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Do amplifiers really sound the same?

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sergeauckland said:
No, that's not quite right. One's comparing the direct path against the other path which includes the PAuT. However, this PAuT is driving the dummy load, which can be as complex as one likes, and so is being compared with a straight piece of wire. Unless the power amplifier driving the 'speakers is badly flawed, any error due to the PAuT will be audible. If nothing's audible either way, then the PAuT must be transparent.
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I understand the test. Let's say your threshold of distortion audibility is 1%. If the PAuT has 0.9% of distortion, and does the baseline PA, they would sound transparent on their own. But when the signal is passed through the PAuT, the distortion is additive and the PAuT+PA combo now sounds marginally distorted. Would this infer the PAuT is not transparent?
 
Yank said:
I rank this claim right up there with people not being able to tell the difference between Caruso and a Victrola.
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Despite their snazzy persona's all of the Spice Girls seemed equally annoying to me. Although the sporty one can actually sing.
 
James said:
Transparency is both absolute and relative. In the analogous world of photography, the amplifier is a camera lens. It should transfer what it sees from one side and re-create an identical image on the other side on film or sensor.

Some objectivists (Vuk will call them something else) measure transparency with the amount of pin-cushion/barrel distortion (THD), chromatic aberration (IMD), contrast (S/N, dynamic range), colour rendition (FR) throughout the range of apertures (power). The subjectivist would just use the lens and see if it takes a pleasing photograph. AFAIK, the subjective attribute of bokeh, which every photographer understands, cannot be measured just yet - but it is an artefact of the lens.

Maybe we're going around in circles with amplifier bokeh.
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therefore all cameras whether cheap or expensive in price, with identical shutter speeds and pixel resolution etc should produce an identical image?
 
James said:
Transparency is both absolute and relative. In the analogous world of photography, the amplifier is a camera lens. It should transfer what it sees from one side and re-create an identical image on the other side on film or sensor.
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The problem with that analogy is that an amplifier has a linear behaviour (or at least it should have) whereas the behaviour of a lens most certainly isn't - stop it down or open it up and a whole raft of characteristics change.
 
ziggy72 said:
therefore all cameras whether cheap or expensive in price, with identical shutter speeds and pixel resolution etc should produce an identical image?
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If the lens is the same, and all the settings are the same, of course.
 
James said:
Transparency is both absolute and relative. In the analogous world of photography, the amplifier is a camera lens. It should transfer what it sees from one side and re-create an identical image on the other side on film or sensor.

Some objectivists (Vuk will call them something else) measure transparency with the amount of pin-cushion/barrel distortion (THD), chromatic aberration (IMD), contrast (S/N, dynamic range), colour rendition (FR) throughout the range of apertures (power). The subjectivist would just use the lens and see if it takes a pleasing photograph. AFAIK, the subjective attribute of bokeh, which every photographer understands, cannot be measured just yet - but it is an artefact of the lens.

Maybe we're going around in circles with amplifier bokeh.
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The difference is that the camera is a tool for the artist. Most, if not all, of the great photographers used the best cameras available, until companies realised that having a famous photographer using their brand was a definite plus in terms of sales. In the days of film, most did their own developing and printing, too, so technical knowledge was (and is) high.

The subjectivist comes in to play only when, appropriately, choosing the subject and arranging the composition.

Photography isn't remotely analogous with HiFi anyway. One is creative, the other entirely passive.
 
James said:
I understand the test. Let's say your threshold of distortion audibility is 1%. If the PAuT has 0.9% of distortion, and does the baseline PA, they would sound transparent on their own. But when the signal is passed through the PAuT, the distortion is additive and the PAuT+PA combo now sounds marginally distorted. Would this infer the PAuT is not transparent?
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It is normal for the measuring instrument to have accuracy of at least 10x better than what you're trying to measure. So, the monitoring power amp should have far less distortion, flatter frequency response and less noise than the PAuT. When the straight-wire bypass test was devised, I guess sometime in the 1950s if not before, one could get laboratory-standard amplifiers with low enough distortions whilst "normal" HiFi amplifiers had rather more.

