Do all amplifiers sound the same? Level matched listening test

[MAB]

My mother told me not to click on links on the internet as not safe . She was a wise women.

Share concerns with Peng that this is badly framed post to start with. The question is obvious even before any tests. Not all amps level matched sound the same.

To go to extremes, my first Lo-Fi was a Polish made turntable with an amp and 4W speakers. For 1970's was really posh looking black and orange design. Don't have measurements for it but it was likely below 20dB SINAD.

My Parasound amps exhibit a hiss at ear distance which is annoying but ultimately does not translate into real world use issues. I can tell my Rotel amps from Byrston on LCR with very high level of confidence. When I bridge Bryston to 1000W, level of confidence goes even higher and when I bridge Rotels can still tell the Bryston with high level of confidence.

The test is fine though. PMA took the time to create two files of amps driven to distortion, which in and of itself is a interesting and worthwhile thing.

I am not here to debate PMA's wording, rather to take the test.

 

[Buckeye Amps]

particularly as mine were the result to extended listening tests - using ears rather than with a microphone.

What secret sauce exists within an audio signal that our ears can discern but the vast suite of measurement metrics cannot detect?

Most of us already know the answer to this...

 

[MAB]

Probably due to two factors. 1) some of us have a life and 2) some of us probably enjoy swapping amps etc. even if they don't necessarily sound different.
It's all part of the hobby isn't it?

Yeah, comparative testing is hard, not exactly fun. Yet we are all here!!!
Part of the hobby is knowing what we are doing when we swap stuff.

 

[TurtlePaul]

I downloaded and listened to the files. I could not hear a difference but I don't want to reply to the poll without doing an ABX comparator, which I don't have time for today.

 

[Sal1950]

Let me cheat and use Peter Aczel's qualifiers for amplifier sound.

"What about the amplifier?
Vastly exaggerated in importance by the audiophile press and high-end audio dealers. In controlled double-blind listening tests, no one has ever (yes, ever!) heard a difference between two amplifiers with high input impedance, low output impedance, flat response, low distortion, and low noise, when operated at precisely matched levels (±0.1 dB) and not clipped. Of course, the larger your room and the less efficient your speakers, the more watts you need to avoid clipping."

Paste This In Your Hat.

Paste This in Your Hat!

 

[Oddball]

The test is fine though. PMA took the time to create two files of amps driven to distortion, which in and of itself is a interesting and worthwhile thing.

I am not here to debate PMA's wording, rather to take the test.

Right, but why would you ever want to drive amps to distortion? I certainly would not unless extreme circumstances were calling for it. I know how it sounds and it ain't pretty. Luckily the amps and speakers survived that hot and exciting summer.

 

[pma]

@Sal1950 That’s it. Hard to accept for audiophiles. And the “SINAD” requirement is not high. On the other hand, many tpa3255 amps tested here have output impedance at high freq about 1ohm and this makes them distinguishable with some speakers. Still, we have those stupid 5W SINAD charts as a measure of amplifier “quality”.

 

[peng]

My mother told me not to click on links on the internet as not safe . She was a wise women.

Share concerns with Peng that this is badly framed post to start with. The question is obvious even before any tests. Not all amps level matched sound the same.

To go to extremes, my first Lo-Fi was a Polish made turntable with an amp and 4W speakers. For 1970's was really posh looking black and orange design. Don't have measurements for it but it was likely below 20dB SINAD.

My Parasound amps exhibit a hiss at ear distance which is annoying but ultimately does not translate into real world use issues. I can tell my Rotel amps from Byrston on LCR with very high level of confidence. When I bridge Bryston to 1000W, level of confidence goes even higher and when I bridge Rotels can still tell the Bryston with high level of confidence.

My A21 did not hiss audibly but the transformer (big toroid) hum is audible if the room is quiet.

 

[Sal1950]

An extreme point to illustrate this. I bought a Benchmark AHB2 amp on a rave recommendation and its exceptional measurements to replace SETs I'd been previously using. Instead of listening to music, I found myself listening to Muzak such that I wanted to turn down the volume - kiss of death surely. I bought or borrowed numerous ss amps and listened to each for between a week and a year to establish their worthiness in my system. Some were dire while others excited the soul and neither group was influenced by price.

Extreme for sure. That's one I imagine might even pass the "wife listening from the kitchen" test.
You have a Benchmark AHB2 amp, a completely transparent to the source, "near straight wire with gain" amp.
And a 1930s-40s level of high distortion, non-linear SET amplification.
No wonder you could hear a difference.
I'll take a pass on making any comment for your preference of the SET.

 

[MAB]

Right, but why would you ever want to drive amps to distortion? I certainly would not unless extreme circumstances were calling for it. I know how it sounds and it ain't pretty. Luckily the amps and speakers survived that hot and exciting summer.

To prove I am sometimes wrong. I've often said "it's fairly easy to hear the differences between amps when driven to distortion". I don't tend to drive amps to distortion in my setup, and have never done a controlled listening test of two amps driven to distortion, and have only seen one other test of amps drive to equivalent distortion (unfortunately it was a low-impedance speaker that likely interacted with a tube amp in the test).

I failed to hear a difference in the samples PMA provided. I find that interesting all by itself. It's very likely that my past experiences were with amps driven to different levels of distortion since I never measured carefully as is done here. Which isn't means my past experiences aren't exactly a fair comparison.

edit: last sentence for clarity

 

[pma]

The amps were just at the boundary of occasional clipping for very very short time. This is normally inaudible. We can discuss it after the poll is closed.

