The glossary pages provide definitions for over 2680 PA-related terms. If you can't find the term you are looking for, or would like any of the existing definitions to be expanded, please email me − likewise of course if you find any errors in the links etc. Use of this information is conditional upon acceptance of the Disclaimer on the PAforMusic home page.
In the list below, the most commonly looked-up terms are in bold, lighting-specific terms are in pink, and video-specific terms are in orange.
The definitions for these terms are given on the assumption of their use in the context of PA systems; many of the terms have more general meanings when used in a wider context. Where more than one definition is given for a term, the definitions are numbered (1), (2) etc.
Some of the definitions themselves use terms (such as "signal") in a specific way − most of these are links (just the first time they are used, in each definition), so just click on them to see the meanings that are intended.
The most common uses of the 3-pole XLR for audio are in balanced interconnections from stage sources (mostly microphones and DI boxes) to mixers − see the diagram − and in balanced feeds from mixers to graphic equalisers, active crossovers and power amplifiers. However, an interconnection should not be assumed to be balanced solely because it uses an XLR connector. Pin 2 is generally used for the hot leg of the balanced pair, and pin 3 for the cold leg (though some early American equipment had this reversed). Caution: Note that balanced analogue interconnections may carry phantom power, which may damage equipment not intended to handle it.
In all such audio interconnections, the standard arrangement is that cables are fitted with a male connector at one end and a female connector at the other; this enables cables to be readily extended by coupling two or more of them end-to-end. The signal direction is from the female end of the cable to the male end (so, the pins 'point' in the direction of signal flow).
The 4-pole XLR is mostly used for carrying DC power. A common pin allocation is for pin 1 to be 0 V (because this makes contact first), pin 2 to be +12 V, pin 3 to be +24 V and pin 4 to be +48 V, but this should not be assumed. On many cameras, pin 1 is 0 V and pin 4 +12 V, but again this should not be assumed. It is strongly advised to always use only the manufacturer's recommended power supply unit.
The 5-pole version is occasionally used for stereo interconnections, and is also used for the control cables in DMX stage lighting applications. However, note that in the DMX application the signal direction is from the male end of the cable to the female end − this is the reverse of the gender standard used in audio applications.
In some DMX applications 3-pole XLRs (just the same as audio ones) are used instead of 5-pole types; this is possible because nearly all DMX applications require only 3 wires. In these cases, the same gender standard applies as for 5-pole DMX interconnections (i.e. the reverse of the audio standard).
The name 'XLR' is believed by many to be an abbreviation for 'extra low resistance', though it is more likely to be just an identifying type code made up by the original manufacturers. Nevertheless, it may be used as a mnemonic for the usual pin-allocation when making balanced connections to the terminals of the 3-pole type: pin 1 = X = Earth, pin 2 = L = Live (hot), pin 3 = R = Return (cold). Also known as a 'Cannon' (frequently mis-spelled 'Canon'), as one of the most popular makes is ITT-Cannon. See also Neutrik, TA4 and Pin 1 problem.
a pictorial comparison of stereo microphone techniques.
There are no more definitions on this page. (The space below is to facilitate linking to the last few terms above.)
This page last updated 21-Jan-2019.