Can you hear a difference in Sound between Audio Amplifiers?

[ski2xblack]

I think I may need to host a little amp face-off at my place between the Pass Labs, Classe and Emotiva amps.

Please throw a Crown drive core amp in the mix, too.

 

[Irvrobinson]

Wow the poll results are interesting so far. It tells me you guys need to do a little more listening and not so much overthinking

As someone who has over 10 years of audio design experience and about 15 years measuring and analyzing and most importantly LISTENING, I can tell you my experience even in controlled listening tests is amps can and do sound different even if they measure well and aren't driven beyond their means. The degree of audibility differences depend on a lot of factors, including loudspeaker load, quality of the loudspeakers, room acoustics, source material, etc. I think I may need to host a little amp face-off at my place between the Pass Labs, Classe and Emotiva amps. Could be fun (especially if there is ample supply of alcohol involved),despite the amount of work involved.

How about that? The Supreme Overlord comes out of the closet, so to speak.

Over-thinking things is a personality flaw I have, but for me excellent solid state dedicated power amps have never sounded different enough I could pick them out in some sort of play-off like a DBT. For me, the differences were always measured by listening fatigue - how long did I want to listen. Yes, some poorly engineered amps did sound different, like the amp section of my old Marantz 2270 receiver, but from my first power amp, an Adcom GFA-545, in comparison tests the amps sounded ostensibly alike. I did often wonder, though, why a live piano could be listened to for hours without fatigue, but not my audio system.

The first product that convinced me there might be differences between amps was the Krell KMA-100MkII, a 100w/ch Class A monoblock from the late 1980s. In the early 1990s I acquired a mint pair at an estate sale, which I intended to resell for a profit. All amps basically sounded alike, and only audiofools thought there were differences, right? I was using a PS Audio 200cx at the time, a popular and highly rated 200w/ch solid state amp, and I swapped in the Krells just to make sure they functioned properly. I was using ADS L1530 speakers. After about an hour I was surprised at how easy it was to keep listening, and I listened all evening, until my wife yelled at me to turn it off. Listening fatigue was much reduced; I listened for hours every day, driving her crazy. I ended up putting the 200cx in a closet, and much to my annoyance keeping the Krells, and running two 20amp circuits to power them, as they dissipated 800w each, and blew my 15amp circuit breaker unless I turned off the lights and powered them up in sequence.

The always-on, constant-speed fans in the Krells finally annoyed me, and I auditioned several other amps in my system. The only one I could afford that sounded like the Krells was the new (at the time) Madrigal-designed Mark Levinson 334. (A Threshold was close.) I sold the Krells for almost as much as I paid for them, and lived with the Levinsons until last year. I tried other amps in my system for the several years I owned the Levinsons, often because friends wanted to see how their amps compared to the 334, which Stereophile raved about after I bought them, but none made listening so fatigue-free for hours. That is until I tried an ATI AT3002, lent to me by a friend who was a previous Krell owner, and said was the ATI was surprising. The ATI was as good, so I sold the Levinsons, which were about twelve years old, and would soon need new power caps, and bought an ATI for about what I got for just one Levinson on the used market.

I've never heard the Emotiva, but my local dealer once did a Classe versus McIntosh comparison, trying to sell me on a McIntosh, using B&W 802D speakers. They sounded identical to my ears. I have heard Pass Labs XA160s, but not in my system. The Pass Labs amps are intriguing, because they measure differently, but I wouldn't bet I could pick out any of these amps in a comparison test, no less a DBT. Give me one for a couple of evenings however, and I might form an opinion, depending only on how long I want to listen.

As for listening and not over-thinking, most of us don't get a chance to audition such a wide range of equipment. It's just too much of a PITA with 100lb++ power amps, even assuming they are available for auditioning, which they often aren't.

 

[gene]

That would be very interesting. Is it safe to assume that such a comparison would be conducted with as much objectivity as previous AH face-offs? I'm thinking DBTs, followed by FR measurements of the speakers to explain any audible differences, followed by measurements of the amps to explain any differences in the speaker measurements? Does that make sense?



This is what I suspect as well, but it would be nice to have that question answered in scientific manner.

