Attaching the plug-on transmitter to the microphone Microphones with a metal casing should be used for optimal signal transmission. Loosen the locking ring (2) by rotating it in the clockwise direction past the center point. This unlocks the XLR-3 plug (1) of the plug-on transmitter. Connect the plug-on transmitter's XLR-3 plug (1) to the XLR-3 socket of the microphone. Tighten the locking ring (2) by rotating it counter-clockwise in the direction of the arrow.