If tubes amplifiers measure poorly, why are they perceived as sounding better?

[Jim Taylor]

Tube amplifiers certainly don't sound better to me. How did you come to this conclusion?

Where does my post say anything about tube amplifiers sounding better? Please don't put words in my mouth. This paper simply discusses a mechanism in the ear which parallels increasing harmonic distortion with increasing SPL.
I simply found the paper, and thought it might be of value here ... or at least interesting ... in light of two posts by other well-respected members.

 

[Jim Taylor]

Part of tube sound is likely due to a voltage divider effect between the amp's output impedance and the speaker's input impedance. The amp's output impedance will be fairly stable over frequency, while the speaker's will vary quite a bit with frequency. The speaker in effect modulates the tube amp's response by the varying impedance over frequency the speaker presents to the amp. So that tube amp is likely to produce a different type of tube sound when different speakers of different impedance characteristics are connected to it. A low Zout S.S. amp will not be affected by this mechanism, what with e dozen or so milli-ohms of output Z they usually have. The S.S. amp looks at the speaker and say, "Speaker, you are coming along with me, do you understand? You do not get to argue, sorry.".

Yes ... part. That is well known, and has been cited by many here (including me) many times. This paper cites another mechanism that works within the ear and may be responsible for distortion profiles that increase with output being "heard" differently.

 

[Jim Taylor]

Do we know if this "aural harmonic envelope" (AHE) is the same for different people?

If I understand it correctly, it's unique for each individual.

If a musical instrument has the same AHE as me,

Again .... if I understand it correctly, the AHE is an operation of your cochlea/brain, not an external instrument.

 

[Cbdb2]

It follows that this same mechanism will mask harmonics arising in the sound reproduction chain if they follow this pattern.

If a musical instrument has the same AHE as me, does this mechanism mask the instruments harmonics?

 

[Jim Taylor]

It follows that this same mechanism will mask harmonics arising in the sound reproduction chain if they follow this pattern.

If a musical instrument has the same AHE as me, does this mechanism mask the instruments harmonics?

Interesting. I hadn't thought that the pattern ...

To an amount of nearly 10% of the fundamental for sound pressure levels (SPL’s) of 90dBA and above. Even for the moderate SPL of 80dBA, the 2nd harmonic is at the equivalent of 65dBA or normal voice level, and the 3rd at 45dB. This is still ~40dB above the average human threshold of hearing,

... would occur in the real world. That was an assumption, and I should not make assumptions. Good point, and bad on me.

 

[Salt]

Interesting. I hadn't thought that the pattern ...

To an amount of nearly 10% of the fundamental for sound pressure levels (SPL’s) of 90dBA and above. Even for the moderate SPL of 80dBA, the 2nd harmonic is at the equivalent of 65dBA or normal voice level, and the 3rd at 45dB. This is still ~40dB above the average human threshold of hearing,

... would occur in the real world. That was an assumption, and I should not make assumptions. Good point, and bad on me.

Well..

 

[mhardy6647]

PS We miss you, Gilda!

 

[SIY]

I have been reading about this for years, please, can somebody help me, and pinpoint a study showing this is actually a scientific fact? Has there been any respectable double-blind study showing that some people can differentiate a tube amp from a solid amp and actually prefer the tube sound? You know, without this, this whole conversation has no ground.

Of course there isn't. Handwaves and (a few) plausibility arguments, but no-one has actually demonstrated a "tube sound." Nor, for that matter, actually provided a universally accepted definition of it.

 

[Timcognito]

As SIY says there is no generic tube design or sound, and in the past many were designed using the designer's ears as a guide, many schematic variations and tweeks. My little Audio Research CA-50 (1997) was as detailed as many coveted SS designs of the same period, because AR wanted that sound. As I understand, many tube designs struggle at one end or other or both of the frequency range and that was true of the CA50, which had a sub out, rare for a tube amp.

Here's what Nelson Pass says about design (please don't shoot the messenger, me)

The Sweet Spot - Pass Labs

Introduction Every audiophile understands the concept of the “sweet spot”, that happy balance of conditions that elicits the best possible sound. It can be a particular listening spot, the best positioning of loudspeakers, or the fortuitous combination of components which … Continue reading →

www.passlabs.com

 

[Chr1]

This may have been posted elsewhere, but also helps to explain why valves can sound better than they ought to :

Why Tubes Sound Better by Ken Rockwell

Why Tubes Sound Better by Ken Rockwell

www.kenrockwell.com

 

[Madlop26]

This may have been posted elsewhere, but also helps to explain why valves can sound better than they ought to :

Why Tubes Sound Better by Ken Rockwell

Why Tubes Sound Better by Ken Rockwell

www.kenrockwell.com

These are subtle effects most audible to musicians and very dedicated music lovers; casual listeners (people who "listen" with their eyes open while doing something else) usually won't notice, but sometimes the difference is so obvious that people's wives will comment that "wow, that sounds much better" when people use tubes at home.

yep, there you have it, from subtle to obvious, no need to read the rest

 

[Chr1]

And your point is?...

..."no need to read the rest."
I'm afraid that this indicates either arrogance or ignorance to me.
Or both.
Perhaps you are just way more knowledgeable than Ken Rockwell however.

