What are the best audio amplifiers in consumer audio?

[RichB]

I happened to browse Bryston's web site again, and I'm still baffled. Bryston amps are about twice the price of a competitive ATI amp. Not that I'm pushing ATI, I didn't even vote, but what's the big deal with Bryston? They're even as ugly as ATI.

If you buy into that all amps do not sound the same, then there sound be measurable distortion characteristics that correlate.
There have been reviews that measured amps with 2-tone tests that show increased intermodulation distortion, particularly adding odd-harmonics.

Here are some amps that look alike in single tone tests, that look quite different with 2-tone tests.

The Bryston's look good:
http://www.hometheaterhifi.com/power-amplifiers/power-amplifiers-reviews/bryston-3b-sst2-stereo-power-amplifier/page-4-the-bryston-3b-sst2-power-amplifier-on-the-bench.html

As do Parasound (especially when in class-A):
http://www.hometheaterhifi.com/power-amplifiers/power-amplifiers-reviews/parasound-halo-a-31-power-amplifier/page-4-on-the-bench.html

Cinenova had more harmonics:
http://www.hometheaterhifi.com/power-amplifiers/power-amplifiers-reviews/earthquake-sound-cinenova-7-multi-channel-power-amplifier/page-4-the-earthquake-cinenova-7-power-amplifier-on-the-bench.html


Classe looks great:
http://www.hometheaterhifi.com/power-amplifiers/power-amplifiers-reviews/classe-ca-m600-monoblock-power-amplifier/page-4-the-classe-ca-m600-power-amplifier-on-the-bench.html

My working theory is that power in load being equal an amp that produces less IM with multi-tone tests can sound better.
That makes more sense to me than my ability to hear distortion 80 DB below the signal.

My wife would probably not appreciate look of the Bryston. Luckily, Parasound in black passed muster

- Rich

 

[gene]

If you buy into that all amps do not sound the same, then there sound be measurable distortion characteristics that correlate.
There have been reviews that measured amps with 2-tone tests that show increased intermodulation distortion, particularly adding odd-harmonics.

Here are some amps that look alike in single tone tests, that look quite different with 2-tone tests.

The Bryston's look good:
http://www.hometheaterhifi.com/power-amplifiers/power-amplifiers-reviews/bryston-3b-sst2-stereo-power-amplifier/page-4-the-bryston-3b-sst2-power-amplifier-on-the-bench.html

As do Parasound (especially when in class-A):
http://www.hometheaterhifi.com/power-amplifiers/power-amplifiers-reviews/parasound-halo-a-31-power-amplifier/page-4-on-the-bench.html

Cinenova had more harmonics:
http://www.hometheaterhifi.com/power-amplifiers/power-amplifiers-reviews/earthquake-sound-cinenova-7-multi-channel-power-amplifier/page-4-the-earthquake-cinenova-7-power-amplifier-on-the-bench.html


Classe looks great:
http://www.hometheaterhifi.com/power-amplifiers/power-amplifiers-reviews/classe-ca-m600-monoblock-power-amplifier/page-4-the-classe-ca-m600-power-amplifier-on-the-bench.html

My working theory is that power in load being equal an amp that produces less IM with multi-tone tests can sound better.
That makes more sense to me than my ability to hear distortion 80 DB below the signal.

My wife would probably not appreciate look of the Bryston. Luckily, Parasound in black passed muster

- Rich

You will see amp misbehavior with single tone tests as well. I've NEVER measured an amp that did better with multi-tone distortion than another amp but worse or even the same with single-tone distortion than the other amp.

 

[AcuDefTechGuy]

If you buy into that all amps do not sound the same

Who cares if they sound exactly the same or not?

The salient question is do they sound GOOD powering YOUR speakers at the VOLUME you need?

 

[fuzz092888]

Who cares if they sound exactly the same or not?

The salient question is do they sound GOOD powering YOUR speakers at the VOLUME you need?

I think your word a day calendar got stuck

 

[RichB]

Who cares if they sound exactly the same or not?