 

[Oddball]

You really don't want to drive amps to distortion for extended periods of time. I have done it multiple times during the summer of 2018 and it really is not pretty. I admit it was stupid but the hype of the national team climbing up the ranks has put the entire city and country on fire, so things got a bit extreme.

So the bad part is that apms clipping brought major distortion to speakers, sounding like they are tearing apart, and then eventually the amp shouts down - that was at full volume. When we replaced them with Crown 2kW amps things were back in business. Not sure how the speakers survived that power, but they serve well to this day.

 

[peng]

The test is fine though. PMA took the time to create two files of amps driven to distortion, which in and of itself is a interesting and worthwhile thing.

I am not here to debate PMA's wording, rather to take the test.

The test is great! Wording is fine too if one read everything instead of just the title(hope that is clear).

I listened to the file using my desktop LS50 driven by a Fosi amp at the time. Since just AB I could not hear a difference so I guess there is no need to do a DBT one right? I will try to do it on another system where I would use my headphone..

 

[DSJR]

What a sheltered life you've led. Far from all amps sounding the same, there's a massive difference despite what readings might suggest.


An extreme point to illustrate this. I bought a Benchmark AHB2 amp on a rave recommendation and its exceptional measurements to replace SETs I'd been previously using. Instead of listening to music, I found myself listening to Muzak such that I wanted to turn down the volume - kiss of death surely. I bought or borrowed numerous ss amps and listened to each for between a week and a year to establish their worthiness in my system. Some were dire while others excited the soul and neither group was influenced by price.

edit - @Sal1950 beat me to it, but my comments below stand I feel -

You've got yourself used to SET amps, which by all accounts over the years, massively distort and are usually rather low powered I seem to recall, so almost certainly imparting a 'sonic flavour' to your reproduced sound at home you appear to like very much!

Now, take out your SET amp(s) and replace with a basically non-distorting (into any reasonable load) Benchmark and *of course* you'll hear that something is missing - I'd expect nothing less. Your preference for the SET is akin I suspect to me liking milk and sweetening in my tea (it took me a while to go from semi-skimmed milk to skimmed - and then back again when I married), or putting a mixer with a half decent whisky that's refined enough on its own to be drunk as-is

We in the UK 'flat earth fraternity, used to like hideous-response speakers (little deep bass, 'projected' vocals and poor tweeter crossover implementation which we then balanced with a dull fruity-bass vinyl source. Change the vinyl source to 'digital' and the sound became relentless and screaming - do any other oldies here remember this? Step forwards to today and try the very same CD discs on a now vintage player into a properly balanced system- and the 'sound' is absolutely fine! No wonder the flatter-measuring speakers of the early 80s weren't liked in comparison with the peaked-up 'two maker' systems we loved in our mis-spent youth, as they were deemed boring and lifeless in comparison with the domesticated PA amps and speakers we loved back then

It'll be a difficult 'cure' for someone like yourself I suspect. These days, I'd not know where to start, but it could begin with gaining a little knowledge of psycho-acoustics I'd suggest. I did something with my rig a couple of months ago which by my own reckoning should have made the sound more 'clinical' and 'bass light,' yet when I didn't have much time and switched the rig on, stuck a disc quickly in the player to enjoy a particular piece of music, I had bass, I had a sweet enough top and a good helping of 3-D as well, as much as my gash old system can manage. I was aghast when I looked to confirm which amp was playing, as I'd completely forgotten which it was. So much for pre-conceived ideas formed previously by sighted listening at random volumes.

That's my take anyway, for what it's worth

 

[pma]

This is a difference of spectra of the original digital music file and the file recorded from one of the DUT amplifiers.

Around 20kHz it is the effect of DAC/ADC reconstruction/anti-alias flters.

 

[MAB]

The test is great! Wording is fine too if one read everything instead of just the title(hope that is clear).

I listened to the file using my desktop LS50 driven by a Fosi amp at the time. Since just AB I could not hear a difference so I guess there is no need to do a DBT one right? I will try to do it on another system where I would use my headphone..

I'd still do a proper test.
It's easy to generate both false-positive and false-negative otherwise. Each error has a different cause, but both errors matter.

 

[Cbdb2]

It was not. See this published report: https://www.audiosciencereview.com/...ts-did-show-amplifiers-to-sound-different.23/

Why did you omit this? It makes it an invalid test. Clipping and recovery are non linear effects and can be different for different amps and sound different. I wouldnt be surprised if one amp clipped more (higher % distortion 1% of the time).

 

[IPunchCholla]

Is there an easy way to do a double blind test of the two files on a Mac?

 

[Hear Here]

What secret sauce exists within an audio signal that our ears can discern but the vast suite of measurement metrics cannot detect?

Most of us already know the answer to this...

Don't ask me - I'm not an amplifier designer.

Don't tell me that an amp designed doesn't ask people to listen to and comment on its sound before they release it on the general public. Beta testing, etc

If you can't tell a great sounding amp from a good sounding one, get your hearing fixed, rather than look at measurement to offer the answer.

 

[MAB]

Is there an easy way to do a double blind test of the two files on a Mac?

Try foobar2000

foobar2000 for Mac

foobar2000

www.foobar2000.org

They have an ABX comparator plugin:

https://www.foobar2000.org/downloads/foo_abx-mac.fb2k-component