Do amplifiers sound the same??

[annunaki]

Hey all! I thought I would post on this controversial topic. I would like to post some of the conclusions I have come to. There are a few rules though.

1) No personal attacks from either camp.

2) Keep an open mind about either side


Conclusions:

In double blind tests, where amplifiers are all set to the same distortion levels, output impedances, output levels, frequency response and load, I do believe they are indistinguishable.

In most applications, in the home, when amps are changed around, I do believe that differences can be heard.

In those applications, in the home, when differences are heard, they are rarely due to the fact that one amplifier actually 'sounds' better.

Rather, the differences one notes are due to the following:

Output impedance differences, frequency response discrepencies, dynamic output capability changes, onset of audible distortion, how well an amplifer handles the given load and some others.

It is the afformentioned differences in the two amplifiers that people are actually hearing. Because most people are not going to go through blind testing 'equalizing' procedures, they will come to the conclusion that one amplifier sounds better than the other. Not the fact, that when equalized in a lab type procedure, they are indistiguishable.


In light of my own conclusions, I still say, listen and buy what suits you. I also say that is someone believes they heard a difference between two amplifiers in their home, they probably did, not because they actually (blind lab test) sound differently, but because of one of the differences I stated above. It is one side of the said differences that their ear prefers in that case.

Maybe this will help to clean some of the confusion on this ongoing debate?

 

[Rip Van Woofer]

Inherent in your reasons for amps sounding different are parameters, like the ones you listed, that are measurable. With which I agree. A lot of the subjective types on the other hand argue that amps sound different for mysterious reasons that are beyond measurements. Which is hooey!

I might take some issue, though, with some of your listed parameters. Frequency response differences, especially, are seldom found in modern solid state equipment which are uniformly flat. Some tube and "esoteric" SS designs will have significant frequency response errors of course. Then it's apples and oranges - and the differences are both measurable and audible of course. But an Adcom and a Levinson (say) will sound the same when all else is equal and they're driven within their limits

Likewise, modern "mainstream" amps all have low output impedances, so that's a non-issue...unless, again, we're comparing "mainstream" gear with "esoteric" and tube/based, which can have high output impedances. Again, an easily measurable difference that can have audible consequences. Usually frequency response errors which brings us back to the first paragraph!

But I agree that, when the going gets tough (inefficient speakers, large rooms, high SPLs, difficult speaker loads) then the men get separated from the boys. But there's no mysterious "x factor" at work, subjectivist dogma to the contrary. Just the ones you quite correctly listed.

So, you're not a total ignorant slut!

 

[annunaki]

What I meant by frequency response was all internal processing shut off eqs, loudness, bass, treble and the like. There can be small differences in response, but as you stated, they are fairly small if any.

What do you mean I am ignorant??

 

[j_garcia]

I have two amps in my bedroom - an Audiosource Amp One A rated at 80w and the Marantz in my sig rated at 95w (AB mode). Both are setup and I can switch between them by swapping cables quite easily. I have not done a level matched test, only comparing between what I percieve as roughly the same level, and I can say there is clearly a difference between the two. The Audiosource sounds more detailed in the mids and highs, while the Marantz sounds softer and has more pronounced bass but also seems to bring out more depth from the presentation (Patricia Barber's Companion). While I like detail, something about the way the Marantz sounds is more pleasing with these speakers.

 

[Kurt C.]

but both amps, at the SAME TIME, receiving the SAME SIGNAL, from the SAME PRE-AMP, pushing differently located LIKE speakers, WILL, expose any differences, as BEST comparison.....

Different speaker locations, even slight ones, will cause significant sound differences. So this example doesn't tell us whether or not the amps caused the differences you heard.

Don't take my word for it. Harman International recently published an excellent article how critical speaker/room interactions are and why we all benefit when audio engineers take an objective approach to improving the listening experience here.

I recommend that everyone read the article so that this discussion doesn't turn into a name-calling fest quite as quickly as the last few on this topic have.

