Mike Lethby was lucky enough to go backstage on the Sheffield leg of U2's Zoo TV tour. He reports on the equipment and techniques used and gives a fascinating insight into the mechanics of a major concert.

Joe O'Herlihey, sound engineer-in-residence to U2 since before the world had even heard the name, had already taken more journalists through the nuts and bolts of his latest tour than he could remember. Midway through a worldwide marathon, the band arrived in Britain in June to play just four shows: Earl's Court, the new Sheffield Arena, the SEC, and Manchester G-Mex. Predictably, ticket demand far outstripped supply. Less predictably, the tour, dubbed 'Zoo TV', showed a very different face of U2 from the one we'd become used to. Gone were the vast stadium dates, and with them the stadium-style bombast that had lit a critical backlash against the band who, just a few years ago (circa Unforgettable Fire), could do no wrong.

This was, in image at least, a leaner, meaner U2, aiming to pump the new raw energy of their Achtung Baby album into live pyrotechnics. And make no mistake about it, 'Zoo TV' is a mighty show. A blockbuster, as they say in the book business, which floored most of those critics who gathered to dish the dirt at Earl's Court.

It was at Sheffield's resplendent new Arena, one of the best-sounding large venues built on these shores for many years, that the affable Mr O'Herlihey invited me to take a tour of his domain.

He explained that the band themselves prefer a low interview profile. They'd rather let the music speak for itself — and they're happy to see the effort put into the production side duly acknowledged. It's a refreshing attitude. There's many a world-class band whose tour management won't let you photograph a mains plug or interview a tea lady without permission signed in blood, in triplicate!

Months of work have gone into every aspect of this tour. The two-hour-plus show boasts the only rock visuals to rival Prince — it's that innovative. It also sees the band very much on form and in hi-NRG mode. Admire them, too, for not insisting on one sprawling night for binocular owners at Wembley Stadium.

The production borders on the immense, though not in the sense of 'we've-got-the-biggest-stage-in-the-universe' overkill. The immensity is mostly hidden from the punters, in a sub-stage labyrinth of satellite links, MIDI racks, monitor consoles, quadraphonic radio mic sends and video feeds.

Out front, the most impressive sights are (a) ranks of garishly-painted Trabant cars suspended from the ceiling, (b) masses of flickering video screens around the stage flashing subliminal ZooSpeak, and (c) a second, small stage, one third the way out into the arena floor, connected to the main stage by a narrow catwalk.

Sitting by the latter can be a dangerous affair — you find yourself in the eye of a hurricane of pandemonium when the band moves out to Stage 'B'. But then intimacy, in a way, is what sets this tour apart from the rest.

Joe had barely half an hour in which to propel me around the A-Z of Zoo TV. My apologies to him, therefore, if any minor elements have been omitted. But as you'll see, there's more than enough to be going on with.

We begin, appropriately, with an insight into how Joe, the band and their PA company since 1982 — Clair Brothers of Pennsylvania — came to be together in the first place.

Joe, U2 & Clairs: A Brief History Of Time

I asked Joe how the tripartite relationship between U2, himself and Clair Brothers had evolved.

"In 1978 I owned a small PA company in Ireland — some of the lads on this tour ran that company for me in Cork when I was away on tour. We first got U2 on a college gig in Cork in September 1978 — they'd only recently formed — and we did a couple of tours around Ireland, the usual bars and pubs, and finally ended up on a small UK tour. They got signed up after that, in late '79, and I've been with them ever since, really; I've only missed three or four gigs up till now."

U2 first used Clair Brothers some three years later.

Joe: "We used them at the New York Palladium on the War tour in 1982/83, because they could hang the system and they'd been in the Palladium a few times before. They were in there already that weekend, I think, so we agreed to share a system with The Psychedelic Furs. And I've used them ever since.

"It's their attention to detail — they've got a real frontier attitude to technology; they don't leave any stone unturned until they get the fine details right. Plus, it takes a long time to build up a relationship with people. Joe Ravitch is my crew boss — he did that show at the Palladium and he's been here ever since, apart from a couple of tours.

"The PA system is one thing but at the end of the day you've got to live with people for two years on tour: you've got to do a day's work, do a show, put it back in the truck and it's a very difficult thing. People are human — or otherwise — so you have to get the right combination of bodies, you know?

