XLR Connectors Explained and the Future of Pro Audio Connectors
The XLR plug is the standard for pro audio and video applications. The plug is actually an electrical connector by design. Not unlike the more ubiquitous 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 3-pin XLR is the most widely used, and is the standard as a balanced audio connector for professional 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with various pin numbers including XLR-LNE mains power connector which had red insulation and shrouded pins and since been replaced by the Neutrik PowerCon connector.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 However, this turned out to be dangerous to equipment and has since been replaced by the Neutrik Speakon connector.
Female XLR connectors are designed to first connect the ground pin before the other pins make contact as the male XLR connector is inserted. Due to the fact that the ground connection is made before the signal lines make contact, XLR’s can be plugged and unplugged without interference from external signals, a common problem with RCA connections. There is some discrepancy between various manufacturers between swapping pin 2 (normal input) and pin 3 (inverting input), but this reflects nothing more than their own pre-existing standards before any standards existed. Pin 1 is always the ground, or earthly return pin, and is often connected to the internal shell or case.
Lastly, the XLRM male connector is used for output and the XLRF connector is used for input. So, for example vocal microphones will have a XLRM connector .Signal cables or patch cables have the XLRM at one end and the XLRF connector on the other. Mixing boards and various multi-track recording equipment pieces typically have XLRF inputs and XLRM returns which lead back to the stage, or to other components.
XLR connectors have been the standard in the professional recording and audio 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.
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