Glossary of terms


Amps The unit of measurement for electrical current. In lighting terms, each lantern requires a certain number of amps which must not exceed the total amps available.

Bar Metal bar from which lanterns are hung, sometimes fitted with sockets for providing power to the lanterns.

Barndoors Adjustable plates attached to the front of a fresnel lantern to roughly control the light beam.

Batten Lantern consisting of several flood lanterns joined together horizontally.

Birdie Slang term for a ‘Par 16’ lantern, which is a low-voltage miniature Parcan.

Boom Vertical bar, typically used behind the proscenium arch to give side lighting positions.

Colour frame Holder for a colour gel on a lantern.

Dimmer Device for controlling the amount of electricity sent to the lanterns.

Followspot Profile spotlight with special features to allow an operator to direct the light as required.

F.O.H. Abbreviation of ‘front-of-house’. In lighting terms, meaning any lighting position above the auditorium.

Gate The optical centre of a profile lantern, where the shutters are positioned and where an iris or gobo can be inserted.

Gel Coloured plastic film placed in front of a lantern to colour the light. Known as ‘gel’ because it was originally made from gelatine.

Gobo Small metal cut-out shape, used to project an image.

Grelco Brand name for a small adapter allowing 2 plugs to be ‘paired’ into 1 socket.

Hook clamp Clamp for attaching a lantern to a bar.

House lights The permanent lights over the auditorium for lighting the audience before and after the show.

Iris Small adjustable device for narrowing the beam diameter in a profile lantern.

Lamp Theatre name for a lightbulb.

Lantern Generic term for any stage light unit.

Lens Glass optical device that affects the light beam in various ways depending on type.

Multicore Cable with several circuits inside, typically 6 ways – for saving on cable runs.

Patch panel Rows of plugs and sockets for connecting the lighting sockets to the dimmers.

Reflector Device in all lanterns for reflecting the light forwards from behind the lamp.

Rig Term used to describe all the lanterns as set for a production (e.g. ‘the lighting rig’). Also, rigging is when all the lanterns are hung in position.

Safety bond Metal wire which is looped around the lantern and the bar to stop the lantern falling if the hook clamp fails.

Safety chain As above, but a chain instead of wire.

Shutters Blades in a profile lantern which alter the shape of the beam.

Socapex Type of multicore cable. (See ‘multicore’).

Spider Group of plugs or sockets which connect to a multicore cable.

Stand Free standing unit on which one or more lanterns may be mounted.

Tails See ‘spider’.

Throw The distance from the lantern to the object being lit.

T.R.S. Abbreviation of ‘toughened rubber sheath’, but actually slang to describe extension cables (which are made out of toughened rubber sheath…)

Wattage The amount of power needed to run the lamp, measured in ‘watts’.

Yoke Bracket which supports the lantern from the hook clamp.


AFL After Fade listen; a system used within mixing consoles to allow specific signals to be monitored at the level set by their fader of level control knob. Aux. sends are generally monitored AFL rather than PFL.

Analogue Circuitry that uses a continually changing voltage or current to represent a signal. Compare with "Digital"

Attenuation Reduction in a signal level; the opposite of gain. See page *.

Auxiliary mix A mix which is subordinate to the main mix. Facilities provided for this mix are more sparse (e.g. rotary instead of linear faders) and it is often used to feed effects units or foldback speakers. See page *.

Balance A control which varies the balance between the level of the channel of a stereo signal, usually by attenuating one channel (e.g. if the control is turned to the left, the right channel is attenuated.) This changes the perceived placing of the stereo signal within the stereo image. Compare with Pan.

Balanced A sound connection where the signal is split into two halves, one of which is inverted, to reduce interference. See page *.

Band A portion of the frequency spectrum. The term is often used to refer to a frequency range on an equaliser.

Bandwidth The difference between the lowest and the highest frequencies which may be reproduced by a recording medium. OR The difference between the lowest and the highest frequencies which are affected by a filter.

BNC Bayonet connector

Cans The ring intercom system used for backstage communications during a show.

Cardioid Meaning ‘heart-shaped’; describes a microphone polar pattern. See page *.

Centre Stage The centre of the stage widthways.

Chorus An effect where a signal is delayed and added to the original sound to add "fullness".

Cold Signal The out of phase component of a balanced audio signal. See page *.

Compressor A dynamic processor. See page *.

