this doesn't happen too often these days, but it still can, so having a good tuner should always be a serious consideration.

MCINTOSH MR-67, 71, 78 and 80- All of these tuners are "classics" and among the finest tuners ever made. The 78 and 80 are solid state and have superior RF capabilities, but the sonics are not quite as good as the tube models. All are as good or better, if aligned properly and updated, than any tuner made today (at least that I've heard). Every McIntosh tuner ever made is at least "very good", and is also well built. I'm not as impressed with their amplifiers, though some of the tube units were quite good. Their tube preamplifiers were just fair (unless the phono stages are used on their own).

Further- I was also very impressed with the McIntosh MX110 tuner/preamplifier, which I owned years ago, and I even had one in the store just before I left Toronto. According to one reader, the MX110 has a tuner similar to the MR-67. The performance of the preamplifier section is respectable. The build quality is excellent as usual.

Caveat- A different reader informed me that "the MX 110 had some less-than-common (today) tubes in its circuit, and your readers may want to check availability of replacement tubes before purchasing the unit." This advice is also true for many other tube tuners from the "Golden Age of Audio".

The earlier reader also informed me that the MR-77 tuner, a model that I don't believe I am familiar with, actually outperforms the more famous MR-78 in sonics:

The MR-77 is "a better sounding tuner than the MR78 with (less) phase shift and wider frequency response because if does not have the ultra sharp cutoff used in the 78 to get the adjacent channel ability. It was design(ed) by Richard (Modafferi) along side the 78 and uses the same RIMO filter. It does not have the narrow band switching and therefore less capable for DX'ers. It was for this reason the 77 was redesigned into the 78, not for ultimate sound quality but to beat the competion at one thing - DX'ing."

SCOTT 310E, 350C and 4310- The 310E & 350C are great buys for the money, while the 4310 is one of the finest tuners ever made. Some audiophiles feel it is even better than the Marantz 10B. It is extremely rare and usually very expensive (unless you get lucky!). Generally speaking, the Scott tuners are more desirable than their Fisher "counterparts".

FISHER 100B and 1000- The 100B is probably the very best value for a vintage tuner, considering both sonic and build quality. It is preferable to the Dynaco FM-3 in every way, but it’s obviously rarer and costlier. The 1000 was Fisher’s finest tuner and one of the very best ever made for that matter. A true collector’s item, both rare and expensive.

CAVEAT: The Fisher 1000 must have a circuit modification to achieve its full sonic potential. The (overly complex) cathode follower and output stage must be totally removed, so that the output signal will come directly from the multiplex adapter. This is highly detailed work, and should be done only by a qualified technician.

FURTHER: It is possible that the Fisher 200B tube tuner may be an even better value, if modified, but I have heard differing opinions on this subject. I will try to get some direct experience with this model.

SANSUI 9900- This is the best value of the vintage solid-state designs I've heard, and it's built "like a tank", inside and outside. It came out in the early 1980s. It is full-bodied and clean, but somewhat "dark" sounding, so the ultra-highs may be rolled-off.

YAMAHA CT-7000- This is another outstanding component that should have been part of the list from the very beginning. I don't have extensive experience with this tuner, but I remember that its sound was superb, it picked up a lot of stations and it was beautifully built. It was deceptively elegant and simple in appearance, because most of the controls were hidden behind a front panel. Highly desirable. (For me, this tuner was "the one that got away".)

DAY SEQUERRA STUDIO TUNER- This is a superb tuner, the best value ever made by Day-Sequerra. It supposedly even sounds better than the much more expensive "Broadcast Reference", according to Stereophile, in a courageous (for them) review by Larry Greenhill. Their latest model may sound even better, but it will cost much more. These models are probably the finest solid-state tuners ever made.

TANDBERG TUNERS- All of them were at least excellent, and "the top of the line", the TPT-3001A, is one the finest solid state tuners I have ever heard, and is even competitive with the Day Sequerra Studio and the McIntosh MR-78 & 80. It does have possible problems with repairs though.

MARANTZ 10B and 20- The 10B is the most famous tuner ever made and it's also the best sounding that I have ever heard, or am aware of, if it is properly aligned and optimized.

Its sonics strengths are an unprecedented naturalness, a huge soundstage, excellent separation of instruments and superb retrieval of low-level information, including "dynamic contrasts". The bass reproduction is its main weak point. It is also not quite as "refined" or as "sensitive" as some of the finest modern transistor models listed here; the Day Sequerra, McIntosh, Tandberg, Yamaha.

