The Quad 66 preamplifier: a design masterpiece

[godofwealth]

Quad UK was established in the 1930’s and is renowned for its electrostatic loudspeakers. But along the way Quad designed great electronics. Their design was always geared at sensibility. Their preamplifiers always had intelligent tone controls. Given that the vast majority of recordings are simply awful (to my ears!), particularly studio pop, the absence of tone controls is a grievous error in modern preamplifiers. Yes, Roon DSP can serve as a tone control, but it is so thoughtlessly designed that it’s useless for the average listener.

I recently reacquired the venerable Quad 66 preamplifier with its distinctive spaceship tablet remote. It’s a design that had been unsurpassed by many more expensive preamplifiers in the area of intelligent tone controls. A touch of the tablet is all you need to make harsh recordings more palatable. The tablet offers different levels of tilt, two HF filters and bass LF step controls. All can be canceled with a touch of a button. One can adjust the tone from the listening chair. The remote tablet is so powerful that it can be placed anywhere. Line of sight is not required.

For once a remote control that doesn’t look like it came out of some generic remote control assembly line. I’ve owned plenty of high priced preamplifiers that have awful remote controls. And no tone controls. Yuck!

The Quad 66 is now really hard to get in working condition. I lucked out in getting a really good version for a few hundred bucks. It has a great moving magnet phono stage. It sounds like whatever you want it to sound like with the clever use of tone controls. No, it won’t give you ARC tube dynamics, but at its price you can’t expect that. But it sounds gorgeous with my Quad 2905. It makes you enjoy listening to old recordings.

Why can’t today’s high end manufacturers design an intelligent preamplifier like the Quad 66? Hope some manufacturers are listening. Folks, you can do so much better. Look at the design of the Quad 66. Learn from it how to design an intelligent user interface.

 

[microstrip]

Nice to read about the 66 preamplifer from another Quad fan! I collect Quad equipment and and own a complete 66/606mk2/CD67/FM66 system with the ESL63, that I listen from time to time with pleasure. As you say, this system is extremely user friendly and well designed - only recently some equipment have got comparable remotes in ergonomics and easy of use. The 606 mk2 is also a bargain, and has an excellent transparency, particularly considering its price and age.

 

[godofwealth]

I’m a long-time Quad collector. I have the original 57’s with the Quad 33/303/FM3. And the newer 2805/2905 ‘s. I still like the 57’s for its “pipe and slippers” sound (caricature of the elderly British gents who used to listen to the 57’s).

 

[Dogberry]

It lacks the remote, but the 34 (and the 44) have the same tone controls. DaDa electronics also sell kits of capacitors to upgrade these older amps (along with ones for Quad power amps).
I had the 66 and 67 CD players, and keep a pair of 34s, an FM4 and a trio of 306 power amps. The II/forty monoblocks and 2905 speakers remain in daily use.

 

[Al M.]

Given that the vast majority of recordings are simply awful (to my ears!), particularly studio pop, the absence of tone controls is a grievous error in modern preamplifiers.

Agreed. Plain stupidity of the industry for the sake of "purism". My Octave HP 700 has an optional tone control, an option that I took.

I hardly ever use it, but it comes in very handy with some bass-anemic rock albums, for example. Just crank up the bass a bit on a few recordings that need it (usually between 3 and 6 dB), and an otherwise not at all enjoyable album becomes very much so.

When I don't use the tone control, as is the case with the vast majority of my listening, it is completely bypassed (you have to press the tone control button to activate it), so there is no loss of quality. Even so, the activated tone control is very transparent.

There really is absolutely no reason for not having a tone control at all.

 

[MarkusBarkus]

Learn from it how to design an intelligent user interface.

...seen here is one of the early Quad owners using the interface. Alas, the future ain't what it used to be.

 

[godofwealth]

It lacks the remote, but the 34 (and the 44) have the same tone controls. DaDa electronics also sell kits of capacitors to upgrade these older amps (along with ones for Quad power amps).
I had the 66 and 67 CD players, and keep a pair of 34s, an FM4 and a trio of 306 power amps. The II/forty monoblocks and 2905 speakers remain in daily use.