Condenser A type of microphone. See page *.

Crosstalk Interference between adjacent channels. See page *.

 Cue (as a noun) a single, identifiable action required of the sound operator, or sound material relating to this action.

  • (as a verb) to instruct the sound operator to perform a predefined action, or to prepare sound material for this occurrence.

e.g: "The sound operator cued (prepared) the cassette to its cue-point (the point from which the predefined action starts) ready for the Stage Manager to cue him (tell him to go) with his cue (a predefined action.)" See page *.

dB A decibel.

De-essing Removing the sibilant components of a vocal signal. This is done using a compressor with an equaliser highlighting the sibilant frequencies (6 - 10 kHz) inserted into the sidechain.

DI Direct Injection (Box).

DIN Deutsche Industrie Normal. A set of German standards. Often used to refer to multipole plugs conforming to these standards.

Downstage The front of the stage.

Drain wire A bare metal wire in contact with the screen along the length of a cable, used for terminating the screen.

Dry Signal A signal which has not been processed. .

Dynamic A type of microphone.

Dynamics Changes in the "volume" or level of a signal. Dynamic processors alter the volume of a signal to modify the dynamic range (the range over which the volume varies.)

Effect A device which is used to modify a proportion of an audio signal which is then fed back into the main mix c.f. Processor.)

EQ Equalisation.

Equaliser A device which allows narrow bands of frequency in an audio signal to be boosted or cut as desired, usually to correct for distortion, to remove feedback, or to enhance the sound.

Expander A dynamic processor.

Feedback A whine caused by sound "chasing itself" around a system.

Figure-of-Eight A microphone polar pattern.

Flange An effect where the phase of a signal is slightly modified and then added to the original signal, leading to interplay between the two signals.

Float A microphone rigged on the front of stage to pick up stage dialogue.

Fly Tower The tower above the stage, into which scenery and lighting may be raised ("flown.")

FoH See Front of House.

Foldback A set of speakers (and the system which drives them) so that performers can hear themselves and other relevant parts of a performance.

Forestage The part of the stage in front of the Proscenium Arch. This covers the orchestra pit, and can be flat, stepped (by inserting different segments), or removed entirely.

Frequency The number of times that something happens in a given period of time. Often used to count the pulses of air in a sound wave, thus quantifying the pitch of a musical note.

 Front of House The "public" area of the theatre, including the public corridors, toilets, box office foyer, bar, and the auditorium up to the Proscenium Arch.

FX Effects.

Gaffer tape A strong cloth-backed tape which sticks anything to anything. Usually available in black, white and silver. Sometimes referred to as duct tape.

Gain Amplification; the opposite of attenuation.

Gate A dynamic processor. .

Grid The arrangement of flown bars above stage.

Group A sub-mix on a large mixer.

Headroom The difference between the operating level and the maximum level of a recording media.

Hot Signal The in-phase component of a balanced audio signal.

Howlround Feedback.

High pass filter (HPF): A filter which attenuates frequencies below its cutoff frequency.

Hypercardioid A microphone polar pattern.

Hz Hertz. A measure of frequency.

IEC Internationale Electrotechnique Commission. An organisation which has set international standards covering connectors and pre-equalisation standards (see page *) amongst other things.

 Ladder A device to help people reach high things! OR An arrangement of lighting bars which resembles a device to help people reach high things (often referring to two lighting ladders permanently fixed to the side walls of the auditorium close to the stage.)

Lavalier A microphone worn on clothing (e.g. in a tieclip) or on the body. Often used as radio microphones.

Limiter A dynamic processor.

LX Lighting.

LX tape PVC tape coated with an adequate, but not over-powerful adhesive. Useful for securing and coiling cables, labelling and insulating.

Mask To conceal something from the audience. (e.g. if a stage microphone cannot be seen from the auditorium, it is said to be masked.)

MIDI Musical Instrument Digital Interface. See page *.

Midstage The centre of the stage depthways.

Mix A collection of audio input signals, in the correct proportion to form a useful output.

 Monitor A speaker or set of speakers used to listen to a signal for reference purposes rather than to use it for its intended purpose.

Mono Monophonic. An audio system providing a single channel of sound, and hence no directional information.

Near field Some people prefer the term 'close field', to describe a loudspeaker system designed to be used close to the listener. The advantage is that the listener hears more of the direct sound from the speakers and less of the reflected sound from the room.

