Why Audio Amplifiers Can Sound Different

[PENG]

That needs some additional qualification. What SPL's, frequency ranges?
For those who would like to see more comprehensive testing, more information, data, whatever, go to MillerAudioResearch, register, and browse the lab reports.

Ambient tails as is the decay of sound?

It could be recorded better.

This may change with inexpensive increased storage, less expensive data plans, and the like.

Nostalgia has a way of hanging on.


How do the Quad amps you have bench? Being that they're old, have they suffered any degradation?

I read the Miller research/avtech tests and then understood why my 10 years old avr-3805 sounds as good as my A21 most of the time in my 2 channel room.

I am sure amps can sound different. Fortunately, I found that the difference I perceived are relatively small. So small that such differences become almost meaningless if I just move my speakers or listening position, even with speakers that have good off axis performance.

Regarding degradation, I did some tests with REW and found roll off in an old Marantz from 8k and up and I know the average untrained listener won't even notice in an AB comparison using typical jazz and pop music.

 

[AcuDefTechGuy]

I read the Miller research/avtech tests and then understood why my 10 years old avr-3805 sounds as good as my A21 most of the time in my 2 channel room.

I am sure amps can sound different. Fortunately, I found that the difference I perceived are relatively small. So small that such differences become almost meaningless if I just move my speakers or listening position, even with speakers that have good off axis performance.

Regarding degradation, I did some tests with REW and found roll off in an old Marantz from 8k and up and I know the average untrained listener won't even notice in an AB comparison using typical jazz and pop music.

Are you sure you don't want to strap on a stethoscope for critical listening?

 

[highfigh]

This thread raises a good question for those who think they sound the same- "Why did you choose your amplifier?"

 

[3db]

This thread raises a good question for those who think they sound the same- "Why did you choose your amplifier?"

I chose my Yammy RX-V1800 because I wanted to get into BluRay and HDMi, get a room correction facility, it sported 7.1, and Yamaha's track record for proven reliability and customer satisfaction. It replaced my old Technics 5.1 AVR. As far as sounding different, the Yammy can push my PSBs louder then my Technics before starting sound strained. However during normal listening levels, I would say they were on par for sound quality. That's listening to stereo, towers running full range without sub, and without room correction.

 

[Seth=L]

@3db

Which reminds me, should you be updating your signature.

 

[3db]

@3db

Which reminds me, should you be updating your signature.

As soon as I get it installed and running. I haven't had the chance yet. Been too busy. I saw the deal and went for it knowing I wouldn't be able to install it right away.

 

[tyhjaarpa]

When I was buying amp I listened couple amps with speakers I have and found out that some amps sounded little dull when other had much clearer and more open sound. So yes amp can change sound in my experience. Only thing changed in chain was amp and I was not expeting big change in sound but I was wrong and I'm happy that I did listen the amps before buying as I was about to buy one of those dull sounding amps first by recommendations.

 

[ski2xblack]

If reproduction isn't accurate, that the result may sound good is only happenstance, and you may just be listening to a consistent coloration that you've deluded yourself into thinking sounds good.

Hold on now, it's only delusional if the coloration is psychological in nature. In this case it's a tube amp audibly processing the sound, in ways that are measurable and objectively real. It's basically a matter of preference. It doesn't make sense to me to bend to some sort of prevailing orthodoxy if it's your own ears that are the final arbiter and they clearly and unequivocally like one thing over another.

I felt compelled to respond based on my own, often confounding experience of poor performance by standard objective measures coinciding with sublime subjective experiences, specifically in regards to triode amps I've owned or built. They're kooky devices.

FWIW, in carefully level matched but otherwise uncontrolled conditions, I could not hear a difference between a Pass Labs XA50, a middling NAD, or road worthy Crown amp. At least on that particular day, with those particular speakers, in that particular room...but I feel confident in my conclusion that amps with linear response, low distortion, low output impedance, and operating within their limits pretty much sound the same, regardless of class.

