Originally Posted by Nyal Mellor
Originally Posted by arnyk
Probably not. The maximum output voltage without clipping that you can get out of a power amp will depend on the signal. Pure tones demand more power supply and heat sinks than music. The less extreme low frequency content, the less extreme highs, and the more impulsive nature of the music, the more voltage the amp can deliver.
Really, so you can get a significantly more peak output voltage with a music signal as opposed to a sine wave?
Yes. For a middle-of-the-road AVR running all channels, yes and by quite a bit. For a power amp with a very stiff power supply like a Krell, yes but less so.
From what A9X-308 said above the supply rails determine peak output voltage and I imagine they are reasonably steady in a well designed amp.
He appears to be using a power amp like a Krell, with a very stiff power supply, as his standard.
I would 100% understand what you say if you were only talking about average power or whatever the correct term is for that. With low crest factor signals the average power required is much higher than with high crest factor signals.
Yes .But as everybody seems agree, music has a large crest factor. Sine wave = 3 dB, dynamic music or movie = 20 dB. Music never has a crest factor of less than something like 8 dB. 3 dB is double the power, 6 dB is 4 times the power, 10 dB is 10 times the power and 20 dB is 100 times the power.
Here is a relevant graphic from a thread in the stereo forum:
And here is a conservative estimate of what the same average AVR would look like for low
crest factor music:
So, the first graph looks pretty dire, and that is what the high end ragazines publish. Coincidentally, it looks like something that sells expensive amplifiers. Whooda thunk! ;-)
The second graph is much more like what people actually hear in their listening rooms.Edited by arnyk - 7/16/13 at 2:00am