[dB Cooper]

Here's my take on the "do all amps sound alike" question:

[doug s.]

I was expecting that. Amps do sound different. They amplify the source differently. Some will be more noisy, they power low frequency and high frequency different. When this question gets raised people's responses aren't telling the whole story. Everything we hear out of your speakers is the source amplified. So if you are going to talk about amps sounding the same and then exclude the source its makes the whole topic pointless.

ya, amps sound different.  but once a level of quality is reached, along w/synergy between amp & speaker, the differences become small.  and, no, you don't need to spend multi-thousands to get there. same, imo, goes to the source - once you reach a level of quality, at a relatively sane price, the differences become small.  the preamp is the "glue" that holds everything together.  best to get this to your liking; it will have the largest impact of your electronics, imo.  then tweak your sources, ancillaries, and amp/speaker interface all you like.   

in my system, the preamp is now a constant.  sources, too - i have reached a level where i'd have to make a big financial increase to get relatively small improvements.  (and no, i have not spent a huge amount to get where i now am w/these.)  of course, with tunas, that's a different story - i have a small weakness for trying different tunas...    speakers and amps are what i like to experiment with, but lately, i have not done much w/that, as my present main speakers are so big, my living/storage space is too small to move them from the main rig.        i'd have to sell them to go on w/more speaker (and therefore amp) auditioning, and they're keepers...

doug s.

[Freo-1]

Another relevant perspective was described by Markus Sauer in the January 2000 Stereophile article "God is in the nuances". He talked not necessarily about sound attributes but the emotional response of the listener. In the blind study he cites people had different emotional responses like degrees of relaxation or anxiety to the same pieces of music played through a completely "analog" system consisting of turntable and tube amplification vs. "digital" system of CD player and SS amplification. Of note, a third system of CD player with tube amplification produced, as expected, results falling in the middle. This means that both the source and amplification (unfortunately they did not separate out pre- vs. main amplification) is perceived by the listener and responded to. Interestingly, people with "Hi-Fi" experience seemed to at times prefer the sound of one system (digital) while their emotional response went the other way, i.e. feeling more relaxed with the analog system.

One needs to be careful, and not read too much into those types of articles.   The implied reasoning (that tubes and vinyl is closer to live music than digital and solid state) is just plain wrong. 

Most of the setup's that I have heard that were the "closest" to live music happened to be with large dynamic multi driver speakers, high resolution digital source, and solid state amps.  To be sure, I have heard a lot of tube/vinyl setups that sounded great.  However, IMHO, there are too many variables with tubes and vinyl to get consistent results.  I'll stick with jitter free hi resolution digital setups connected to tried and true designs from the likes of Nelson Pass, thanks. 

There are many possible combinations to get good sound, so one should not put too much stock in any one set of opinions on what's best.   Audio people are passionate about their music, and do not always agree on the best way to get there.  Always go with your own impressions.

The take away is that, yes, power amps do make a difference, and one needs to get a power amp that matches the needs of your speakers. 

[doug s.]

freo, i agree w/your fondness of electrocompaniet amps.  i still use them w/my subs, after i went to tube amps for the mains.    and, while i could live with solid state amps, i could not imagine living w/a s/s preamp.

the most realistic sound i have ever heard from an audio system was tubed and winyl.  speakers differed, but they all had in common high resolution, full frequency range from below 20hz to >20khz, good dynamics, and the ability to go loud w/o compressing.  cd's thru these systems sounded great, but not as good - or real - as w/winyl.

i think one of the "tricks" to get the best sound out of a tube-based rig is to actively cross over to subs, and use solid state amplification on the subs.

doug s.

[Freo-1]

freo, i agree w/your fondness of electrocompaniet amps.  i still use them w/my subs, after i went to tube amps for the mains.    and, while i could live with solid state amps, i could not imagine living w/a s/s preamp.

the most realistic sound i have ever heard from an audio system was tubed and winyl.  speakers differed, but they all had in common high resolution, full frequency range from below 20hz to >20khz, good dynamics, and the ability to go loud w/o compressing.  cd's thru these systems sounded great, but not as good - or real - as w/winyl.

i think one of the "tricks" to get the best sound out of a tube-based rig is to actively cross over to subs, and use solid state amplification on the subs.

doug s.