Here’s my Quad 33/303 with an Eversolo DMP-A6 that has the same form factor driving my 2805s. Very nice and compact and cool running in hot summer months. There’s an interesting story about the design colors of the 33 preamp. Not everyone was thrilled with Peter Walker’s color scheme — the orange fascia struck people as a bit too tacky. But he was a stubborn old codger who refused to be swayed by public sentiment, even if it meant lower sales. In the end, Quad sold a lot of the 33 preamps. And the new Quad owners have brought it back to life with the 303 amplifier.

 

[microstrip]

Here’s my Quad 33/303 with an Eversolo DMP-A6 that has the same form factor driving my 2805s. Very nice and compact and cool running in hot summer months. There’s an interesting story about the design colors of the 33 preamp. Not everyone was thrilled with Peter Walker’s color scheme — the orange fascia struck people as a bit too tacky. But he was a stubborn old codger who refused to be swayed by public sentiment, even if it meant lower sales. In the end, Quad sold a lot of the 33 preamps. And the new Quad owners have brought it back to life with the 303 amplifier.

View attachment 153635

I consider the FM3/33/303 combo a masterpiece of audio design - so much that a few years ago when an almost new set of latest units showed for sale I sold my old battered units to get this almost mint version. This system was part of my high-end dreams since while I was a student - the father of a good friend has it with JBLs. According to the Quad: The Closest Approach. book around 120000 33 units were manufactured.

 

[ssfas]

I’m a long-time Quad collector. I have the original 57’s with the Quad 33/303/FM3. And the newer 2805/2905 ‘s. I still like the 57’s for its “pipe and slippers” sound (caricature of the elderly British gents who used to listen to the 57’s).

I've owned various quad amplifiers.The TILT control and current dumping amplification are patented, hence not used elsewhere, except Devialet copied the current dumping principle in their D-Premier / Expert / Astra high-end units. I also had a pair of fully restored ESL63, but the wife objected.

All these units are serviceable by Quad at a very modest cost.

The reissued 33/303 has the TILT control (current dumping wan't till later). It is much more than a tone control.

I also have a copy of the QUAD book by Ken Kessler. Rob Flain gave me a copy on a trip up to Huntingdon. It comes in useful.

 

[godofwealth]

Current dumping was copied by many designers, from Nelson Pass to Nakamichi (Stasis amplifiers) to Devialet. But, the essence of the idea was to combine both feedback and feedforward through a bridge circuit. It's a remarkable idea, but typical of the creative genius of Peter Walker. There was a gathering of British audio manufacturers in the first half of the 20th century and a bit later, which Walker would attend regularly. They included some really bright folks, but anytime someone had a hard problem to solve, they'd ask Peter for help, who would always come up with a solution they had overlooked.

My favorite Walker anecdote was one where someone asked him what he thought of his Quad ESL loudspeaker. He replied with a characteristic frankness that is so absent in today's high end audio industry. He said the ESL was a "terrible loudspeaker", but that all the others were much worse! He was always trying to figure out a better solution. It took him 18 years to release the ESL '63, most of that time was to make it more reliable. But it turns out there were a bunch of other designs up his sleeve he came up with after the '63 that never saw the light of day. It's too bad that the new owners of Quad haven't put any effort into realizing these unrealized ideas of Walker.

 

[microstrip]

(...) My favorite Walker anecdote was one where someone asked him what he thought of his Quad ESL loudspeaker. He replied with a characteristic frankness that is so absent in today's high end audio industry. He said the ESL was a "terrible loudspeaker", but that all the others were much worse! He was always trying to figure out a better solution. It took him 18 years to release the ESL '63, most of that time was to make it more reliable. (...)

