XLR Connectors Exposed and the Future of Pro Audio Connectors
The XLR connector is commonly used in professional audio and video applications. The plug is actually an electrical connector by design. Not unlike the more common RCA connector, which used regularly with home audio and video electronics, the XLR connector is different in several important ways.
Originally designed and manufactured by James h. the connector was first called the “Cannon X,” and after the addition of a latch the “Cannon XL” and finally the “XLR” after having a rubber compound added to the connectors.
The most common is the 3-pin XLR3, used almost universally as a balanced audio connector for high quality microphones and connections between equipment. Other configurations are also widely used including the 4-pin XLR4, for Clear-Com and Telex intercom headsets and DC power connection for film and video cameras. XLR5 is the standard for DMX512 digital lighting control as well as dual element microphones and dual channel intercom headsets. XLR6 is widely used as a connection for dual channel intercom belt-packs.
There are also a number of obsolete configurations with various pin numbers including XLR-LNE mains power connector which had red insulation and shrouded pins and since been replaced by the Neutrik PowerCon connector. Until recently, XLR3 connectors were also widely used with 2-conductor loudspeaker cables, with either pin 2 or 3 as live (varies depending on the manufacturer) and pin 1 as the ground . However, this turned out to be dangerous to equipment and has since been replaced by the Neutrik Speakon connector.
XLRF connectors are made to connect the ground pin first, before the other pins make contact while the XLRM is being inserted. Because the ground connection is made first, before the signal lines make contact, XLR connectors can be inserted and removed without interference from external signals, a typical problem with RCA connections. Even nowadays there is discrepancy between different manufacturers between whether pin 2 is udes as the normal input and pin 3 as the inverting input or vice versa, but this reflects nothing more than their own pre-existing standards before any standards existed. Pin 1 is always the earthly return or ground pin, and often soldered to the internal shell or case.
Lastly, the XLRM male connector is used for output and the XLRF connector is used for input. So, a microphone for example will have the XLRM connector. Signal cables will have XLRM at one end and an XLRF connector at the other. Mixers and other multi-track recording equipment components will have XLRF inputs, and XLRM returns to stage, or out to other components.
XLR connectors are the standard in the professional audio and recording industry. XLR plugs are typically referred to as “balanced” and help reduce noise interference, especially over long spans. Quality varies depending on the manufacturer, but for high end applications please can check out Canare, Mogami and Neutrik.
Recently, the advent of USB microphones that connect directly to a PC or MAC have gained popularity. So far, USB microphones are primarily intended to be used as studio microphones, and live stage vocal microphones continue to use the standard XLR connections.