The funny thing is that one of the reasons for switching to SS gear and away from tubes back in the day was the economics. It was (and still should be) cheaper to make an equivalent (power wise) SS amp than a tube amp. Doing away with the output transformer saves a bunch of money and the shipping weight goes down. That point has been rendered moot with the advent of high-end boat anchor SS amps which have face plates that weigh more than entire amps weighed in the 1960s/1970s.
Why Tube Amps Sound Different (and better) Than SS Amps
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Not a charlatan in the audio sense but *magically* transmuting his amplifier into gold.
My imitation of a Paul Harvey.
Now you and MEP are jogging my memory. IIRC they were using at that time RS1bs that really are not that difficult to drive. (I have years of experience with them; what they do need is power) But the speaker requires two amps: one to drive the midrange panel and one for the bass towers and they were only using the amps on the midrange panels. And many amplifiers are much happier when they only have to drive above 120 Hz or so. (Depending on what xover one used with the speaker.)
Actually, the speakers used were the Infinity Delta. Arnie Nudell had offered up a pair of the Beta speakers, but MF declined because the Beta speakers had to be bi-amped. The Delta speakers retailed for $5K. This article appeared in the September/October 1989 issue of the TAS (volume 14/issue 61). The Crown amp was the PSA-2 and the Threshold amp was the S-500 Stasis. According MF, David Clark had over attenuated the VTL amp, "making it obviously lower in volume compared to the other amps." David Clark had also inserted a resistor in the Crown output to make the load from the Delta speakers more manageable for the Crown amp but Manley snipped out that resistor so that all amps would see the same load. Unknown at the time apparently was the fact that David Clark was a consultant to Crown.
For the life of me I can't possibly think of one reason I would want to try that little experiment. My KSA-250 might not be a good candidate for that experiment even if I was motivated to try it (which I'm not). The KSA-250 really doesn't care so much about the load it's presented with. If you raised the nominal impedance of the speaker load so that it was above 8 ohms, it would probably make a difference. Anything below 8 ohms and the KSA-250 is just going to keep putting out more power.
I think you could make a $500 speaker hard to drive if you wanted to. I honestly know nothing about the Infinity Delta speaker and have never heard of it other than from the article.
That's the same fallacious reasoning used in 1980 to explain why analog lovers didn't switch to digital. If digital had truly sounded better, most have have switched over at that time. But people listened, compared and didn't switch. If Carver made a truly outstanding amplifier that really sounded like music, it wouldn't matter if it was SS or tubes or some combo of the above. It's about the music not the technology.
What amazes me is just how black and white people see a situation. It's like tubes have no, zip, nada redeeming virtues. Hell years ago I once asked Dan D'Agostino if there was any property of tubes that he tried to emulate in his amps and one of things he mentioned was voltage swings.
For sure.
But I do not call him spending personally (that means one also needs to include all his engineering knowledge-experience-skills gained over decades in engineering) 4 days on a bespoke product that could never go into manufacturing or service/maintenance as it stood a cheap product.
There is a very very big difference to making a one-off "bench" amp and something that goes into production that has to have durability/tolerances/etc - think of each stage involved within an amplifier that was modified in a non-standard production way.
However it would had been interesting if Bob had stated how much it would cost to actually "convert" that bench amp into one that could be sold; bearing in mind each amp off the model production line would need to have the exact same spec-quality-performance.
Why it is rare prototypes never exactly match production models whatever sector even outside of audio.
Cheers
Orb
Why it is interesting with T+A and their high voltage SS designs (HV model).
Although it seems some reviewers prefer their reference model that can switch between high power or high current mode (S10 or M10 amps) on the fly.
Cheers
Orb
Here is a link to the famous Carver challenge that was hosted by Stereophile: http://www.stereophile.com/content/carver-challenge
To summarize, Stereophile agreed that Carver won the challenge by making his $700 amp sound 'identical' to a CJ Premier 4 amp.
To summarize, Stereophile agreed that Carver won the challenge by making his $700 amp sound 'identical' to a CJ Premier 4 amp.
Mep,
here though is the further follow-up, where they concluded after much lengthier time with the amp and further thought-approach a difference could be noted:
The Blind leading the Deaf: http://www.stereophile.com/asweseeit/487awsi/index.html
Nothing can be fully concluded, although J. Gordon Holt did use I think a technique-approach that I hinted to earlier when he managed 4/5 correct.
Anyway it is interesting as it highlights the challenges to actually perceive differences between casual listening and then also blind listening, with some food for thought from Mr Holt; as I said earlier most go into such comparison unprepared and with the wrong music (indeed one does not even need whole music track but small segments with a specific trait).
So to summarize, it was never concluded either way to a complete satisfaction (J. Gordon Holt only managed to complete 5 tests after their extended casual listening where they started to notice there were differences).
Hence why IMO the only valid/useful aspects in the discussion are the engineering/technical and also the approach required to differentiate between products when actually going from casual to blind test.
Cheers
Orb
here though is the further follow-up, where they concluded after much lengthier time with the amp and further thought-approach a difference could be noted:
The Blind leading the Deaf: http://www.stereophile.com/asweseeit/487awsi/index.html
Nothing can be fully concluded, although J. Gordon Holt did use I think a technique-approach that I hinted to earlier when he managed 4/5 correct.