IMO the ESL 63 is the real masterpiece of Peter Walker. Although probably the cult of the ESL 57 surpasses that of the younger cousin, the ESL 63 is a merging and audio science and stereo knowledge that still is unique. Peter Walker work on mathematically creating an electrostatic point like speaker using delay lines and all his previous knowledge about electrostatic speakers is still unmatched, unless digital DSP is used. I bought my first pair of ESL63 unheard, immediately after I read the extensive two part review in HiFi News in 1982 and still consider it my best ever high-end buy. Although I understand the appeal of the older model that I also owned, used within its dynamic limitations, the ESL63 is still unsurpassed in many aspects.

 

[godofwealth]

I own both the '63 version (the later 2805) and the original ESL '57. It's clear the '63 is technically superior, and addresses all the faults of the original '57 (which is quite directional -- get up and the highs disappear). But, I suspect something gets lost in the translation. All the miles of delay wire cabling in the '63 give it a bit of glare on many recordings. The bass is a bit leaner as well. There's no doubt in my mind why the original '57 continues to have its adherents. It has this musical quality to it that's a bit like comparing solid state and tube amplifiers. I've suggested to quite a few Quad restorers that perhaps now with DSP, we can redesign the '63 to do the delay lines completely in digital, and get rid of all that cabling. But I think it's not going to happen because of the sheer cost of the engineering involved. With the costs as they are, I doubt Quad now makes much money selling the newest 2812X.

 

[microstrip]

I own both the '63 version (the later 2805) and the original ESL '57. It's clear the '63 is technically superior, and addresses all the faults of the original '57 (which is quite directional -- get up and the highs disappear). But, I suspect something gets lost in the translation. All the miles of delay wire cabling in the '63 give it a bit of glare on many recordings. The bass is a bit leaner as well. There's no doubt in my mind why the original '57 continues to have its adherents. It has this musical quality to it that's a bit like comparing solid state and tube amplifiers. I've suggested to quite a few Quad restorers that perhaps now with DSP, we can redesign the '63 to do the delay lines completely in digital, and get rid of all that cabling. But I think it's not going to happen because of the sheer cost of the engineering involved. With the costs as they are, I doubt Quad now makes much money selling the newest 2812X.

Well, first time I hear about intrinsic glare in the ESL63. I have listened to them having glare several times, but is was due to improper setting in the room, poor system matching or simply inadequate room acoustics. IMO the speaker is so free of glare that room reflections can easily create a weak, thin or dirty sound, particularly in choral recordings. The well known and abused Cantate Domino recording can sound either sublime or miserable in the ESL63. By far the best set up I listened was a ESL 63 room set up by Peter Walker - when I congratulated him on the set up he just modestly said something like "happy to know you enjoy, we have been doing it for some time".

Just to have a better idea of what you are addressing, can you refer to a few recordings that "give a bit of glare" on them?

 

[godofwealth]

The Quad ''63 has been around for more than 4 decades, and it has been the subject of countless reviews. Many of these have noted the problem with treble glare, so it's not a new observation of mine. One of the first to point this out was Richard Heyser in a detailed numerical assessment of the Quad '63 in Audio magazine, shortly after it was released in the US market in the early 1980s. Heyser was bothered by what he termed a "treble fuzz" on hard piano transients. He reported on a detailed set of measurements in his review, finally attributing it to floor bounce. Many others have attributed the treble glare to other factors. John Atkinson of Stereophile attributed the problem to the dust covers, and to the problem that the mylar membrane doesn't quieten down nicely. The standard waterfall plot reveals fairly hashy behavior compared to well-designed box loudspeakers. Alan Shaw who designs Harbeth loudspeakers views this somewhat chaotic behavior of electrostatics as the primary reason he's not enamored of this approach. Robert Greene and Harry Pearson in The Absolute Sound also have noted in their reviews over the decades of the treble glare with the '63's. Harry Pearson thought it was transformer ringing. Robert Greene conjectured it might be the reflections of the stators -- if you plot the treble response of the '63 at a fairly detailed level without doing too much smoothing, you see a series of ripples that represent the reflections of the sound as it hits the stators.

