Do all amplifiers sound the same? Level matched listening test

[MaxwellsEq]

@MaxwellsEq You can do it in three days, in a week, as you like … one test per day. It is still valid.

Yes, I will.

 

[Cbdb2]

As I noted in the article though, I don't know how they determine the 1% in the age of analog scopes and dynamic music. So I don't consider this very trustworthy but for transparency, I included it in my write-up.

And thats clipping "about 1% of the time" not 1% distortion, which is confusing. How that correlates to PMAs test with some clipping is rather obscure.

 

[Cbdb2]

You would need to measure distortion to know what maximum power is. How would you measure distortion with pink noise?

You can also look for clipping.

 

[pma]

And thats clipping "about 1% of the time" not 1% distortion, which is confusing. How that correlates to PMAs test with some clipping is rather obscure.

Close to clipping would be more correct term, as shown here. Probably no clipping at all as the peaks are very short and would not result in PSU voltage drop.

Comparison of level matched data from the original music file and ADC recorded file from amp output.

Original data


ADC record from the amp output

 

[Sokel]

I don't enjoy repeating the same spiel of mine on the "power" term, but I would repeat this for convenience. So, I guess the test your keep asking for might actually be: What's the maximum Voltage and current the amp can deliver, with pink noise input, and for what duration?

I don't think power should be use in this case, because people (as they always popped up and saying something...) would say it is not the "watts", but current that we need to worry about blablabla..). The fact is, if the max power is say 500 W into 4 ohms with test duration lasting 2000 ms, it would seem like a good number but we would not know how much of that 500 W was dissipated in the amp's output stages. One way to get around that would be to do something like the "power cube" (imo outdated..) tests, or Amir's reactor load test (I prefer that) and I assume you probably referred to that test, but one that last longer than a few ms, and with pink noise instead a 1 kHz, am I right about that?

Yes, that's closer.

IMO such request is pointless in case of amplifiers. It makes sense with speakers. Music cannot be substituted by a pink noise. Only short passages might be considered such, especially when DR is high. Such pink noise power parameter for amplifiers would be misleading. Noise is a stationary random signal. Music is a non-stationary transient signal. Quite a big difference.

Depends on the noise.
If you look at the settings of the FSAF test I posted, CF is about 15dB for the PN, that's far from stationary.
(REW also warns you about it if you set test level too high)

 

[pma]

Depends on the noise.
If you look at the settings of the FSAF test I posted, CF is about 15dB for the PN, that's far from stationary.
(REW also warns you about it if you set test level too high)

Stationary vs non-stationary signals?

There are nice technical definitions in textbooks and wikipedia, but I'm having a hard time understanding what differentiates stationary and non-stationary signals in practice? Which of the follow...

dsp.stackexchange.com

Anyway, I do not see a single reason to use FSAF method to test amplifiers. Accuracy, resolution and dynamic range would be worse than that of the stepped sine and there is a large space for operator's and system mistakes. It may make some sense with speakers.

 

[krabapple]

Careful about this version of ABX test. It is designed to make you fail such comparisons more than succeed.

The change came about some 10 years ago when there were a number of blind audio challenges being posted online. I passed many of them with then ABX plugin shocking many people who thought these challenges were impossible to pass. I explained during the arguments that ensued, how I would find the critical segment in a clip by trial and error. Once there, I would then run the full test and pass it. This was enabled by the previous version of the plugin providing the information as to whether you passed or failed in every trial. This way I could identify the segment and see if i could pass it in the next trial. If I failed, then I would go to find another segment.

....which, as I've argued before, is a method and a result that has absolutely f*ck-all to do with the bog-standard, extremely common sort of difference-hearing claim that (sighted) listeners have been making since home audio became a thing and which you'll find in every issue of Stereophile and every day on WhatsBest?

And after you've forensically trial-and-errored your way to a reliable 'tell' -- a tiny sliver of music that reveals a difference in instant A/B switching, -- can you go back and still reliably 'tell' the difference, blind, when listening to *the rest of the music*?

 

[MaxwellsEq]

....which, as I've argued before, is a method and a result that has absolutely f*ck-all to do with the bog-standard, extremely common sort of difference-hearing claim that (sighted) listeners have been making since home audio became a thing and which you'll find in every issue of Stereophile and every day on WhatsBest?

