Just in case Michael Eavis rings you up and asks you to appear next year, Andy Wood provides a guide to sound reinforcement at the Glastonbury Festival - what to expect when you turn up, how it works, and why it pays to be nice to the engineers...

For a musician, the ultimate drug must be performing live: the roar of the PA and the smell of the crowd (or the roar of the crowd and the smell of the PA? - Ed). Certainly, most of us would swap a night down the pub for a night on stage at the Hammersmith Apollo, but when it comes to something the size of Glastonbury Festival - with an 80,000 crowd and a PA the size of a small village - we're talking the stuff of dreams. Playing at Glastonbury is not a question of turning up with your trusty Fender Twin and just plugging in.

When it comes to festivals, Glastonbury is the largest of its kind in Europe, if not the world: 17 stages featuring over 1000 artists over three days with an attendance of over 120,000. The sheer size of the event is overwhelming. A huge, strident wind-powered generator stands over a myriad of tents, cars, marquees and stages in a blaze of breathtaking colour. If you can imagine moving the population of a large town - including much of its service and supply paraphernalia - to a valley in the middle of Somerset, you get some idea of the scale.

As well as the 17 official stages, the smaller tents and sound systems provide a vehicle for every conceivable type of entertainment, from rock to comedy, mime to folk, poetry to circus - with the sound systems as varied as the acts themselves. Everything from large flown arrays through to home-made cabinets made from pipes and plastic cups, running on power supplies varying from wind-power to pedal power.

To add to the mayhem, many of the market stalls also have fully working PAs, which although officially limited to 2kW in size, continue throughout the night transforming makeshift shopping areas into huge raves. Somehow, Martin and H/H rigs find their places in amongst the bric-a-brac, complete with laser and intelligent lighting accompaniment.

Main stage

As in previous years, the main stage is the domain of Britannia Row Productions, best known for their work with Pink Floyd and Peter Gabriel. In the absence of the famous Pyramid stage, which had burned down the previous week, they've built their rig around a stage borrowed for the occasion. To cover the hinterland of the main arena, a 50,000 watt (50kW) Turbosound system has been installed consisting of two arrayed stacks of 18 Flashlight mid/high cabinets, flown 40ft off the floor with 20 sub-bass cabinets stacked underneath each array. As the flown wings protrude so far out from the stage, a further four boxes of Floodlight are placed stage left and right, and are fed with mid/top to give added clarity to the audience directly in front of the stage. Plus, to fill the area behind the FOH control tower, a further four Flashlight and four sub-boxes are positioned behind the FOH position, with a delay added to make sure that all the sound arrives at the same place at the same time.

With a rig of this size, the musicians need much more information than can be provided by the monitors. The delay in information getting to the stage from the main rig is surprisingly high, so Floodlight sidefills are positioned left and right, pointing sideways onto the stage and mixed to the artists' liking: hence phrases such as "more red in the sidefills, please".

Stage crew chief and monitor engineer Mick Sturgeon works alongside Doug Pope, Guy Gillan and Simon Thomas, who are assigned to monitors, mics and line checks respectively, with Production Manager Peter Brotzman overseeing the whole stage and organizing the difficult task of loading each band on and off. Radio 1's Andy Kershaw entertains the troops on and off the stage inbetween sets, as Brian Jordan and Neg in the Production Office perform the equally demanding job of getting the bands in - and turning away liggers...

The main stage uses a single Ramsa S840 40:8 monitor desk. With half an hour or so planned between each band, a talent-rotation system keeps things moving along. With one band on stage and playing, the gear for the next band is brought to the back of the stage from a loading area at rear stage right, and multicores are installed. Each band provides a channel plot for monitors and FOH, and these are plotted on wooden slats which are pulled into position prior to each act. As one band finishes and is loaded off, the next band's backline and instrumentation is pushed forward, and line checks are done on all channels. A pretty standard selection of Klark-Teknik EQs plus dbx and Yamaha FX units are available to those bands who have not brought their own racks.

John Gibbon, working the stage monitors along with Mick Sturgeon, explains how the system works.

"With all line checks and channel plots in place, the desk is handed over to each guest engineer. One monitor engineer 'baby-sits' with him, whilst the other prepares the multicores for the next act. It's a well-organized system - that's why it works."

In contrast, most of the other stages use two duplicate sets of equipment, and alternate them for each act. With more time available on the main stage, the need for this is mercifully avoided, a single desk providing the twin advantages of more room to work and less things to go wrong. The only glitch in the system occurs when both Peter Gabriel and Jackson Browne turn up with their own monitor desks especially for the occasion. Room has to be made at the side of the stage for each desk, which is then alternated with the S840.

Front of house

At the FOH position, Britannia Row's Doug Hall and Dave Pringle are running the same rotation system as on stage, with one baby-sitting the desk while the other plans for the next band and arranges the correct mic plot slats. Here is the heart of the PA system: a Yamaha 4000 52:8 FOH desk running through five FX racks containing Summit Audio compressor-limiters, Eventide H3000 harmonisers, plus graphics, FX and gates from Lexicon, Yamaha, AMS, Symetrics, BSS and Drawmer. Four Turbosound LMS780 Loudspeaker Management Systems are also in use on both main and sidefill stacks. Finally, a link is taken from the desk to BBC Radio 1, who, as well as recording the event for future broadcast, provide Channel 4 and MTV with their audio links for live broadcast.

Again, the time between sets allows for a single desk to be used in this position. Nevertheless Peter Gabriel, who as well as bringing the monitor desk and a selection of extra lighting (which has to be built in shifts between each preceding set), delivers the knockout blow by supplying his own FOH desk (plus FX racks) - in the shape of another Yamaha PM4000. It is delivered on the morning of his performance by Gabriel's own engineer Hugh Richards. This second desk, used throughout Gabriel's recent world tour, is eventually placed behind the first Yamaha PM4000 to create a secondary mix position for FOH engineer Peter Walsh.

