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Old 10th Feb 2011, 7:36 pm   #1
David Goodall
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Default Quad II versus Current dumpers ?

I am at last in a position, some 25 years after having been first beguiled by a pair of Quad electrostatics (Esl 63s) to buy some. I'm not sure how possible it is going to be to listen to various setups. Esl 57s or Esl 63s. Amp combinations etc. I was wondering what the consensus is (If any) regarding the Quad IIs versus the Current dumpers.
What did Peter Walker have to say on the matter.
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Old 10th Feb 2011, 8:32 pm   #2
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Default Re: Quad II versus Current dumpers ?

I have a pair of ESL63's and have used them with Quad II's, 303 and both the 405 and 405-2 amplifiers. My personal preference is either of the 405 variants - not from an audio quality perspective but from a 'fit & forget' reliability point of view. There are of course one or two who will argue the 405 isn't reliable or poorly designed etc. but my experience doesn't support this.
The ESL's were designed to run with higher powered amps - and it isn't coincidence that they are rated to handle to output of the 405 amps as that is what would have been used in the R & D process.
The lower powered Quad's do sound essentially the same when driving the '63's - but they 405's have that reserve of power to call upon when required.
PJW ruffled a few feathers when he made that famous quote " all amplifiers sound the same provided they are competently designed and are run within the design parameters". I still have the articles from the HIFi comics when he put his money where his mouth was and arranged for blind tests to be conducted, using some of the HiFi fraternity as thelistening panel. The end result was that no-one was able to reliably pick any differences between the Quad II,303 or 405.

Mike

Last edited by Brian R Pateman; 10th Feb 2011 at 10:19 pm. Reason: Quote removed.
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Old 10th Feb 2011, 8:48 pm   #3
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Default Re: Quad II versus Current dumpers ?

That's AMAZING! and wonderful, all at the same time. Thank you very much for that Mike. I would love to read the article you mention.
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Old 10th Feb 2011, 11:49 pm   #4
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Default Re: Quad II versus Current dumpers ?

Quote:
Originally Posted by audiomm View Post
PJW ruffled a few feathers when he made that famous quote " all amplifiers sound the same provided they are competently designed and are run within the design parameters". I still have the articles from the HIFi comics when he put his money where his mouth was and arranged for blind tests to be conducted, using some of the HiFi fraternity as thelistening panel. The end result was that no-one was able to reliably pick any differences between the Quad II,303 or 405.
I'm really interested in the details of this quote. I've seen it referred to lots of times, with various different wordings but I can't seem to nail down exactly what Peter Walker said and when he said it. As far as I can tell (I never met him) he seems to have been rather a careful speaker. I imagine he would never claim that the three amps below all sound the same, despite the fact that each one is 'competently designed' for the job in hand (very cheap domestic reproduction, robust PA use in a factory/club/village fete, top quality hifi). I own all three amps and even I, with my old cloth ears, can tell them apart. And even at low power their measured distortion levels are very different. So I suspect that what Peter Walker actually said was a bit more qualified. Can anyone point me to the definitive version ?

I'd also be interested in any references for listening tests. I already know of James Moir's article (Wireless World, Jul 78) where the three Quad amps were compared. The listening panel were anonymous but Moir describes them as "all well known and experienced listeners". However they didn't represent the entire spectrum of opinion. Moir described people who thought that transistor amplifiers always sound different from valve ones as belonging to a "cult". And he says of the listening panel "The cult members that were invited to take part in the tests accepted but subsequently withdrew ... ". So it might be argued that the people who stood the best chance of being able to distinguish between the amps (or, at least, believed that they did) had selected themselves out of the test.

I also know of the articles published later the same year (Hi-Fi News, Nov 78) by Martin Colloms and his colleagues, perhaps in response to Moir's original ? They also struggled to tell the difference between amplifiers in blind tests although they did, just about, manage it. But again I'd be grateful for references to any other 'scientific' tests .

To get back to the OP's original queries. I'm not sure that there really is a consensus opinion in the case of the Quad II vs the Quad 405 - there are adamant supporters and denigrators on each side. We do know what Peter Walker thought about transistor amps though. In Ken Kessler's book 'QUAD - The Closest Approach' he reports a 1994 interview with Peter Walker. A short extract reads:

KK: At what point did you feel that transistors were acceptable for your amplifiers ?

