Double Blind tests *did* show amplifiers to sound different

[A.West]

Great- that’s what I needed to know- I’m constantly seduced by beautiful, chunky amps which promise to transform my listening experience but I want to believe that, aside from features and build quality, an amp is basically an amp! This complex thread has just about convinced me that I’m right and saved me £3000 or so!

Well if it makes you feel better, I do note that the $30 class D 7 WPC stereo amp I bought from Amazon sounds pretty bad. So there is a bottom limit below which one should not go. In general, if you want your system to sound noticeably different, change your speakers, or less expensively, change the placement of your speakers. Or use DSP/room correction. Those things can create audible changes orders of magnitude bigger than going from good technical purity to great technical purity. To my ears.
Amir gets upset because my AVR's preout is -1db at 16khz and -2.5db at 20khz, a frequency almost anyone who can afford audiophile gear is unable to hear, and which could be fixed with an equalizer adjustment, just in case I decide to listen to a Dog Whistle Concerto as the composer intended, and despite widely preferred Harman curve rolling off highs much more than that.
I think objective audio science should compare cost vs audible benefit, measured not just by instruments but also by many (blind) ears.
I guess the Harman Curve has been the biggest investment in such measurement of and adjustment to listener perception.

 

[Ingres3225]

Well if it makes you feel better, I do note that the $30 class D 7 WPC stereo amp I bought from Amazon sounds pretty bad. So there is a bottom limit below which one should not go. In general, if you want your system to sound noticeably different, change your speakers, or less expensively, change the placement of your speakers. Or use DSP/room correction. Those things can create audible changes orders of magnitude bigger than going from good technical purity to great technical purity. To my ears.
Amir gets upset because my AVR's preout is -1db at 16khz and -2.5db at 20khz, a frequency almost anyone who can afford audiophile gear is unable to hear, and which could be fixed with an equalizer adjustment, just in case I decide to listen to a Dog Whistle Concerto as the composer intended, and despite widely preferred Harman curve rolling off highs much more than that.
I think objective audio science should compare cost vs audible benefit, measured not just by instruments but also by many (blind) ears.
I guess the Harman Curve has been the biggest investment in such measurement of and adjustment to listener perception.

I think a big part of the problem for consumers like me is that we think ‘surely that £5000 amp will totally transform my system beyond anything my current £400 amp can achieve!’ without the inclination to trawl through forums and threads like this one which suggest otherwise via measurements and direct testing- we think that the whole industry can’t be pulling the wool over our eyes so brazenly! But I believe you about there being a lower limit as well- I don’t fancy delving down there!

 

[welsh]

Thank you for reiterating you dogmatic opinion, SIY.

As I said in my reply to March Audio, it would be easier for me to believe that my perceptions were entirely due to presumptions and biases if my perceptions didn't differ so often from what I anticipated.

This is a well-worn subjectivist ‘escape hatch’. In sighted listening, being surprised at a perceived result is of no greater interest to science than having a pre-existent expectation ‘confirmed’.

 

[welsh]

I'm sure you've also done detailed measurements of the final product.
If so, you then can be confident that the product will "sound right" when it arrives in the customers hands.

Sure, right along the lines of the anti-MQA DAC designer who includes MQA so as not to lose any potential sales.

Or in the case of perfectly sensible speaker manufacturers who feel obliged to include bi-wirable connections for fear of losing sales to audiophools...

 

[Sal1950]

Or in the case of perfectly sensible speaker manufacturers who feel obliged to include bi-wirable connections for fear of losing sales to audiophools...

Sure but you can't blame them. Business is business.

 

[Head_Unit]

Or in the case of perfectly sensible speaker manufacturers who feel obliged to include bi-wirable connections for fear of losing sales to audiophools...

It's because the cable makers are controlling them via those microchips in the COVID vaccines...