 

[Irvrobinson]

Hold on now, it's only delusional if the coloration is psychological in nature. In this case it's a tube amp audibly processing the sound, in ways that are measurable and objectively real. It's basically a matter of preference. It doesn't make sense to me to bend to some sort of prevailing orthodoxy if it's your own ears that are the final arbiter and they clearly and unequivocally like one thing over another.

So you're saying that if people knowingly prefer coloration, and they know the sound is indeed colored, they're not delusional? How can one disagree with that? There's no way around, though, that "sounds good" is a situational preference, accuracy is a decision, because you may not like the result.

Accuracy may not always sound good, but to paraphrase Duke Ellington, if accurate reproduction sounds good, it really is good.

 

[ski2xblack]

...there's no way around, though, that "sounds good" is a situational preference, accuracy is a decision, because you may not like the result.

Accuracy may not always sound good, but to paraphrase Duke Ellington, if accurate reproduction sounds good, it really is good.

Agreed, but only up to a point.

A truly "accurate" system is no small achievement. I'll bet very, very, very few folks ever get there. But i seems a safe assumption that everyone with a stereo finds enjoyment in listening to their music collection, even if their playback rigs are not monuments of accuracy.

Seriously, the more I think about it, the more accuracy in the context of this weird hobby seems hopeless. We start out with source material that lacks any sort of established standard, and which reflects who knows who's idiosyncratic tastes, leaving us with a broad range from excellent to crap recordings. When we play these "box of chocolate" recordings, we're probably not using the exact same speakers, nor in exactly similar acoustical environments as the music was mastered in. Our systems, primarily the speakers, and local acoustics will add their own coloration. I could go on, but you get the idea. In this context, amps with distinct sonic qualities are small potatoes.

End of the day, all I really care about is if it sounds good.

 

[Ampdog]

Not much left to say, except perhaps that one is delighted by the sound - er - NO! Let me rather use the term 'sober' - posts all round.

Perhaps to condense: It is so sad thet folks do not realise that the only sense available to enjoy music with and thus judge what we desire, is also (like other human senses) relatively uncalibrated for purposes of scientific comparison. Sensitive? Yes! Consistent/repeatable? Sadly no. Thus so much of the dissentment so unnecessary - if one will just forego this as a personal shortcoming. (Any study of hearing psychology will actually show this characteristic to be an occasional advantage. But that is another story.)

Not to disagree with Gene (perhaps we don't) but through a multitude of tests human hearing has pretty well been "modelled" to the exclusion of mysterious unmeasurable esoteric characteristics. Using that knowledge, measurements can really qualify an amplifier in terms of adding nothing audible, provided the right measurements are taken.

I am also somewhat surprised by the stress in the article by Mr C ..... on square wave testing, in that while he is correct, it has been old hat for decades: Initial check with a square wave for what to look for, followed by a finer frequency-phase plot of the relevant area for more detail. Still, good to be reminded. But again (sorry, unable to resist): Those plots by sometimes knowledgable writers of "dramaric" overshoots and claims - without showing x-axis figures. Disturbances well into the r.f. field ..... nobody ever said cables etc. do not make a difference per se. (Plus to boot square waves of rise times containing frequencies w-a-a-y above audio.) Sorry.

It has been shown by naughty people like myself that folks claiming to be able to hear differences when aware of what they are listening to, suddenly lose that ability with blind tests.

Etc. Folks will by now recognise that I as a designer can only endeavour to make an amplifier 'blameless' in the sense introduced by Douglas Self. Not too difficult to achieve, in both s.s. and tube types. Boasting? No, it just works that way, particularly with the aid of modern measuring instruments and simulation software.

So why do all amplifiers not sound the same? I would modestly say that audible distortion figures (up to and exceeding 1%??) have become the norm with tube amplifiers, while with s.s. products the zero-chasing to the right of the distortion figure decimal point has left the gate wide open for other effects from high-order distortion, the intermodulation of such in supersonic areas where amplifier plots are no longer well defined ...... but most members reading here know what I mean!