Of course, Peter Walker himself was having none of this second-guessing. His view was that "if you don't like what's coming out, pay more attention to what's going in"! That's the primary reason why all his Quad preamplifiers had extensive set of tone controls. Strangely enough, the only source that Walker said didn't need tone control adjustment was the BBC live broadcasts on FM radio! In particular, he thought vinyl replay was plagued by high frequency distortions, and recommended using a sharp treble filter while replaying discs. That's not surprising if you see the tracing distortion curves of even high end moving coil cartridges. Of course, with CD and streaming, many of these issues go away, but new ones are introduced (like quantization distortion).

I think the only way to appreciate the treble glare problem with the '63 is to compare it with other loudspeakers, which is of course a dicey proposition as you're comparing apples and oranges. But with the Harbeth Monitor 40.1, I hear a much more gentle high frequency sound, especially on piano. Also, my much larger Soundlab G9-7c has a gentler treble response than my 2805 or 2905's. I haven't heard the newly redesigned 2812X, but Kent McCollum (who restored my 2905s) says it's much better at handling high volumes than previous '63 designs. I wish again someone would redesign the '63 using DSP instead of analog delay lines with inductors and miles of thin wire. That's the only way we're going to know in the end what's causing this issue.

 

[microstrip]

The Quad ''63 has been around for more than 4 decades, and it has been the subject of countless reviews. Many of these have noted the problem with treble glare, so it's not a new observation of mine.

Yes, but as far as I have read it is due to room issues or the review conditions. I addressed it in my previous post.

One of the first to point this out was Richard Heyser in a detailed numerical assessment of the Quad '63 in Audio magazine, shortly after it was released in the US market in the early 1980s. Heyser was bothered by what he termed a "treble fuzz" on hard piano transients. He reported on a detailed set of measurements in his review, finally attributing it to floor bounce. Many others have attributed the treble glare to other factors.

Exactly - a problem exacerbated by his room acoustics, as we can read in his review. IMO his ESL63 review is an example of why people do not trust in measurements. He carried them at 3m distance in a room.

John Atkinson of Stereophile attributed the problem to the dust covers, and to the problem that the mylar membrane doesn't quieten down nicely. The standard waterfall plot reveals fairly hashy behavior compared to well-designed box loudspeakers.

Sorry, IMO no way the measurements or comments of John Atkinson suggest any glare or transient smearing - thr contrary.

Alan Shaw who designs Harbeth loudspeakers views this somewhat chaotic behavior of electrostatics as the primary reason he's not enamored of this approach.

Well, I do not consider the general opinion of Alan Shaw on electrostatics relevant on our posting - it does not prove anything on this subject. ESL63 surely have many lovers and many detractors. As all high-end gear.

Robert Greene and Harry Pearson in The Absolute Sound also have noted in their reviews over the decades of the treble glare with the '63's. Harry Pearson thought it was transformer ringing. Robert Greene conjectured it might be the reflections of the stators -- if you plot the treble response of the '63 at a fairly detailed level without doing too much smoothing, you see a series of ripples that represent the reflections of the sound as it hits the stators.

Robert Greene refers to glare in hard piano transients in an apologetic way : "Listen for this in any case. Many people do not seem to notice. Some people find it annoying." "though real evidence is missing" .

Sorry I do not remember the review of Harry Pearson of the ESL63 - can you point me the issue number?

Of course, Peter Walker himself was having none of this second-guessing. His view was that "if you don't like what's coming out, pay more attention to what's going in"! That's the primary reason why all his Quad preamplifiers had extensive set of tone controls. Strangely enough, the only source that Walker said didn't need tone control adjustment was the BBC live broadcasts on FM radio! In particular, he thought vinyl replay was plagued by high frequency distortions, and recommended using a sharp treble filter while replaying discs. That's not surprising if you see the tracing distortion curves of even high end moving coil cartridges. Of course, with CD and streaming, many of these issues go away, but new ones are introduced (like quantization distortion).