"We've got the right blend; I've changed a few people to get the element of 'frontierism', as I call it. Young guys who are very enthusiastic and want to get it done right. It's not an in-house party for 40 year-olds!"

Zoo PA

The European tour, and consequently the PA system in use, was quite different from the American outdoor shows which followed. However, the difference is mostly a question of orientation — many of the US shows were performed in-the-round — and of scale. The show itself remained essentially the same.

Clair Brothers' standard PA cabinet is the S4 full-range active enclosure. 'Standard' is actually something of a misnomer, since the basic design has been around almost 15 years but the internals have evolved constantly ever since. Roy Clair told me recently "we should really be calling them S5s or S6s," but as changes have been incremental rather than radical, they've settled for the 'Series 2' tag instead.

Joe: "We're basically carrying a reduced number of Series 2 S4s: 56 here as against 72 in America. Our US system is arranged stage left and stage right, left and right sidefills, rear fill system stage left and stage right. Here, we don't have the rear fills and there's no sidefill requirement as such."

Likewise, Clairs opted not to use delay systems on the tour. Joe: "Delays work well for different reasons for different bands, but in this case the attention span is focused from a show point of view right on the stage. We debated whether or not to use delays but we decided the focus of attention has to be on the stage, because of the Zoo TV aspect, the media side of things.

"One thing that's new, from a technology point of view, are the Clair Brothers 'Piston' P4 nearfield/in-fill boxes, positioned stage left and stage right in a cluster of six a side. Basically what they do is bring the effect of the overhead system right down onto centre stage at the front, from a focusing point of view, so when you walk from the desk to the centre stage vocal position, the sound of the system follows you right into the centre point and down. Plus, with most flown systems, spillage from underneath the PA can be fairly difficult to handle. With this show, because of trigger-sensitive treatments we've got and things like that, it's very important for me to have as much control as I possibly can — and that's where the 'Piston' boxes help me."

Why 'Piston'?

Joe: "Because it's like a drive. When I first heard the prototype they didn't have a name for it; they had the S4s running and when they kicked in this thing, it was like an extra drive coming into the system. It felt like it was pushing it... and so to me, I thought of it as being like a piston. And I think they've sort of attributed that name to me [laughs]. But," he adds, "it's actually called a P4, and we're using the first ones.

"We're also using new servo bass bins, which are made by Servotech, called the Servo Drive Bass Tech 7 — and it's a really happening low end. It's just for treatment, dialled in on a cue or bus send — so it can be as much or as little as you wish. Everything is driven by Carver amps, through standard Clair Brothers racks and distribution."

In The Mix

Joe went on to talk about the task of mixing 'Zoo TV', which he and assistant Robbie Adams performed chiefly on an ATI Paragon console and a Clair Brothers CBA desk, assisted by an effects inventory designed to duplicate those used in the studio for the recording of Achtung Baby.

Joe comments: "It's our first time in this Arena [Sheffield], and the first time in my career that I've been asked to supply a microphone for a hammer or a door bell." He continues: "The detail on this tour, to perform Achtung Baby, is pretty intense. There's pioneering stuff with the video side of 'Zoo TV' and it's my responsibility to ensure we get the best audio quality possible.

"The attention to detail is monumental compared to what it used to be. I'm not saying we didn't take care in the past but now it's a lot more demanding, because of the studio treatments we're using live — which can work fine in the studio but in a live context they can be completely out of whack! For example, right at the start there's this completely mad vocal treatment. It's totally disorientating because you don't know what to expect. The start of the show is such a spectacle, then Bono starts singing and it kicks you again. It's as close as we can get it, as a performance mix, to the album.

"It's nice. It's not an endurance test, but it's one of those things where you really have to get into what you're doing as well as keeping a handle on what's happening on stage. Bono likes a lot of communication — audience participation — and if it's a bit funky down there, he might end up singing into the side of a microphone instead of the front of it, or whatever.

"My Clair Brothers sound crew chief, Robbie Adams, is my assistant and it's basically a performance mix between us going hell-for-leather, running and jumping, and bouncing and shouting at each other from time to time."

As I watched, all the real action took place on the ATI Paragon. Virtually the only thing that got moved on the Clair console was a pack of Marlboro! Both pairs of hands were constantly at work, although the prevailing atmosphere, considering Joe's description, was surprisingly calm.

The ATI console, highly regarded in its native America, is not often seen on these shores. O'Herlihey's endorsement of it stems from his policy of taking time out between tours to check out what other PA companies and engineers are doing.