The salient question is do they sound GOOD powering YOUR speakers at the VOLUME you need?

Some folks love to upgrade. Some folks hate to upgrade.
For me, It's about accuracy, freedom from clipping or limiting, and lack of distortion that make it sound wonderful.
Since my experience is that amps do sound different, then why and what measurements are good indicators are interesting.

If your experience is that amps do not sound different (one better than another), then I suppose these discussions are not interesting.

- Rich

 

[AcuDefTechGuy]

I think your word a day calendar got stuck

Hey, there's nothing wrong with expanding the vocabulary. "Salient" is a good word.

 

[AcuDefTechGuy]

Since my experience is that amps do sound different...

I think everyone can agree that it is possible for one amp to sound better than another amp if the former has less distortion, less clipping, less noise, etc.

It just depends on the amps, speakers, distance, volume.

 

[Nestor]

If amps sound different, what measurements correlate with those differences?


Sent from my iPad using Tapatalk

 

[lsiberian]

Amps definitely can sound different. Mine are far too noisy ATM. I'm definitely looking to upgrade in the future, but I'm not annoyed enough by the noise to do so yet. It's not a ground loop either I already tested that theory.

 

[bang4bucker]

HomeTheaterHifi: The Pass Labs X600.8 Monoblock Power Amplifier on the Bench

http://www.hometheaterhifi.com/power-amplifiers/power-amplifiers-reviews/pass-labs-x600-8-600-watt-monoblock-power-amplifier/page-4-on-the-bench.html

View attachment 14443

Here is an amplifier that costs $11K each measures terribly and wins an editor's choice award.

I know that amps can measure well and sound different when driving load. But...

- Rich

still looks good to me, considering it's probably at very high power output which most people don't listen at. what i see is a good harmonics structure where even order harmonics are more dominant than odd order ones. afaik, even order harmonics are more ear friendly. most fully balanced amps will have odd order harmonics dominating due to balanced topology supressing even order harmonics and then make the measurements look good. and this is where measurements and sound quality collide

 

[PENG]

still looks good to me, considering it's probably at very high power output which most people don't listen at. what i see is a good harmonics structure where even order harmonics are more dominant than odd order ones. afaik, even order harmonics are more ear friendly. most fully balanced amps will have odd order harmonics dominating due to balanced topology supressing even order harmonics and then make the measurements look good. and this is where measurements and sound quality collide

I posted this link more than once before but here it is again for those who are interested to know why Nelson Pass himself had written about these odd/even harmonic stuff.

https://passlabs.com/articles/audio-distortion-and-feedback

Following is part of what he said in that technical article if you don't have time to read the whole article.


"Harmonic Distortion and Sound
Many audiophiles believe that 2nd harmonic is to be preferred over 3rd harmonic. Certainly it is simpler in character, and it is well agreed that orders higher than third are more audible and less musical. However when given a choice between the sound of an amplifier whose characteristic is dominantly 2nd harmonic versus 3rd harmonic, a good percentage of listeners choose the 3rd.

I have built many examples of simple 2nd and 3rd harmonic “types” of amplifiers over the last 35 years. When I say “types” I mean that they used simple Class A circuits described as “single-ended” versus “push-pull” and so tended to have a 2nd harmonic versus 3rd harmonic in the character of their distortion, but were not made to deliberately distort.

Anecdotally, it appears that preferences break out roughly into a third of customers liking 2nd harmonic types, a third liking 3rd harmonic, and the remainder liking neither or both. Customers have also been known to change their mind over a period of time.

However the issue is partially obscured by the fact that the 3rd harmonic type amplifiers usually have lower total distortion. Third harmonic usually appears with a negative coefficient, resulting in what we think of as “compressive” - the example in figure 3. It's worth noting that odd orders on nonlinearity also can be seen altering the amplitude of the fundamental tone -something a distortion analyzer doesn't ordinarily display.