Unfortunately, the 10B costs a lot of money and it is also very difficult to maintain. A serious FM enthusiast should always have an excellent backup tuner when investing in a 10B.

The Model 20 was an economical, solid-state version of the 10B and it also had an oscilloscope. It has very good sound and is also very well built. The later Marantz tuners did not sound as good.

10B CAVEAT- Potential purchasers of the 10B should always find out about the current condition of their photocells. Why? They almost always eventually "break down" and are critical for both the muting control and the mono/stereo switching to work properly. They are difficult and expensive to replace (around $ 400). I've heard that they can be "bypassed" if necessary, but this is a labor intensive job, and will also be expensive.

Further Information A reader, from Germany, sent me this letter with some of his observations and what could be some important information concerning the Marantz 10B tuner. After some minor editing:

"(I) read your comments about the Marantz 10B tuner. I had several of them, and love it. The Scott 4310 and 310E are as good, but different. The 10B sounds more like a beautiful pentode amplifier with NOS KT88s, while the Scotts (not the 350's) sound more like SE triode amps. I had once a NOS (From Angela Instruments) Fisher FM 1000, that was wonderful as well.

Marantz 10B Photocells: This is actually a minor problem: They leak usually, because they are not properly closed anymore. They let light in then (sorry for my bad English). All that needs to be done is to carefully open them and laquer them newly. That's all, and then they work fine again. No need to get new ones."

Personal Note- I'd love to hear the Scott 4310, but they are real difficult to find.

Marantz also made, of course, some very famous tube amplifiers (the 8B and 9) and a tube preamplifier (the 7C). They are not desirable because their typical purchasing costs are much too high in relationship to their actual sonic performance. (Of course, if a "real deal" becomes available, that is a totally different story.)

In purely sonic terms, both amplifiers are excellent, especially after routine modifications. The Model 9 monos are still competitive, on the appropriate loudspeakers, with all but the finest amplifiers made today. The 7C preamplifier is a different story. Unless it is seriously modified, meaning "totally gutted", it can not equal the performance of the better (now used) preamplifiers from the 1980s, let alone of today. I actually heard a fully rebuilt 7C on a number of occasions, which was owned by an audiophile friend of mine. The work was done by the original designer, the now late Sid Smith, and it was an excellent performer.

The recent "reissues" are also not worth their asking price. The 7C is particularly overrated. In fact, in overall sonic quality, it is not even equal to most of the Class C preamplifiers, despite the expensive retail price and what has been written elsewhere (TAS). Its overly complicated layout was obsolete years ago. This enthusiasm is just simple nostalgia.

DYNACO FM-3- This unit is very easy to find as many thousands were made. All the tuners above outperform it, but it can still sound very good. I recommend waiting for one in mint condition, both visually and sonically. This is the unit to get if you are on a very tight budget, or FM reception is not a high priority.

Relevant Anecdote- I still remember comparing a FM-3 to a Magnum-Dynalab FT101A on the Toronto CBC FM classical station, while it was broadcasting a live (or on tape) orchestral concert, and the FM-3 proved to be noticeably superior in sonics. I was shocked at the time. The Magnum Dynalab was much more sensitive and quiet though. That revelatory experience compelled me to listen to every tube FM tuner I could find for the next 10 years. I heard most of them, and ended up with the Marantz 10B.

The solid-state version of the FM-3, the FM-5, doesn't sound as natural, but it is more sensitive and has both a selector switch and a volume pot, so it can also be used as a simple line preamplifier.

ACCUPHASE T-100- I've seen and heard this tuner on many occasions, though I don't recall auditioning it for a lengthy time within my own system. I do remember that it was sonically competitive with the finest of the competition, and that it was also beautifully built, a pleasure to use and very reliable.

As for its sonics, it was smooth, quiet, clean and detailed, and with no "rolloff" of the frequency extremes. A true alternative to the better McIntosh and Tandberg models. It beat out all the (transistor) Magnum Dynalab models I was selling at the time. The owners of this tuner were always very satisfied with it, which is probably the highest and most important observation of them all.

