Connectors, XLR

Originally manufacturer by Cannon, and still called "Cannon plugs" by some old-timers.

What does XLR stand for? According to wikipedia:

Originally the "Cannon X" series, subsequent versions added a Latch ("Cannon XL") and then a Rubber compound surrounding the contacts, which led to the abbreviation XLR.[1]

Today, Switchcraft and Neutrik are the two largest manufacturers. Pomona is often a less expensive brand, and there are a number of lesser quality products available.

Audio
3-pin XLR connectors are used to connect various pieces of audio equipment. These devices can include mixers, microphones, power amplifiers, self-powered loudspeakers, Compressors/limiter/gates, effects processors and other processing equipment. 3-pin XLR connectors are often used on multi-pair Snakes. Audio snakes use a large multi-core cable, which is made up of many smaller shielded pair microphone cables. Input connectors are typically female, while outputs are male. A snake may have a stage box (or connector panel) at one end, and a fanout at the other. In recording situations and installations it is not uncommon to see snakes that have fanouts on both ends.

Prior to the development of Speakon connector, 3 pin XLR was widely used for connection of speakers to amplifiers. Speaker cables were conventionally wired with female connectors each end to help differentiate them from shielded cable. Interesting results when amplifer accidentally plugged into microphone led to decline of the connector's use to Speakon.

Other Uses
DMX cable also uses an XLR style connector, however, it contains 5 pins. Often, other devices, such as hazers, smoke machines, and occasionally lighting equipment will use 3 pin XLR for control.
4-pin XLR connectors are often used in conjunction with DMX controlled power supplies to supply power and control signal to devices such as Color Scrollers, DMX Gobo Rotators, DMX Irises, and other 4-pin DMX accessories. 4-pin XLR is also very common when used in work lights for equipment, such as Littlites (gooseneck lamps). 4 pin XLR can also be used for carrying low voltage power, conventionally with - on pin 1 and + on pin 4.
Even rarer are 6pin and 7pin XLR connectors.

Note there are two different pin configurations of 6pin.

Originally Posted by derekleffew

Be aware there are two different XLR-6 pin configurations--one symmetrical and one offset.
from Neutrik - Frequently Asked Questions :

Quote:
Why does my 6-pin XLR not fit into the Neutrik 6-pin XLR?
Currently there are two configurations of conventional 6 pin XLRs. The NEUTRIK 6 pin XLR meets the industry standard according IEC 61076-2-103. Nevertheless NEUTRIK offers both types of 6 pin configurations. The standard NEUTRIK 6 pin has black insert - the insert of the non-standard configuration is gray.
The difference in the part #s is the addition of an “S” – for example:
Standard 6 pin male XLR cable connector –nickel housing/silver contacts = NC6MX
Same part with non-standard pin configuration = NC6MXS

[Edit: The black insert is the non-symmetrical layout. For the ETC RFU, you'd want the gray insert for the "5pin with an extra pin in the center." So, according to Neutrik at least, the symmetric is the non-standard.][/quote]

Below are Switchcraft part numbers for the most common connectors, but any of a number of manufacturers can substitute. The most popular competitor is Neutrik, pronounced "NOYtrick."
D3M = panel mount, 3pin, male
D3F = panel mount, 3pin, female
A3M = inline, 3pin, male
A3F = inline, 3pin, female
A4M = inline, 4pin, male
A4F = inline, 4pin, female
A5M = inline, 5pin, male (DMX-512A approved/required)
A5F = inline, 5pin, female (DMX-512A approved/required)

# of Pins and Uses
2pin:
Very rarely used to carry power from amplifiers to loudspeakers
Sometimes used to carry 6-24 VDC to power electronic devices

3pin:
The most common audio mic- and line-level connector.
Clear-Com type intercom systems.
Also used to provide power for some consoles' Littlite.
Used by lesser automated lighting fixtures and smoke machines to carry DMX or proprietary control data.
Once used for as standard connector between amplifier and speaker.

4pin:
Intercom headset connectors.
As color scroller, gobo rotator and other lighting gadgets' power and data connectors.
Also used to provide power for some consoles' Littlite.
Also used in low voltage DC power.

5pin:
Most common use (and the only connector approved for) transmission of DMX-512A-2008.
Intercom stereo headset connectors.
Stereo microphones.
Some analog control systems having one common and four analog outputs.

6pin:
(Note that there are TWO non-compatible pin configurations of 6pin connectors. See Why does my 6-pin XLR not fit into the Neutrik 6[pin XLR? from Neutrik's site for explanation/information.)
Some two-channel intercom systems
ETC wired RFUs
ETCLink protocol
Element Labs Versatube signal and control
Used with rigging's weight-sensing load cells

7pin:
Some analog control systems having one common and six analog outputs.