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If "Tube Sound" Is a Myth, Why Tubes?

Inner Space

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However, note that a similar justification can be used in dismissing anyone writing sighted impressions of speakers too. But we've gone over why those seem acceptable, including Amir's sighted reports.
In passing, they're not acceptable to me. I have found speakers to be far more subject to sighted biases than anything else.
 

MattHooper

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In passing, they're not acceptable to me. I have found speakers to be far more subject to sighted biases than anything else.
I understand and respect that point of view.

But given getting scientifically-justified results for much of what we do isn't tenable, yet we still have to make decisions and actions, then it seems "plausibility" is a pragmatic approach. I myself use the heuristic "extraordinary claims require extraordinary evidence." If my neighbor tells me he just bought a new dog, then it's reasonable for me to accept his say-so or even a paper receipt from a pet store. Sure he could be lying or deluded, but there is nothing implausible about his claim that determines I must have more rigorous evidence to provisionally accept the claim.

But if he claimed to have just bought a living Tyrannosaurus Rex as a pet, that's obviously an extraordinary claim and I"ll want a scientific level of evidence.

Applied to audio: Speakers can measure objectively different and sound different. So a report "I heard X difference between speakers A and B" is plausible, not an extraordinary claim. Yes, if I wanted to have a scientific-level of confidence I'd only accept blind test reports. But as a practical matter, I can accept "ok, you heard those differences" provisionally, with the caveats that of course there could be error, as is the case in much of our daily experience."

I take the same approach regarding tube amps/ss amps, though with a higher degree of skepticism (because the fact it's a "tube amp" doesn't automatically entail a sonic difference from a SS amp).

We all navigate these waters our own way. Cheers.
 

MattHooper

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I have heard tube warmth and then remembered that the tubed component wasn't actually in the signal chain at the time. I was just looking at the glow. It really is easy to hear what you expect to hear.
Hell yes! That's for sure.

But I think it's important to keep a distinction: The fact that a subjective report *could* be only due to subjective bias and not a real change in the sound doesn't automatically mean that it IS a case of mere subjective bias. (Talking here in regards to technically plausible sonic differences, not implausible). It's just the case you can't be sure it's either or, without more stringent testing.

But I see quite a lot of people raise the issue of placebo/bias/expectation effects as if to wave away the idea someone is hearing something really changing in the sound. So "it's probably just that you heard what you expected to hear" rather than the live option "the sound actually changed."
I'm not saying you've taken that hard a stance, but I do see it often implied when subjective reports are dismissed.

(I once had an amp designer offer to build me an amp switcher - to switch between different amps on the same speaker. Kinda wish I took him up on the offer as I'd try it out with the Bryton and CJ amp for blind testing).
 

Inner Space

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Speakers can measure objectively different and sound different. So a report "I heard X difference between speakers A and B" is plausible, not an extraordinary claim. Yes, if I wanted to have a scientific-level of confidence I'd only accept blind test reports. But as a practical matter, I can accept "ok, you heard those differences" provisionally ...
Absolutely, but I think this is the root of the problem. As a practical matter, of course, we don't need blind testing as a control when it comes to claiming audible differences between speakers. But complete your hypothetical sentence: "I heard X difference between speakers A and B ... and subjectively I preferred B." Sighted, there could be huge bias behind that subjective preference - size, brand, mass, appearance, apparent technology or lack thereof ... many more factors than occur with mere electronics. So I think blind listening is important in validating an honest subjective preference, not as a "gotcha" against the difference claim itself.
 

Blumlein 88

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Absolutely! Precisely why anyone here can justify dismissing it if they want and I completely understand. However, note that a similar justification can be used in dismissing anyone writing sighted impressions of speakers too. But we've gone over why those seem acceptable, including Amir's
sighted reports.



All good questions.

Do I think it's likely I could distinguish the Bryston from the CJ in a blind test? In this case: yes. I base this on the fact many people more knowledgeable than I am about electronics say that tube amps can indeed sound different for various technical reasons. Unlike, say, the cable debate, this is generally uncontroversial (even Arny Kruger agreed with this!). ETA: Mine is an old Conrad Johnson amp which back in the day were generally held to produce a "classic tube amp sound" (rounder, softer and all that). Note: when Bob Carver produced the infamous stereophile blind test result, claiming succesffully that he could re-jig one of his solid state amps to sound indistinguishable from the CJ tube amp, he did so by changing various parameters of the SS amp - someone detailed those technical changes in this thread I believe. Presumably he wouldn't have bothered to change a thing if they actually measured/sounded indistinguishable in the first place without modification.