Marantz 10B "Competitors"- Not everyone feels that the Marantz 10B is the finest tuner ever made. Here are two contrary opinions I've received (and edited) from real "Tuner Freaks" (my phrase):

"There is one FM tuner that beats them all. It is the REL tuner. (Radio Engineering Laboratories) This tuner was designed and built by Major Armstrong himself who owned part of REL. It was made after the Korean war and only a few hundred were manufactured before it was withdrawn because it cost more to make than it was sold for. It was a mono tuner but there was provision for a one volt multiplex output. When used with a good decoder, it is BY FAR the best FM tuner ever made. It was designed for continuous operation and has a hollow chassis. Radio station WNCN used one for years as their monitor and they used to be able to bring in their Boston affiliate direct from atop the Hotel Pier in NYC. It had a sensitivity of 2 DB for 40 DB of quieting. Saul Marantz made a copy prototype but decided against reproducing the tuner because it would be too expensive."

"The Rohde Schwarts were made in early to mid 70' for the German broadcast industry (as monitor relays) and they sold at that time for 22000 marks...They were used as relay receivers and their sound quality is simply outrageous. They blow away my Marantz 10b in sound quality, staging, resolution and low frequencies. They are better than my Mac 67b and Md 102 (Magnum Dynalab) that I sold last year. I just wanted to bring these to your attention because they (tuner and stereo descrambler as a pair) may constitute the best analogue FM reception in the world and I thought you may consider them in your discussions." (10/03)

CAVEAT-Please be advised that the readers’ letters posted on this site are solely the opinion of that reader and may not necessarily represent or reflect the opinions of Arthur Salvatore or High-End Audio. These letters furthermore, are not to be taken as being endorsed by Arthur Salvatore or High-End Audio. They are posted because they may be edifying, thought provoking or entertaining.

MARANTZ 10B TUNER- A reader sent me some information concerning this legendary tuner which appears to update (and contradict) what I have previously posted about it within The Vintage File. Here's his letter, with only some minor editing, and, in this instance, the reader also requested attribution, and I've obliged him.

"I have been reviewing some comments you have posted on your site regarding the Marantz 10-B tuner. Some of these I find highly misleading. In particular, I wish to comment on the following (comments now posted on your site):

'10B CAVEAT- Potential purchasers of the 10B should always find out about the current condition of their photocells. Why? They almost always eventually "break down" and are critical for both the muting control and the mono/stereo switching to work properly. They are difficult and expensive to replace (around $ 400). I've heard that they can be "bypassed" if necessary, but this is a labor intensive job, and will also be expensive.'

The photocells in question are known professionally as LDR’s (light-dependent resistors). They consist of nothing more exotic than single or double cadmium disulfide photo cells positioned on one side of a common NEON pilot lamp (for monaural switch), or on both sides of a NEON pilot lamp (for stereo switch).

The same applies to the muting switch (single cell, single NEON lamp). Replacement internal component parts can be found right on the shelves of most Radio Shack stores. To restore them, all that is needed is to unsolder them, remove them from the tuner and slice through the housings vertically with a jeweler’s saw blade, remove the components and replace in-kind with fresh parts. Then, you reseal the container with electrical tape and reinstall them. $400 to repair them is absurd.* The parts should not cost more than about $10 total for all three of them, plus your time.

'Marantz 10B Photocells: This is actually a minor problem: They leak usually, because they are not properly closed anymore. They let light in then (sorry for my bad English). All that needs to be done is to carefully open them and laquer them newly. That's all, and then they work fine again. No need to get new ones.'

This, too, is very misleading. I have never heard of any original Marantz LDR network leaking light. The units in original condition are mounted in such a way that unless they have been physically disturbed or messed with, they normally cannot “leak” light. The most common failures are caused by intermittent or burned out NEON lamps within the housings or deteriorated cadmium disulfide photo cells. Incidentally, early examples of the LDR modules were cylindrical, whereas in later production, the modules were made in a long rectangular shape.

It amazes me to read such misinformation, when such common failures can be quite simple to resolve. I personally own three of the 10-B tuners and can attest to the ease with which these repairs can be affected."

Personal Notes- "Absurd"* is the correct word for the normal world, but not within our crazy "audio world", where I have seen even worse repair, modification, accessory and component rip-offs. Richard Links seems to know what he's talking about, so competent owners of the Marantz should find the above information very helpful for DIY repairs. The others are at the mercy of their local technicians, but I would still make a copy of the Link's letter, which may prove helpful when negotiating the repair costs.
Further- Richard Link sent me some more information, which may also prove helpful. Here it is...