"It's never a foregone conclusion, as far as I'm concerned. I came across the ATI board on Steve Miller's tour. I've always been looking to accommodate as many effects as possible within hand's reach and it seemed very good in that respect. Listening to it, I found it had an exceptionally transparent EQ which did what you asked of it, and the on-board dynamics — input noise gates and compressors — were fantastic, without having to look at a rack. It's basically a dbx 904 compressor in there and a Drawmer 201 gate: the best of components built right into the console. It works very well and it's a very 'musical' desk, which is another thing.

"It's got 16 aux busses, 40 discrete inputs, and 16 mono subgroups which can turn into 16 inputs if you want, with full-blown EQ but without the dynamics or reassignable auxiliaries. So you've got 56 inputs if you need them, and you can use it that way because you've got eight independently mutable VCAs and a VCA master, which you can use instead of your subgroups. There's also eight auxiliary stereo returns with a good 3-way parametric EQ and mute routing.

"I just find it a very usable desk. Even someone who's not used to the ATI can go up to it and it's not the Starship Enterprise syndrome: it's simple to operate, which I appreciate."

Sound On Stage

'Quad monitoring' is one of the most impressive technical ideas on 'Zoo TV'. It's available to Edge, Bono and Adam, and allows monitor engineer Steve McCale to pan each musician's monitor mix around the stage wedges to follow their movements.

Joe explains: "Steve has a quad pan facility to route their mixes as they're travelling to whatever destination and position they're in, which is a new design — a bit of frontier technology! When the band members move around, their dedicated mixes go with them. Rather than a pushbutton it's on a joystick, so it's quick and very precise."

Quick it may be, but with Bono's vocal mix potentially appearing in a plethora of sidefills and overhead wedges, Steve's job is no easy ride. "Again, in the sidefills, the image moves to be a combination of Edge's and Bono's mix in each side of the stage area."

Another tricky aspect is avoiding feedback on the small 'B' stage. Joe explains: "We 'ring' the system out using a separate EQ for the 'B' stage; but it's always a bit touch-and-go depending on the audience noise level. The entire band goes down to the 'B' stage and plays there, so that in itself is a bit of a concept!"

"Edge has four vintage Vox AC30s and two Randall amplifiers, for a combination of various different echoes, source and natural, all of which make up the Edge sound."

Part of the 'B' stage solution lies in the band's use of Future Sonics in-ear monitors — a device also employed by Phil Collins on the recent Genesis tour.

Says Joe: "We have to use in-ear monitors, because the band spend a lot of time on the 'B' stage, about 120 feet in front of the main stage — it's also about 100 feet in front of the PA system. We use them for time-alignment, so that they can play in time with the PA.

"To the uneducated eye they look like a glorified hearing aid, but they're indispensable for us and they're really great. We had a lot of difficulties at the start, as you'd expect: you'd stand in front of the PA and it would squeal like crazy. But they were definitely the way to go for us, to enable all this to happen...

"They also make my life an awful lot easier, from a monitoring point of view — when the band are out in front, we don't have loads of wedges out there — because it needs to be concise and precise."

There's still an undertow of concern about the safety of in-ear monitors in general. Does that aspect worry you?

Joe: "That was the one crucial factor which made the thing work for us. The band had to determine themselves whether they wanted to be blown out of the water with level. But when you actually put them on, it's a very listenable thing; it's quality not quantity, there's no excessive levels. And the good thing about these particular Future Sonics units is there's a certain amount of — but not too much — ambience, to give a 'feel' of what's going on in your surroundings. And we're cheating a little bit: we feed them some microphone ambience so they don't feel completely cut off."

A few words about the backline before Joe leads me into the monitoring dungeons. He explains: Edge has four vintage Vox AC30s and two Randall amplifiers, for a combination of various different echoes, source and natural, all of which make up the Edge sound. His patching network is done by Bob Bradshaw and it comprises all the effects and treatments that he uses in the studio. They go through these six amplifiers and Bob's network — which basically controls a complete recall patch for each different sound. And then it's my problem to get it all to sound right out there!

"It's fairly deep technology, but Edge is a very 'techno' guy so he's well in tune with all of this; he knows what everything is doing at any one given time."

The other backline component of note is something which most young unsigned bands would be only too happy to take as their main PA system: Adam's bass rig — a standard JBL Concert Series PA system.

