Electret mic XLR adapter module

Details: Category: Designs and Projects

This is a little surface mount module, with all parts ready installed other than the three transistors.

Functionally this is mostly equivalent to my larger condenser mic board, if built using the electret input circuit with the NPN phase splitter and NPN balanced output stage, with the addition of a gain pot as with my dynamic mic design.

It has similar triple filtering/decoupling for the zener regulator, with around a 5V internal supply for the phase splitter and electret capsule bias feed.

I'm using KSC1845 transistors with these so far; they are a very good low noise device and rather cheaper and easier to obtain than the ZTX I've used in other mic circuits. I will do a comparison between the two transistor types at some point.

The PCB module size is approximately 41mm long by 18mm wide and 4mm thick (less the transistors).

PCB module, as supplied, without the transistors installed:

And with transistors installed, plus some connections.

At the left, the M pad is mic signal, G is mic ground. At the right, G is ground (XLR pin 1), A and B are the signal outputs & phantom power in, to XLR pins 2 & 3.