Amplifier tonal changes

[Goliath]

You've probably heard this before sometime or another - "I had a Yamaha amp and it sounded bright" and "I now have an Arcam amp and it sounds so much smoother!".

If two amplifiers have different gain structures and volume pots, and most are different, then I would think the change in relative volume at the same position on the pot would result in tonal changes.

For example, if an Arcam amplifier had a less sensitive pot compared to another amplifier, one may interpret this volume discrepancy as more 'laid-back'. If an Onkyo receiver has a more sensitive pot, with more gain, then relatively speaking the tonal characteristics would have to change at the same relative level.

All goes back to the Fletcher-Munson equal loudness curves. Loudness varies with the frequency, so if there changes in output, the volume difference could be interpreted as a tonal change. This could explain why some amplifiers are perceived as sounding different when all that has changed is the relative volume.

Agree/disagree?

 

[ski2xblack]

In testing situations, people will notice and generally prefer the amp with higher output, even if the difference is so slight the subject doesn't explicitly realize it's louder. That's why for a proper ABX test output voltages are carefully matched. In an informal comparison without level matching, then F-M curves (and other factors) would come into play.

 

[Pyrrho]

You've probably heard this before sometime or another - "I had a Yamaha amp and it sounded bright" and "I now have an Arcam amp and it sounds so much smoother!".

If two amplifiers have different gain structures and volume pots, and most are different, then I would think the change in relative volume at the same position on the pot would result in tonal changes.

For example, if an Arcam amplifier had a less sensitive pot compared to another amplifier, one may interpret this volume discrepancy as more 'laid-back'. If an Onkyo receiver has a more sensitive pot, with more gain, then relatively speaking the tonal characteristics would have to change at the same relative level.

All goes back to the Fletcher-Munson equal loudness curves. Loudness varies with the frequency, so if there changes in output, the volume difference could be interpreted as a tonal change. This could explain why some amplifiers are perceived as sounding different when all that has changed is the relative volume.

Agree/disagree?

Yes, that could explain some of it. But I think it is primarily the placebo effect. Once one hears someone claim that Yamaha receivers are bright, that is what most people say who express an opinion about it. Reality has little impact against prejudice.

For those who need it, if Yamaha receivers really were bright (i.e., had excess treble), it would show up in frequency response measurements. But they measure flat, just like they are supposed to. So we ABSOLUTELY KNOW it is something other than what the amplifier is doing that is causing many people to say that it is bright. Yet this fact seems to have little impact on those who are determined to believe nonsense.


Edited to add:

From past experience, I know that people make up all sorts of excuses for the BS they believe. If someone brings up damping factor, read this article:

http://www.audioholics.com/audio-amplifier/damping-factor-effects-on-system-response

Here is a quote from page 2 of the article:

Using the criteria that 0.1 dB is the smallest audible peak, the data in the table suggests that any damping factor over 10 is going to result in inaudible differences between that and one equal to infinity. It's highly doubtful that a response peak of 1/3 dB is going to be identifiable reliably, thus extending the limit another factor of two lower to a damping factor of 5.

Basically, damping factor is a non-issue in practically all amplifiers, except to people who are guided by delusions instead of reality.


Here is another article on this topic, with the same basic conclusion, written by Floyd E. Toole (Damping, Damping Factor, and Damn Nonsense):

http://www.roger-russell.com/wire/damptoole.htm

 

[Goliath]

Yes, that could explain some of it. But I think it is primarily the placebo effect. Once one hears someone claim that Yamaha receivers are bright, that is what most people say who express an opinion about it. Reality has little impact against prejudice.

For those who need it, if Yamaha receivers really were bright (i.e., had excess treble), it would show up in frequency response measurements. But they measure flat, just like they are supposed to. So we ABSOLUTELY KNOW it is something other than what the amplifier is doing that is causing many people to say that it is bright. Yet this fact seems to have little impact on those who are determined to believe nonsense.

For those who need it, if Yamaha receivers really were bright (i.e., had excess treble), it would show up in frequency response measurements. But they measure flat, just like they are supposed to. So we ABSOLUTELY KNOW it is something other than what the amplifier is doing that is causing many people to say that it is bright. Yet this fact seems to have little impact on those who are determined to believe nonsense.

I agree with everything you've said. The human bias position is the go-to position I use in these arguments. If bias can steer perception into a state that agrees with our subconscious then it could explain away a great many anecdotal reports. However I would like to try and focus on real changes that may lead one to think that the tone had changed.

Audiophiles could just argue "well how can most people agree on the same things re Yamaha? Mass delusion? Yes, frequency response is flat at 1 kHz, on the test bench into resistive loads, but what about reactive loads from 20-20kHz?"

The way that I see it, people can experience audible differences in three major ways - 1. either via engineering real audible differences due to lopsided comparisons which ensures non-parity (ie listening at different levels, slow-switching, sighted bias ) 2. imagining differences not inherent in the equipment at all, due to the placebo effect 3. experiencing real audible differences that are really false positive outcomes (eg comb-filtering artifacts by shifting positions on the couch, even by 2-4 inches, may lead to subtle audible differences.

Granted, placebo effect can never be discounted here, but I suspect that people experience changes that are self-made. I think in many cases the differences are real and there are real physical explanations for it, it's not all imagined in the subconscious.I do think the relative gain and volume pot argument is a credible one which could explain ones observations.

 

[mtrycrafts]

I agree with everything you've said. The human bias position is the go-to position I use in these arguments. If bias can steer perception into a state that agrees with our subconscious then it could explain away a great many anecdotal reports. However I would like to try and focus on real changes that may lead one to think that the tone had changed.

Audiophiles could just argue "well how can most people agree on the same things re Yamaha? Mass delusion? Yes, frequency response is flat at 1 kHz, on the test bench into resistive loads, but what about reactive loads from 20-20kHz?"

The way that I see it, people can experience audible differences in three major ways - 1. either via engineering real audible differences due to lopsided comparisons which ensures non-parity (ie listening at different levels, slow-switching, sighted bias ) 2. imagining differences not inherent in the equipment at all, due to the placebo effect 3. experiencing real audible differences that are really false positive outcomes (eg comb-filtering artifacts by shifting positions on the couch, even by 2-4 inches, may lead to subtle audible differences.

Granted, placebo effect can never be discounted here, but I suspect that people experience changes that are self-made. I think in many cases the differences are real and there are real physical explanations for it, it's not all imagined in the subconscious.I do think the relative gain and volume pot argument is a credible one which could explain ones observations.

Well, if the amp output impedance is very low, FR will be flat if it was so into a resistor which most are from 20-20kHz. FR I not measured at 1kHz. Power can be.

If levels are off, then yes, one could hear differences due to it regardless how one interprets that difference.

The biggest cause is not comparing blinded or levels matched, not equipment caused.
Or, in the case of Yamaha, herd mentality? Certainly not the component or it would show under DBT condition.

 

[Pyrrho]

...
Or, in the case of Yamaha, herd mentality? Certainly not the component or it would show under DBT condition.

Yes. A properly conducted DBT would show it, if it were a real difference in the gear rather than due to human psychology.

 

[PENG]

When I was shopping for speakers many years ago, I thought the Arcam AVR-300 was warmer and sweeter than my Denon AVR-3805. I bought the speakers without the Arcam, the room they were in was quite different obviously, but the speakers sounded just as warm and sweet as I heard it in the show room driven by the Arcam. Base on my own experience, with amps one could get close to the point of diminishing return easily and quickly. Once there, Placebo becomes the dominant factor, just my 2 cents..