Low distortion in AVR vs sound quality

[RichB]

Agreed, as you say noise floor is important at low levels... but this reasoning leads to thinking that THD+N measurements at full output are much less relevant than usually thought (as transient peaks in music last for milliseconds and even 10% distortion might be inaudible) while measurements at low level, on the contrary, are probably more important.
Your thoughts?
Am I missing something?

Maximum power is important but (IMO) distortion at 1 watt and below is more important when you take into account the average listening levels. All amps should be tested at 1 watt and below.

Distortion specifications at 1 kHz and maximum power are interesting but not going to tell you much about low level distortions and linearity into load. Deviation from linearity is not considered to be distortion, for some reason.

- Rich

 

[lashto]

Agreed, as you say noise floor is important at low levels... but this reasoning leads to thinking that THD+N measurements at full output are much less relevant than usually thought (as transient peaks in music last for milliseconds and even 10% distortion might be inaudible) while measurements at low level, on the contrary, are probably more important.
Your thoughts?
Am I missing something?

We are all missing quite a lot

Agree with @RichB, the 1W perf is very important. And generally more measurements are needed to 'understand' how an amp sounds. @Archimago does a pretty good job. Four measurement points should be pretty good: say at 1w, at 5-10W, at ~50% of power and at full power. And for all these power levels a full-band HD view would be much better that the 'simple' 1kHz THD graph.
Even all that data might not always be enough to get a sure/full picture on how an amp sounds. Should be pretty good though and a lot better than we have nowadays.

P.S.
the sample graphs above are from the Pass ACA measurements. A very interesting read and a prime example on how HD is quite far from being the 'evil' presented around ASR.

 

[Flak]

Well, THD and noise are different in nature...
there might be an advantage in measuring noise at low levels though... we can check with our ears whether Noise is audible or not at our listening position by not playing music.
If we can't hear it (if not eventually by putting our ears a few centimeters from the tweeter) than it's not audible I think

 

[Lbstyling]

Having bought some Kali LP6's to test against my horns (circa 0.1% distortion), I'm quickly coming to the conclusion that I need over 100db with low distortion. The kali's are good, and have excellent pattern control, but they loose too much quality before they are loud enough for me. Amir's test rooms 'loud' may not corrilate with mine room either at 10m X 9m X 4m.

But even in my smaller room, the sound becomes audiably distorted at too low a level. Perhaps the LP8 would make the difference.

I think much of the population may conflate the sound of distortion with 'loud' in preferences.