 

[Dan Banquer]

Do all Amplfiers sound the same

I think there a few reasons why solid state amplifiers can be different.
1. Noise
2. Grounding: also part of noise.
3. The distortion spectrum they produce into a reactive load, which can be level dependent.
4. The thickness of the front faceplate. Greater thickness means better everything.

 

[MacManNM]

I think there a few reasons why solid state amplifiers can be different.
1. Noise
2. Grounding: also part of noise.
3. The distortion spectrum they produce into a reactive load, which can be level dependent.
4. The thickness of the front faceplate. Greater thickness means better everything.

I agree with all but #3. A greater amount of distortion will not be created unless the amp is of bad design. A low output impedance and high damping factor will take care of this.

 

[Kurt C.]

.....J_Garcia, I'm going to propose the bass of the Marantz simply, sticks out, more to you, with it not being as clean....your reference to the mids and highs of the other amp being more detailed, says to me it could be cleaner throughout the entire frequency response....

I'm going to propose that the differences you heard were more likely due to imperceptible differences in volume. If you don't at least crudely match volume levels with an SPL, we'll never know.

Actually, I have a better idea, why don't you ship your system to me for a few weeks so that I can do the comparison.

 

[j_garcia]

I have an SPL meter I can compare at the appropriate levels. I agree with Mule though, the "lack" of bass exhibited by the Audiosource is likely more accurate and less pronounced, but the "fluffy" bass produced by the Marantz is just more pleasant, and I think that is one of the things Annunaki is getting at - listening will reveal more than what the amp's specs alone are telling you. How one amp reacts to or handles the load of a certain speaker at a given SPL will be different from another amp, and the characteristics of each will give you a slightly different sound if one struggles with that load and the other does not.

 

[Rip Van Woofer]

Without careful level matching (to 0.1 dB), subjective comparisons are meaningless and merely anecdotal. Small, otherwise unnoticeable differences in level can be interpreted as qualitative differences where none exist. Considerable experimental evidence on human hearing dating back decades supports this.

My bottom line is: Audio technology and human hearing are purely physical phenomena. Human perception is perhaps not purely physical but falls under psychology -- not mysticism, metaphysics or religion. Science is the best tool we have for understanding the physical world and human psychology. Furthermore, we humans are not only easily fooled, but good at fooling ourselves. Science is the best tool (not perfect - nothing human is) we have to compensate for this natural failing. So I trust science over fallable, unaided perception and unconscious human bias when it comes to understanding the physical world, including audio.

Dan Banquer's list, again, are purely measurable phenomena, not mysterious "x factors" unknown to science. AFAIK, Dan's ideas on the importance of noise etc. are somewhat controversial in the EE community but at least it's a genuine controversy.

(I hope he's wrong, because I cannot get rid of the tiny bit of hum in my DIY amps!)

 

[Kurt C.]

....Kurt, I walked back and forth and stood right in front of the speakers....room conditions or placement didn't have anything to do with it....this is another point

Recal from optimizing subwoofer placement that moving the sub a couple of inches can drastically change the way it sounds because of differences in the way room modes are excited. The same is true of any speaker with output below 300 Hz.

I don't think walking around the room eliminates this difference.

Take a look at the article I linked. Although it focuses on speakers, the take-home point is that it takes a great deal effort to make sure that differences you perceive are really due to differences in the sound that comes out of a given component and not due to the room, sound level, or visual cues.

 

[nowonder]

To take room placement out of the equation, couldn't you just swap the two amps and do the comparison again? If you observe the same results for the same amp using the opposite speaker, then clearly the room placement didn't make the change...

--nw

 

[Kurt C.]

..the decay times of the Mac were obviously and simply longer....the sound had a hooded effect, and I guess it took a simultaniously running K2 to expose that....please give me a reason for that beyond damping factors to variable extremes.....

Do you think the Audiosource could be just barely clipping? That would explain the lack of smooth decay and veiled sound. Was this through your 902s? How tough a load are they? I guess you could crank it up a bit louder to see if the difference becomes more pronounced.

The point is that sonic differences between two good amps (as defined in the start of this thread) should be vanishingly small. If there are clear differences after obvious variables have been eliminated. There is probably something wrong with one of the amps.