Audiophiles have been accused of using 2nd or 3rd harmonic distortion as tone controls to deliberately alter the sound. I suppose that there are people who like it that way, but I don't think this is generally the case. For reasons which will become clearer when we talk about inter-modulation distortion, high levels of any harmonic become problematic with musical material having multiple instruments, and the argument that 2nd or 3rd adds “musicality” doesn't quite hold up.

The sound of 2nd order type circuits is often praised as “warm” and by comparison 3rd order type circuits are often noted for “dynamic contrast”. 2nd order type amplifiers seem to do particularly well with simple musical material, and 3rd order types generally seem to be better at more complex music."

It would seem that this is actually a complex and subjective thing, the "myth" about how even harmonics are more pleasing is probably one of those half true thing perpetuated via hearsay over time. A bit like the belief that speakers are more likely to be damaged under powered than over powered.

 

[RichB]

From Passlabs:

However the issue is partially obscured by the fact that the 3rd harmonic type amplifiers usually have lower total distortion. Third harmonic usually appears with a negative coefficient, resulting in what we think of as “compressive” - the example in figure 3. It's worth noting that odd orders on nonlinearity also can be seen altering the amplitude of the fundamental tone -something a distortion analyzer doesn't ordinarily display.

Thanks. That is new information.

- Rich

 

[PENG]

Thanks. That is new information.

- Rich

It is complicated and definitely not not black and white.

 

[bang4bucker]

I posted this link more than once before but here it is again for those who are interested to know why Nelson Pass himself had written about these odd/even harmonic stuff.

https://passlabs.com/articles/audio-distortion-and-feedback

Following is part of what he said in that technical article if you don't have time to read the whole article.


"Harmonic Distortion and Sound
Many audiophiles believe that 2nd harmonic is to be preferred over 3rd harmonic. Certainly it is simpler in character, and it is well agreed that orders higher than third are more audible and less musical. However when given a choice between the sound of an amplifier whose characteristic is dominantly 2nd harmonic versus 3rd harmonic, a good percentage of listeners choose the 3rd.

I have built many examples of simple 2nd and 3rd harmonic “types” of amplifiers over the last 35 years. When I say “types” I mean that they used simple Class A circuits described as “single-ended” versus “push-pull” and so tended to have a 2nd harmonic versus 3rd harmonic in the character of their distortion, but were not made to deliberately distort.

Anecdotally, it appears that preferences break out roughly into a third of customers liking 2nd harmonic types, a third liking 3rd harmonic, and the remainder liking neither or both. Customers have also been known to change their mind over a period of time.

However the issue is partially obscured by the fact that the 3rd harmonic type amplifiers usually have lower total distortion. Third harmonic usually appears with a negative coefficient, resulting in what we think of as “compressive” - the example in figure 3. It's worth noting that odd orders on nonlinearity also can be seen altering the amplitude of the fundamental tone -something a distortion analyzer doesn't ordinarily display.

Audiophiles have been accused of using 2nd or 3rd harmonic distortion as tone controls to deliberately alter the sound. I suppose that there are people who like it that way, but I don't think this is generally the case. For reasons which will become clearer when we talk about inter-modulation distortion, high levels of any harmonic become problematic with musical material having multiple instruments, and the argument that 2nd or 3rd adds “musicality” doesn't quite hold up.

The sound of 2nd order type circuits is often praised as “warm” and by comparison 3rd order type circuits are often noted for “dynamic contrast”. 2nd order type amplifiers seem to do particularly well with simple musical material, and 3rd order types generally seem to be better at more complex music."

It would seem that this is actually a complex and subjective thing, the "myth" about how even harmonics are more pleasing is probably one of those half true thing perpetuated via hearsay over time.

yep, warm or "neutral" is a matter of taste. and taste can not be argued. but i'm sure that X600.8 amps won't sound warm (or any sound) if not pushed too hard.

