Understand roadies, communicate with sound men, know when something's gone hideously wrong. Then look it up in Ben Duncan's PA dictionary.

Amp Rack: used to torture roadies, it's a box filled with amplifiers until it's heavy enough to constitute a danger even to macho weightlifters.

Array: a group of horns or bins, stacked in a special configuration, eg vertically, or splayed out.

Aux rack: a rack full of 'goodies', usually FX units.

Board: slang for the mixer, from the US.

Bins: a nickname for horn-loaded bass speakers, because of the cabinets' bin-like appearance when wheeled across the stage. They're also used by roadies to kip in.

Breakers: short for 'circuit breakers', a resettable mains fuse found on amp racks.

Cannon: an XLR plug or socket, named after the original maker, Cannon Electric.

Compression driver: a specialised drive unit, screwed to the back of HF horns.

Console: another name for the mixer.

Daisy Chain: a cable which links the input signals from one amplifier to the next, and then on to the next (ad lib). This happens in a big PA, where two or more amplifiers are being driven from the same signal.

Desk: yet another name for the mixer.

Diaphragm: the bit which usually expires when speakers get zapped by a bad howlround. Found inside the compression drivers, it's equivalent to a guitar speaker's cone, but is usually made of aluminium foil, dome shaped not unlike a contraceptive of the same name. Discarded ones are commonly used as ashtrays.

Drive unit: synonym for the loudspeaker guts, as distinct from the complete cabinet.

Delay tower: a PA stack placed towards the back rows of a big auditorium, capable of deafening, yet designed for better coverage. The sound has to be delayed for synchronisation, otherwise it would arrive a fraction of a second earlier than the sound from the main PA, perhaps 800 yards distant.

Drumfill: a specialised monitor speaker placed behind the drummer's earhole.

Flying/Flown: PA cabinets suspended above the stage for smoother coverage.

Floor monitor: American for a wedge monitor.

F.O.H: from the theatre, Front Of House.

Full range cab: the classic PAs of the 70s were based on individual cabinets for the bass, mid and high frequencies, whereas a full range cab is like a high power version of a hi-fi speaker or studio monitor, with a balanced set of bass, mid and high drivers mounted in a single enclosure. This arrangement helps the different frequencies integrate better, and also spells more compact PAs.

HF: short for High Frequency, it's a synonym for treble frequencies.

Horn: a flared tube placed in front of a drive unit to magnify the sound, akin to a megaphone. The shapes vary widely: bass horns have square or rectangular profiles, and may be flared on one or two sides only. Mid and high horns are flared in various wonderful shapes (eg: JBL's 'Baby Bums') to control tne dispersion of the sound. Strictly, the horn is just the flared bit, but the whole enclosure is often referred to as a horn.

House console: short for the 'Front Of House Console', it's a trendy name originating from the States for the mixer outfront, amidst the audience.

Long throw: a horn which s shaped to throw a narrow beam of sound over a long distance. It's usually an HF horn, traditionally used to zap the audience on the back row, or convey extra heavy funk at outdoor festivals to distant householders, particularly outraged Tory MPs.

Mids: shorthand for Midrange Speaker Cabinets.

Multicore: a fat cable, running from the mixing desk back to the stage. It comprises a dozen or more mike and line level cables, encased in an overall plastic jacket.

Outfront: the main PA (because from a stage perspective, the audience are "out front").

Radials: a familiar HF horn with straight sides, but a concave flare above and below. It radiates sound over a tightly defined angle, typically quite narrow in the vertical (say 30°), with a wider horizontal spread (say 60°).

Rigging points: on a flown PA cabinet, this is where the hoist and safety chains are fitted. Rigging points are also helpful when tall stacks have to be secured with ropes (after that man with the clipboard has condemned the rig as unsafe).

Room analyser: usually mounted in the FX rack, this gizmo comprises an array of LED bars, which display the sound level at 27 frequencies across the audible spectrum. By feeding the PA with Pink Noise, which nas equal energy at all frequencies, we can observe how the average response of the room and PA deviates from the ideal (flat) frequency response, then apply correction with a graphic equaliser.

Returns multicore: a separate multi-cable carrying high level signals from the crossovers at the F.O.H. position, back to the stage, and on to the PA stacks.

Sidefill: a specialised monitor speaker placed stage left or right.

Snake: slang for the multicore.

Splitter box: a junction box, where 30 or more mike leads can interface with both the outfront and monitor consoles' multicores. But there's often an extra set of sockets, so a mobile recording van can plug in. A sophisticated splitter box may include electronics or transformers to help isolate the various console connections (to prevent earth loops), and to avoid each microphone being loaded down too much.

Stagebox: the box where the mike and DI leads congregate on stage, for onwards transmission down the multicore and/or via the splitter.

Talkback: the intercom between the monitor and outfront mixing.

Trunk: a large box used to store leads, spares and tools.

Wedge: the wedge-shaped monitor speaker in front of the musicians.