 Doug, concur with the observation that tubes crossed over to solid state is the best way to go if tubes are your solution. 

For me, vinyl has too many limitations compared to hi res digital to get it right consistently.  The noise floor is just too high, and physics will always keep it that way.  Also, can't get true surround sound with vinyl.  There are also too many sources of distortion from vinyl for me to enjoy it now.  Hi res digital has truly spoiled me.

Tubes can sound magical.  I've had tubes for many years, and enjoyed them immensely.  However, obtaining Nelson Pass power amps has changed my opinion.  They have a harmonic correctness that tubes just can't quite achieve with my speakers. 

Which brings me to the last point:  I played with subs for years, and they drove me crazy!  It was a revelation to get a large full range speaker (down 2 db at 20 hz).   The bass from these are deep and accurate (as opposed to booming).  Bi-amp provides cleaner overall sound from them as well.

So' it's all good.  All music playback has some flaws,  so what I think happens is that we all have differences as to what we overlook vs. what we will not overlook on playback, hence the differing opinions on what sounds best.

[andy_c]

Read a bit more closely.  The results claimed were not that Mr. Clark could not hear the difference, the claimed results were that nobody involved with the testing procedure could hear the difference.

However, I do notice one issue in his test setup that can account for the results, "all amps sound the same.".

The issue is his ABX box itself.

To make this operate when switching from power amp to power amp without generating nasty switching transients, the source driving both amps under test must be connected to both amps at the same time.  Connecting and disconnecting amplifier inputs while the amp is powered up does generate huge switching transients (as many of you have probably already unfortunately discovered.)   

The solution is to switch amp outputs only, not the inputs.

This means that the inputs of both amps are always tied together through the common input cables.

That's not how the ABX box works.  The most recent version is at left below:



Notice that both the input and output are switched.  All that's needed to eliminate switching transients is a make-before-break connection at the input.  Break-before-make seems appropriate for the output, to avoid connecting amp outputs together.

[JLM]

Interesting discussion, but off topic.

Beyond what the specifications would predict, IMO different amps with identical specifications would typically still sound different, SS vs. SS, tube vs. tube, or SS vs. tube.

[kevinh]

Not all power amps sound the same. However if the amp is capable of driving the load and avoids the 'wrong' sorts of distortion the differences are not significant relative to the Speakers, Room Acoustics and Frequency Response, IMO.

[soundbitten1]

I have seven amps and they all sound different.

[timind]

The original idea behind this thread had been co-opted by another topic which is "what's the most important piece in a system." I split the topic and moved posts which were going in that direction. Here's a link to it http://www.audiocircle.com/index.php?topic=95524.0

It seems like a question worthy of it's own thread.

[geowak]

Well I have read these comments and needless to say, I am very "interested" in this discussion.
Was wondering how many out there had read this-

http://theaudiocritic.com/plog/index.php?op=Default&blogId=1&&page=2

Also how good of a diagnosis is the "powercube" for testing an amplifier? The Parasound A21 (at bottom of page) did pretty well, and I am looking at this amplifier.

Decided it might be worthwhile to REVIVE this thread....

[Mark Korda]

Hi,I just read a review from the latest Stereophile on the Musical Fidelity AMS 100.This amp weighs 220 pounds,puts out 100 watts,gets extremely hot,but runs in class A.20 thousand bucks.John Atkinson ,the reviewer,gives a good explanation on class A operation.He said class A suffers from no (cross over distortion)and has less need for negitve feedback.Cross over distortion consists of high order harmonics and is very audible,not my words,his.Class A is very inefficeint.The amp is transistor.Are not tube SE amps class A?There seems to be a dedicated class of people who love nothing else but those SE tube amps.There's got to be a sound difference....Mark Korda

[Letitroll98]

Low switching distortion can also be found in some chip amps.  I have one in a Pioneer receiver that was measured to have vanishingly low crossover distortion curves by Dr Earl Geddes.  It also has severely compromised power supplies and works only into very benign loads, 8 ohm nominal and +90db sensitivity.  Used with such speakers, it can sound magical, into other speakers, not so much.  Generalizations can be made, such as class A amplifiers sound very clean, but every product has to be taken on it's own merits individually and not judged by one criteria.

