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Double Blind tests *did* show amplifiers to sound different

Benedium

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Source :
https://www.etymonline.com/word/moot

moot (n.)
early 12c., from Old English gemot "meeting, formal assembly" (especially of freemen, to discuss community affairs or mete justice), "society, assembly, council," from Proto-Germanic *ga-motan (compare Old Low Frankish muot "encounter," Middle Dutch moet, Middle High German muoz), from collective prefix *ga- + *motan (see meet (v.)). In early 15c. awful moot was used for "the Last Judgment."

moot (adj.)
"debatable, subject to discussion," by 1650s, from moot case (1570s), earlier simply moot (n.) in the specialized sense "discussion of a hypothetical law case" (1530s) in law student jargon. The reference is to students gathering to test their skills in mock cases.

moot (v.)
"to debate, argue for and against" (mid-14c.), from Old English motian "to meet, talk, discuss, argue, plead," from mot "meeting" (see moot (n.)). Meaning "raise or bring forward for discussion" is from 1680s. Related: Mooted; mooting.
 

restorer-john

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And this one.

1615612498044.png
 

Sal1950

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egellings

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The fact that the amplifiers were allowed to clip every so often would most likely generate clues as to which amplifier was in play, as clipping recovery characteristics are likely to vary among otherwise identical sounding amplifiers and that may be audible. In doing amplifier sound quality comparisons, clipping should never be allowed to occur. Both amps should be operated well within their capabilities.
 

DonH56

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Spkrdctr

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In many online debates, position taken by some that when amplifiers are used that have flat frequency response and low distortion that no double blind tests have shown them to sound different.

Well, I managed to dig up a 32 year old test that says otherwise. What is fascinating is that one of the article/testers was no other than Arny Krueger, the most vocal champion of such arguments in forums!

The article is actually quite short. What I am about to show you is about half of it and contains all pertinent portions. I am happy to field and answer questions that may be in the rest of the article.

So let's start at the top. Here is the title of the 2-page article:

i-nTpXsqF-XL.png


What a headline, no? It says they have "proven" that amplifiers sound different! You almost don't need to read any more but for completeness let's go into it.

Here are the amplifiers in question:

i-xjPp4w3-XL.png


So these are very powerful amplifiers. We are not talking a tube SET amplifier or some other amp that runs out of juice at 20 watts. We have very powerful amplifiers clocking at over 200 watts at 4 ohms.

This being the pre-CD era, a turntable was used. Here are the details of that and the speakers used:

i-3tbhPL7-XL.png


So how did they do? Here are the votes for the three tracks tested:

i-zfdGz3C-X2.png


We see why they say "prove" as the two tracks show statistically that the results are not due to chance.

So the conclusion is as expected:

i-NVbTMcL-XL.png


Not the message we see broadcast on forums.

So what caused the difference? I think it is what I believe to be behind such audibility differences namely what happens at clipping point which occurs far more often than we may think:

i-KCSpjj7-XL.png


No data is presented on what would happen if the volume was turned down.

So there you have it. "Proof" that amplifiers do sound different in double blind tests :D.
Amir, I see what you did. Great post! You back doored the topic very well. I salute your quick wit. :)
 

Spkrdctr

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Indeed my belief is that the difference in amplifier sounds occurs at the limits of their output. It is then that each amp acts very differently than others.
Yes, yes and yes.
 

Spkrdctr

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Comparing SS (solid-state) amp to SS amp it is pretty hard to tell the difference IME unless they are very different (e.g. noise level, output impedance) and the speakers very hard to drive.. Most folk (again IME) greatly overestimate their average power usage but underestimate the peaks, which can be 20 dB (100x the power) higher than the average level.

FWIWFM - Don
Words of wisdom!
 

Spkrdctr

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For a lot of people this hobby is more like a dick measuring contest than anything else.
Yes, every YouTube subjectivist video (well not every single one) they wax eloquently on their ENTIRE audio chain naming each glorious wire, interconnect and device that they have. Showing that they are listening subjectively with very, very good equipment in their opinion. None of that has ANY bearing on any real testing. That is why it is a measuring contest. Whatever you do, never get into a measuring contest with Amir. He uses a yardstick and not a ruler!
 
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Spkrdctr

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It is AMAZING that every time a long dead thread is revived with one post, I start to read the thread and post about it. Only after I'm 15 pages in and 3 posts put up, do I realize that I have posted YET AGAIN on an old long dead thread. I do this EVERY, SINGLE, TIME. It must be old age getting to me. I turned 65 on Nov 17th. The old brain isn't what it used to be. I am such a sucker.
 