 

[RichB]

still looks good to me, considering it's probably at very high power output which most people don't listen at. what i see is a good harmonics structure where even order harmonics are more dominant than odd order ones. afaik, even order harmonics are more ear friendly. most fully balanced amps will have odd order harmonics dominating due to balanced topology supressing even order harmonics and then make the measurements look good. and this is where measurements and sound quality collide

The Pass Labs X600.8 600 Watt Monoblock is rated 600 Watts RMS into 8 Ohms, 1,200 Watts RMS into 4 Ohms.
I am not arguing the point, but those measurements were at 22 volts or 60.5 watts. Not exactly high power. The Passlabs amp measures superbly at 5 volts, but nothing to write home about at 1/10'th its power rating.

Eyeballing these charts to try to use consistent scaling:

At 5 volts, the 2'nd harmonic is 64 DB down and the 3'rd is 80 DB down.

At 22 volts, the 2'nd harmonic is at 58 DB down and the 3'rd is 60 DB down, at it keeps going with the 5'th harmonic at -90 relative to the referenced tone.


The Emotiva XPA-1 Gen 2 mono-block is 600 watts into 8 ohms, 1,000 watts into 4 ohms.

At 12.5 watts, the 2'nd harmonic is 95 DB down and the 3'rd is 104 DB down, 4'th is 110 DB down, etc. into the noise

At 600 Watts (69.2VRMS) , the 2'nd harmonic is at 100 DB down and the 3'rd is 88 DB down, 4'th 103 DB down, 5'th 100 with odd harmonics remaining at -110.

I don't know which one sounds better, but it is clear which one measures better

- Rich

 

[Irvrobinson]

I've always ignored the percent distortion figures, because they don't correlate to the human listening experience. In my opinion, if you want to understand how audible distortion might be, assume your average loud listening level is, say, 85db, and then play a test tone 50db lower than that, or 35db. -50db is not an especially good distortion measurement - it correlates to about 0.3%, yet try to hear the 35db tone in your room. Make the test tone 2KHz so it's easy to hear above normal room noise.

That said, I think an amp that has *any* measurable artifacts above -70db these days makes for a questionable buying decision. I'm thinking -80db is a better objective. All of that talk about 2nd versus 3rd harmonics at -70db or lower seems like cocktail party gibberish. Maybe at -40db it's a conversation worth having, but why buy an amp that distorts like that in first place?

 

[sharkman]

I am NOT of the camp that all amps sound the same. I have too much experience that has shown me otherwise even under controlled listening tests but to each is own.

This has been my experience too, but I wish some in the amps-all-sound-the-same camp could also say to each his own. I've mostly stopped visiting this site because whenever I happen to suggest that amps can sound different, the same 1 or 2 posters repeatedly want to debate and argue.

On the poll, I too find that Parasound is an omission, but it's simply impossible to list them all! In my system the Halo A21 was better than NAD, Emotiva and Adcom. YMMV.

 

[gene]

The Pass Labs X600.8 600 Watt Monoblock is rated 600 Watts RMS into 8 Ohms, 1,200 Watts RMS into 4 Ohms.
I am not arguing the point, but those measurements were at 22 volts or 60.5 watts. Not exactly high power. The Passlabs amp measures superbly at 5 volts, but nothing to write home about at 1/10'th its power rating.

Eyeballing these charts to try to use consistent scaling:

View attachment 14452

At 5 volts, the 2'nd harmonic is 64 DB down and the 3'rd is 80 DB down.

View attachment 14453

At 22 volts, the 2'nd harmonic is at 58 DB down and the 3'rd is 60 DB down, at it keeps going with the 5'th harmonic at -90 relative to the referenced tone.


The Emotiva XPA-1 Gen 2 mono-block is 600 watts into 8 ohms, 1,000 watts into 4 ohms.

View attachment 14454

At 12.5 watts, the 2'nd harmonic is 95 DB down and the 3'rd is 104 DB down, 4'th is 110 DB down, etc. into the noise

View attachment 14455

At 600 Watts (69.2VRMS) , the 2'nd harmonic is at 100 DB down and the 3'rd is 88 DB down, 4'th 103 DB down, 5'th 100 with odd harmonics remaining at -110.

