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Phil Allison[_3_] Phil Allison[_3_] is offline
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Default Measuring audio amp output power

Ralph Mowery wrote:



Is that inductiveness seriously likely to be a problem at audio
frequencies?


I just did a quick check with a 10 ohm 60 watt wire wound resistor and a
couple of other low value resistors.
Used a 100 MHz scope, function generator and Fluke 87 meter.

From low audio up to 20,000 Hz and a sine wave with the 10 ohm WW there did
not appear to be any noticable difference.


** And this is a sufficient test for the purpose.


When I switched to a square wave


** Which has harmonics into the medium and HF bands.


I noticed a large spike on the leading and trailing edges, especially as I
went higher up in frequency.


** All due to the harmonics way above audio range.


From this rough test, I would say that if using sine waves you could get a
close to true test, but if music


** Music signals stop at 20kHz.


or other odd ball waveforms



** An audio amplifier reproducing a square wave will not pass harmonics much above 50kHz top the load - so you are wrong again.



..... Phil