AV Glossary

Throughout this website we use some technical Audio Visual and Event equipment abbreviations and terminology, which may or may not be a little confusing at first. These AV terms with a brief explaination have been listed below. 

ace-bros-av-glossary-event-equipment-hire-londonMany terms have other meanings, nuances (or very in depth technical explanations), which we have avoided to a certain degree, in order to keep the term descriptions and definitions concise. This should get you started and able to identify the most essential words and phrases commonly used in our delightful domain of audio visual, entertainment and event equipment.

As your brothers in AV Hire, we are here to help, so do not hesitate in coming forward with your AV and event requirements and allow us to guide you, through the wonderful world of event equipment hire possibilities.


AV – abbreviation for Audio Visual


Backline – The backline equipment is typically placed in a row across the back of the stage behind the relevant musician, hence the name


Combo – A single item of equipment which combines the head (which holds the amplifier) and the speaker cabinet

Condenser Microphone – A microphone is which sound is converted to an electrical signal by causing the vibration of one of the plates of a charged capacitor, whilst the other plate remains fixed


D.I – Direct Injection

D.I Boxes – Allows unbalanced signal source to be fed to a balanced low impedance input

DMX (DMX-512) – A standardised digital control system interface for stage lighting and similar equipment

Dry Hire – Hiring of individual items of equipment on a ‘self-assemble and operate’ basis

Dynamic Microphone – A microphone in which sound is converted to an electrical signal by causing the vibration of a conductor in a magnetic field, so inducing a voltage in the conductor


Earth lift, Ground lift – A switch found on equipment which provides the facility to disconnect the equipment’s signal earth from its safety earth (for Class I mains powered equipment) or disconnect the signal earth connection between other items of equipment in order to avoid an earth loop (for Class II mains and non-mains powered equipment)


F.O.H – Front of House, the area forward of the stage. Used in reference to producing sound for that area ‘F.O.H Speakers’

FX – An abbreviation for Effects


Gig – slang for live event

Gobo – is a metal plate in the shape of a particular image that is to be projected by a lantern. It is inserted into the lantern at the focal point of the light beam, i.e. it ‘goes before the optics’, giving rise to the abbreviation ‘gobo’


Hz – An abbreviation for ‘hertz’ – the unit of frequency. The number of Hz is the number of complete cycles of change taking place per second


kHz – A unit of frequency. One kHz is 1,000 Hz

kW – A unit of power. One kW is 1000 Watts


LED – Light-emitting-diode, a semiconductor device that emits light when a current is passed through it


MHz – A unit of frequency, one MHz is 1,000,000 Hz, or 1,000 kHz

Mic/Mike – An abbreviation for microphone


Outboard – Describes a facility not provided within the item of equipment in question, but rather provided by an external item


PA System – Originally an abbreviation for ‘Public Address System’, however in general usage the term PA now refers to any system whose primary purpose is to make sound louder or to distribute sound over a wide area.

Par Can – A ‘parabolic aluminised reflector’ lantern consisting only of a lamp and its lamp-holder in a metal can

Passive – Generally describes something that operates without the need for any source of electrical power. The opposite of passive is active

PAT – Portable appliance test is a formal inspection and test procedure to verify the safety of in-service electrical equipment

Phantom Power – An arrangement whereby DC power is supplied through a balanced interconnection between equipment without disturbing the signal being carried by that connection. It is usually used to allow a mixer to supply the power required by condenser microphones and active DI boxes


RGB – An abbreviation for ‘red, green and blue’, the three additive primary colours that are combined in the necessary proportions to create any required colour

RGBA – An abbreviation for ‘red, green, blue and amber’

RGBW – An abbreviation for ‘red, green, blue and white’

RMS Power – An abbreviation for ‘Root-mean-square’, however it is a slight misnomer as this abbreviation in relation to audio equipment refers to the average value of power


Solid State – Describes equipment whose active components are all semiconductors, i.e. equipment which contains no valves


UHF – An abbreviation for ‘ultra-high frequency’. Refers to radio frequencies in the range 300 MHz to 1000 MHz, used by many types of radio microphone and instrument systems


W – Watts, a unit of power. One watt represents a transfer of energy at the rate of one joule per second

Wet Hire – Hiring of equipment or complete systems that includes the personnel to assemble and operate it

WXGA – An abbreviation for ‘wide extended graphics adaptor’


XGA – An abbreviation for ‘extended graphics adaptor’. A standard interface for the connection of display equipment (such as monitors and projectors) to computers

XLR – A type of connector commonly used for professional and semi-professional audio interconnections

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