Testing with DMM

[losacco]

Are there any amp performance test that can be done with a DMM?

[dsavitsk]

You can measure AC voltage, and thus figure out gain and output power.

[TheGimp]

You can measure gain vs frequency if you have a variable frequency source, and thus plot the frequency response of the amp.

[wfmali]

Originally Posted by TheGimp

You can measure gain vs frequency if you have a variable frequency source, and thus plot the frequency response of the amp.

... depends on the DMM - while they all should give the correct rms value at 50/60Hz, I would not trust them too much at higher frequencies like kHz...
Marcus

[indianajo]

Many cheap DMM's have a 600V scale. For measuring B+ this would be handy. (One hand at a time please, use clip leads on the ground. No jewelry). Some Dmm's actually work at this range, some do not. In the Sears Craftsman brand, performance is kind of random. Some of their $30 meters work fine on 460 VAC, some lock up if you actually use them on this, and have to be turned off to reset the computer.

[Michael Koster]

Originally Posted by wfmali

... depends on the DMM - while they all should give the correct rms value at 50/60Hz, I would not trust them too much at higher frequencies like kHz...
Marcus

My experience is most DMMs these days are pretty flat in the audio band and certainly usable for rough audio level measurements. The RS one has a dbu scale and I use it all the time for more precise level measurements.

I would wonder about the RMS accuracy for anything but simple repetitive waveforms with low crest factor, but I only measure sinewaves with it anyway.

Cheers,

Michael