Connecting the Microphone to a Sound Card
To connect a professional microphone with a three pin XLR output connector to the 3.5 mm miniplug mic input of a sound card, a special cable must be purchased or made. For the microphone to work properly, the cable must have the proper type of connector for the sound card (two conductor ‘mono’ or three conductor ‘stereo’ miniplug) and be wired correctly. The correct wiring scheme depends on the type of microphone and the wiring of the sound card’s microphone input. Cable wiring for some common microphone types and sound card connectors are illustrated below.

Connecting Professional Dynamic Microphones
The wires that are connected to pins 1 and 3 of the XLR connector should both be connected to the Sleeve of the mono miniplug. The wire that is connected to pin 2 of the XLR should be connected to the Tip of the miniplug.

Wiring diagram for dynamic microphone to sound card with mono miniplug

If the soundcard uses a stereo miniplug, the configuration is slightly different. The wires that are connected to pins 1 and 3 of the XLR connector should both be connected to the Sleeve of the stereo miniplug. The wire that is connected to pin 2 of the XLR should be connected to the Tip of the miniplug. No connection should be made to the Ring of the miniplug, because dynamic microphones do not require external dc power.

Wiring diagram for dynamic microphone to sound card with stereo miniplug

Sometimes it is impossible to tell if the connector on a sound card is of the mono or stereo variety. If a cable that is equipped with a mono connector is plugged into a sound card input that uses a stereo connector, the microphone should still work. This is because the Ring portion of the sound card jack will make contact with the Sleeve portion of the miniplug on the mic cable, which will connect any dc bias voltage to ground.