All of this may sound like controlled chaos. In fact, the system works extremely smoothly. The key is not to let too many people or too much equipment onto the stage area at any time. If it isn't being used, or about to be used, get it off the stage. Same goes for people - this is not a place to be seen ligging. The effect of this principle is to foster a genuine atmosphere of trust between artists, their crews and the festival stage personnel.

Sonically, the main rig is impressive and meets all expectations - in spite of a 99dB limit imposed and monitored by Mendip Council from the FOH desk. A second limit of 66dB is set for the perimeter fence, and on Sunday prevailing winds dictate further restrictions while Peter Gabriel is performing. Sound limits also cause difficulties at the other end of the site, where a 96dB threshold is placed on the NME Stage run by Scan PA.

The Pretenders' FOH engineer Chris Ridgeway is the first to feel the effects. "I just couldn't get the most out of the performance and felt it was lacking that extra bite," he explains afterwards. On the field however, Scan's Court Black Box system has both clarity and attack, and when Chris returns to mix Bjork the next day, the wind has dropped sufficiently to produce full value for money both in front of and behind the desk.

Doubling-up

As with the main stage, the 60,000 watt (60kW) Black Box rig is partially flown, with two clusters of 12 mid/highs flown on hoists left and right, and 12 bass/sub cabinets stacked underneath. In addition, there are four mid/high and four bass boxes in the photographers' pit, used as front-of-stage infills with the same configuration behind the FOH position as a delay. 'Leapfrogging' - alternating two desks by line-checking one while the other is in service - is the order of the day on the NME stage, with a pair of Soundcraft SM16 40:8 monitor desks shared by Dave Guerin and Simon Higgs.

Production Manager Chris Hannam and Stage Manager Mark Gosling are charged with getting the bands on and off stage, whilst the stage crew of Chris Fitch, Ady Barnard, Matt Vickers and Paul 'Euro' arrange patches, mics and lines - again on a leapfrog basis. With only ten to fifteen minutes between each band on the NME stage, using a single set of equipment is even more impractical here than it is on the main stage. Everything is duplicated, with two monitor and FX feeds sent along two separate multicores to two separate Soundcraft 8000 36-channel consoles and FX racks. As sidefills on the stage itself, Scan employ four boxes of Floodlight each side. All the monitor wedges are Scan's own design.

The Spin Doctors, Peter Gabriel and The Pretenders all make use of Radio Station In-Ear monitors, a system which broadcasts an individual mix direct to each performer via customised earphones.

"Obviously, by getting rid of the wedges there are various benefits - including more room on stage and less wiring," says engineer Chris Ridgeway. "The main benefit, though, is that the artists can get exactly the mix that they require, and at the level that they require it. That way, as an engineer you don't have to worry about any spillage from the monitors getting in the way - either through the mics or across the stage."

FOH on the NME stage, Dennie Vidal and Rob Hodgkinson share the ongoing twin responsibilities of line-checking and babysitting the two Soundcraft consoles - with a 16-channel expander available to both desks offering a maximum of 52 channels on tap. To add spice to the occasion, the boys run an unofficial points system for each guest engineer, judged on a variety of skills including use of effects, problem solving and personality. On the Saturday afternoon, nine points and two stars are awarded to Ultramarine's engineer, and the total is not beaten.

The NME stage outboard includes identical racks of AMS RMX16 and Yamaha reverbs, Roland digital delays, Eventide harmonisers, Klark Teknik EQs and Drawmer gates and compressors. A Soundcraft Spirit feeds DAT, CD and the dulcet tones of John Peel through from the stage. Again, feeds were also provided to Radio 1 and Channel 4.

The leapfrogging system is particularly useful for the smaller stages, allowing for much more time to set up each band. Line checks can be run direct to monitor and FOH desks during the previous band's set. It also facilitates very tight control over both running times and changeover times - very important with live radio and TV broadcasts hooked in. The main and NME stages carry the big-name acts, but elsewhere the Jazz stage grooves unprepossessingly through Sonix Audio's proprietary Fane rig. With a Soundcraft 8000 at the helm, the rig performs consistently well over the three days, peaking on the Sunday with exceptional sets by Steve Williamson and, later, Lucky Dube. Another stage which pleasantly surprises is in The Field Of Avalon, no less, where Julian Spear of Precision Sound is using a brand new Soundtracs 40:8 Sequel II.

Here, both the main PA and the monitors, designed by Precision, feature dual-compression driver-loaded horns with twin 15" loaded full range cabinets underneath. To augment the system, Julian has added a pair of 24" sub-cabinets under the front of the stage. The 6kW system runs via a selection of Hill amplifiers, but the major surprise is the dearth of rack equipment, with only a small selection of Alesis Midiverbs and the ubiquitous Drawmer gates on hand. Julian Spear explains.

"The advantage of the Sequel II from a hire point of view is that all the compressors and general effects are included within the desk, so the need for outboard effects is reduced." The system performs well, to the extent that The Levellers are inspired to perform an impromptu gig on this stage following their appearance on the main stage, Friday night.

The 'tech' gets lower as you wander from the epicentre. The Circus stage survives solely on an old Sunn 8:2 system, still pumping it out despite having seen better days. For me, though, the highlight of the show is at the Green Field site - a pedal-powered generator system. After all, if the main stage can use a wind turbine generating 150kW for the lighting, why shouldn't the punters be expected to put their backs into it for a little music?