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Don Pearce
 
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Default How to measure a dynamic mic's output impedance?

On Sat, 4 Mar 2006 15:03:27 +0100, "Andy"
wrote:

Hello,
I'm a total beginner. How do I measure a balanced or unbalanced dynamic
mic's impedance? Can I do it with a multimeter and, if so, how?

Thank you,
Andy

Yes. Feed the mic into your computer, or whatever, and look at the
output level in real time. Have some sort of source of sound playing.
Now put a variable resistance across the mic output, and adjust it
until the level drops by 6dB. Measure the resistance of the variable
resistance on your multimeter and that, near enough, is the impedance
of the mic.

More accurately, feed the output of the sound card with a signal at
1kHz playing into the mic (it is quite safe) through the variable
resistance, which you should adjust to zero. Measure the voltage
across the mic capsule. Turn the resistance up until the voltage drops
by one half. The resistance of the resistor is now exactly equal to
the impedance of the mic.

Otherwise, go to the manufacturer's web site and look it up.

d

Pearce Consulting
http://www.pearce.uk.com