Secondly, the differences seemed so pronounced that it has left a strong impression that I could tell them apart. (I've had similar situations before, where for instance I heard what seemed to be very identifiable differences between some CDPs/DACs in the 90's, where I was told "they should be indistinguishable," but in blind testing I easily identified them with perfect accuracy. Which isn't to say the same would happen for sure with the amps, but my hunch is it would. Though I WOULD expect that I couldn't identify two decent SS amps in a blind test).

And, yes, those differences are very much some of the classic differences often attributed to tube amps in the high end audio crowd. So, yes, *to some degree* I think even the "subjective audiophools" can be right. But there are lots of caveats (e.g. that not all tube amps are the same, and "well designed" tube amps can sound indistinguishable from SS amps, so while there may be some truth mixed in with subjective reports, there is almost certainly lots of bias "just because the amp has tubes" as well, to untangle).

However....even though that would be the way I would bet, that I could distinguish the CJ from the Bryston....I could be wrong. It's still *possible* that everything I described was sighted bias, and if I couldn't tell them apart in a blind test I would embrace that result as informative.

Unfortunately I don't have a speaker/amp switcher handy for faster switching, nor a voltmeter to ensure exact volume output, so such a blind test is out of my reach for now.
I think you could distinguish it blind as well having owned some CJ (and other tubed) amps.

The CJ has restricted bandwidth at higher powers on both the low and high end of the frequency range. Transformer issue. The final thing Bob Carver had to match with his amp on the big CJ was reducing the reach and power in the bass frequencies. He had to restrict high power bass and damping before all agreed he had met their challenge. When he reduced output of his amp to 65 watts, and only reach down to 30 hz in the bass it matched the CJ. That is something you'll hear blind vs an SS amp on wide bandwidth music.

Here are some specs that were typical of all their amps with tubes. This from the Premier Five he was emulating.
Specifications:
  • Power Output: 200 watts, minimum RMS, at 4, 8, or16 ohms from 30Hz to 15kHz with no more than 1% THD or IM Distortion.
  • Response: 20Hz to 20 kHz, +0, -.5 dB
  • Input Sensitivity: 1.0 volts
  • Hum & Noise: 96 dB below rated power
 
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Robin L

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I can see what you mean. Yes, after a day full of cutting shoot-outs and car chases I'm not looking for a further assault on my ears. Anything that helps me relax....

(Though, again, I'm not just looking for that as I also like attributes that remind me of live sound. I find that solid state, generally speaking, reprouces some aspects more believably - the precision, clarity of transients, impact and dynamics, for instance of a drum set - while the classic tubey sound captures some other aspects. I happen to value the aspects tube amps produce a bit more. Would love to have it all, but reproduced sound, both on the recording and reproduction end, will continue to be a set of compromises).
Hope I'm properly representing this. Jack Vad had respectable but easy on the ears monitoring for his recordings. That would almost always mean some remote set-up, he rarely worked in a studio, had [has?] a fulltime job recording at Davies Hall, San Francisco, where there was a recording booth at the top of the balcony. His home post-production studio was built from the ground up for ideal playback, that was his ultimate standard. But one simply can't bring TOTL monitoring gear to a remote session unless the standard is something like the Stax earspeakers. In any case, while I was using the Stax gear for recording I was also messing around with a Marantz 8b power amp. That amp had all the "passive" components replaced, which might have screwed up the balance, but I doubt it. What I heard when I strapped that amp to an energizer for the Stax earspeakers [enabling me to hear the difference between the 8b and the Stax amp under an "audio microscope"] demonstrated a lot less going on at the frequency extremes but a sense of solidity and focus for the midrange. The 8b was perfect for Sarah Vaughan. It also cut back surface noise of LPs to an obvious degree. I had a similar experience many years later with a Scott 299b, the best amp I have owned for LP playback. Focused midrange at the expense of the frequency extremes seems to be the characteristic sound signature of tubes 'n' transformers compared to solid state, all things otherwise being equal [ha!] I'd suspect that with ear training it would be easy to spot the difference in a double-blind test.

I'd say there's enough measurable difference between something like the Conrad Johnson Premier 12 amps and something like the Parasound monoblocks that it would be detectable in a DBT if the auditors were trained to hear the difference. But I suppose the ear-training would undermine the notion of the DBT. To a certain extant, some folks 'round here take the concept of the DBT as some sort of holy writ. Those questioning the a prioris of DBT are often regarded as heretical at this forum.