I'm going to try to get a switcher box that level matches and is remote controllable like the one Salk used at last Years GTG. DBT protocol is not necessary. The listener can't tell which amp is running. As long as you can level match and instantly switch between amps and preferably not identify to the listener which amp is playing, it should be good enough.

 

[panteragstk]

How about that? The Supreme Overlord comes out of the closet, so to speak.

Over-thinking things is a personality flaw I have, but for me excellent solid state dedicated power amps have never sounded different enough I could pick them out in some sort of play-off like a DBT. For me, the differences were always measured by listening fatigue - how long did I want to listen. Yes, some poorly engineered amps did sound different, like the amp section of my old Marantz 2270 receiver, but from my first power amp, an Adcom GFA-545, in comparison tests the amps sounded ostensibly alike. I did often wonder, though, why a live piano could be listened to for hours without fatigue, but not my audio system.

The first product that convinced me there might be differences between amps was the Krell KMA-100MkII, a 100w/ch Class A monoblock from the late 1980s. In the early 1990s I acquired a mint pair at an estate sale, which I intended to resell for a profit. All amps basically sounded alike, and only audiofools thought there were differences, right? I was using a PS Audio 200cx at the time, a popular and highly rated 200w/ch solid state amp, and I swapped in the Krells just to make sure they functioned properly. I was using ADS L1530 speakers. After about an hour I was surprised at how easy it was to keep listening, and I listened all evening, until my wife yelled at me to turn it off. Listening fatigue was much reduced; I listened for hours every day, driving her crazy. I ended up putting the 200cx in a closet, and much to my annoyance keeping the Krells, and running two 20amp circuits to power them, as they dissipated 800w each, and blew my 15amp circuit breaker unless I turned off the lights and powered them up in sequence.

The always-on, constant-speed fans in the Krells finally annoyed me, and I auditioned several other amps in my system. The only one I could afford that sounded like the Krells was the new (at the time) Madrigal-designed Mark Levinson 334. (A Threshold was close.) I sold the Krells for almost as much as I paid for them, and lived with the Levinsons until last year. I tried other amps in my system for the several years I owned the Levinsons, often because friends wanted to see how their amps compared to the 334, which Stereophile raved about after I bought them, but none made listening so fatigue-free for hours. That is until I tried an ATI AT3002, lent to me by a friend who was a previous Krell owner said was the ATI was surprising. The ATI was as good, so I sold the Levinsons, which were about twelve years old, and would soon need new power caps, and bought an ATI for about what I got for just one Levinson on the used market.

I've never heard the Emotiva, but my local dealer once did a Classe versus McIntosh comparison, trying to sell me on a McIntosh, using B&W 802D. They sounded identical to my ears. I have heard Pass Labs XA160s, but not in my system. The Pass Labs amps are intriguing, because they measure differently, but I wouldn't bet I could pick out any of these amps in a comparison test, no less a DBT. Give me one for a couple of evenings however, and I might form an opinion, depending only on how long I want to listen.

As for listening and not over-thinking, most of us don't get a chance to audition such a wide range of equipment. It's just too much of a PITA with 100lb++ power amps, even assuming they are available for auditioning, which they often aren't.

Very interesting points made. I never would have thought an amp could contribute to listening fatigue. When I experience it a speaker is almost always to blame. That or volume level being too high (concerts).

 

[jinjuku]

Very interesting points made. I never would have thought an amp could contribute to listening fatigue. When I experience it a speaker is almost always to blame. That or volume level being too high (concerts).

Those types of amps are rare as the dodo in today's new equipment market. Now 20 years ago when designers were playing with PWM / Switch Mode that was a different story. I owned a few of them for relatively short times just to go back to big iron. But technology and solutions march on.

 

[Irvrobinson]

Those types of amps are rare as the dodo in today's new equipment market. Now 20 years ago when designers were playing with PWM / Switch Mode that was a different story. I owned a few of them for relatively short times just to go back to big iron. But technology and solutions march on.

I honestly don't know if amps are really any better now, though I suspect they are, because discrete components have gotten so much better over the years, with the notable exception of capacitors. Any random handful of transistors are so much better matched than they were in the 1990s. Precision resistors are now commonplace. The PC age pumped up circuit board design and engineering technology, and everything electronic benefits. But are the amps really better, such that there are no longer differences? I'm not sure.

