How should Mini XLR condenser microphone be wired?


I have bought an AKG WMS 40 (Instrument) kit which comes with the PT 40 bodypack transmitter. This has a mini XLR socket. I am trying to use it with a spare headset mic that had a 3.5mm mono connector (until I cut it off). I have soldered on a 3-pin mini XLR with ground to pin 1 and the signal to pins 2 and 3 shorted. This is how the AKG service manual explains their mics to be wired.

I get no sound from the mic (which does work with my Tascam DR-05 recorder) when using the transmitter, and I have tested the transmitter with a line level source using the included cable in the kit.

I get an odd effect where, if I turn it up very loud, I can hear any touching and general handling of the microphone or headset but the actual sound is not transmitted if I speak or even shout into it.

Any ideas?

Paul Hill

Posted 2016-10-23T13:01:13.237

Reputation: 26



Page 23 of the following document contains the circuit diagram for the PT40 transmitter.

The Schematic indicates that the connection is balanced however the schematic does not indicate a balanced circuit. Pin 3 appears to be a bias voltage supply. Therefore I think that shorting pins 2 and 3 would be inadvisable. Pin 1 is connected to ground via an inductor and signal path is via pin 2.


Posted 2016-10-23T13:01:13.237

Reputation: 7 535


Connection to a body-pack transmitter (of any brand or model) is NOT a simple thing. There are dozens of ways it could be connected. You need to get the connection information for that transmitter, and the wiring diagram for your headset mic in order to properly interconnect them.

Alas, that kind of information is never published and manufacturers are very reluctant to release that information. It is possible to "reverse-engineer" the headset mic and the transmitter input. But short of that, you may not be able to accomplish this simply.

Richard Crowley

Posted 2016-10-23T13:01:13.237

Reputation: 1 849