Joe: "Upstage, there's a lot of wedges and the VidiWalls." These are four walls of monitors, located off stage right, rear stage right, and left and off stage left, upon which are flashed pithy slogans or one-word exhortations of a hip nature. "From a production point of view," Joe continues, "Bono might spend some time in front of it or on top of it, so the wedges up here will take Bono's mix. In a 360-degree show we wouldn't have all this stuff at the back, because of the sightlines."

The visual paraphernalia is completed by sundry back-projection screens and, blazing their spotlights from above the musicians' heads, the aforementioned Trabants. Explains Joe: "Over the 'B' stage there's what we call 'Liberace' — the silver-coloured Trabbie." 'Liberace' served as the DJ's booth from which P.J Fallon spun the discs and made the (anticensorship of the nuclear debate) speech which opened this show.

Monitor World

U2's under-stage monitoring world is a sight to behold. There are no less than five monitor consoles, adding up to around 200 channels in all. "It is," observes Joe without a trace of irony, "quite a lot to deal with."

On stage is a combination of Clair Brothers 12AM single and double wedges; the sidefills are ML18s (a single 18" box) and MM4Ts. Video and audio links smooth communication between monitor engineer and band. With about 36 headphone and upstage/downstage mixes going on, all controlled by a Clair/TC Electronics programmable EQ rack (all assignable, instantly programmable and recallable), they need it!

The main monitor desks are two Harrison SM5s plus a 16-channel 'extender', a Yamaha DMP7, and a Soundcraft 200B. The UK support band, the excellent Fatima Mansions, were catered for by around 10 channels, shared between the Harrison extender and the Soundcraft.

Joe: "Our video reinforcement for the monitor engineers allows them to see at any given time where the band are positioned, which is essential with the quad roving system that's built into most of the mixes for Bono, Edge and Adam."

A 'grand master patch area', taken care of by Scott Appleton, incorporates a telephone land-line which is an intrinsic part of Bono's show, via a system input/output switching matrix. "That," says Joe, "allows us to use the telephone and get good quality audio on both Bono and the person he calls. Depending on the country we're in, Bono might call the President's office at the White House or the local pizza place." It was at the Earl's Court show where a nonplussed local pizza takeaway received an order for 10,000 pizzas from Bono's microphone...

Here, too, are the wireless monitor racks, programmed into the DMP7 for automated fader levels. Joe: "It's also where all the satellite stuff comes in, on a rack of monitors so they can dial in different combinations, swap channels and so on." Outside in the parking lot, there's a gleaming satellite dish of impressive dimensions to feed the system its diet of TV stations and international telephone hook-ups.

Finally, in this silent, flickering enclave, is the main backline and monitoring power distribution area. Power is stabilised, isolated, and computer-controlled with a UPS [Uninterruptable Power Supply] network insuring the computers against power failure — giving up to 40 minutes' grace to turn the stuff off before it goes into electronic tailspin.

Drum Monitors

Along to our right there's another monitor area, this time with two Ramsa WS840 consoles, which cater for drummer Larry Mullen Jr and — courtesy of Dave, Larry's personal monitor engineer — headphone monitoring and clicks to various headphone mixes around the place.

Says Joe: "There's also a lot of effects in the racks here, for Adam, Edge and Bono. We try to keep it as close as possible to the album mix and give them similar treatments. That's why there's as many effects back here in the 'bunker' as out front. It is fairly sophisticated and, I must say, it's the biggest monitor system that ever existed for a rock and roll tour: the most fabulous, the most whatever!"

Des's World

Another cave-like world of adventures deep below stage right is inhabited by The Edge's out-of-sight hardware — five keyboards and racks of sequencers, samplers, and associated MIDI addenda — and by their keeper, Des Broadbery. At the heart of it all is a heavily-modified Apple Macintosh SE/30 computer running Opcode's Vision software, not in its now increasingly-familiar role of live sound 'conductor', but chiefly as a source of keyboard sounds and video cues.

Says Des: "It's basically a Macintosh SE/30.

I had two made by a company called Current Music Technology in Philadelphia; they take the guts of an SE/30 and build it into a roadworthy frame. The finished thing's called 'Mac-in-a-Rack'. It took a long time to get them built, but they're sturdy pieces.''

How much of the set is sequenced?