" . . . the precision, clarity of transients, impact and dynamics, for instance of a drum set . . ."---one of the things I first noticed about the Topping L30 headphone amp was the sound of percussion. Usually there some sort of audio hash obscuring the pitch of the drums. The pitch and clarity of percussion instruments is different, and better, with the Topping amp than what I can recall hearing before on recordings.
 
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Julf

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To a certain extant, some folks 'round here take the concept of the DBT as some sort of holy writ. Those questioning the a prioris of DBT are often regarded as heretical at this forum.
Like democracy, properly executed DBTs are not perfect, but better than the alternatives. How do you suggest dealing with the most significant influence on perceived sound by far - confirmation and expectation bias?
 

Robin L

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Like democracy, properly executed DBTs are not perfect, but better than the alternatives. How do you suggest dealing with the most significant influence on perceived sound by far - confirmation and expectation bias?
I wouldn't. I think this problem is amplified by self-hypnosis, the tendency for folks to convince themselves that they are hearing something they are not. I'd say self-hypnosis amplifies confirmation and expectation bias. My favorite example being the way people convince themselves that LPs are SOTA when there's an in-your-face distortion on all LPs, one that gradually increases as the LP reaches the end of a side. One needs to go to a lot of effort to convince oneself that the sound is not getting worse as the stylus meets the deadwax. I doubt there's a DBT for that, it involves comparing the overall sound quality of the start of an LP side to the end of an LP side. Too many variables. But, still, an obvious distortion, one that a trained ear will always notice.
 
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Julf

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I wouldn't. I think this problem is amplified by self-hypnosis, the tendency for folks to convince themselves that they are hearing something they are not. I'd say self hypnosis amplifies confirmation and expectation bias. My favorite example being the way people convince themselves that LPs are SOTA when there's an in-your-face distortion on all LPs, one that gradually increases as the LP reaches the end of a side. One needs to go to a lot of effort to convince oneself that the sound is not getting worse as the stylus meets the deadwax. I doubt there's a DBT for that, it involves comparing the overall sound quality of the start of an LP side to the end of an LP side. Too many variables. But, still, an obvious distortion, one that a trained ear will always notice.
Absolutely. The problem is when someone claims to hear differences between, let's say, two ethernet cables. In that kind of situation, a DBT is the gold standard.
 

Wombat

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Tube sound is not a myth. Variations in circuit design and output transformers can deliver a wide range of performance parameters. Accuracy in tube amps generally costs more - significantly more in power amps.

Solid state performs significantly better for the dollar in terms of fidelity and is better generally.

Some like the 'tinted' sound. Preference vs fidelity.
Don't%20tell%20anyone.gif
 

andreasmaaan

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I think you could distinguish it blind as well having owned some CJ (and other tubed) amps.

The CJ has restricted bandwidth at higher powers on both the low and high end of the frequency range. Transformer issue. The final thing Bob Carver had to match with his amp on the big CJ was reducing the reach and power in the bass frequencies. He had to restrict high power bass and damping before all agreed he had met their challenge. When he reduced output of his amp to 65 watts, and only reach down to 30 hz in the bass it matched the CJ. That is something you'll hear blind vs an SS amp on wide bandwidth music.

Here are some specs that were typical of all their amps with tubes. This from the Premier Five he was emulating.
Specifications:
  • Power Output: 200 watts, minimum RMS, at 4, 8, or16 ohms from 30Hz to 15kHz with no more than 1% THD or IM Distortion.
  • Response: 20Hz to 20 kHz, +0, -.5 dB
  • Input Sensitivity: 1.0 volts
  • Hum & Noise: 96 dB below rated power
I love the image of Bob Carver tinkering away with his solid state electronics to recreate the sound of a CJ, like a master art forger using modern materials to forge an old work, not to fool some unsuspecting buyer, but instead to expose the conceits of the art (or in this case home audio) world.
 

Robin L

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I love the image of Bob Carver tinkering away with his solid state electronics to recreate the sound of a CJ, like a master art forger using modern materials to forge an old work, not to fool some unsuspecting buyer, but instead to expose the conceits of the art (or in this case home audio) world.
 

MattHooper

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I love the image of Bob Carver tinkering away with his solid state electronics to recreate the sound of a CJ, like a master art forger using modern materials to forge an old work, not to fool some unsuspecting buyer, but instead to expose the conceits of the art (or in this case home audio) world.

Agreed.

