XLR Cable

An XLR cable is a common cable for lighting and sound in theatres. They are usually used for data, instead of power, but some mixing desks allow phantom power to be sent over them to microphones.

The XLR Connector has a few advantages over consumer audio connectors (such as those with a TRS Connector), as they are much more sturdy, lock into position (so they can't be accidently pulled out) and have a grounded metal casing (so they are grounded as they are plugged in and don't make a noise)

There are multiple varieties of XLR cable, with a varying number of wires running through them. For example, an XLR-3 cable has three wires and three pins on each connector.

XLR-3
XLR-3 is primarily used for balanced audio signals (although cheaper lighting equipment may use them for DMX).

For balanced audio, pin 1 is ground (and connected to the casing), pin 2 is positive/hot and pin 3 is negative/cold.

XLR-4
XLR-4 is less common in theatre, however it is used for the headset connection in some cans systems.

XLR-5
XLR-5 is the standard for DMX cables, although is slowly being replaced by CAT 5 cables.

Pin 1 is the signal common (ground), pin 2 is negative and pin 3 is positive. Pins 4 and 5 are not always used, however they can be used to send a second DMX Universe over a single cable. This requires the connector to be rewired.