Locus Sonus Vitae

Electret Microphone

This revision is from 2018/07/31 09:54.

How to use a electret microphone with a balanced phantom powered input.

We use the Primo EM172, a 12€ high quality electret microphone. The circuit presented here can be use to build a monophonic streambox, or with two of them a binaural head.


The presented circuit power the electret microphone with a bias voltage determined by the value of a zener diode. Usualy 5 volts is enought, by I find out 12v works better with the Primo EM172. I use the +48v from the phantom power, and output a balanced signal, this way a extended length of cable can be used with very little noise.

The circuit is quite simple
[http://gregoirelauvin.net/ftporth/locus/locusWiki/locus%20wiki/primo/primoBalancedSchematic.pdf|left]

Last changed 2023/03/13 15:35