 

[Head_Unit]

Tube amplifiers, for example, SET amps without feedback, clip less harshly, but still clip, however the wave is more rounded and thus in simple terms less harmonics created and less odd order harmonics created. Its a generalization but still factual

IS it? I always thought that, but it doesn't seem borne out by clipping graphs in say Stereophile. Granted however I've never examined tube vs solid-state super closely; I've just noticed that tube amps still have a pretty sharp knee. I'd also think than any "gentler" effect would only last for maybe 1 dB. Hmmm speaking of Stereophile maybe I should write John Atkinson and ask his opinion.
- Putting the shape of the THD curve aside, I wonder if tube amps tend to not have the ugly protection limiting of various solid state designs?
- @Amir has a really good point about those protection circuits, there was an entire Audio Engineering Society paper about this showing some really ugly waveforms-like the voltage snapping to the opposite rail, tons of high frequency oscillation.

 

[Head_Unit]

On AVRs you often have to rotate the knob many times to cover the full range. Compared to an old school amp with a potentiometer which covers the entire range in less than 360 degrees, I feel like the AVR amps are ‘weak.’

Oh absolutely this is a thing! When I worked in autosound and implemented rotary encoders instead of potentiometers, the chips the encoders controlled would do like 0 to -80 dB in 2 dB steps. Complaints galore about knob rotation! "It's so much weaker! I gotta keep turning it up!" It was exactly like the "turning it up to 11" bit in Spinal Tap. So we cobbled out the lowest steps so the volume ramped up fast. (Throwing away all fine control of volume at low levels, alas )

 

[SIY]

IS it? I always thought that, but it doesn't seem borne out by clipping graphs in say Stereophile. Granted however I've never examined tube vs solid-state super closely; I've just noticed that tube amps still have a pretty sharp knee. I'd also think than any "gentler" effect would only last for maybe 1 dB. Hmmm speaking of Stereophile maybe I should write John Atkinson and ask his opinion.
- Putting the shape of the THD curve aside, I wonder if tube amps tend to not have the ugly protection limiting of various solid state designs?
- @Amir has a really good point about those protection circuits, there was an entire Audio Engineering Society paper about this showing some really ugly waveforms-like the voltage snapping to the opposite rail, tons of high frequency oscillation.

Tube amp clipping looks not much different than solid state amp clipping- but the vast majority of tube amps add in another mechanism, blocking, which is much more sonically damaging. One can design the amp to avoid blocking, but very very few are.

It's trivially easy to design solid state amps that clip cleanly and recover instantly, and that's the rule not the exception.

 

[tomelex]

IS it? I always thought that, but it doesn't seem borne out by clipping graphs in say Stereophile. Granted however I've never examined tube vs solid-state super closely; I've just noticed that tube amps still have a pretty sharp knee. I'd also think than any "gentler" effect would only last for maybe 1 dB. Hmmm speaking of Stereophile maybe I should write John Atkinson and ask his opinion.
- Putting the shape of the THD curve aside, I wonder if tube amps tend to not have the ugly protection limiting of various solid state designs?
- @Amir has a really good point about those protection circuits, there was an entire Audio Engineering Society paper about this showing some really ugly waveforms-like the voltage snapping to the opposite rail, tons of high frequency oscillation.

I was trying to emphasize the SET amp, non-feedback SET amps. They act more as a compressor when they are into beginning overload. Tube amps with feedback clip like solid state for the most part. This is another reason (not the only) SET amps seem to play louder, ie you can clip them with less irratable audible effect. Correct, the gentler effect is limited to a few dB on most designs, but the harmonic spray is gentler overall as far as audibility, so a SET just clipping will tend to compress those overloads some. Its not a game changer, but I like to give a positive to something the SET does better than other configurations. Make no mistake, you can clip a SET amp enough and it will sound ugly just like anything else.

As SIY says, basic SET designs and tube designs can suffer from blocking due to the technique used to bias/transfer signal to the power stage, and better designs do not suffer this issue.

 

[MattHooper]

IS it? I always thought that, but it doesn't seem borne out by clipping graphs in say Stereophile. Granted however I've never examined tube vs solid-state super closely; I've just noticed that tube amps still have a pretty sharp knee. I'd also think than any "gentler" effect would only last for maybe 1 dB. Hmmm speaking of Stereophile maybe I should write John Atkinson and ask his opinion.
- Putting the shape of the THD curve aside, I wonder if tube amps tend to not have the ugly protection limiting of various solid state designs?
- @Amir has a really good point about those protection circuits, there was an entire Audio Engineering Society paper about this showing some really ugly waveforms-like the voltage snapping to the opposite rail, tons of high frequency oscillation.

