On Sunday, November 15, 2015 at 6:37:00 AM UTC-8, Cursitor Doom wrote:
Hi all,

This subject continues to severely bug me. I've just read some audio amp
servicing/repair book where the author states that customers often find
it desirable to know an amp's actual output power, and to return an amp
having measured its output power and noted it down for the customer's
info. The trouble is, customers are familiar with "RMS power" - but
there's no such thing! Irms X Vrms = AVERAGE power and that is all that
matters. BUT - try telling that to a typical customer!

So it must all come down to perception. Customers have an idea in their
minds what say 70WRMS sounds like through listening to dozens of various
VRMS labelled amps over the years. So there ought to be some kind of
notional, informal 'conversion factor' between Waverage and "WRMS" we
could adopt to satisfy them without compromising on the accuracy of the
correct measurement, n'est pas? What would that conversion factor be?
Greater or less than unity for a start?
Your thoughts invited.

You are correct on 'average' power but SO WHAT? Measure the average power and tell him it's RMS power. The method you're using is what all the reviewers use so where is the problem? You're being a 'purist' and it will get you NOTHING. Don't shoot yourself in the foot and then complain about the pain..

FWIW I have a little Technics receiver that the manual says is 40 Watts / channel. When I ran it up it sure SOUNDED like more than 40 Watts. When I measured the power supply Voltage of +/- 42 I had my answer. It IS more than 40 Watts under 'music' conditions. Am I upset because the 'lied' about the power? Nope, I'm just fine with it.

G²