PW: 1968. Prior to that you only had germanium transistors which didn't do high frequencies very well. They would blow up a bit and they weren't as good as valves. But in 1968 we could make a transistor amplifier as good or better than valves - not everybody believes that but there we are. That's what we thought.

KK: But do you ever think back that, while the solid-state equipment measured very well, maybe it didn't sound as good as the valve equipment ?

PW: No. I think this going back to valves is partly fashion and partly the fact that you can make a valve amplifier fairly easily and it will always sound good. Transistor amplifiers are much more difficult to design and it's easy to make one that measures quite well but gives current overload and things go wrong like that, secondary breakdown and all sorts of things so it's not so easy. But if you make it properly and do all the measurements properly, and do all the proper listening tests, oh yes, then it's the right way to make an amplifier. It still is. The fashion for valves is, I think, just a fashion.

Cheers,

GJ
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Old 11th Feb 2011, 12:23 am   #5
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Default Re: Quad II versus Current dumpers ?

From memory, the panellists included John Crabbe (HFN), Mike Ballance (Practical Hifi), David Stripp (BBC), Jim Rogers (Rogers) and two others I can't recall - this from a photo in HFN, which carried some of the correspondence laeding up to the tests. Chris Rogers was the most prominent "subjectivist" to withdraw at a late stage, largely because of Walker's insistence on a statistically sound experimental procedure. Barry Fox wrote it up for HFN, I think, and the result was that under those conditions it was not possible to distinguish the amplifiers with an accuracy better than chance.
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Old 11th Feb 2011, 1:31 am   #6
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Default Re: Quad II versus Current dumpers ?

Thanks Ted, I will try to locate those 1978 HFNs - they obviously contain some really interesting 'real time' debates. One of them will also have Barry Fox's write-up in it, I guess. It sounds like he agrees with Moir about the outcome. Moir applied two statistical tests to the data from the listening panel and says that the outcome was "that the residual preferences expressed by the panel were no more than would be achieved by sheer chance (guesswork is the crude term)".

I've rechecked the results of the Colloms tests and it turns out I hadn't remembered them accurately. In fact, of his panel's 13 members 11 could not rank the three amplifiers they were testing on a statistically significant basis. Two could however, and furthermore they agreed on which one was the worst, claiming that the other two were very similar. In another part of the test the listeners were played the same piece of music twice. Sometimes the amp was changed between the playings and sometimes it wasn't. Each listener was asked whether he/she could hear a difference. Apprently most of the panellists did score better than chance on this test.

Cheers,

GJ
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Old 11th Feb 2011, 11:54 am   #7
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Default Re: Quad II versus Current dumpers ?

I note the debate has concentrated on the power amp part of the comparison. But I think it would be reasonable to expect people to have bought the appropriate pre-amp for the power amp. So I wonder how the combination of QCII + Quad II, 33 & 303 and 33 & 405 would have fared in the blind test? I bet the residual mains hum from the QCII would have given it away.
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Old 11th Feb 2011, 12:33 pm   #8
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Default Re: Quad II versus Current dumpers ?

Does anyone remember the ads with a string of twenty(?) Quad amps (303?) connected end to end (with attenuators), and the claim that what comes out at the end is indistinguishable, apart from a little noise, from what you get from a single amp?
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Old 11th Feb 2011, 2:22 pm   #9
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Default Re: Quad II versus Current dumpers ?

It would seem then from these blind tests, that a good 405 with the low noise Op amps fitted, is at least comparable in quality to the Quad IIs. That's all I need to know. There may be a slight musical edge with the valves (Perhaps), but not enough to loose sleep over.
I have been offered a 405 mk1 , with the 44 preamp. Am I right in thinking that these can be upgraded quite easily?
I would also love to read these blind test results/reviews, if they can be found, and scanned.
The above amps are one owner from new, with the FM4 included. They are in mint condition. Does 500 pounds sound about right ?
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Old 11th Feb 2011, 3:31 pm   #10
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Default Re: Quad II versus Current dumpers ?

I'm a past-owner of QuadIIs and a current 34/405 user.
Personally, I can see no reason to go back.
I dare say others will disagree.

