Why Audio Amplifiers Can Sound Different

[highfigh]

I think a lot of the desire in tubes comes from the fact that tube amps are desirable for production of music, like a tube guitar amp. However for reproduction I want music as unchanged as possible. I do not want more distortion, I want the amount of distortion that the artist added- no more. A quality solid state will do this.

That said, most quality tube amps don't add that much distortion, if at all, and also look really, really cool. I honestly think imho that it's more of an appeal to Luddite that draws many folks to tubes. My only real reservation with a tube amp is limited output, but with sensitive speakers this won't be an issue.

At low levels, tubes don't color the sound much, but they do take the edge off of harsh CDs. However, a well-designed tube amp is easily as clean as a similar Solid State amp, with the added benefit of removing unwanted 3rd order harmonics. A tube amp in ultralinear configuration can exceed 20-20KHz easily. A well designed tube amp is also very quiet.

 

[Irvrobinson]

At low levels, tubes don't color the sound much, but they do take the edge off of harsh CDs.

How does this work if they don't color the sound much?

 

[highfigh]

How does this work if they don't color the sound much?

I wrote 'much', not 'at all'. Also, it was a lower powered model and it was run hard. Inasmuch as totally 'distortion-free' is impossible, a little here and there doesn't qualify as 'bad', IMO. As AcuDefGuy wrote- if it sounds good, it is good.

 

[AcuDefTechGuy]

As AcuDefGuy wrote- if it sounds good, it is good.

Damn straight.

I actually got that line from Dennis Murphy.

 

[Steve81]

Damn straight.

I actually got that line from Dennis Murphy.

Which is in turn a quote from Duke Ellington

 

[RichB]

What this thread is pointing out that amps do sound different but that's because some aspect has been measured to cause the audible difference. There is no doubt in my mind that amps that measure the same in all aspects (measured in detail beyond what the audio rags report) WILL sound the same well within their operational limits despite class. I'm also of the school that everything we hear is measurable and our hearing sensitivity is far less capable in discerning nuances than test equipment and a well thought out test plan. I don't believe in "golden ear super hearing capabilities" either. Trained listening yes.. but even that ability changes with age.

Speaking of Golden Ears:


Blind Testing, Golden Ears, and Envy. Oh My!

http://www.audiostream.com/content/blind-testing-golden-ears-and-envy-oh-my

The trouble with all this stuff is there is a ton of snake oil.
I do believe we all have very different acceptable price windows and not all objections are based on Envy.
Often peoples visceral reactions are based on the "Stop me before I kill again" mentality; the need for there to be no differences so they can stop worrying and enjoy their system.
IMO, everyone is a subjectivist since they often site their own listening experiences to point to invalidate the experiences of others.

Concerning measurements, not many are measured into resistive loads.
When it is done, it use usually with a monstrous amp like the XPR-1.
I have not seen reactive load measurements with an AVR.
Even if done, that would not be "fair" in that reviewer might pick a load that is not representative and unduly pan products.

IM may be underestimated. HomeTheaterHifi stated in a review IM distortion was calculated including products +/-250hz of the tone.
They pointed out the need for examining the full FFT plot, which AH does as well.
If that is correct, the industry might like it but it does not make sense for audibility of IM distortion.
If an amplifier driving a reactive load fails to deliver the instantaneous power required, this is not considered distortion even though it is not accurate and will alter the sound reproduction.

Even though I have heard amps sound different, source components make a bigger difference in my system.

- Rich

 

[Irvrobinson]

I wrote 'much', not 'at all'. Also, it was a lower powered model and it was run hard. Inasmuch as totally 'distortion-free' is impossible, a little here and there doesn't qualify as 'bad', IMO. As AcuDefGuy wrote- if it sounds good, it is good.

Taking the edge off harsh CDs, if this effect is real, is a gross coloration at the amplifier level. Easily measurable in a simple 1W frequency response sweep.

 

[Irvrobinson]

Which is in turn a quote from Duke Ellington

Which had nothing to do with music reproduction, he was referring to original performances. 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.

 

[AcuDefTechGuy]

Which is in turn a quote from Duke Ellington

There's no such thing as originality anymore, is there?

Everything derives from something else.

 

[3db]

There's no such thing as originality anymore, is there? .

Ohh I dunno.. After I get over the shock of my reflection in the mirror, I know the mold that was used to create me was burned.

 

[highfigh]

Taking the edge off harsh CDs, if this effect is real, is a gross coloration at the amplifier level. Easily measurable in a simple 1W frequency response sweep.

If the harshness comes from IM distortion in the player and is due to the LP filter used to remove the aliasing frequencies, it's just acting as a filter, not as a source of distortion. The same result can be had by turning the tone control down a step and I don't see many people calling that 'distortion' or 'gross coloration', other than the cork sniffers.