Nowadays, with even everyday HiFi amps having vanishingly low distortion, it might be difficultto find something of even lower distortion to act as the monitoring amplifier. However, if we accept that the threshold of audibility for distortions is somewhere around the 1% (depending on the harmonic structure) then the earlier standard for "perfection" of 0.1% es exemplified by the Leak Point Ones, and Williamson amplifiers, still holds. WHatever the harmonic structure, if distortions at all levels and frequencies is less than 0.1%, that's transparent, certainly for most people, if not everyone.

If the PAuT has distortion of 0.9%, fairly typical for a valve amplifier, then any modern SS amp will easily be 10x better.

S.
 
john dolan said:
I have a hi fi mag from a few years ago that the reviewer did a factory visit and while he was there he noticed a few guys in a corner and when he asked what are those guys doing the manager told him they were testing different solders for sound.

If you don't believe me phone them up and ask them instead of insinuating i just lied about it.
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I am in no way insinuating you lied about it John. I am insinuating that solders do not, under any circumstances, have a different sound.

I may have been insinuating....no, I'll come right out and say it. You are far too gullible for your own good. Sorry, but there it is.

Chris
 
sergeauckland said:
One's comparing the direct path against the other path which includes the PAuT. However, this PAuT is driving the dummy load, which can be as complex as one likes, and so is being compared with a straight piece of wire. Unless the power amplifier driving the 'speakers is badly flawed, any error due to the PAuT will be audible. If nothing's audible either way, then the PAuT must be transparent.


S.
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Aren't you comparing a switch and path, with a switch and amp and path?

Slightly different if that is the case as we need to know if the switch itself lessens potential transparency overall.

Doesn't not connecting two amps to the pre amp effect the performance of the pre-amp or indeed does having the two power amps driving various loads do the same to each other?

Again maybe this all lessens potential transparency overall and is distorting the baseline result?
 
sergeauckland said:
It is normal for the measuring instrument to have accuracy of at least 10x better than what you're trying to measure. So, the monitoring power amp should have far less distortion, flatter frequency response and less noise than the PAuT. When the straight-wire bypass test was devised, I guess sometime in the 1950s if not before, one could get laboratory-standard amplifiers with low enough distortions whilst "normal" HiFi amplifiers had rather more.

Nowadays, with even everyday HiFi amps having vanishingly low distortion, it might be difficultto find something of even lower distortion to act as the monitoring amplifier. However, if we accept that the threshold of audibility for distortions is somewhere around the 1% (depending on the harmonic structure) then the earlier standard for "perfection" of 0.1% es exemplified by the Leak Point Ones, and Williamson amplifiers, still holds. WHatever the harmonic structure, if distortions at all levels and frequencies is less than 0.1%, that's transparent, certainly for most people, if not everyone.

If the PAuT has distortion of 0.9%, fairly typical for a valve amplifier, then any modern SS amp will easily be 10x better.
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No disagreement there, but I was merely trying to show how your test is flawed if transparency was marginal to begin with.
 
spxy said:
Aren't you comparing a switch and path, with a switch and amp and path?

Slightly different if that is the case as we need to know if the switch itself lessens potential transparency overall.

Doesn't not connecting two amps to the pre amp effect the performance of the pre-amp or indeed does having the two power amps driving various loads do the same to each other?

Again maybe this all lessens potential transparency overall and is distorting the baseline result?
Click to expand...

If you seriously believe that a switch lessens transparency or that connecting two power amps affects the pre-amp, then nothing will convince you. Nothing with any science attached anyway. Carry on with your dlusions.

Next you'll be suggesting different solders sound different.

S.
 
James said:
No disagreement there, but I was merely trying to show how your test is flawed if transparency was marginal to begin with.
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Yes, but any test instrumentation cannot be marginal to begin with or it's useless.We're talking engineering here, not HiFi.

S.
 
ultrawomble said:
The problem with that analogy is that an amplifier has a linear behaviour (or at least it should have) whereas the behaviour of a lens most certainly isn't - stop it down or open it up and a whole raft of characteristics change.
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It's a question of scale. Amplifiers are rarely perfectly linear, just as the technically perfect lens does not exist.

avole said:
The difference is that the camera is a tool for the artist.
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No, it's a tool for recording an image. I have several cameras and I don't consider myself an artist.

avole said:
Photography isn't remotely analogous with HiFi anyway. One is creative, the other entirely passive.
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Both are technical means to subjective performance. I think the analogue is a lot stronger than you'd care to accept.
 
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