Anyway it is interesting as it highlights the challenges to actually perceive differences between casual listening and then also blind listening, with some food for thought from Mr Holt; as I said earlier most go into such comparison unprepared and with the wrong music (indeed one does not even need whole music track but small segments with a specific trait).
So to summarize, it was never concluded either way to a complete satisfaction (J. Gordon Holt only managed to complete 5 tests after their extended casual listening where they started to notice there were differences).
Hence why IMO the only valid/useful aspects in the discussion are the engineering/technical and also the approach required to differentiate between products when actually going from casual to blind test.
Cheers
Orb
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Orb-The two links you provided above are the same link and we don't get the rest of the story of how Holt came to the conclusion that you really could hear a difference between the two amps. If we call the article I posted the link to "Round 1," Carver won Round 1.
2nd link should not had been there, not sure how you manage to score it 1-1 as this is not football
BTW the follow up article I linked makes it very clear they did hear differences that were highly noticable under the same listening conditions as the 1st time (that is the link you provided).
It became much more challenging when then changing those conditions to a more stringent format, which I alluded to requries a very specific approach and one JGH even alluded to with his 4/5 blind test result - just to add this is something JGH has also mentioned in conversations.
Anyway I think you are reading way too much into the articles, as I said the only valid parts in reality is.
a) many technical variables involved to null match the amps beyond frequency response and distortion (less a factor than other aspects).
b) initial listening (1st article) and they were surprised how comparable they sounded with no or little differences.
c) spending more time with the amp (2nd article) they then managed to identify differences much more easily using same listening conditions, however going from that casual listening condition to a stringent blind test requires a very specific approach to even possibly pass the test and conclusion is that it is very easy to be unprepared when one thinks differences are so "large" from the casual experience.
d) there is no victory or score either way as nothing else was really concluded.
Thanks
Orb
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Orb-There is obviously more to the story here. The article you linked to said the story was continued on page 117, but we never got there. The article you linked to said they could hear differences after the first challenge was over and SP conceded to Carver that he 'won.' I still want to read about what happened after the first challenge and prior to the link you posted. That is where the rest of the story is.
What I do find interesting is that in this stage of his career, Bob Carver chose to design and build tube amps. I believe it shows that he likes working with tube circuits and that he likes the way they sound. I also believe he has come up with some new innovations that he thinks improves current tube amp design techniques. Bob is claiming a 50 year tube life for the output tubes in most of his amps and actually offers a 20 year warranty on the output tubes used in his Silver 7 amps.
What I do find interesting is that in this stage of his career, Bob Carver chose to design and build tube amps. I believe it shows that he likes working with tube circuits and that he likes the way they sound. I also believe he has come up with some new innovations that he thinks improves current tube amp design techniques. Bob is claiming a 50 year tube life for the output tubes in most of his amps and actually offers a 20 year warranty on the output tubes used in his Silver 7 amps.
2nd link should not had been there, not sure how you manage to score it 1-1 as this is not football
BTW the follow up article I linked makes it very clear they did hear differences that were highly noticable under the same listening conditions as the 1st time (that is the link you provided).
It became much more challenging when then changing those conditions to a more stringent format, which I alluded to requries a very specific approach and one JGH even alluded to with his 4/5 blind test result - just to add this is something JGH has also mentioned in conversations.
Anyway I think you are reading way too much into the articles, as I said the only valid parts in reality is.
a) many technical variables involved to null match the amps beyond frequency response and distortion (less a factor than other aspects).
b) initial listening (1st article) and they were surprised how comparable they sounded with no or little differences.
c) spending more time with the amp (2nd article) they then managed to identify differences much more easily using same listening conditions, however going from that casual listening condition to a stringent blind test requires a very specific approach to even possibly pass the test and conclusion is that it is very easy to be unprepared when one thinks differences are so "large" from the casual experience.
d) there is no victory or score either way as nothing else was really concluded.
Thanks
Orb
The other thing worth noting. Carver said his amp was nulling -39 db. One would expect that might be audible. And as JGH said, 4 out of 5 is not significant. Suppose he was just one less. 3 of 5 or one the other way 4 of 5. Many complain when this sort of objection is brought up. One can use the random number function in a spreadsheet to see how often 4 of 5 happens. I just did and in 100 trials, which done 5 at a time is 20 runs, it occurred 5 times that 4 of 5 at random turned up. That is one in four by chance. Suggestive, but simply not enough to be conclusive.
I don't know it was 'hard' to drive. But the EMIT's and EMIM's had low impedances. I seem to recall they had very little change in phase or back EMF, but the impedance was usually around or even below 2 ohms for the whole range they covered. So a given amp might find them no problem to play them, but the output impedance of the amp if not quite low would interact enough to change the response. The VTL had an output impedance approaching an ohm, apparently the Crown had some fraction of an ohm and the Threshold must have had very small output impedance. Three different FR curves. One would expect them to sound different even if everything else was completely identical.
I heard Gammas and Deltas on one occasion. They were being driven by an moderate sized intergrated amp. So I don't think they were hard to play. Sounded pretty good too.
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Infinity must have done something different in later models as the EMIMs/EMITs in the RS1bs and Betas were 4 ohm.
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