How to wire an XLR Connector (balanced)

A balanced system is used in pro audio with an overall screen covering a twisted pair. Pin 2 on the XLR is 'hot' and carries the positive going signal, whilst pin 3 is 'cold' and provides the return. Any interference that penetrates the overall braided screen affects both the 'hot' and 'cold' wires simultaneously, and due to the balanced transformer or electronics at the pre-amplifier is effectively ignored as the pre-amp only amplifies the difference between 'hot' and 'cold'.

The female XLR uses the same pin numbering but pins 1 and 2 are reversed .

How to wire an XLR connector (unbalanced)

The unbalanced system is used for high impedance microphones over short distances, and is not recommended for professional use due to susceptability to any RF noise - such as lighting sources, taxi radios etc.

Pin 1 is shorted to pin 3, at either end of the cable

How to wire a 1/4" Jack Plug

The tip of the jack is 'hot' and carries the positive going signal, whilst the sleeve is 'cold' and carries the ground.

To wire to an unbalanced twin core cable, connect the blue or 'cold' wire to the sleeve as well.