 

[Rip Van Woofer]

Nice try, Mule....but a miss! "The power of suggestion" refers, I am sure, to the fallibility of perception due to bias. I trust my hearing, and with input from reason they tell me that two competenly designed solid-state signal paths regardless of price or pedigree are transparent and indistinguishable, within the limits I've stated earlier. I have myself heard "differences" that, when pursued and investigated with even a little rigor, have disappeared.

Based on what I've read by Mr. Linkwitz, I think he'd agree with me.

 

[j_garcia]

Mule isn't running the Amp One, I am The Amp One is 2 Ohm stable, but it is also a smaller (1U rackmount) amp comparatively. The PM7200 is a "normal" sized amp, about the size of a standard receiver, in a dual monoblock config with two BIG heatsinks and capacitors. I'm sure the Amp One clips before the PM7200 does. The 902s are a pretty easy load to drive and my bedroom is relatively small (about 12 x 14). They are 8 Ohm nominal and 89dB sensitive.

I'm not disagreeing at all that two comparable amps will sound more similar than not; I completely agree with that. However, two amps of very different designs (maybe class AB vs class D) that have similar specs have the potential to sound different when driving an identical load.

 

[Kurt C.]

The only careful, double-blind tests that I have participated in were to compare CD players, so I can't claim to be an expert.

However, after reading the results of many similarly performed comparisons of good amplifiers, I have yet to see evidence that a human has ever demonstrated the ability to distinguish between two good amps when all visual cues and known variables were eliminated.

I accept that there may be flaws in double-blind testing that, when eliminated, may allow someone to do it, but it hasn't happened yet. This leads me to conclude that any differences that may exist are extremely small.

We all seem to accept Linkwitz as an authority. I haven't seen a firm statement from him on whether 'good' amps sound different or not. He does rank factors that influence sound reproduction in decreasing order of importance here and lists rooms and speakers above amps, DACs and cables. The fact that he puts amps on the list suggest that he thinks they might.

 

[mtrycrafts]

.....Rip, would you say that a McIntosh solid-state amplifier might fall into this category?...

What is the speced frequency response of that Mc??? Output impedance? Mc is not an esoteric amp even though it is tubed. They know how to design amps.




.pushing differently located LIKE speakers, WILL, expose any differences, as BEST comparison.....

Maybe that is the problem then, differently located speakers. This by itself will cause differences even if no amps are switched.

I firmly believe there's merit in high damping factor for cleanness, and you can pitch your decay charts in the campfire as far as I'm concerned....this hobby ain't about scopes and meters.....

It should be part of it. Some refuse though. Science is part of audio. Beliefs are just that.

 

[mtrycrafts]

Both are setup and I can switch between them by swapping cables quite easily. I have not done a level matched test, only comparing between what I percieve as roughly the same level, and I can say there is clearly a difference between the two.

You just answered your own explanation. You hear differences because of level differences, most likely. You can be off as much as 1 dB spl, demonstrated in experiments, doing it strictly by ear. You may want to use an spl meter with your method, and a test disc after you set levels by ear

 

[mtrycrafts]

.....Rip, thy signature, doth surely contradict thy statement.....


"Regrettably, much misinformation and outright nonsense has been publicized to promote certain 'high-end audio' products. The power of suggestion works exceedingly well when listeners do not trust their own hearing." -- Siegfried Linkwitz

What Siegfried meas is that to hear, you don't need help from your eyes as it will mislead you. So, by using your eyes, you are not really hearing as bias has interfered with hearing.

 

[mtrycrafts]

Different speaker locations, even slight ones, will cause significant sound differences. So this example doesn't tell us whether or not the amps caused the differences you heard.

Don't take my word for it. Harman International recently published an excellent article how critical speaker/room interactions are and why we all benefit when audio engineers take an objective approach to improving the listening experience here.

I recommend that everyone read the article so that this discussion doesn't turn into a name-calling fest quite as quickly as the last few on this topic have.

Maybe they will listen to you??? I tried, nothing works. Hard to give up old belief systems.