No manufacturer ever wants to sell their amp (or other gear) as coloring the sound, adding any distortion. So like other gear, tube amps have been sold with all sorts of technical rationalizations that they are somehow reducing distortions found in SS amps, getting you "closer to the music" (the pure signal). So a lot of audiophiles and reviewers fall in line with this. (You get similar pitches made for vinyl, with the "vinyl gives you thewhole, original waveform, digital chops it up and misses information!").

Though to be fair, I do see quite a number of reviewers acknowledge the tendency of tube amps to distort/color the sound. (Though often in the context of saying "but the tube amp under review actually gets you closer to the music.")

I'm fine with a dollop of coloration.
 

SIY

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But I suppose the ear-training would undermine the notion of the DBT. Absolutely untrue.

To a certain extant, some folks 'round here take the concept of the DBT as some sort of holy writ. Those questioning the a prioris of DBT are often regarded as heretical at this forum.
My comment in red. And regarding the second part, a correct way to express this is, "To a certain extent, people who care about reality and using the tools of science to ascertain it take the concept of the DBT as some sort of most basic control in determining audibility. Those questioning the a prioris of DBT are advocating pseudo-science and superstition."
 

Robin L

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My comment in red. And regarding the second part, a correct way to express this is, "To a certain extent, people who care about reality and using the tools of science to ascertain it take the concept of the DBT as some sort of most basic control in determining audibility. Those questioning the a prioris of DBT are advocating pseudo-science and superstition."
Like I said before:

sutherland_body_snatchers.jpg
 

levimax

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Agreed.

No manufacturer ever wants to sell their amp (or other gear) as coloring the sound, adding any distortion. So like other gear, tube amps have been sold with all sorts of technical rationalizations that they are somehow reducing distortions found in SS amps, getting you "closer to the music" (the pure signal). So a lot of audiophiles and reviewers fall in line with this. (You get similar pitches made for vinyl, with the "vinyl gives you thewhole, original waveform, digital chops it up and misses information!").

Though to be fair, I do see quite a number of reviewers acknowledge the tendency of tube amps to distort/color the sound. (Though often in the context of saying "but the tube amp under review actually gets you closer to the music.")

I'm fine with a dollop of coloration.
Hi Matt, I hope you can do some DBT amp testing some day as I would love to hear your comments.... the equipment needed is not extensive or expensive. Regarding the "coloration" of tube amps, I believe you can get 90% of it just by putting a 1 Ohm 10 watt resistor in line with the speakers of a SS amp. This simulates the internal resistance of the output transformers and will give you a FR and damping factor very similar to a tube amp. I am skeptical about hearing distortion differences between amps but FR differences due to internal resistance can add up to multiple dB differences at some frequencies. I saw a chart of a Klipsch Horns somewhere where there was a 10 dB difference at some frequency in FR between SS and tube amps due just to internal resistance differences.... I think I could even hear that.
 

dfuller

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Hi Matt, I hope you can do some DBT amp testing some day as I would love to hear your comments.... the equipment needed is not extensive or expensive. Regarding the "coloration" of tube amps, I believe you can get 90% of it just by putting a 1 Ohm 10 watt resistor in line with the speakers of a SS amp. This simulates the internal resistance of the output transformers and will give you a FR and damping factor very similar to a tube amp. I am skeptical about hearing distortion differences between amps but FR differences due to internal resistance can add up to multiple dB differences at some frequencies. I saw a chart of a Klipsch Horns somewhere where there was a 10 dB difference at some frequency in FR between SS and tube amps due just to internal resistance differences.... I think I could even hear that.
If it means anything, the output impedance of the ST-70 II is well under an ohm from both 4 and 8 ohm outputs (~0.7R or lower on 8 ohm, 0.5R or lower on 4). I'm not sure that you can simplify it to "it's just higher output impedance". More likely the sound is related to the fact that tube amps are both higher distortion and roll off quite a bit of top end (referencing the ST-70 II again, it's 2dB+ down at 20KHz).
 

Julf

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If it means anything, the output impedance of the ST-70 II is well under an ohm from both 4 and 8 ohm outputs (~0.7R or lower on 8 ohm, 0.5R or lower on 4). I'm not sure that you can simplify it to "it's just higher output impedance". More likely the sound is related to the fact that tube amps are both higher distortion and roll off quite a bit of top end (referencing the ST-70 II again, it's 2dB+ down at 20KHz).
Even 0.5 Ω is pretty high (compared to solid state amps that easily do 0.05 Ω).
 
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