And after you've forensically trial-and-errored your way to a reliable 'tell' -- a tiny sliver of music that reveals a difference in instant A/B switching, -- can you go back and still reliably 'tell' the difference, blind, when listening to *the rest of the music*?

I agree. After 5 listens then 16 ABX comparisons with IEMs I "felt" I could sense a tell. The ABX says I failed statistically to detect a difference.

But casually listening via speakers later in the day - the two clips sound identical. There's no "night and day", there is no "warm" vs "cold" or "fatigue" vs "relaxing".

My cat, who also listens to music with me didn't seem to detect a difference either (perhaps there is a difference that only she can hear, but she just doesn't care).

 

[pma]

And after you've forensically trial-and-errored your way to a reliable 'tell' -- a tiny sliver of music that reveals a difference in instant A/B switching, -- can you go back and still reliably 'tell' the difference, blind, when listening to *the rest of the music*?

The current method of foo abx is correct, the previous version that was providing the info between the trials was not. It is a DBT test, not the hint test.

And I completely agree - that

a tiny sliver of music that reveals a difference in instant A/B switching

says nothing if you can go back and still reliably 'tell' the difference, blind, when listening to *the rest of the music*? In fact, the answer is NO. During normal listening there will be no difference. And that "tiny segment" is often chosen as cheating, like if the tiny DC shift suddenly disappears at the end of the music sample, resulting in audible click. Or enormous gain used to amplify the initial part of the music sample. Been there, seen that.

 

[pma]

We are getting more votes on “I can hear a difference” without posting a valid ABX test report. Please note that such votes are not considered as trustworthy.

 

[krabapple]

The current method of foo abx is correct, the previous version that was providing the info between the trials was not. It is a DBT test, not the hint test.

And I completely agree - that

says nothing if you can go back and still reliably 'tell' the difference, blind, when listening to *the rest of the music*? In fact, the answer is NO. During normal listening there will be no difference. And that "tiny segment" is often chosen as cheating, like if the tiny DC shift suddenly disappears at the end of the music sample, resulting in audible click. Or enormous gain used to amplify the initial part of the music sample. Been there, seen that.

Science asks: is it humanly possible to hear any difference at all between A and B? The forensic method is one way to answer that with a Yes.

Ironically, the forensic method also answers the question: is it likely that Joe Goldenears Blow heard the difference ... the one he says he 'always' hears, the one is that is like 'night and day', the one that 'hurts his ears', the one that was like a 'veil'?

If it required the forensic method for an Amir to detect the difference, and Joe Blow didn't use that method, the answer is: NO.

 

[Deepinton]

Very interesting reading through all this. I am in the process of ABx testing mc 501's (that some on this forum helped me get going), vs Hypex NCx 500, driving 802d's, but not able to make much progress due to lack of help keeping things "blind". I'm curious to hear if we can expect a similar split with pre-amplifiers? As in " do all similarly spec'd pre-amps sound the same"?

 

[MaxwellsEq]

Very interesting reading through all this. I am in the process of ABx testing mc 501's (that some on this forum helped me get going), vs Hypex NCx 500, driving 802d's, but not able to make much progress due to lack of help keeping things "blind". I'm curious to hear if we can expect a similar split with pre-amplifiers? As in " do all similarly spec'd pre-amps sound the same"?

Phono and microphone amplifiers may measure and even sound different, but line-level preamplifiers are not challenging.

 

[El_Arte]

The question loses a lot of detail.

I have an amp that generates 0.2% of H2. I can identify it reliably.

What’s the THD+N threshold assumed?

 

[Svend P]

I have an amp that generates 0.2% of H2. I can identify it reliably.

Try this

Listening Test

www.klippel.de

 

[krabapple]

The question loses a lot of detail.

I have an amp that generates 0.2% of H2. I can identify it reliably.

What’s the THD+N threshold assumed?

Your amp emits deuterium?

Remarkable.

 

[MaxBuck]

Your amp emits deuterium?

Remarkable.

I think he's saying it emits hydrogen. In which case evacuate the neighborhood.

 

[krabapple]

I think he's saying it emits hydrogen. In which case evacuate the neighborhood.

H2 (deuterium) is an isotope of hydrogen.

 

[Adis]

True.

 

[El_Arte]

How could I travel at high warp otherwise?