"It is unfortunate that the Marantz Company did not apparently release an official service manual on the 10-B. If they had, matters might have been better for all of us. Tom Cadawas is the leading expert on service issues surrounding the 10-B, however."

I received a letter from a reader regarding these amplifiers, which I barely even remember. I don't have any clear memory of ever hearing, let alone owning, a pair of any of their models.

"I wanted to ask if you had ever had any experience with any of the Ampex made amplifiers that were used in their high-end consoles? NOT their industrial/theater amps NOR the amps used in the "famous" suitcase amps fitted wit the JBL D216 speakers. There are 5 models that I know of. Monoblock amps running 6V6, EL34 (2 versions, one tube rectified), 6L6 and finally both stereo and mono-block amplifiers using 6973 tubes. (very different amps.)

In my own system, I was running Manley Neo Retros, and did a blind substitution with the 6973 monoblocks with 5 local audiophiles whose ears I trust. Even though we disagree on what we LIKE, we all tend to hear similar differences in sound.

It was with some sadness when I revealed to them that they had unanimously voted the Ampex monos as besting the Manley amps! (running in both SET and PP) Frankly.....given what I had paid for the Manleys...I didn't want to believe it! I have been a tube collector for years, and so had shuffled through DOZENS of different tubes in the Manley's (Primarily the 6SN7 and 6SL7 input tubes where I had gone through about 40! matched pairs of different types over about 3 years of listening. But I accumulated 6-8 different quads of 300Bs, and a dozen or so 5U4 rectifer quads along the way. As you know, the input tubes can make an enormous difference, but even the best combos did not compete with the stock tubes installed in the Ampex when I received them.

I later sold the Manley's, and used some of the proceeds to have the Ampex completely rebuilt for me on custom chassis that were suitable for display. Like the Altec/Tutay amps...they were never really meant for display and so were not "finished". Just bare metal chassis...

I now own one set of each of the other amps just for colectors sake. And while they are certainly not "common", it appears that many hundreds of each were sold and so they regularly show up on eBay. At least for the 6973 based mono amps, I understand that Ampex had the iron custom wound by Triad...which probably explains a good deal of their quality.

In any case, I am extremely pleased with the quality of these amps in MY system. (Stacked Quad ESL's / Wyetech (prototype) Preamp / SME 10 / Musical Fidelity DAC / CD / Genesis Digital Lens / REL Tuner, Wasatch cabling, Bybee filters on the amp inputs etc.), but was curious to hear whether you had ever experienced any of them. I am convinced that (when properly updated) they can compete with quite a few of the megadollar components out there. In any case, I thought they might appeal to you as a somewhat extraordinary audio value. Meaning I believe them able to compete FAR outside of their price range."

Personal Notes- If the above is true, these Ampex amplifiers, or at least the reader's 6973 monos, are one of the finest vintage amplifiers ever made. Even better, they are totally unknown, and/or ignored, by the vintage crowd (though for how long now). Accordingly, as the reader states, they could be one of the very best values around, outperforming many amps that are far more expensive (even after the mods).

Considering this reader's (and his friends!) surprising experiences, and their still reasonable initial cost, I would say these amps are well worth making the effort, time and financial investment to do a total rebuild. That means Teflon coupling caps, high quality resistors, all film B+ power supply caps, a chrome chassis, new RCA females, an AC receptacle and speaker binding posts etc.

A reader recently sent in this short concise observation about three well-known vintage tube tuners, plus something new (for me). Very minor editing and my bold:

"I once owned these units, both in near perfect condition, and did several direct comparisons. While the Scott 4310 was a sensitive and good sounding tuner, the constant clicking from multiple relays was unique to say the least; the pure & rich sound of the Marantz 10B was unbeatable! Both units surpassed my McIntosh MR 71. The 4310’s construction did not compare to the overall quality of the 10B.

Having owned almost every piece of Scott equipment at some point in time, I had interesting results comparing a Marantz 8B (wired for triode) vs. a pair of slightly modified Scott 240 mono blocks (tests conducted with an amplifier switch). Surprisingly the 240 held its own vs. the 8b, other than an ever so slightly lacking bottom end vs. the triode amp. I found the 240 to be an inexpensive alternate to the excellent 8b. My speakers are Klipchorns."