Interestingly, in the 1980s and 1990s there were easily discernible differences in digital electronics. Well, at least I thought so. There were definitely CD players and DACs that rubbed me one way or another. I remember the first time I heard my old Levinson No39 CD player in 1997. It was so wonderful to listen to I was flabbergasted. About 2004 or so, the ICs available at every stage, including line-level driver amps, became good enough that now most DACs seem to sound as good as the Levinson. But amps are not that IC-based at all, and while components have improved, ICs have improved so much more. I'll be honest, I do wonder if a Class A Pass Labs thing would sound better than the ATI. Since I'm happy with the ATI, I'm not willing to pay to find out, but I do wonder.

 

[cpp]

Wow the poll results are interesting so far. It tells me you guys need to do a little more listening and not so much overthinking

As someone who has over 10 years of audio design experience and about 15 years measuring and analyzing and most importantly LISTENING, I can tell you my experience even in controlled listening tests is amps can and do sound different even if they measure well and aren't driven beyond their means. The degree of audibility differences depend on a lot of factors, including loudspeaker load, quality of the loudspeakers, room acoustics, source material, etc. I think I may need to host a little amp face-off at my place between the Pass Labs, Classe and Emotiva amps. Could be fun (especially if there is ample supply of alcohol involved),despite the amount of work involved.

thanks Gene

 

[gene]

I honestly don't know if amps are really any better now, though I suspect they are, because discrete components have gotten so much better over the years, with the notable exception of capacitors. Any random handful of transistors are so much better matched than they were in the 1990s. Precision resistors are now commonplace. The PC age pumped up circuit board design and engineering technology, and everything electronic benefits. But are the amps really better, such that there are no longer differences? I'm not sure.

Interestingly, in the 1980s and 1990s there were easily discernible differences in digital electronics. Well, at least I thought so. There were definitely CD players and DACs that rubbed me one way or another. I remember the first time I heard my old Levinson No39 CD player in 1997. It was so wonderful to listen to I was flabbergasted. About 2004 or so, the ICs available at every stage, including line-level driver amps, became good enough that now most DACs seem to sound as good as the Levinson. But amps are not that IC-based at all, and while components have improved, ICs have improved so much more. I'll be honest, I do wonder if a Class A Pass Labs thing would sound better than the ATI. Since I'm happy with the ATI, I'm not willing to pay to find out, but I do wonder.

ATI makes solid amps. I am sure they would very very neutral sounding with almost any load. With my speaker system, I do need a solid 600-1kwatt of power when I run my speakers full range with LFE signal. The Classe and Pass Labs amps I have on hand do great for 90% of my music listening but at very high volume with Blu-ray music like Jienat, they both go into clipping during intense bass passages. In comparison, the Emotiva XPR-1s don't break a sweat. I am not convinced that the Emotiva's are as smooth sounding at low power however. This is why I am eager to do a comparison test between the 3 amps soon.

Back when I setup the Status 8T system both myself and Shane Rich (the engineer who designed them) heard sonic differences when we switched out the amps. Granted it wasn't an instantaneous switch but we both heard the same things. The Pass Lab's amp was very detailed and perhaps a bit forward while the Classe seemed smoother. The Axiom amp didn't fair well at all, especially in the bass frequencies, which I was surprised about since it had a lot of output power. I think it just didn't like to drive very low impedance loads b/c of the post filter feedback network. My Denon and Marantz amps sounded great at low to moderate listening levels but just ran out of gas when the volume was turned up.

 

[jinjuku]

The Axiom amp didn't fair well at all, especially in the bass frequencies, which I was surprised about since it had a lot of output power. I think it just didn't like to drive very low impedance loads b/c of the post filter feedback network.

May be that my memory needs refreshed but I seem to recall that Axioms offering was not well received. That it turned out a bit of a dog (?).

