Ralph Mowery wrote:

"Phil Allison"


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.



Do try and keep up. This is about the output of the amplifier. It does not
mater what the amp is going to pass.

** Huh ????

Since amplifiers cannot pass the harmonic frequencies, they will NOT appear at the output.


From a quick test with a couple of wire wound resistors an audio frequency
square wave was producing a spike on the leading and trailing edges of the
ww resistor.

** An "audio frequency square wave" must have its harmonics filtered out above the audio band.

However, what you have is a *WIDE BAND* square wave with its fundamental at an audio frequency.

I understand your test and a similar one to compare low value WW resistors for such inductance. Normally you see overshoot and ringing at frequencies in the low MHz range on the scope - using a 100kHz square wave.



.... Phil





.... Phil


It did not do that with a carbon resistor.