Active (Speakers) Speakers which have an amplifier built in to them and do not require an external amplifier.
ADC Analogue to digital converter.
Amplifier (Amp) A device used to increase the volume (or amplitude) of signals, typically used to power passive speakers
Analogue Recording or storing information as electrical signals. Can suffer from interference from external sources such as mobile phones.
Balanced Signal A type of signal carried by cables with three conductor connectors that are not as susceptible to external noise.
Bit Depth The number of bits used to record each sample. The more bits used the greater dynamic range of the sound.
BPM Beats Per Minute - a measurement of the speed of music. Also a DJ show held annually at the Birmingham NEC!
Buzz An unwanted sound or noise caused by vibrations and electronic equipment.
Crossover (speakers) A device for splitting frequencies and sending them to the correct loud speaker and avoiding phase cancellation.
DAC Digital to analogue converter.
Decks Devices used for spinning Records or CDs. These will be hooked up to mixers and or speaker systems.
Digital An interference free means of recording or storing information as a series of the numbers 1 and 0.
DMX Digital Multiplexing. A communication protocol for lighting that allows lights to be controlled externally.
Effects (FX) A means of signal processing that affects sound and gives it a novel quality. Examples would be delay, reverb or echo.
Frequency Frequency is defined as a number of cycles of sound waves per second, we perceive this as pitch.
Ground A route for electrical signal to either go to earth, or as a reference point for voltages.
Ground Loop Isolator A device which isolates the shield ground of an audio signal, and helps to remove hum or buzz from a signal chain.
Haze Typically from more expensive machines, a type of vapour that is not as thick as normal smoke, but hangs in the air longer, and tends to fill a room for longer.
Hum An unwanted form of noise that typically occurs due to ground loops. Normally at 50Hz due to the frequency of mains power.
IEC Three pin removable power cable. Also sometimes known as a 'Kettle Lead'.
ILDA This connection is used for controlling laser systems. It is capable of sending lots of data including letters and graphics, enabling you to create a laser shows that includes custom projected messages and logos.
Impedance (Ohms) The amount of resistance in a speaker that relates to the amount of power it can take.
Input The signal going into a unit.
Interface A unit that helps to communicate between hardware and a computer.
Jack A cable connector that is used for a wide variety of audio equipment. Available in two sizes.
Jog Wheel In DJing, a jog wheel is a wheel simulating the function of a turntable (also called a vinyl deck), and can be used to control playback of a CD, DVD, MP3 player or computer. A jog wheel is used to navigate within a piece, to speed up or slow down to the music or to produce sound effects such as scratching.
Key An attribute of music which defines the starting note and general pitch range for a piece of music.
LED Light emitting diode. An alternative light source to traditional filament light bulb. Typically more energy efficient and longer lasting than traditional filament light bulbs.
LED Bar A series of LEDs that are arranged in a bar, typically used for uplighting.
Loop A section of audio that is repeated to form a loop of music.
MIDI Musical Instrument Digital Interface. A communication protocol that allows hardware and software to pass musical information.
Mix Finishing a song or track that seamlessly continues into the next track or song.
Mono Recorded or broadcast sound that comes from a single channel.
Moving Head A lighting fixture that can move in the both horizontal and vertical dimensions and can have movements and patterns programmed via DMX.
MP3 A compressed digital audio format that is widely used. Is space efficient, but is lossy and is significantly worse quality than lossless formats.
Noise Used to describe unwanted sound that comes from unintentional sources, such as vibrations or electrical interference.
Output The signal coming out of a unit.
Par Bar Typically a package of four or more par cans, which are arranged on a lighting T-bar.
Par Can A single, basic lighting unit that consists of an element (or bulb) that is.
Passive (Speakers) Speakers that do not have an internal amplifier, and require power from an external amplifier.
Pitch How humans perceive fundamental frequencies of sound which allows us to differentiate between notes and tell if a note is high or low.
RCA (Phono) A stereo cable type with red and white terminations typically found on outputs of DJ equipment.
RGB A colour model in which the three primary colours of light are red, green and blue. Any other colour can be created from a combination of these three fundamental colours.
RMS Root mean squared. An average for the power output of speakers or amplifiers.
Sample Rate The number of times a second a digital number is stored. Directly related to the high frequency output.
Serato A computer based program by Pioneer that assists in mixing digital music.
Signal Chain The way and order that units are linked together, which forms a chain and you can use to trace where the signal is going.
Smoke (Fog) The vapour that comes from a smoke machine or fogger. Typically thick, will need regular blasts to keep a room filled.
Sound Card A piece of hardware that controls the input and output of sound to and from a computer.
Sound Active A mode included in lot of modern fixtures that allows the unit to change patterns in time with audio which is collected from a microphone included on the unit.
Speakon (Speakeron) A heavy duty cable termination typically used on speaker cables with safety locks to reduce the risk of falling out.
StarCluster A type of laser that emits lots of small dots of light, that when combined can appear like the effect of stars in the sky.
Stereo Recorded or broadcast sound that comes from two different channels corresponding to the left and right ears.
Strobe A type of light that typically flashes on and off at a fast rate (around 10-12 times a second) that creates a particular lighting effect.
T-Bar A type of lighting stand that is characterised by its 'T' shape, as it has a long thin central pole, with a horizontal bar to hold lights on top.
Term Meaning
Traktor A computer based program by Native Instruments that assists in mixing digital music.
Tweeter A typically small speaker for higher frequencies
Unbalanced Signal A type of signal more commonly found in consumer audio products that is more susceptible to external noise.
Virtual DJ A computer based program by Atomix Productions that assists in mixing digital music.
Wattage (W rating) A measure of power for speakers or electronic equipment. 
WAV / AIFF Uncompressed digital audio formats that are typically used in professional and studio audio applications.
Woofer A typically large speaker for low frequencies.
XLR A 3 pin cable connector typically used for transferring audio information from speakers, mixers and microphones.