BTW, the thread on said receiver can be found here: http://www.audiocircle.com/index.php?topic=68889.0   

[*Scotty*]

My position is that amplifiers can definitely sound very similar or the same to one another.
  This can happen when you don't ask enough from them to separate the great from the merely mediocre. A friend of mine is fond of saying he can jump as high as Michael Jordan,if the ceiling in the room is only eight ft. high.
 If I dumb down the the signal going into the amplifier far enough you won't be able hear the differences, that's all it would take.
 I would suspect that many times when no differences are reported during comparisons that is what has happened without the participants in the test even being aware of it.
 The power cube measuring method looks like an interesting approach to gathering data about an amplifiers performance envelope.
  I would also like to see a graph of the frequency vs. distortion showing a distortion level that is constant with respect to frequency. For example .002 THD at 50Hz.,1kHz.and 10kHz.
 When the distortion rises with increasing frequency this is not a good thing.
 It would also be nice to see graph of distortion vs power that was constant in level,a flat line,from the very lowest power level to power level available to that available just before the onset of clipping.
 A great many amplifiers have more than ten times the distortion at their lowest output levels than they have at a 20 or 30 watt power level. They also show an increasing distortion level that may be as much as ten or more times higher as they approach their rated power output.
 The consequence of this distortion vs power curve that has a deep knee in the middle is that its point of lowest distortion does not occur at power levels that are usually used, which is frequently between 1 and 4 watts rms.
  No graphic representation of an amplifiers performance will take the place hearing the amp driving your loudspeakers in your own home.
Scotty
 

[jkelly]

If I had to sum up the whole amp thing, for me, I would say the amp's presentation,
of the music is what is really different. 

Some amps have everything congested in the center - and other
create a 3D holographic presentation. 

I realize tone can be different and the raw power of the amp provides
strength in certain frequencies, but for me presentation is what I look for
and it is different with every amp.

[AJinFLA]

I don't think I've ever seen anyone (sane) actually state "all amplifiers sound the same". Please provide the quote if I missed it.
The obvious fallacy is that it would be impossible to determine if all X is different. How do you test all amplifiers?
What I have seen, is people (like Mr Clark) state that, under conditions x, y & z, a bunch of amplifiers could not be distinguished from one another by a bunch of people. That's not at all the same as stating that "all amps sound the same". The very fact that conditions x, y and z had to be instated....tells you that...they don't.
There are a great many factors than can and do effect the "sound' you hear, both electro-acoustically....and psychologically.

Perhaps the more reasoned question would be, "do all amps sound different?" Now instead of the impossibility of testing all amps, we only have to find two that are indistinguishable to support the hypothesis.
Of course, how does one "hear" an amplifier, when it's the final block in a signal chain, connected to an often complex impedance with which it interacts? One would have to state the conditions.
Under certain conditions, it is quite provable that certain amplifiers, do indeed "sound' the same, to any observer willing to try.
I think, that, might be the gist of Clarks thrust into this madness.

cheers,

AJ

p.s. Letitroll, I've got one of those "Geddes" Pioneers in the arsenal as well. Has no problems driving true 4 ohm speakers, but like you said, PS is not robust enough to handle more demanding (oddly designed?) speaker loads. When operated within it's linear range (D Clark anyone?), it is indeed what I would consider "transparent", i.e., no signature that I can detect....though I wasn't there when the recording was made...nor do I have infallible acoustic memory storage in the noggin, even if I was

[Mitsuman]

In theory, all power amps "should" sound the same. That is they shouldn't have a "sound" at all. In the real world, as they interact with other components upstream and downstream, they most certainly do not sound the same.