Speaking personally as an engineer, an amplifier is a 'bit of kit' that does a job, a black box.
I want the signal to go in one end, and come out the other, with suitably more 'ooommph' but with as little deviation from the input signal as possible.

I read somewhere that Walker saw no point in changing from valve to transistor amps until there was good reason to do so.
I'm pretty sure that Quad were the last of what I call the 'big three' (The others, ofcourse, being Leak and Radford) to put transistor amps into production.

In my opinion, and my own experience, nothing else quite comes close to a Quad405.
No doubt, you have read Gordon J. King's report, where he was struggling to measure distortion with all of the (at that time) equipment available at his disposal.
http://quad405.com/testreports.pdf
OK, so you couldn't get an AP in 1976, but I think it proves a point.
You will also read of reliability problems, well, I've not had any, maybe I've been lucky.

The 44 is a useful bit of kit, slightly more versatile than the 34, which meets my need suitably (turntable and CD player) Circuitry inside is very similar.

It has long been my belief that Peter Walker is the most gifted audio engineer, (with Peter Baxandall a close second.)

I can't comment on the FM4, I'm afraid!
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Old 11th Feb 2011, 3:38 pm   #11
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Default Re: Quad II versus Current dumpers ?

David,

What colour is the case and the buttons of both the 44 and the FM4? I believe earlier ones have a brown coloured case with yellow buttons, with the FM4 display being green. The later ones have a grey case with grey buttons, and the FM4 display is orange.

Try tuning the FM4 over the full range without an aerial connected and see if there is any self generated interference detectable.

Otherwise Quad gear (of that era) is good stuff in my 'umble opinion - compared to others around then.

Would I pay £500 for mint condition? - possibly for a later 44 and FM4. But as we all know, the price is what the buyer is prepared to pay (esp. on eBay).
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Old 11th Feb 2011, 3:58 pm   #12
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Default Re: Quad II versus Current dumpers ?

Quote:
Originally Posted by G8HQP Dave View Post
Does anyone remember the ads with a string of twenty(?) Quad amps (303?) connected end to end ...
I never saw the ads but I met a retired chap at last year's QUADfest http://www.quad-musik.de/ who had been a Dutch distributor for Quad and he told me that he had actually hosted a demo of this in his own shop (it was thirty 303's if he and I remember correctly). They had offered a reward of 1,000 guilders (about £400 ?) to anyone who could reliably tell the difference between one amp and thirty amps. At the end of the demo they still had their money

Cheers,

GJ
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Old 11th Feb 2011, 4:47 pm   #13
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Default Re: Quad II versus Current dumpers ?

Of course, some might say that the first 303 destroys the 'musicality' so there is nothing left for the remaining 29 to damage!
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Old 11th Feb 2011, 8:00 pm   #14
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Default Re: Quad II versus Current dumpers ?

Quote:
Originally Posted by GrimJosef View Post
I never saw the ads but I met a retired chap at last year's QUADfest http://www.quad-musik.de/ who had been a Dutch distributor for Quad and he told me that he had actually hosted a demo of this in his own shop (it was thirty 303's if he and I remember correctly). They had offered a reward of 1,000 guilders (about £400 ?) to anyone who could reliably tell the difference between one amp and thirty amps. At the end of the demo they still had their money

Cheers,

GJ

Brilliant.
Just what I like to hear. I too have done demo's and it really slaps the audiofools in the face
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Old 11th Feb 2011, 10:16 pm   #15
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Default Re: Quad II versus Current dumpers ?

Hi,

Now if was down to my heart I’d go for the Quad II, but if I was down to the electronics engineer in me I’d go for the 405. Whatever both the Quad II and 405 power amplifiers were audio engineering milestones.

Sadly to re-valve a Quad II is now a costly exercise, especially with GEC KT66’s.

Terry.

Quote:
Originally Posted by David Goodall View Post
I am at last in a position, some 25 years after having been first beguiled by a pair of Quad electrostatics (Esl 63s) to buy some. I'm not sure how possible it is going to be to listen to various setups. Esl 57s or Esl 63s. Amp combinations etc. I was wondering what the consensus is (If any) regarding the Quad IIs versus the Current dumpers.
What did Peter Walker have to say on the matter.
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Old 11th Feb 2011, 10:54 pm   #16
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Default Re: Quad II versus Current dumpers ?