(Again unable to resist: With apology to High-Figh: Never 'eat' anything that squirts from a machine - or the mouth of a salesman!
Oops ....)

 

[Irvrobinson]

Seriously, the more I think about it, the more accuracy in the context of this weird hobby seems hopeless.

No, it isn't, because we don't use random recordings to determine accuracy. You use measurements and reference recordings. As has been pointed out multiple times, anyone can take in-room measurements at reasonable cost, and anyone can make high quality reference recordings using a $200 hand-held digital recorder in their own room. The recordings do not have to be Grammy contenders. I do agree, from experience, that the doubling of the acoustics from a recording is audible. It's sort of interesting to hear, actually.

 

[TLS Guy]

How is that precisely? I'm not as well versed as you. How would you explain this to the layman?

I have been busy getting ready for England, and leave today. I have been think how to reply to your question. In addition I have never owned or serviced an amp with Triple Darlington output stage, so I have had to become more familiar.

In order to get decent power out of an amp the output stage is divided, and one half produces the +ve deflection the other the -ve. So in many ways it is a flip fop switch. The commonest arrangement is the quasi complimentary compound pair, the Darlington pair next and fully complimentary compound the least common.

The Darlington is attractive because the output transistors are all PNP or all NPN. In the other arrangements you have the problem of matching PNP and NPN output devices. In addition providing higher current to low impedance loads, with less heat dissipation is also attractive.

Now to increase power you can parallel devices. For instance the Quad 303, 606 and 909 use triples, but the arrangement is such that the six transistors act effectively as one quasi complimentary compound pair.

In classic triple Darlington the transistors are cascaded. This I have found is where the problem arises, as there is delay with frequency between the switching of base to emitter. This results in time smear.

There are a lot of variations on this topology, with Bryston using a novel triple Darlington topology and Nelson Pass has designed with triple Darlington.

I have no idea if the Niles is classic Darlington or not. However Niles are not known as an amp manufacturer particularly.

So classic Darlington triple has phase shift or time smear, if you will, with increasing frequency.

Having said that the vast majority of loudspeakers are totally awash in phase and time anomalies.

Just to be clear, I now see the Bryston paper on Darlington was R & D. All their production output stages have been of the quasi complimentary variety, which they concluded was the best arrangement.

 

[ski2xblack]

No, it isn't, because we don't use random recordings to determine accuracy. You use measurements and reference recordings. As has been pointed out multiple times, anyone can take in-room measurements at reasonable cost, and anyone can make high quality reference recordings using a $200 hand-held digital recorder in their own room. The recordings do not have to be Grammy contenders. I do agree, from experience, that the doubling of the acoustics from a recording is audible. It's sort of interesting to hear, actually.

I completely agree about system optimization, that's certainly not hopeless, I was just griping about the source material.

Great point about reference recordings, particularly if they are of your own instruments in your own home. Nothing like banging on the drum, then playing the recording to see if your rig can deliver the goods.

 

[highfigh]

I completely agree about system optimization, that's certainly not hopeless, I was just griping about the source material.

Great point about reference recordings, particularly if they are of your own instruments in your own home. Nothing like banging on the drum, then playing the recording to see if your rig can deliver the goods.

Are you listening from the same place as you were when playing the instrument(s)? It's hard to play something AND hear all of the nuances that are audible to a critical listener because the player is in one position and it's different from the prime listening seat. I think this would work as the person recording the sounds, as long as the initial test is mono. Once someone adds one mic, it changes everything WRT the recording AND how the sound couples to the room- adding a speaker changes it again.

And yet, we try.

 

[highfigh]

There are a lot of variations on this topology, with Bryston using a novel triple Darlington topology and Nelson Pass has designed with triple Darlington.

I have no idea if the Niles is classic Darlington or not. However Niles are not known as an amp manufacturer particularly.

I have been watching some YouTube videos of Pass, talking about his work with JFets and SITs, which were originally called VFet. I had a VFet amp from the '70s and it really was different. Wide response, clean, quiet and unfortunately, the amp designs proved to be fragile.

