XLR connector
Encyclopedia
Electrical connector
An electrical connector is an electro-mechanical device for joining electrical circuits as an interface using a mechanical assembly. The connection may be temporary, as for portable equipment, require a tool for assembly and removal, or serve as a permanent electrical joint between two wires or...
, primarily found on professional audio
Professional audio
Professional audio, also 'pro audio', refers to both an activity and a type of audio equipment. Typically it encompasses the production or reproduction of sound for an audience, by individuals who do such work as an occupation like live event support, using sound reinforcement systems designed for...
, video, and stage lighting equipment. The connectors are circular in design and have between 3 and 7 pins. They are most commonly associated with audio interconnection, but are also used for lighting control, low-voltage power supplies, and other applications.
XLR connectors are available from a number of manufacturers and are covered by an international standard for dimensions, IEC 61076-2-103. They are superficially similar to the older and smaller DIN connector
DIN connector
A DIN connector is a connector that was originally standardized by the , the German national standards organization. There are DIN standards for a large number of different connectors, therefore the term "DIN connector" alone does not unambiguously identify any particular type of connector unless...
range, but are not physically compatible with them.
History and manufacturers
Los Angeles, California
Los Angeles , with a population at the 2010 United States Census of 3,792,621, is the most populous city in California, USA and the second most populous in the United States, after New York City. It has an area of , and is located in Southern California...
(now part of ITT Corporation
ITT Corporation
ITT Corporation is a global diversified manufacturing company based in the United States. ITT participates in global markets including water and fluids management, defense and security, and motion and flow control...
), and for this reason it was sometimes colloquially known as a cannon plug or cannon connector, though this term has since completely fallen out of usage in the industry. Originally manufactured as the Cannon X series, subsequent versions added a latch (Cannon XL) and then surrounded the female contacts with a resilient polychloroprene
Neoprene
Neoprene or polychloroprene is a family of synthetic rubbers that are produced by polymerization of chloroprene. Neoprene in general has good chemical stability, and maintains flexibility over a wide temperature range...
, which resulted in the part number prefix XLR.
The Switchcraft
Switchcraft
Switchcraft, Inc. was established in 1946 to manufacture jacks, plugs, and switches. The original plant was located on West Diversey Street in Chicago. The company moved to a larger facility at 1328 N. Halsted Street in 1948 and in 1958, the operation moved to 5555 N...
corporation later started manufacturing compatible connectors, followed by Neutrik
Neutrik
Neutrik is a Liechtenstein company which manufactures connectors which are used in audio and video recording studios and concert sound systems. Their product range includes XLR-type connectors, speakON connectors, powerCON connectors, patch bays, BNC connectors and special connectors for industrial...
. Neutrik made a number of improvements to the connector and their second-generation design (known as the X-series) had just four parts for the cable connector and eliminated the small screws used by both Cannon and Switchcraft, which were prone to working loose, falling out, and becoming lost. These improvements made Neutrik the most popular brand of XLR connector.
Unbranded XLRs are also made by far-east manufacturers. Originally these were copies of the Cannon or Switchcraft designs, but in recent years the Neutrik designs have also been copied.
Design
XLR connectors are available in male and female versions in both cable and chassis mounting designs, a total of four styles. This is slightly unusual as many other connector designs omit one of the styles (typically a chassis mounting male connector).The female XLR connectors are designed to first connect pin 1 (the earth pin), before the other pins make contact, when a male XLR connector is inserted. With the ground connection established before the signal lines are connected, the insertion (and removal) of XLR connectors in live equipment is possible without picking up external signals (as it usually happens with, for example, RCA connectors).
The number of pins varies from three to seven. XLR connectors from different manufacturers will intermate, with the exception of Switchcraft 6 pin models, which use a non-standard arrangement for the pins.
Three pin
Three pin XLR connectors are by far the most common style, and are an industry standard for balanced audioBalanced audio
Balanced audio is a method of interconnecting audio equipment using impedance-balanced lines. This type of connection is very important in sound recording and production because it allows for the use of long cables while reducing susceptibility to external noise.Balanced connections use...
signals. In previous years, they were also popular for loudspeaker connections, but they have been superseded by the Speakon connector
Speakon connector
The Speakon is a type of cable connector, originally manufactured by Neutrik, mostly used in professional audio systems for connecting loudspeakers to amplifiers. The same manufacturer produces another connector dubbed PowerCon, which is designed to carry mains power rather than audio signal...
in this application.
Rechargeable devices exist that use three-pin XLR connectors. These can be found on electric powered mobility wheelchair
Wheelchair
A wheelchair is a chair with wheels, designed to be a replacement for walking. The device comes in variations where it is propelled by motors or by the seated occupant turning the rear wheels by hand. Often there are handles behind the seat for someone else to do the pushing...
s and scooters. The connectors carry from 2 to 10 amps at 24 volts.
An obsolete use for three pin XLR connectors was for MIDI data on some Octave-Plateau synthesizers including the Voyetra-8
Voyetra-8
The Voyetra-8 is an eight voice polyphonic analog synthesizer. Released in 1982 by Octave-Plateau Electronics , it was one of the first analog programmable synthesizers to be rack-mountable and remains one of the most flexible digitally controlled analog...