I don't know which one sounds better, but it is clear which one measures better

- Rich

Having both Pass Labs X350.5 and Emotiva XPR-1 Amps side by side at my place doing listening tests and the most extensive bench tests done in our industry, I'd personally save my money and get the Emotiva's. Pass Lab is a fine amp but I prefer the less expensive, more powerful, less distorted Emotiva's. For bass intense music the Emotiva's don't break a sweat while I watched the VU meter on the Pass Lab's amp dim out b/c the power supply ran out of juice. Not something I'd be too proud of if I dropped almost $12k on a two-channel amp. That being said, the Pass Lab's cosmetics and build quality blow away the Emotiva's IMO. So if you want something more impressive looking, than the Pass Lab's is the better choice.

 

[gene]

This has been my experience too, but I wish some in the amps-all-sound-the-same camp could also say to each his own. I've mostly stopped visiting this site because whenever I happen to suggest that amps can sound different, the same 1 or 2 posters repeatedly want to debate and argue.

On the poll, I too find that Parasound is an omission, but it's simply impossible to list them all! In my system the Halo A21 was better than NAD, Emotiva and Adcom. YMMV.

Don't let a few trolls beat you down. It's not uncommon for people that think everything is so black and white are often not seeing the whole picture to come to such rash conclusions.

 

[gene]

I posted this link more than once before but here it is again for those who are interested to know why Nelson Pass himself had written about these odd/even harmonic stuff.

https://passlabs.com/articles/audio-distortion-and-feedback

Following is part of what he said in that technical article if you don't have time to read the whole article.


"Harmonic Distortion and Sound
Many audiophiles believe that 2nd harmonic is to be preferred over 3rd harmonic. Certainly it is simpler in character, and it is well agreed that orders higher than third are more audible and less musical. However when given a choice between the sound of an amplifier whose characteristic is dominantly 2nd harmonic versus 3rd harmonic, a good percentage of listeners choose the 3rd.

I have built many examples of simple 2nd and 3rd harmonic “types” of amplifiers over the last 35 years. When I say “types” I mean that they used simple Class A circuits described as “single-ended” versus “push-pull” and so tended to have a 2nd harmonic versus 3rd harmonic in the character of their distortion, but were not made to deliberately distort.

Anecdotally, it appears that preferences break out roughly into a third of customers liking 2nd harmonic types, a third liking 3rd harmonic, and the remainder liking neither or both. Customers have also been known to change their mind over a period of time.

However the issue is partially obscured by the fact that the 3rd harmonic type amplifiers usually have lower total distortion. Third harmonic usually appears with a negative coefficient, resulting in what we think of as “compressive” - the example in figure 3. It's worth noting that odd orders on nonlinearity also can be seen altering the amplitude of the fundamental tone -something a distortion analyzer doesn't ordinarily display.

Audiophiles have been accused of using 2nd or 3rd harmonic distortion as tone controls to deliberately alter the sound. I suppose that there are people who like it that way, but I don't think this is generally the case. For reasons which will become clearer when we talk about inter-modulation distortion, high levels of any harmonic become problematic with musical material having multiple instruments, and the argument that 2nd or 3rd adds “musicality” doesn't quite hold up.

The sound of 2nd order type circuits is often praised as “warm” and by comparison 3rd order type circuits are often noted for “dynamic contrast”. 2nd order type amplifiers seem to do particularly well with simple musical material, and 3rd order types generally seem to be better at more complex music."

It would seem that this is actually a complex and subjective thing, the "myth" about how even harmonics are more pleasing is probably one of those half true thing perpetuated via hearsay over time. A bit like the belief that speakers are more likely to be damaged under powered than over powered.

Of course if you design the amp to be fully differential from input to output, use the right amount of feedback, have a robust power supply, etc, you can lower both even and odd order distortions. The type of logic where one should deliberately make a certain type of distortion higher than another doesn't work in areas of amplification requiring extreme sensitivity and amplification of small signals such as the telcom world. I don't think Audio should be the only exception to this rule b/c it doesn't fly in ANY other industry using amplifiers from DC to LIGHT!