Personally I have a great liking for valve power, being realistic though for brute force versus cost, and of course power use/efficiency transistor amps come out tops.
Due to the size of my house a valve amp is at its best, so that is the way it will remain. I don't need 100w+, 2 to 3 quality watts is ample here, good quality efficient speakers also fit the bill.
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Old 12th Feb 2011, 12:35 am   #17
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Default Re: Quad II versus Current dumpers ?

Quote:
Originally Posted by GrimJosef View Post
I'm really interested in the details of this quote. I've seen it referred to lots of times, with various different wordings but I can't seem to nail down exactly what Peter Walker said and when he said it. As far as I can tell (I never met him) he seems to have been rather a careful speaker. I imagine he would never claim that the three amps below all sound the same, despite the fact that each one is 'competently designed' for the job in hand (very cheap domestic reproduction, robust PA use in a factory/club/village fete, top quality hifi). I own all three amps and even I, with my old cloth ears, can tell them apart. And even at low power their measured distortion levels are very different. So I suspect that what Peter Walker actually said was a bit more qualified. Can anyone point me to the definitive version?

I'd also be interested in any references for listening tests. I already know of James Moir's article (Wireless World, Jul 78) where the three Quad amps were compared. The listening panel were anonymous but Moir describes them as "all well known and experienced listeners". However they didn't represent the entire spectrum of opinion. Moir described people who thought that transistor amplifiers always sound different from valve ones as belonging to a "cult". And he says of the listening panel "The cult members that were invited to take part in the tests accepted but subsequently withdrew ... ". So it might be argued that the people who stood the best chance of being able to distinguish between the amps (or, at least, believed that they did) had selected themselves out of the test.
As I recall, PJW’s original “stake our reputation” challenge was in Hi Fi News around mid-1977, July perhaps. I am not sure if I can locate a copy. It generated some interesting correspondence in Wireless World in 1978, as well. Peter Baxandall’s letter in Wireless World January 1978 reprises some of PJW’s original statement and conditions, and does refer back to the July, 1977 issue of HFN.

I have the Quad print on the Moir test outcomes, and can scan and post if you like.

Having seen PJW at some of the London audio shows in the second half of the 1970s, I’d say that he had a touch of the showman in him, but was not at all dogmatic, and not much ruffled by the goings on. Quite different to what one found at one or two other manufacturer’s stands, where the “true believer” atmosphere was palpable. (Although they were offering excellent products that would have stood on their own feet without the hype.) Around the time of the comparative tests, at one maybe two of the shows Quad was offering headphone comparisons of the Quad II, Quad 303 and Quad 405. PJW was totally unperturbed by the fact that some visitors were able to correctly identify each amplifier, and when I asked the question, the response was more-or-less the East Anglian equivalent to the Gallic shrug, with a comment to the effect that it was a relatively trivial test.

Also available was a direct vs. via the FM3 test, using a fancy signal generator (STC 1000?) to feed RF to the FM3.

There seemed to be some general antagonism at the time towards Quad (and others of the “old guard” establishment) and at one show I heard some negatives on Quad from Ken Kessler. (His epiphany must have come later.)

Also at one of the shows, I did ask PJW what was the design life or expected life of Quad equipment. His answer was not precise, but went something like – if someone had ten years of good reliable use out of an amplifier, then it had fairly done its job. My Quad 606 is now 20 years old and still in daily use, untouched since new. The Quad 405-2 is 25 years old, but needed a new power rectifier back in 1999. So maybe I’m doing better than average. My own experience of Quad reliability is about the same as most other equipment I have purchased in the last 25 years (Nakamichi, Meridian, Sony, Carver, NEC, Yamaha, Luxman, Pioneer, Panasonic, JRC, NAD, Icom, etc.). But one-off samples are hardly the basis for generalizations.

Cheers,
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Old 12th Feb 2011, 12:43 am   #18
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Default Re: Quad II versus Current dumpers ?