.
Four pin
Four pin XLR connectors are used in a variety of applications.They are the standard connector intercom
Intercom
An intercom , talkback or doorphone is a stand-alone voice communications system for use within a building or small collection of buildings, functioning independently of the public telephone network. Intercoms are generally mounted permanently in buildings and vehicles...
headsets, such as systems made by ClearCom and Telex
Telex
Telex may refer to:* Telex , , a communications network** Teleprinter, the device used on the above network* Telex , a Belgian pop group...
. Two pins are used for the mono headphone signal and two pins for the unbalanced microphone signal.
Another common use is for DC power connections for professional film and video cameras and related equipment.
Other uses for the four pin XLR include some scrollers (colour changing devices for stage lighting), AMX
AMX192
AMX192 is an analog lighting communications protocol used to control stage lighting. It was developed by Strand Century in the late 1970s. Originally, AMX192 was only capable of controlling 192 discrete channels of lighting. Later, multiple AMX192 streams were supported by some lighting desks...
analog lighting control (now obsolete) and some pyrotechnic equipment.
Five pin
Five pin XLR connectors are the standard for DMX512 digital lighting control.Other common uses are for dual-element or stereo microphones (two balanced audio signals with a common ground) and stereo intercom headets (3 pins for the stereo headphone signal - left, right, and ground, and 2 pins for the unbalanced microphone signal).
Seven pin
Seven pin XLR connectors are used on several models of Le Maitre and Ultratec fog machines for remote control.An obsolete use for seven pin XLR connectors was analogue lighting control signals.
Obsolete patterns
The power Cannon (also called the XLR-LNE connector) had shrouded pins and red insulation, it was intended as a mains
Mains electricity
Mains is the general-purpose alternating current electric power supply. In the US, electric power is referred to by several names including household power, household electricity, powerline, domestic power, wall power, line power, AC power, city power, street power, and grid power...
power connector
Power connector
Power connector may refer to:* AC power plugs and sockets* Industrial power plug* DC connector* Blade connector, commonly found in cars for quick connection of wiring to electrical components* IEC 60309 , so-called "Commando" plug and socket...
, but has been superseded by the IEC 60320 series of connectors and increasingly, more recently, the PowerCon
PowerCon
The PowerCon is an electrical connector manufactured by Neutrik for connecting mains power to equipment in a small space. It looks and works similar to the Speakon with the line connector inserted in the chassis connector and twisted to make contact and lock...
connector developed by Neutrik
Neutrik
Neutrik is a Liechtenstein company which manufactures connectors which are used in audio and video recording studios and concert sound systems. Their product range includes XLR-type connectors, speakON connectors, powerCON connectors, patch bays, BNC connectors and special connectors for industrial...
.
The loudspeaker Cannon (known as a PDN connector) had blue or white insulation (depending on its gender
Gender of connectors and fasteners
In electrical and mechanical trades and manufacturing, each half of a pair of mating connectors or fasteners is conventionally assigned the designation male or female...
), was intended for connections between audio power amplifiers and loudspeaker
Loudspeaker
A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
s. These were a commercial failure and are now obsolete.
Technical usage information
This section contains more technical information relating the most common applications of XLR connectors.Three pin - audio
Electronic Industries Alliance
The Electronic Industries Alliance was a standards and trade organization composed as an alliance of trade associations for electronics manufacturers in the United States. They developed standards to ensure the equipment of different manufacturers was compatible and interchangeable...
Standard RS-297-A describes the use of the XLR3 for balanced audio
Balanced audio
Balanced audio is a method of interconnecting audio equipment using impedance-balanced lines. This type of connection is very important in sound recording and production because it allows for the use of long cables while reducing susceptibility to external noise.Balanced connections use...
signal level applications:
 |
|
| Pin | Function |
|---|---|
| 1 | Chassis ground Ground (electricity) In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth.... (cable shield) |
| 2 | Positive polarity terminal (hot) |
| 3 | Return terminal (cold) |
Prior to the introduction of this standard, the wiring of pins 2 and 3 varied. The pin 2 "hot" and pin 3 "cold" convention was typically used by European and Japanese equipment manufacturers, but American companies used pin 3 "hot" and pin 2 "cold". This caused problems when interconnecting equipment with unbalanced connections. The pin 3 "hot" convention is now obsolete but is still found on vintage equipment. Pin 1 has always been ground, and many connectors connect it internally to the connector shell or case.
Although covered in AES48-2005 and in AES54-3-xxxx, there is still some disagreement on the best way to handle the usage of pin 1 at both ends of a cable, particularly with respect to the cable shield, the connector's shell, signal ground, and a third cable conductor connected to pin 1, which may (or may not) be connected to the shield. The main controversy is whether the shell of the connector should be connected to pin 1 or the shield, or left floating. AES standards mentioned above recommend that shells of cable-mounted connectors should never be connected to pin 1 or the shield, because inadvertent contact of the shell with another grounded surface while in use can create unwanted current paths for fault current, potentially causing hum and other noise. On the other hand, equipment containing active circuitry should always have pin 1 connected to the conductive enclosure of the equipment as close as possible to the point where the signal enters the enclosure. The argument centers around the radio frequency shielding provided by the shell of the connector, which may be reduced if it is left floating. An alternative solution is to connect the shell to pin 1 and the shield through a small value capacitor, providing RF shielding but allowing very little audio-frequency current to flow. This capability can be built into a fixed jack or a cable terminated with XLR connectors.