Des: "Most of the set is covered, in so far as there's no live keyboard playing. But there are four songs which don't use the sequencer at all. Edge uses triggers, one or two album samples from my Akai samplers, which he starts from his MIDI pedals on stage. I can change all the patches on my screen. Each track of Vision runs different instruments for different songs. Also running off Vision are Larry's drum click track — an Akai shaker sample — and Edge's trigger for 'I Still Haven't Found...' from a MIDI gate.

How is the video side synchronised up?

Des: "Video is synch'd to the sequencers, but some of it is completely free-form: Bono can dial up whatever he wants with his remote control on stage.

"Everything is run through this American-built CAD in-line recording desk, the only desk I found capable of taking 16 inputs in a rackmounted format to 16 outputs, if I want to use all those. I'm sending six lines to Joe, because everything's mixed here; I put on some effects and Joe puts on some more! Plus I'm sending lines to monitors and patching them out to everywhere else."

Des adds his observations about the Opcode Vision software: "The Opcode guys are well happening. I'm using the last but one version, and I'm currently testing the latest version for them, which I'll hopefully use on our outdoor shows. They've implemented some of the changes I've asked for in the new version; in fact, I'm right in the middle of an interview with them on the phone now, if you'll excuse me!"

The Z Of Zoo

"We've been out since early February and we're looking forward to a break before returning to America for the outdoor shows," explained Joe O'Herlihey as we concluded the guided tour. I observe that while it's all undeniably impressive, both technically and in its effect, there's an awful lot of fragile technology around the stage for the gremlins to work their magic on.

Joe: "So far, touch wood, we've had no problems, mainly because of the computer-controlled AC. And AC is, on a live show, basically the reason why gremlins exist: if your power is unstable, if you see different voltages, that's what drives this type of gear crazy.

"So we've spent an awful lot of money and adhered religiously to fine-tuning the whole thing. We pick up the odd buzz if we're very close to a broadcast station or the like, but it doesn't happen very often."

And so it was time to return to the mix riser — to join the 40-or-so assorted crew, management, record company types and liggers — and enjoy the show.

The effect of the technology is, happily, to liberate the performers from the stage's traditional confines. Because it's simple to take their guitars and play from halfway out in the audience, that's what the band do — with relish. Because it's easy to telephone George Bush's office from stage via satellite to ask a discomforted aide what the boss is doing, that's what Bono does. Because Joe and his crew make it feasible to recreate complex studio treatments in a 12,000-seat arena, that's what the audience gets.

The Show

When Bono takes the stage at Sheffield, a picture of insouciance in shiny black leathers basking in a shower of strobe lights, the effect is electric. He shouts: "This is the best venue in England." (Loud cheers) "If they built more places like this, bands like us would get off our asses and play more." (Louder cheers.) He's dead right.

It's pure rock'n'roll theatre with an edge (if you'll pardon the pun). It's what every mean young pub band would love to do if only they had the cash.

The opening number is a shock both visually and audibly: VidiWalls pump and monitors flicker; Bono's vocals emerge as a strangled growl, as intended. The PA sounds extremely clean, hard edged, well defined, but relaxed and low on fatigue. Joe knows his stuff.

Later, Bono emerges with a giant plastic champagne bottle and promises "I'll be back with the real thing." He returns, girl in hand, to spray the crowd with bubbly. For 'Desire', he strides out in a gold lame suit, kisses his image in a gilt-framed mirror, and shouts "You're so fucking beautiful!"

He flicks through TV channels on his remote control; the Trabants dip their bonnets, headlamps lighting the stage in salute. A belly dancer takes the 'B' stage for 'Mysterious Ways', a little predictable perhaps but quite effective. Bono name-checks local boy Peter Williams, Zoo TV's set designer, before the band launches into 'Still Haven't Found What I'm Looking For', segueing into 'Stand By Me', another surprise. The crowd sing along to 'Dancing Queen' (Bono: "Have you heard of Lou Reed? Well, he's heard of Sheffield.") and to 'Pride (In The Name Of Love)' — the oldest U2 song on offer.

There are no drum solos, dry ice, sermons or histrionics. Just four guys playing as well as they've ever played — and doing things with their high technology wonderworld that are perfectly capable of making an audience's hair stand on end.

In a summer full of massive tours and huge expectations, U2's 'Zoo TV', with all its one-night stands, elaborate jokes, flying Trabants and great music, was the gig you simply couldn't have missed.