 Notching (as a verb) filtering out a narrow band of frequencies (e.g. to remove feedback.)

 (as an adjective) a filter specially designed to filter out a narrow band of frequencies with a high Q factor and an adjustable centre frequency.

Octave A musical interval which corresponds to a doubling of frequency.

OFC Oxygen Free Copper.

Omni (-directional) A microphone polar pattern.

Pad A device for reducing the level of a signal. This could either be an electrical pad (e.g. an adapter containing an electrical network to reduce a voltage level, or a control on a mixing desk or microphone to switch in such a circuit) or a mechanical pad (e.g. is attached to a microphone to restrict the sound pressure levels reaching the diaphragm).

Pan A control for placing a mono signal within a stereo image. Compare with Balance.

Parametric EQ Equalisation where the centre frequency of the EQ band can be adjusted. The Q factor (width of the band) is usually fixed, but can be adjusted on the more expensive units.

 Patch (as a verb) to allocate the correspondence between inputs and outputs, usually using a patchbay.

  • (as a noun) a correspondence between inputs and outputs, usually on a patchbay or in a synthesiser.

Peak The maximum level of a signal or the maximum permissible level to which an input may be driven. A signal exceeding this level is said to be peaking.

Peak Limiter A dynamic processor.

PFL Pre-fade listen.

Phantom Power A method of sending power down a microphone cable.

Phase The timing difference between two electrical waveforms expressed in degrees where 360 degrees corresponds to a delay of exactly one cycle.

Pit The orchestra pit. The area underneath the forestage. The forestage can be removed to create an open pit, or left in place to create a closed pit.

Polar Pattern The correlation between where a sound source is and how much of it a microphone picks up. See page *.

Popshield A fine mesh supported by a fixed ring , which is placed between a vocalist’s mouth and a microphone. The mesh diffuses any large blasts of air (e.g. from "p" and "b" sounds) and so reduces "popping".

Processor A device which is used to modify an audio signal in its entirety (c.f. Effect.)


Pros(cenium) arch The arch which separates the forestage (in the auditorium) from the main part of the stage (under the fly tower.)

PZM Pressure Zone Microphone.

Q factor A measure of how wide the frequency range is over which an analogue filter takes effect. A high Q factor gives a filter which affects a narrow range of frequencies, useful for removing feedback without unduly affecting the wanted portion of the sound. A low Q factor gives a broad filter useful for "colouring" the sound.

Release The time taken for a level or gain to return to normal.

Repatch To alter the patching between shows or during a show. See page *.

Rifle A microphone polar pattern. .

Screen A conductive layer to provided to exclude interference, and often to provide a return path for a signal.

Shotgun A microphone polar pattern.

Show Relay A system by which the action on stage can be monitored in other areas. This can refer to audio and video systems.

Sibilant A whistling or hissing sound. Often refers to the hissing effect when "s", "sh" and "z" sounds are picked up by a microphone at close range.

Sidechain The signal in a compressor, expander, limiter or gate which is monitored to determine the level of attenuation to be applied to the main signal. By default, the sidechain signal is the same as the main signal, but for specialist work such as de-essing or "ducking", a modified (e.g. equalised) or totally separate signal may be used.

SPL Sound Pressure Level.

Stage Box A box fitted with many audio connections on the end of a multicore cable.

Stereo Stereophonic. An audio system providing two channels of sound, hence giving the listener spatial information in one dimension (usually "left / right".) Most modern recordings are in stereo.

Suspension Microphone suspension.

Transient A unique pulse, often caused by mains interference. See page *.

UHF Ultra High Frequency: the part of the radio spectrum between 0.3 and 3 GHz. Some radio mics operate in this band; see page *.

Unbalanced A sound connection consisting of a single signal conductor, where the signal is returned along the screen conductor. Compare with balanced.

Upstage The rear of the stage.

VHF Very High Frequency: the part of the radio spectrum between 30 and 300 MHz. Many radio mics operate in this band;

Watt A unit which measures power.

Wet Signal A signal which has been processed by an effects unit. See page *.

White noise A random signal with an energy distribution that produces the same amount of noise power per Hz.

Windshield A close-fitting foam cover which protects the head of a microphone from wind, thereby reducing whistling noises. Larger rifle mics are sometimes fitted with windshields constructed from a fleece material, which gives protection against stringer winds.

XLR A balanced audio connector.