 

[AcuDefTechGuy]

Wow the poll results are interesting so far. It tells me you guys need to do a little more listening and not so much overthinking

As someone who has over 10 years of audio design experience and about 15 years measuring and analyzing and most importantly LISTENING, I can tell you my experience even in controlled listening tests is amps can and do sound different even if they measure well and aren't driven beyond their means. The degree of audibility differences depend on a lot of factors, including loudspeaker load, quality of the loudspeakers, room acoustics, source material, etc. I think I may need to host a little amp face-off at my place between the Pass Labs, Classe and Emotiva amps. Could be fun (especially if there is ample supply of alcohol involved),despite the amount of work involved.

It may be possible that some people can and some people cannot tell the difference.

If you could do just a single-blinded comparison/ GTG (hopefully with a bunch of guys), it would be great.

I've never heard of a single study that was able to show a statistically significant difference in amp sound. Perhaps you could publish this event. It might be the first ever published study to show that amps do sound differently.

If people could tell which amp is Emotiva vs Pass vs Classe in a single-blinded level matched comparison 80% of the time, I think we would all be very impressed.

 

[3db]

Listener fatigue.. interesting concept that just may work for amplifier testing. Its proven that accuracy of auditory memory is short lived so I don't put a lot of stock into reviewers that spout on about how much better one amp sounds over another when it takes longer than 5 minutes to switch amps. Listener fatigue could work if one can guarantee that you are in the right frame of mind and not tired to begin with.

How about that? The Supreme Overlord comes out of the closet, so to speak.

Over-thinking things is a personality flaw I have, but for me excellent solid state dedicated power amps have never sounded different enough I could pick them out in some sort of play-off like a DBT. For me, the differences were always measured by listening fatigue - how long did I want to listen. Yes, some poorly engineered amps did sound different, like the amp section of my old Marantz 2270 receiver, but from my first power amp, an Adcom GFA-545, in comparison tests the amps sounded ostensibly alike. I did often wonder, though, why a live piano could be listened to for hours without fatigue, but not my audio system.

The first product that convinced me there might be differences between amps was the Krell KMA-100MkII, a 100w/ch Class A monoblock from the late 1980s. In the early 1990s I acquired a mint pair at an estate sale, which I intended to resell for a profit. All amps basically sounded alike, and only audiofools thought there were differences, right? I was using a PS Audio 200cx at the time, a popular and highly rated 200w/ch solid state amp, and I swapped in the Krells just to make sure they functioned properly. I was using ADS L1530 speakers. After about an hour I was surprised at how easy it was to keep listening, and I listened all evening, until my wife yelled at me to turn it off. Listening fatigue was much reduced; I listened for hours every day, driving her crazy. I ended up putting the 200cx in a closet, and much to my annoyance keeping the Krells, and running two 20amp circuits to power them, as they dissipated 800w each, and blew my 15amp circuit breaker unless I turned off the lights and powered them up in sequence.

The always-on, constant-speed fans in the Krells finally annoyed me, and I auditioned several other amps in my system. The only one I could afford that sounded like the Krells was the new (at the time) Madrigal-designed Mark Levinson 334. (A Threshold was close.) I sold the Krells for almost as much as I paid for them, and lived with the Levinsons until last year. I tried other amps in my system for the several years I owned the Levinsons, often because friends wanted to see how their amps compared to the 334, which Stereophile raved about after I bought them, but none made listening so fatigue-free for hours. That is until I tried an ATI AT3002, lent to me by a friend who was a previous Krell owner, and said was the ATI was surprising. The ATI was as good, so I sold the Levinsons, which were about twelve years old, and would soon need new power caps, and bought an ATI for about what I got for just one Levinson on the used market.

I've never heard the Emotiva, but my local dealer once did a Classe versus McIntosh comparison, trying to sell me on a McIntosh, using B&W 802D speakers. They sounded identical to my ears. I have heard Pass Labs XA160s, but not in my system. The Pass Labs amps are intriguing, because they measure differently, but I wouldn't bet I could pick out any of these amps in a comparison test, no less a DBT. Give me one for a couple of evenings however, and I might form an opinion, depending only on how long I want to listen.

As for listening and not over-thinking, most of us don't get a chance to audition such a wide range of equipment. It's just too much of a PITA with 100lb++ power amps, even assuming they are available for auditioning, which they often aren't.

 

[gene]

May be that my memory needs refreshed but I seem to recall that Axioms offering was not well received. That it turned out a bit of a dog (?).