Personal Notes- I have no experience with either the Scott tuner or their 240 amplifier. I can verify the McIntosh/Marantz comparison, since I have owned both of them over the years. The Scott amplifier looks really interesting, considering there's no hype over it (as far as I know), which means it may be able to be found at a bargain price.

"I recently read some comments (see April 2008) sent to you by a reader concerning these units. I have a CR-2020 and would just like to add my 2 cents in the discussion. Here is my impression:

-Extremely good tuner, the best I ever had. Beats the hell out of my Yamaha digital tuner.
-I replaced the pre-amp stage with a B&K Pro 10MC and got better (slightly but noticeable) soundstage clarity and definition of instruments. This may be because the B&K is better or just because the Yamaha is so old. I don't know.
-I am still using the power stage (100+ Watts) and I find that it is quite good. That being said I haven't had a chance yet to compare it to a modern S.S. amp." (9/08)

I received some interesting modification tips from a reader. I have no experience with them myself, though I owned a number of FM-3s over the years. If anyone else can make a contribution to this subject, I will also post it. Here it is, with some minor editing and my bold:

"...There are a few simple modifications (of the FM-3) that can improve its sound. Specifically, replacing the PECs (packaged electronic circuits), which look like multi-legged ceramic capacitors. The discriminator circuit can be replaced with the same circuit made from good quality discrete resistors and capacitors (schematic in the Dyna manual).

The audio de-emphasis circuits (one for each channel) should also be replaced. Whether due to deterioration with time, or incorrect circuit values, they cause a significant roll-off in the high frequencies. Many years ago the Boston Audio Society had a tuner clinic, and reported that several FM-3s they tested had about a 5 dB rolloff at 10 kHz. David Berning designed a replacement circuit which he detailed in a letter to The Audio Amateur, and the circuit was reprinted in Glass Audio Vol 3, No. 1, p. 22. He claimed, that with these modifications, the FM-3 was close to the Marantz 10B in sound quality!" (6/09)

I've long been a serious enthusiast of tube tuners from the 1960s/70s, and I still own one of them today. Here's a letter from a reader which offers a useful perspective on some of the more famous models. There's some editing and my bold:

"The Fisher 100B is one of my favorite tube tuners, in part because it is so relatively simple compared to the megabuck tuners of the period which had innumerable useless bells and whistles. However, there are two versions at least. The earlier version had a stereo-mono switch that used a simple relay, giving a direct signal path. The later version used a biased solid-state diode array for switching. The problem with this is that the signal must pass through these diodes, even if the system is switched manually to stereo.

This is the same array that was used on most later Fisher tuners, and the 500C and 800C receivers. It's an unnecessary piece of over-engineering, that actually degrades the signal compared to a simple relay. In fact, automatic stereo switching is unnecessary anyway, since all stations broadcast in stereo all the time now. So look for the earlier FM100-B.

I also have a Scott 310E, a Scott 4310*, and a Fisher FM 1000*, but they all have problems... My strong bias is that old engineering relics should be in working order, or they are just landfill. Unfortunately, the market doesn't back up my opinion. The worst are the 'audiophiles' who rave over the sound of old amplifiers with leaky coupling capacitors and other grossly out-of-spec parts." (02/12)

*Personal Note- These are among the finest (and rarest) tuners ever made, if optimized.

Here's an interesting and informative letter from a reader concerning vintage (analog) tuners, which I have always favored for my personal use, assuming they are in good working order. There's minor editing and my bold:

"I agree the McIntosh MR-78 is not the best sounding tuner they ever made. The MR 67 sounds better. Also, the Fisher tube tuners sound excellent. I also liked the tube Sherwoods. The thing that made the 78 so great was ability to pull in tough signals. Especially with super narrow selection and selection of filters. These options do improve reception but at the expense of sonics. On the other hand, the 78 could pull in FM stations while the previous mentioned tube tuners would just get static. So to be fair, if reception is a major issue, then the 78 should considered. If the location allows good reception, then the Mac and Fisher tube tuners are cheaper and better sounding.

I would also look into the Luxman T-12 they are cheap with good sensitivity and sonics. Also two ways to improve the sound of the 78. First, get it out the original cabinet and onto some isolation cones. I use Goldmunds. Second, use an open sounding interconnect such as Straightwire. This combination tames the Mac's booming bass and opens the highs giving a more neutral tonal balance. Best of all, they don't require modifications.
P.S. McIntosh will send a photocopy of the owners manual for less than what eBay charges." (03/12)

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