[ProAudio] Microphones question

Jim Brown jim at audiosystemsgroup.com
Sat Jun 12 12:50:20 PDT 2021

On 6/12/2021 9:15 AM, Dan Lavry via ProAudio wrote:
> was hoping that someone would talk about how to measure the electronic 
> part of the mic, without contributions from the membrane.

I posted two methods earlier in the thread. Drive the DUT from a 
generator with a high value resistor in series, making it a constant 
current source. Measure the voltage across the DUT (the mic) and use 
Ohm"s Law with that known value of current. This provides the magnitude 
of the impedance. If the measurement is done with synchronized generator 
and receiver, as with TEF or FFT, it yields complex impedance, that is, 
R + jX. For 1% precision, the series resistor must be 100x the impedance 
of the DUT.

This is LONG established practice. We were doing this with TDS (TEF) for 
loudspeakers in the early '80s.

Jim Brown

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