He seems to be trying to make his with as few components possible and had been achieving good output, low distortion and great S/N.

 

[Irvrobinson]

Are you listening from the same place as you were when playing the instrument(s)?

No, you have someone else play the instruments. Or sing. Baritone & bass male speaking voices are also very revealing. I get great results with stereo recordings. Some of the handhelds, like mine, have crossed cardioid mics, so all you have to do is put it on a cheap stand and press the record button. For a while I found recording sounds and playing them back to assess my system somewhat addictive. I was curious about how this or that would sound. Often non-musical stuff. A manual typewriter was interesting.

 

[highfigh]

No, you have someone else play the instruments. Or sing. Baritone & bass male speaking voices are also very revealing. I get great results with stereo recordings. Some of the handhelds, like mine, have crossed cardioid mics, so all you have to do is put it on a cheap stand and press the record button. For a while I found recording sounds and playing them back to assess my system somewhat addictive. I was curious about this or that would sound. Often non-musical stuff. A manual typewriter was interesting.

Did you use sources that tended to be percussive, with fast transients like the typewriter, or just various things?

 

[Irvrobinson]

Did you use sources that tended to be percussive, with fast transients like the typewriter, or just various things?

My wife is a drummer, so I have several recordings of her drum kits. Her 22" kick drum moves a lot more air in a residential sized room than one would expect from most recordings. I've also become very picky about how high frequency drivers reproduce cymbals. Wood on brass is a very distinctive sound that most people can instantly recognize as sounding real or not. Most systems don't sound real on dark ride cymbals and chinas.

We have a piano in the house, though not in my listening room, and I've recorded that. Pianos are very revealing of the bass to midrange crossover, and exaggerated bass, like a lot of folks apparently like to listen to here, sounds horrible on an acoustic piano recordings. Like it's two different instruments playing. Pianos produce quite a bit of bass, but it is subtle and foundational to harmonics.

My wife also plays the vibraphone, which has some cool room acoustics imaging effects. You notice them more in the recording, perhaps because you're not focusing on watching the musician play.

My step daughter plays the flute (she has a degree in flute performance), and she has played along with a recording of herself standing between my speakers. That was super cool.

A slammed car door is another cool test.

 

[Seth=L]

I have been busy getting ready for England, and leave today. I have been think how to reply to your question. In addition I have never owned or serviced an amp with Triple Darlington output stage, so I have had to become more familiar.

In order to get decent power out of an amp the output stage is divided, and one half produces the +ve deflection the other the -ve. So in many ways it is a flip fop switch. The commonest arrangement is the quasi complimentary compound pair, the Darlington pair next and fully complimentary compound the least common.

The Darlington is attractive because the output transistors are all PNP or all NPN. In the other arrangements you have the problem of matching PNP and NPN output devices. In addition providing higher current to low impedance loads, with less heat dissipation is also attractive.

Now to increase power you can parallel devices. For instance the Quad 303, 606 and 909 use triples, but the arrangement is such that the six transistors act effectively as one quasi complimentary compound pair.

In classic triple Darlington the transistors are cascaded. This I have found is where the problem arises, as there is delay with frequency between the switching of base to emitter. This results in time smear.

There are a lot of variations on this topology, with Bryston using a novel triple Darlington topology and Nelson Pass has designed with triple Darlington.

I have no idea if the Niles is classic Darlington or not. However Niles are not known as an amp manufacturer particularly.

So classic Darlington triple has phase shift or time smear, if you will, with increasing frequency.

Having said that the vast majority of loudspeakers are totally awash in phase and time anomalies.

Just to be clear, I now see the Bryston paper on Darlington was R & D. All their production output stages have been of the quasi complimentary variety, which they concluded was the best arrangement.

Thanks for taking the time to reply. As far as how the amplifier sounds to me I would describe it as clean and powerful. I know that's incredibly vague. It definitely doesn't sound "boxed in" like the A-1D does, that thing sounds awful, must be something wrong with it.

I added the Niles to the system and the only difference I could notice without any doubt was completely unrestrained power for my requirement.