XLR is a name for a specific style of locking connector. The term comes from: X for the series, L for locking, and R for rubber insert. In most cases, when someone says XLR cable, they are referring to an audio cable with 3-pin XLR connectors, although the connector is available from two to seven pins. Most microphones and professional sound equipment have 3-pin XLR connectors, allowing easy interfacing between devices. Originally invented by Cannon, (thus sometimes called a "Cannon-plug"), in the 1930's. XLR. The predominant manufacturers are Switchcraft and Neutrik. For more, see the collaborative Article Connectors, XLR.