Quote:
Originally Posted by TuningIndicator View Post
I read somewhere that Walker saw no point in changing from valve to transistor amps until there was good reason to do so.
I'm pretty sure that Quad were the last of what I call the 'big three' (The others, of course, being Leak and Radford) to put transistor amps into production.
The valve-to-transistor transition period was an interesting time. Crossover distortion was viewed as the big bugbear with transistor amplifiers, and was usually ascribed as being an inevitable outcome of Class B operation that needed to be smoothed out as best could be done, usually with copious negative feedback. But asymmetry (both in average slope and tightness of curve at the x-axis) in Lin-type quasi-complementary output stages was a more subtle aspect that needed attention. Quad may have been one of the first to address this in a production amplifier with its output triples as used in the 303. In 1969 Shaw then Baxandall separately developed progressively simpler circuits using a diode in the conjugate pair, and Baxandall wrote quite a bit on the topic, initially in Wireless World September, 1969. That said, I can’t actually think of a commercial amplifier that I know for sure used the Baxandall circuit, but I suspect that it was quite common.

Leak had been an early mover with the germanium quasi-complementary Stereo 30 in 1963. It moved up to silicon transistors in 1968 with the Stereo 70, and then reworked the smaller amplifier to use silicon transistors as the Stereo 30 Plus. But as I recall, it stayed with the basic Lin circuit, with lots of NFB.

Whereas Quad had worked at ironing out the shortcomings of the quasi-complementary circuit, J.E. Sugden saw Class A as the way to go to avoid “transistor sound”, and I think its early models, initially under the Richard Allan name, just predated the Quad 303. I suspect that the Quad view of the Class A option would have been that it was too inefficient, hence the need to pursue Class B improvements.

Radford went the fully-complementary route, maybe a year or so later than the Quad 303, although I am not sure of the timing. This was seen as overcoming the asymmetry problem, although there is a viewpoint that at higher audio frequencies some asymmetry creeps in. Drawbacks at the time were the scarcity, cost and fragility of PNP power transistors. Possibly when the Quad 303 was designed, PNPs that could do 45 watts per channel were either not available or prohibitively costly. I think that the original Radford transistor amplifier was something like 30 watts per channel. The SPA50, 50 watts fully complementary dated from circa 1971. New entrant Cambridge at the end of the 1960s also opted for the fully complementary output.

Odd-man-out was Rogers, who opted for transformer-drive for its initial solid-state Ravensbourne amplifier, a contemporary of the Quad 303. I haven’t figured out whether this configuration avoided the quasi-complementary asymmetry.

Cheers,
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Old 12th Feb 2011, 1:12 am   #19
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Default Re: Quad II versus Current dumpers ?

I think it's all been said above, however, I can't help but add that much as I adore my re-built Quad II's, the 303 is at least as good and the extra power and cool running are a huge bonus. The best 405 is the mk2, as the circuit track seemed better laid out as I remember and the relaxed limiting would be a benefit with any half decent loudspeaker.

The thing is, all three of these amps are old now, the caps will almost certainly be tired if they're over twelve years or so old and Quad's choice of supply (and speaker in the 303) caps was economical, or the best available back then for the physical size and rating. The 303 and 405-2 benefit hugely from these caps being replaced with modern low-ESR versions of possibly higher voltage working and replacement circuit boards are readily available from Dada Electronics or net-Audio.

of course, the choice of preamp is important too and all of the Quad preamps from 77 backwards can be sensitively fine tuned to open the sound up further. Indeed, the dada updates for the 33 preamp were nothing short of spectacular, transforming a tight-a*sed and rather constrained old preamp into something far more comparable with established modern models and more truthful to the source. The Richard Bryce mod to mostly remove the sub 35Hz rolloff helped hugely too (only one capacitor on each output board - I wanted to keep the tone control option).

Lovely old amps these once fettled, and great for '63's
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Old 12th Feb 2011, 1:25 am   #20
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Default Re: Quad II versus Current dumpers ?

Lots of useful stuff there, thanks. When I said that I know of Moir's WW article I should have explained that this is because I've actually got a copy of that issue. At the foot of the piece are a few references, one of which is to an article called 'Rational Amplifier Testing' written by Peter Walker for HFN, July '77. So if this is the one you meant then you were spot on with the date ! I really must get over to the Bodleian library in Oxford (I think they'll still let me in) and pull HFN '77 and '78 up out of the stacks. It could make a very informative afternoon's reading ! Thanks again.

Cheers,

GJ
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