It sounded ok on my old RBH T30-LSE speaker system. In fact, I liked the bass but felt the highs were a bit harsh. The first sample blew up during my bench testing and the second sample blew two channels during a simple speaker cable swap. Later they recalled all field units, but I still have my until with 6 working channels. Haven't checked out their newest iteration but it seems to be very similar in design (minus the lack of protection failure I hope).

 

[gene]

It may be possible that some people can and some people cannot tell the difference.

If you could do just a single-blinded comparison/ GTG (hopefully with a bunch of guys), it would be great.

I've never heard of a single study that was able to show a statistically significant difference in amp sound. Perhaps you could publish this event. It might be the first ever published study to show that amps do sound differently.

If people could tell which amp is Emotiva vs Pass vs Classe in a single-blinded level matched comparison 80% of the time, I think we would all be very impressed.

A lot of this is load dependent. You get a speaker like a Status 8T and it separates the men from the boys in amplification. A speaker like the Pioner AJ, not so much I think

 

[AcuDefTechGuy]

I'm going to try to get a switcher box that level matches and is remote controllable like the one Salk used at last Years GTG. DBT protocol is not necessary. The listener can't tell which amp is running. As long as you can level match and instantly switch between amps and preferably not identify to the listener which amp is playing, it should be good enough.

Double-blinded may not be feasible, but it needs to be at least single-blinded. The listeners should NOT be told which amp is being played.

Can the listeners tell you which amp is the PassLab & which is the Emotiva 6 out of 6 times or only 3 out of 6 times? Or something like that.

 

[AcuDefTechGuy]

A lot of this is load dependent. You get a speaker like a Status 8T and it separates the men from the boys in amplification. A speaker like the Pioner AJ, not so much I think

I think it's safe to say that no published study in history has used $60,000 speakers to test the amps' limits. I don't think anyone here has ever compared amps driving such a monster speaker as the 8T in FULL RANGE 2.0 Pure Direct.

Perhaps the Status 8T is the ticket that shows the world for the first time that amps do sound differently!

 

[KEW]

A lot of this is load dependent. You get a speaker like a Status 8T and it separates the men from the boys in amplification. A speaker like the Pioner AJ, not so much I think

This speaks to an interesting point. It would be really good if you could also test using a more conventional high quality speaker.
The first question is "Is there a difference?"
The second is "If so, is the difference of practical concern?"
The Status 8T exist in a rarefied ether-sphere of extremes and discovering performance differences with amps driving them doesn't help people with $amp decisions regarding more pedestrian systems. It wouldn't surprise me if you ultimately discovered the Status 8T's exceeded any amps capabilities (though they may show okay by their spec's.

Why did you get rid of your Aragon amp(s)? Did you find others were better?

 

[cpp]

I think it's safe to say that no published study in history has used $60,000 speakers to test the amps' limits. I don't think anyone here has ever compared amps driving such a monster speaker

the only place I ever saw a $60,000 speaker was at a audio show or at a neighbors home in Isleworth and those were some Wilson's Maxx3 driven my Lamm ML3 amps.

 

[jinjuku]

I think it's safe to say that no published study in history has used $60,000 speakers to test the amps' limits. I don't think anyone here has ever compared amps driving such a monster speaker as the 8T in FULL RANGE 2.0 Pure Direct.

Perhaps the Status 8T is the ticket that shows the world for the first time that amps do sound differently!

Going to point out amps that run out of juice for starters.

 

[jinjuku]

It sounded ok on my old RBH T30-LSE speaker system. In fact, I liked the bass but felt the highs were a bit harsh. The first sample blew up during my bench testing and the second sample blew two channels during a simple speaker cable swap. Later they recalled all field units, but I still have my until with 6 working channels. Haven't checked out their newest iteration but it seems to be very similar in design (minus the lack of protection failure I hope).

I would consider that to backup the rather negative reviews I have read.

 

[3db]

Going to point out amps that run out of juice for starters.

All this tells me is that a competently deigned amp that runs of juice is trying to drive a load its not designed to handle and as result will sound different than an amp that can handle the load. Its like comparing apples to oranges.. They are both fruit but I'd never drop a slice of apple into a nice wheat beer.