XLR Plugs Exposed and the Future of Pro Audio Connectors
Posted by admin on May 26th, 2009 filed in Uncategorized
The XLR connector 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. Cannon, the connector was originally called the “Cannon X,” and later the “Canon XL” and finally the “XLR” after the addition of the latch (XL) and rubber compound (XLR) which surrounds the connectors.
Most commonly found is the XLR 3-pin, which is used universally for professional microphones and as a connector 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. The XLR5 connector is the standard for DMX512 digital lighting control and also is used for dual element microphones and dual channel intercom headsets. XLR6 is widely used as a connection for dual channel intercom belt-packs.
There are several now obselete configurations with additonal pins including the XLR-LNE mains power connector, which was identified by its red insulation and shrouded pins, and has now been replace by the Neutrik PowerCon connector. Until recently, XLR3 plugs 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 . Ultimately, this application turned out to be potentially harmful to equipment and the XLR has been replaced by the Neutrik Speakon connector.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. 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.
Finally, the male XLRM connector is used for output and the female XLRF connector is used for input. So, for example vocal microphones will have a XLRM plug.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 in XLR cables varies greatly depending on the manufacturer, but for professional use please 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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