 

[highfigh]

Ohh I dunno.. After I get over the shock of my reflection in the mirror, I know the mold that was used to create me was burned.

And I hear they beat the crap out of the mold-maker.

 

[highfigh]

Speaking of Golden Ears:


Blind Testing, Golden Ears, and Envy. Oh My!

http://www.audiostream.com/content/blind-testing-golden-ears-and-envy-oh-my

The trouble with all this stuff is there is a ton of snake oil.
I do believe we all have very different acceptable price windows and not all objections are based on Envy.
Often peoples visceral reactions are based on the "Stop me before I kill again" mentality; the need for there to be no differences so they can stop worrying and enjoy their system.
IMO, everyone is a subjectivist since they often site their own listening experiences to point to invalidate the experiences of others.

Concerning measurements, not many are measured into resistive loads.
When it is done, it use usually with a monstrous amp like the XPR-1.
I have not seen reactive load measurements with an AVR.
Even if done, that would not be "fair" in that reviewer might pick a load that is not representative and unduly pan products.

IM may be underestimated. HomeTheaterHifi stated in a review IM distortion was calculated including products +/-250hz of the tone.
They pointed out the need for examining the full FFT plot, which AH does as well.
If that is correct, the industry might like it but it does not make sense for audibility of IM distortion.
If an amplifier driving a reactive load fails to deliver the instantaneous power required, this is not considered distortion even though it is not accurate and will alter the sound reproduction.

Even though I have heard amps sound different, source components make a bigger difference in my system.

- Rich

I think a lot of people do their listening tests after changing more than one piece or aspect of their system, which makes the test invalid to a great degree. Changing an amp is one thing, changing the amp and moving one speaker (or more) throws the test out the window.
I don't worry about maximum power specs because I NEVER operate at that level. It's nice to know, but I'd rather know how it sounds at a normal listening level and how much headroom it has from that level.

I'd like to see someone do amplifier testing with some of the "special" power and before/after allowing the amps to warm up for the recommended time. I was told by a sales rep that the power cords he bought reduced the warmup time from several hours to about 20 minutes.

 

[3db]

And I hear they beat the crap out of the mold-maker.

Apparently not... You're here posting as well.

 

[highfigh]

Apparently not... You're here posting as well.

Hardy, har har!

 

[Irvrobinson]

If the harshness comes from IM distortion in the player and is due to the LP filter used to remove the aliasing frequencies, it's just acting as a filter, not as a source of distortion. The same result can be had by turning the tone control down a step and I don't see many people calling that 'distortion' or 'gross coloration', other than the cork sniffers.

Perhaps I need a harshness filter, but this is hogwash. Nothing a tube amplification circuit does is going to remove IM distortion in the source signal, unless it has a poor frequency response curve, and that is gross coloration.

 

[3db]

Perhaps I need a harshness filter, but this is hogwash. Nothing a tube amplification circuit does is going to remove IM distortion in the source signal, unless it has a poor frequency response curve, and that is gross coloration.

My harshness filter .... one per channel

 

[Chu Gai]

I'm certain amps sound different. The question is, do we measure the right things? I have maintained for years not nearly enough attention is paid to low signal behavior, only at power. How much THD at 200 watts? Much more we should answer what is the performance at a fraction of a watt. Not important you say? Well I can tell you the ear is far more sensitive to trouble at very low signal levels, that at full bore.

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.

Those tests really sort it out. The reason I believe is that we are very sensitive to ambient tails. If you think about it there is huge evolutionary advantage to that.

Ambient tails as is the decay of sound?

We get back to the pop classical divide. Pop music is highly produced with purposely built in distortion and very little in the way of natural ambient information.

It could be recorded better.

Low bit rate streams really show this up, as they wreak havoc on the ambient tails. The wisdom is it is not important.

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

I really don't like bit rates lower than 320 kbs, and even then it is problematic 640 is better and no loss in a codec better still.

Quite honestly I don't like listening to class A/B amps, I don't think they sound right and I can and have picked them out. I think class A designs do sound better, and is probably the reason for the tube persisting.

Nostalgia has a way of hanging on.

I use Quad current dumping amps. I think they do best any standard A/B and to me they give far more relaxed and detailed listening. I admit part of this is that all my speakers are designed and voiced with these amps. However I have tested other speakers with these amps. I can tell you that I think the top end B &W speakers sound significantly better powered by Quad than MAC.

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

 

[Chu Gai]

My harshness filter ....

Now, wouldn't it be interesting to run tests on people before and after having two drinks?

 

[3db]

Now, wouldn't it be interesting to run tests on people before and after having two drinks?

Definately