 

[Madlop26]

And your point is?...

"No need to read the rest."
I'm afraid that this indicates either arrogance or ignorance to me. Or both.
Perhaps you are just way more knowledgeable than Ken Rockwell however.

My point is: the article states the usual arguments about tube amps, but still no scientific proof that this added distortion makes the experiences better, lots of subjective claims by an "expert", who ends up giving you lots of buying links.

 

[MaxwellsEq]

This may have been posted elsewhere, but also helps to explain why valves can sound better than they ought to :

Why Tubes Sound Better by Ken Rockwell

Why Tubes Sound Better by Ken Rockwell

www.kenrockwell.com

I've read it. Interesting. What it should say throughout is NOT "better" but perhaps "nicer" - i.e. "Why tubes sound nicer". They don't actually sound better. Line-level tube designs, done well, are audibly indistinguishable from transistor line-level designs. Tube power amplifiers are much more difficult to make accurate, due to output transformers and high output impedance.

There are some statements in the article which are nonsense: especially about solid state amplifiers only working well when driven hard and tube amplifiers working better at the normal lessons we listen at. That's silly!

 

[Chr1]

My point is: the article states the usual arguments about tube amps, but still no scientific proof that this added distortion makes the experiences better, lots of subjective claims by an "expert", who ends up giving you lots of buying links.

There's also no evidence to show that tube amp distortion is unpleasant to those who use them either. I can assure you that I enjoy the distortion of mine.
To me, you are simply showing arrogance and/or ignorance by not reading the rest of the article. No one is claiming that they are more high fidelity.
Perhaps you should check the title of this thread.

 

[Randolf]

... and they are right. The boom is the result of the output impedance of the tube. It's higher than typical solid state amps and leads to kind of a slight loudness effect, depending on the impedance curve of the speaker. You can get the same effect with solid state amps with EQ, or by adding a resistor in series to the speaker, thereby increasing its output impedance.

Any high output impedance amplifier adds an equalizing effect to your system. It can be inaudible, small or huge depending on the speaker/headphone impedance curve. It may be beneficial or bad. You can use https://github.com/rwhomeaudio/FreqRespGraph to calculate the effect on a frequency response. Example 9 shows a very bad case, low impedance Headphone (with peaking impedance at 100 Hz) on a very high output impedance amplifier:

 

[SIY]

Perhaps you are just way more knowledgeable than Ken Rockwell however.

Rockwell's article is the usual combination of handwave, inapt analogy, and complete lack of any audibility testing.

edit: I should mention that in the one actual DBT he did, he admits he heard no difference.

 

[Chr1]

Perhaps you, or anyone could point me towards some tests that show that people who enjoy the sound of the harmonic distortion of tubes are either wrong or experiencing nothing but placebo?
I am sure there will be some who are experiencing placebo, but highly doubt that it is as widespread as made out here.

(The implication being, that if you enjoy the sound of valves these days, you are just kinda stupid. This is the bit that I have issue with.)

Obviously there is much variation in tube amps and the effects of their harmonic distortion can be very subtle. I suspect that this was the case when Rockwell did not notice the difference. Are you suggesting that he doesn't know what he is talking about? Or are you suggesting that they sound the same as SS?
Personally, I don't think either.
My 2c, but each to their own. This is why I like to discuss these things.

Edit: I do think that the Rockwell article title is a tad problematic. The addition of "can", and "to some people" would be better imho!

 

[Jim Taylor]

Here's what Nelson Pass says about design

Nelson Pass is a businessman. The information he offers favors his business model.

And your point is?...

..."no need to read the rest."
I'm afraid that this indicates either arrogance or ignorance to me.
Or both.
Perhaps you are just way more knowledgeable than Ken Rockwell however.

I fail to see how critique of sad old audio tropes constitutes arrogance or ignorance. If a person (Ken Rockwell, in this instance) is knowledgeable, let them use that knowledge to support truthful and verifiable statements in relation to the audio world, not simply repeat unsupported assertions.
To paraphrase a saying, "With greater knowledge comes greater responsibility".

The implication being, that if you enjoy the sound of valves these days, you are just kinda stupid. This is the bit that I have issue with.

As has been said many times in these pages, tube designs which have distortions measured below the threshold of human hearing cannot be distinguished from solid-state designs which have the same qualifications. The main negatives associated with the use of tubes is their greater cost and higher maintenance.

However, the majority of tube designs that I have seen (and I don't claim to have seen them all) have been affected designs. They have characteristics that are above the threshold of human hearing. Much of the gush and hyperbole associated with these designs leads one to believe that the obvious imperfections inherent in these products are deliberate, and introduced to support a fanboy base of buyers who have been led to believe that the imperfections are "better" or "more realistic".

That's sad. Sad at the least, and arguably disingenuous.

 

[mhardy6647]

Ke. RO

Rockwell's article is the usual combination of handwave, inapt analogy, and complete lack of any audibility testing.

edit: I should mention that in the one actual DBT he did, he admits he heard no difference.

Ken Rockwell. 'Nuff said.
A man with a phenomenally high opinion of his own insight.