A very reasonable advice. When I got a top CD player - the dCS Vivaldi stack - I found that many CDs that I considered to have some king of glare become great sounding. Listening to the "Bella figlia dell'amore" vocal quartet of the Gulini Rigoletto in the ESL63 was an unique experience.

I think the only way to appreciate the treble glare problem with the '63 is to compare it with other loudspeakers, which is of course a dicey proposition as you're comparing apples and oranges. But with the Harbeth Monitor 40.1, I hear a much more gentle high frequency sound, especially on piano. Also, my much larger Soundlab G9-7c has a gentler treble response than my 2805 or 2905's. I haven't heard the newly redesigned 2812X, but Kent McCollum (who restored my 2905s) says it's much better at handling high volumes than previous '63 designs. I wish again someone would redesign the '63 using DSP instead of analog delay lines with inductors and miles of thin wire. That's the only way we're going to know in the end what's causing this issue.

I have compared them with all kind of box speakers during decades, not directly with the Harbeth' s as they are not my cup of tea, sorry.

My point is simply that with adequate room and system matching there is no problem with glare with ESL63 and some electronics or rooms can create it. It is owner/listener responsibility to tune the system.

The same way many people find that SoundLab's have glare - just match them with an inadequate amplifier and they sound glassy. I have listened to them sounding great and sounding terrible - so I say my A1 Px's still sound great!

 

[godofwealth]

I agree that with proper system matching and room setup, the glare can be greatly reduced. In my case, the 2905s are placed in a long narrow dining room about 5-6 feet from the back wall. I use a parallel JJ 322 300B SET amp, which gives around 25 watts. I find this ample for driving my 2905s. The combo sounds gorgeous in that textures are warm and not grating to my ears. The long narrow room helps also -- I recall somewhere Walker saying that's an ideal type of room for the Quads. It took me a long time to figure out how set up the 2905s. The smaller Quads are easier. The 57s are the easiest. They work almost anywhere with almost any type of amplifier. The 2805s that I have are the "natural finish" and they're somewhat picky. When I tried driving them with a Pass First Watt Class A amplifier, they sounded pretty awful. Grainy and simply lacking in bass. But, with the Quad 303, or the Quad Artera, they sound nicer. Of course, a tube amplifier brings out the best in these also.

Quads are an acquired taste. They're really demanding -- I had to get my panels refurbished by Kent McCollum since the Chinese made Quads are unfortunately not as reliable as the UK ones were. The glue comes off. Their resale value is simply abysmal. But, if you're hooked on their sound, as I have been for 30+ years, nothing else suffices. But, Quad lovers are a tiny part of the audiophile market. I would guess less than 1% of WBF members own Quads, whereas 99% own big box loudspeakers. Folks like the thump-thump sound of big box loudspeakers, I suspect somewhat due to the fact that 99% of WBF members listen largely to rock and roll. Quads were never designed for rock and roll. As Walker said, he favored "documentary reproduction", where some musicians play on a stage, and your goal is to reproduce that sound. Rock and roll doesn't fit this category.

 

[Dogberry]

I have my 2905 speakers in the middle of a large open plan area, with open space behind them as well as in front.

On the reverse side of that chimney breast are the sources and pre-amps:

The iPhone panorama is taken from my listening position, which does not need to be centred as I have only one working ear and cannot hear stereo.

 

[DasguteOhr]

The ESL 63.2 QA version from Manfred Stein is a phenominal speaker, with more stable foils.The motor base to adjust the exact listening height is a nice feature.
The motor base to adjust the exact listening height is a nice feature.

ESL 63.2 QA Elektrostaten

QUAD - die Heimat der elektrostatischen Lautsprecher, Kopfhörer, Jecklin Float Kopflautsprecher, legendäre Röhrenverstärker (QUAD II) und vieles mehr zur naturg

www.quad-musik.de

 

[godofwealth]

Here’s my setup for my 2905s.