The standard signal flow for audio is that the output of equipment is a male connector and the input is female. This is the opposite of many other connector standards which normally use female connectors for outputs, a convention influenced by the need to prevent accidental contact with dangerous voltages, for example power sockets. However, the voltages of audio signals are not hazardous and a male XLR is of simpler construction to the female and can easily be incorporated in the body of a microphone
Microphone
A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1877, Emile Berliner invented the first microphone used as a telephone voice transmitter...
.
To reflect the fact that equipment often requires an input on a jack or an XLR connector, Neutrik also offers several models of combination connector that accept both XLR and 0.25 in TS or TRS
TRS connector
A TRS connector is a common family of connector typically used for analog signals including audio. It is cylindrical in shape, typically with three contacts, although sometimes with two or four . It is also called an audio jack, phone jack, phone plug, and jack plug...
plugs.
Four pin - DC power
The most common standard is for pin 1 to be ground and pin 4 to be 12 volts (nominal), with pins 2 and 3 unused. This configuration is used on most professional video cameras and is also common on audio equipment designed for location use.There are other non-standard arrangements, particularly found on older equipment.
Five pin - DMX512
The 5 pin XLR is the standard connector for DMX512, the most common protocol for controlling professional lighting and related equipment. Whilst the DMX512 standard allows for two separate circuits (known as universes) to be carried over a single cable, the vast majority of equipment is only designed for a single universe and hence it is common practice to only use 3 of the 5 pins.Additional usage information
At one time XLR3 connectors were also used extensively on loudspeaker cables, as when first introduced they represented a new standard of ruggedness, and economic alternatives were not readily available. The convention was that a two-conductor loudspeaker cable had XLR3 female connectors on both ends, to distinguish it from a three-conductor shielded signal level cable, which has an XLR3 female at one end and an XLR3 male at the other. Either pin 2 or 3 was live, depending on the manufacturer, with pin 1 always the 'earthy' return. This usage is now both obsolete and dangerous to equipment but is still sometimes encountered, especially on older equipment. For example, some loudspeakers have a built-in XLR3M as an input connector. This use was superseded in professional audio applications by the Neutrik Speakon connectorSpeakon connector
The Speakon is a type of cable connector, originally manufactured by Neutrik, mostly used in professional audio systems for connecting loudspeakers to amplifiers. The same manufacturer produces another connector dubbed PowerCon, which is designed to carry mains power rather than audio signal...
.
Phantom power
Some microphones such as condenser microphones require power. An alternative to battery power is phantom power, which consists of direct current applied equally through the two signal lines of a balanced audio connector (in modern equipment, usually an XLR connector). The supply voltage is referenced to the ground pin of the connector (pin 1 of an XLR), which normally is connected to the cable shield or a ground wire in the cable or both. When phantom powering was introduced, one of its advantages was that the same type of balanced, shielded microphone cable that studios were already using for dynamic microphones could be used for condenser microphones as well, in contrast to vacuum-tube microphones, which required special, multi-conductor cables of various kinds.With phantom power, the supply voltage is effectively invisible to balanced microphones that do not use it: e.g., most dynamic microphones. A balanced signal consists only of the differences in voltage between two signal lines; phantom powering places the same DC voltage on both signal lines of a balanced connection. This is in marked contrast to another, slightly earlier method of powering known as parallel powering or T-powering (from the German term Tonaderspeisung), in which DC was overlaid directly onto the signal in differential mode. Connecting a dynamic microphone (especially a ribbon microphone
Ribbon microphone
A ribbon microphone is a type of dynamic microphone that uses a thin aluminum, duraluminum or nanofilm ribbon placed between the poles of a magnet to generate voltages by electromagnetic induction...
) to an input that had parallel powering enabled could very well damage the microphone severely, but this is not normally so with phantom powering unless the cables are defective or wired incorrectly.
XLD keyed variant
The XLD connector is a keyed variant of the XLR connector. The keys prevent accidental mixing of XLR and XLD connectors. XLD plugs and sockets are used mostly in professional audioSound recording and reproduction
Sound recording and reproduction is an electrical or mechanical inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording...
and video electronics cabling applications.
The XLD connector is used with the Audio Engineering Society
Audio Engineering Society
Established in 1948, the Audio Engineering Society draws its membership from amongst engineers, scientists, other individuals with an interest or involvement in the professional audio industry. The membership largely comprises engineers developing devices or products for audio, and persons working...
AES42 digital microphone interface standard.
The connectors are similar to XLR but with an extra coding key and groove that allows control over the intermating of XLD plugs and XLR sockets. A connector with the coding key installed will not mate with a connector that does not have the matching groove. By suitably keying connectors, analog microphone can be protected from damage by the high current digital phantom power supply provided for digital microphones.