| Glossary of PA Terms - X
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The glossary pages provide definitions for over 2680 PA-related
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In the list below, the most commonly looked-up terms
are in bold, lighting-specific terms are in
and video-specific terms are in
X connector *
X curve *
XLRF, XLR-F *
XLRM, XLR-M *
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.
A sub-miniature coaxial
connector, sometimes used with
See also Microdot.
An abbreviation for 'extended curve'.
The response required of equipment to correctly process the
analogue optical sound track
specified for film audio by ISO
Bulletin 2969, now largely replaced by improved techniques.
Various forms are specified, to allow for the different
of large cinemas and smaller rooms.
Also called the 'wide-range curve'.
See also Academy curve.
An abbreviation for 'extended graphics adaptor'.
A standard interface
for the connection of display
equipment (such as monitors and projectors) to
computers. The standard gives a resolution of
1024 pixels horizontally
and 768 pixels vertically. The
See also VGA,
The most commonly encountered standards, their resolutions
and aspect ratios are tabled under the entry for
A type of connector
commonly used for professional and semi-professional
audio interconnections −
both analogue and
In PA work the
3-pole ('3-pin') type is used
extensively. In these applications the pole marked
"1" is generally used for the
signal earth connection.
The connector's design ensures that, when being
mated, pin 1 is the first
to make contact. The metallic outer
shell of the connector
may in theory be used as an additional earth
but in cable-mounted
connectors it is usually left unconnected
(rather than being linked to pin 1) in order to avoid
earth loops occurring by
incidental contact with other connector shells or
In chassis-mounted connectors
the shell is usually connected to signal earth.
Its most common audio uses are in
balanced interconnections from
stage sources (mostly microphones
and DI boxes) to
mixers − see the
and in balanced feeds from mixers to
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 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 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
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
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,
Pin 1 problem.
(3 pole) image
has female contacts.
An XLR socket, either
cable-mounted such as commonly
attaches to a microphone,
or else panel-mounted such as is commonly used as a
connector on mixers.
has male contacts.
An XLR plug, either
cable-mounted such as commonly attaches
to the microphone input
connectors of mixers,
or else panel-mounted such as is commonly used for the
connectors of mixers.
An abbreviation for
A pair of cardioid
microphones at the same
location, whose axes of
optimal pick-up are positioned at an
angle (typically between 90º and 135º).
This arrangement is used for stereo
recording or for live broadcast purposes (one microphone for the
left side, and one for the right), not for
Also called the 'coincident microphone' technique, because
sounds arrive at the two microphones at essentially the same time.
See also A-B pair,
NOS (1) and
a pictorial comparison of stereo microphone techniques.
(To view the image full-size in Explorer,
hover your mouse over the image and click on the green
'expand' icon that appears in the bottom right-hand
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This page last updated 25-Jan-2018.