XLR connector
From Wikipedia, the free encyclopedia
The XLR connector is an electrical connector design. XLR plugs and sockets are used mostly in professional audio and video electronics cabling applications, for microphones and line level signals. Home audio and video electronics normally use RCA connectors for line level signals generated by a preamplifier. Phone plugs are also used for microphones in home and computer applications.
In reference to its original manufacturer, James H. Cannon, founder of Cannon Electric in Los Angeles, California (now part of ITT Corporation), the connector is colloquially known as a cannon plug or cannon connector. 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] Many companies now make XLRs. The initials "XLR" have nothing to do with the pinout of the connector. XLR connectors can have other numbers of pins besides three.
They are superficially similar to the older and smaller DIN connector range, but are not physically compatible with them.
Contents |
[edit] Patterns of XLR connector
The most common is the three-pin XLR3, used almost universally as a balanced audio connector for high quality microphones and connections between equipment. XLR3 was also used to transmit MIDI data on some Octave-Plateau synthesizers including the Voyetra-8. XLR4 (with four pins) is used for ClearCom and Telex intercom headsets and handsets, DC power connections for professional film and video cameras and older versions of AMX analog lighting control. XLR5 is the standard connector for DMX512 digital lighting control and is also used for dual-element microphones and dual-channel intercom headsets. XLR6 is used for dual channel intercom beltpacks.
Many other types exist, with various pin numbers. Most notable are two now obsolete three-pin patterns manufactured by ITT Cannon. The power Cannon (also called the XLR-LNE connector) had shrouded pins and red insulation, it was intended as a mains power connector, but has been superseded by the IEC mains connector and increasingly, more recently, the PowerCon connector developed by Neutrik.
The loudspeaker Cannon had blue or white insulation (depending on its gender), was intended for connections between audio power amplifiers and loudspeakers. 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[citation needed] was that a two-conductor loudspeaker cable had XLR3F connectors on both ends, to distinguish it from a three-conductor shielded signal level cable which has an XLR3F at one end and an XLR3M 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 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).
Lighting control for entertainment applications is widely connected using five pin XLRs. While only three pins are used to carry the DMX512 signal, the design allows expansion with the remaining two pins considered for use with Remote Device Management (RDM) and Architecture for Control Networks (ACN) and also prevents users from confusing lighting with common XLR3 audio cables. Unfortunately, five pin XLRs still allow the use of lower-grade (non-110 Ohm) microphone cable for transmission of signals. Some manufacturers of DJ lighting and professional lighting are still using three-pin connectors as their standard. Manufacturers such as Leviton and Lightronics have even established new protocols not compatible with DMX512 that use three pin XLR to control lighting devices (primarily dimmers made by the same manufacturer).
Rechargeable devices exist that use three-pin XLR connectors. These can be found on electric powered mobility wheelchairs and scooters. The connectors carry from 2 to 10 amps at 24 volts.
 XLR-LNE two-pin male and female connectors, originally used for mains power connections. Note that the panel connector is shrouded for safety reasons. |
 Male and female XLR4 panel connectors |
 Female XLR5 panel connector |
 Female XLR6 panel connector |
[edit] XLR3 connectors
EIA Standard RS-297-A describes the use of the XLR3 for balanced audio signal level applications:
 |
|
| Pin | Function |
|---|---|
| 1 | Chassis ground (cable shield) |
| 2 | positive polarity terminal ("hot") |
| 3 | return terminal[2] ("cold") |
- When looking at the 'holes' of a female connector, the top left hole is 2, top right is 1, and bottom is 3.
- When looking at the pins of a male connector, the top left pin is 1, top right is 2, and bottom is 3.
Some audio equipment manufacturers reverse the use of pin 2 (properly the normal input) and pin 3 (inverting input). This reflects their own previous usage before any standard existed. Pin 1 is always ground, and many connectors connect it internally to the connector shell or case.
Although covered in AES48-2005 and in AES54-3-xxxx, it is worth noting that there is 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 wire connected to pin 1 — which may (or may not) be connected to the shield.
An XLR3M (male) connector is used for an output and an XLR3F (female) for an input. Thus a microphone will have a built-in XLR3M connector, and signal cables such as microphone cables will each have an XLR3F at one end and an XLR3M at the other. At the stage box end of a multicore cable, the inputs to the mixing desk will be XLR3F connectors, while the returns to the stage will be XLR3M connectors. Similarly, on a mixing desk, the microphone inputs will be XLR3F connectors, and any balanced outputs XLR3M connectors.
Neutrik also offers several models of "combo" jacks that accept both XLR and 1/4" TS or TRS plugs.
[edit] Mnemonics
There are several mnemonics for remembering the pinouts and wire colors of an XLR connection. One involves writing the numbers 1, 2, and 3, followed by the letters X, L, and R, and making a connection between L, "line", and R, "return":
- X [External or Ground or Shield]
- L [Line or Live]
- R [Return]
For cabling with shield, red, and black leads, "solid rocket booster":
- Solid [Shield]
- Rocket [Red]
- Booster [Black]
For cabling with ground/shield/green, white, and black leads, "George Washington Bridge":
- George [Ground or Green]
- Washington [White]
- Bridge [Black]
[edit] 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) 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.
[edit] Digital XLR
 |
This section is written like an advertisement. Please help rewrite this section from a neutral point of view. |
XLR connectors have been developed to give greater RF rejection. Two models by Neutrik (an industry standard manufacturer) have been released.
The EMC Series is a specifically designed version of the XX series to give enhanced RF screening for critical applications in live performance and recording where there are particular problems with radio transmission. The design guarantees a continuous RF shield connection from the cable to the chassis connector housing via a circular capacitor around the cable shield. The circular capacitors act as high-pass filter with a cut-off frequency around 10 MHz. An EMI suppression ferrite bead with 24 Ohm at 1 MHz between pin 1 and the cable screen provides a low-pass filter for improved RF rejection.
The XCC cable connector Series with circumferential shield contact provides excellent RF-protection to transmit digital audio signals most efficient and reliable. This XLR features a coaxial ground spring and a coaxial hex crimp ferrule at the cable entrance for proper and reliable transition of the shield to the shell. This is designed for the transmission of digital signals according AES42.
The idea is that digitisation could happen at the capsule instead of the snake head or console. The initial gain structure would then occur directly at the capsule, along other other measures such as filters. [3]
[edit] See also
[edit] References
- ^ Rane Professional Audio Reference description
- ^ Audio Engineering Society. AES14-1992 AES Standard for professional audio equipment—Application of connectors, part 1, XLR-type polarity and gender.
- ^ http://www.sounddevices.com/notes/recorders/788/aes-42-support-in-788t/ AES 42 Support @ Sound Devices
[edit] External links
- Audio usage
- Lighting control usage
- Making XLR cables
- A brief history of the XLR connector
- How to build Microphone Cable using XLR's
|
||||||||||||||||||||