Ralph_Cramden

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Peter J Walker, 1978:

PW: An amplifier should, within its limits of voltage and rate of change of voltage,
(which is slew rate limiting) if you keep within those two it should be very much
better than any program material. These are the things that are measured at .01
per cent or .05 per cent. But what is listened to is usually a program with 2 or 3
per cent distortion in the first place. That's the least you can get on records,
tapes, and such things. Listening tests are usually not done in this region of .01
percent distortion. I'm quite convinced within that range the amplifier is just as
perfect as you like to make it. It's quite possible to put 50 amplifiers in cascade,
each one into a load, potted down into the next one, and to listen to the 50th one
or to listen to the first one, and the sound will be virtually the same. So I think you
can make an amplifier just as good as you like, and no more different than a
piece of wire. But where they vary, when these tests are done, are a whole lot of
areas. To start with, you can compare one amplifier with a bass cut-off of 20 Hz
and another one that goes right down to DC. If you've got a program with a bit of
fluffing going on at 5 Hz or so, the speaker cone in one case will be moving, and
in the other case it won't be moving, so the sound from the speaker will be
different. This isn't really a condemnation of the amplifier, it's that they shouldn't
have this 5 Hz stuff there in the first place. So if you compare an amplifier with a
straight wire, you've really got to make the straight wire have the same
bandwidth as the amplifier, and the same terminating impedance as the
amplifier. Once you do all these things, then the amps will be just as good as the
straight wire. The peripheral effects are what get people into trouble. You can
see why you find these differences in amplifiers. You can always find them. If
people test two amplifiers and say, "These sound different," there's no magic in
it. Spend two days, maybe a whole week in the lab, and you find out exactly why
they're different and you can write the whole thing down in purely practical,
physical terms. This is why these two sound different, and the cause is usually
peripheral effects. It is not really a case of good or bad amplifiers, it's that the
termination impedances are wrong, or something of that sort.

 

Barry_Sound

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Hi everyone and merry christmas.

Was just reading on amplifiers. Blind tests in general show that audible differences among hifi amplifiers are basically non-existent if properly level matched and not clipping (which shouldnt happen with typical listening volumes).

Here´s a question to anyone of you who has experienced maybe a dozen amps over the years in this hobby. Did they sound different to you or was the whole swapping pointless in regards to sound? (I understand there are several reasons to change an amp, lets talk about sound only.)

PS: Here´s an interesting read
Peter Aczel: What I have learned after six decades in audio
"There are significant differences in topology, measured specifications, physical design, and cosmetics, not to mention price, but the sound of all properly designed units is basically the same."
https://www.reddit.com/r/audiophile/comments/dt4xin/_/f6v7lhd
 

Purité Audio

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If the amplifer is driven into clipping then it may well sound different, of all the amps I have compared in every ‘class’ A, A/B, D ,H etc I have never heard any difference , having said that all the amps I tried were properly designed, Benchmark, Purifi NCore etc.
Keith
 

SIY

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Hi everyone and merry christmas.

Was just reading on amplifiers. Blind tests in general show that audible differences among hifi amplifiers are basically non-existent if properly level matched and not clipping (which shouldnt happen with typical listening volumes).

Here´s a question to anyone of you who has experienced maybe a dozen amps over the years in this hobby. Did they sound different to you or was the whole swapping pointless in regards to sound? (I understand there are several reasons to change an amp, lets talk about sound only.)

PS: Here´s an interesting read
Peter Aczel: What I have learned after six decades in audio
"There are significant differences in topology, measured specifications, physical design, and cosmetics, not to mention price, but the sound of all properly designed units is basically the same."
https://www.reddit.com/r/audiophile/comments/dt4xin/_/f6v7lhd
Peeking can lead to all sorts of conclusions. And in the case of the Reddit guy, certainly did.


"...was the whole swapping pointless in regards to sound?"

No. Amps really do differ in power and drive capability. I swapped out the 100 watt nCORE amps in my NAD for 500 watt Nilai and NCx500 amps and it definitely enhanced how loud I could play things cleanly. So there's a point to targeted amp-swapping.
 

Gorgonzola

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If the amplifer is driven into clipping then it may well sound different, of all the amps I have compared in every ‘class’ A, A/B, D ,H etc I have never heard any difference , having said that all the amps I tried were properly designed, Benchmark, Purifi NCore etc.
Keith
So apparently there was no harm in reviving this 2016 thread ... at least for a moment or two.

I can't challenge a person like Purite when they say that they have never heard any difference between properly designed amps working within design parameters for power, impedance load, etc.. They haven't, I have.

A big contributor, IMHO, is harmonic spectrum. It's observable that two amp can have basically identical SINAD but show quite different harmonics. I'd venture that blind tests would show that amp 'A' with high 2nd and/or 3rd order harmonics sounds different than amp 'B' with low 2nd/3rd but a forest of higher order will sound different to most people at least some of the time.
 

Purité Audio

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Poorly designed equipment with audible distortion, why would anyone use that?
Keith
 

GXAlan

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Poorly designed equipment with audible distortion, why would anyone use that?
Keith

Seems like tube products are a financially viable business for many companies…

If you allow the possibility that some tube gear has sufficient distortion to be audible and that some listeners prefer this distortion, then it follows that solid state gear with same transfer function would be preferable due to heat/reliability issues.
 
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