In article , Serge Auckland
wrote:

"Rob" wrote in message
...


Many thanks - copied to file for future reference! I'm still confused
by 'power'. This is presumably covered to a point with your
distortion criterion, but I remain to be convinced that most
amplifiers are by any means linear as the volume goes up.

How can they not be? Non-linearity causes amongst other things harmonic
distortion, so provided the THD is below 0.1%, then the linearity is
similarly assured.

I am slightly wary of the above statement. If you are using THD as a guide
I'd prefer to explicitly extend it over a range of frequencies and powers
*and* to various types of load. The reason being various types of 'dynamic'
nonlinearity which the figures might otherwise miss.

I'd also tend to use a THD+Noise value as otherwise effects like PSU
intermod might be missed as their components don't crop up at harmonics of
the test frequency in most cases. I've seen amps where the THD value was
low, but where there was much more LF garbage due to this.

Slainte,

Jim

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