As I think I've mentioned before, presuming first the case of a tube amplifier sounding different from solid state, explanations for the sound based on clipping characteristics never made much sense to me. Like most audiophiles who enjoy tube amps, I find that the sound is simply different, at whatever volume. Whereas the clipping hypothesis would seem to imply the sonic difference should only occur when an amp is pushed in to clipping territory. As I understand it, that would be pretty rare as most of us aren't driving our amps in to clipping in normal use, and occaisional clipping wouldn't explain the persistant sonic differences.

 

[SIY]

Like most audiophiles who enjoy tube amps, I find that the sound is simply different, at whatever volume.

As long as you peek.

 

[MattHooper]

As long as you peek.

"presuming first the case of a tube amplifier sounding different from solid state"

If you don't think tube amps can sound different, it's a moot discussion.

 

[SIY]

"presuming first the case of a tube amplifier sounding different from solid state"

If you don't think tube amps can sound different, it's a moot discussion.

“Think” has nothing to do with it. “Evidence.”

 

[MattHooper]

“Think” has nothing to do with it. “Evidence.”

Actually...if you think there is no evidence, you think tube amps can't change the sound, right? ;-)

I know you are among the hardest skeptic here about tube amps making a sonic difference, but can I presume you don't actually reject all possible
cases where a (functioning) tube amp might alter the sound of a system?

If so, that would seem to be pretty extreme. Even the irascible Arny Krueger acknowledged that tube amps can sound different from solid state.

My point being, again, when a tube amp does in fact sound different in a system, what causes this? I gave my reason for some skepticism that it would be all about clipping. But of course I could be wrong.

And, if your position is that there is no plausible technical explanation for how a tube amp could alter the sound of a system, and no solid evidence has ever been produced for the proposition, then...yup...this isn't a question for you

 

[SIY]

Actually...if you think there is no evidence, you think tube amps can't change the sound, right? ;-)

Non sequitur.

 

[krabapple]

As long as you peek.

David Clark's ABX website showed positive 'difference' ABX results for a tube vs SS amp, using the old hardware comparator. I can't find the site anymore or I would give you more details.

Also, it has long (for as long as I've been following/participating in the 'Great Debate' online ...way too long now) been accepted by even fanatical DBT enthusiasts that tube vs SS is one of the corner cases where amp differences can manifest 'for real' in normal listening.

They also accept that it does not mean they must.

 

[SIY]

David Clark's ABX website showed positive 'difference' ABX results for a tube vs SS amp, using the old hardware comparator. I can't find the site anymore or I would give you more details.

Also, it has long (for as long as I've been following/participating in the 'Great Debate' online ...way too long now) been accepted by even fanatical DBT enthusiasts that tube vs SS is one of the corner cases where amp differences can manifest 'for real' in normal listening.

They also accept that it does not mean they must.

A solid state amp with a similarly high source impedance will sound the same. Ditto comparing a very low source impedance tube amp to a normal solid state amp. The devices are irrelevant.

 

[MattHooper]

Non sequitur.

Why?

You do understand conditional statements, such as "presuming first the case of a tube amplifier sounding different from solid state"...right?

IF you acknowledge that a tube amp can sound different, then the question I asked is entirely reasonable. Does clipping adequately explain the way a tube amp would sound different?

But you seemed to imply it was a moot question, talking instead about "peeking," when I had already conditioned the question adequately.

It follows that if you don't think a tube amp CAN sound different, then it's a moot question, as you seemed to treat mine. But if you DO think a tube amp CAN sound different, then the "peeking" part is a non-sequitur, given a question conditioned on "when a tube amp sounds different."

 

[krabapple]

A solid state amp with a similarly high source impedance will sound the same. Ditto comparing a very low source impedance tube amp to a normal solid state amp. The devices are irrelevant.

If you're going to be obtuse, I won't bother.