Led Zeppelin's recent performance was hailed as a revelation, with landmark songs praised for their power.
Employing digital technologies to faithfully reproduce the classic rock sound forged by legendary group Led Zeppelin during their recent one-off show at London's O2 Arena presented the band's production crew with some unique challenges. Aaron Greenwood reports.
Renowned for their classic valve-amped recordings and no-nonsense approach to live performances during their heyday, Led Zeppelin arguably represent the consummate old school rock act.
Unlike contemporaries including the Rolling Stones, who have continued to tour and ultimately embraced new live performance technologies in the process, Messrs Plant, Page and Co have lived off the reputation forged during their heyday, long after the band's official break-up following the untimely death of drummer John Bonham in 1980.
However, following the passing last year of Ahmet Ertegun, who signed Led Zeppelin to Atlantic Records in 1969, Plant, Page and bassist John Paul Jones, announced they would reform for a one-off show in tribute to their late mentor at the O2 Arena in London.
Reaction to the announcement of the concert, which was staged in December, bordered on hysteria amongst diehard fans, many of whom were not even born during the band's most successful period in the mid- to late-1970s.
More than one million fans pre-registered for tickets to the show, causing a meltdown of the band's official ticketing website.
The vast majority's efforts were in vain, with just a lucky 18,000 securing tickets to the show at a cost of $US255 by way of electronic lottery.
Amazingly, the most eager punters began lining up outside the venue more than 24 hours prior to the show in a bid to secure the best seats in the general admission area.
The challenge of reproducing the band's classic rock sound nearly 20 years after their last performance at an Atlantic Records event in 1988 fell to a team that included well-known FOH engineer 'Big Mick' Hughes and Roy Williams, the latter of whom was responsible for monitoring Plant's vocal reproduction and output.
UK-based equipment rental company Major Tom supplied a massive Meyer Sound MILO sound reinforcement system for the show.
The company previously supplied a scaled-down version of the system for Prince's sold-out series of 21 performances at the same venue in August.
The system employed by Led Zep comprised 72 MILO high-power curvilinear loudspeakers, with a centre hang of six MICA high power curvilinear loudspeakers, and ten flown 700-HP subwoofers per side.
Ground stacks included nine 700-HPs per side, and four MICAs per side for outfill.
In addition, one MICA per side along with eight UPA-1Ps were strung across the stage lip for front fills.
Three Galileo loudspeaker management systems handled 36 outputs, and a SIM 3 audio analyser was used by Meyer Sound's director of European Technical Support Luke Jenks to tune the system.
At front-of-house, Hughes and Williams employed a Midas XL8 Live Performance desk supplied by London-based Brittania Row.
Plant reportedly personally requested the addition of the XL8 to the band's equipment rider, having been impressed by its performance at Metallica's Wembley gig last summer. Following the show, Plant visited the Midas factory to get better acquainted with the XL8.
According to Williams, the production team worked solidly to hone the group's live sound using the digital desk.
"The transition from analogue wasn't as hard as I had anticipated," he says.
"I had known prior to the start of rehearsals that two engineers would be working on the show; one to monitor the band and one to concentrate on Robert's vocals and effects.
Not the easiest thing to do: two engineers, two pairs of ears and two egos! Mick and I have known one another for more than 30 years and are both from the Black Country so that helped a lot.
"The XL8 allowed me to create my own 'world' to work in with just the vocal mic and eight effects - leaving Mick to create his world without either of us getting in the other's way. No blood was drawn, we had a blast and more importantly we're still friends."
Hughes says one of the biggest issues the production team faced was in regards to what extent they should tinker with the classic Zeppelin sound.
"[Initially] I was in a dilemma," he says. "But then I listened back to some of the old bootleg albums that were made of Led Zeppelin gigs in the 1970s, and really, there is no bass to be heard at all-not because you couldn't record it, but because the sound reinforcement systems at the time couldn't reproduce the levels we can achieve today.
"I couldn't see the point of going back to that sound. At the risk of upsetting the purists, I decided that the gig had to sound like it was [being staged in] 2007 not 1977."
"So we mixed it as if Led Zeppelin had never stopped playing in the time since their last gig."
Not surprisingly, Hughes says the digital desk provided much-improved flexibility and versatility compared to any analogue alternative.
"The XL8 gave us an unlimited amount of options," he says. "It was a good job we did as the input list grew to more than 70 channels, and if we'd gone analogue we would have had to use two desks."
The operation of the console made it really easy for Roy and myself to divide the work surface. Being able to set the last bay of the console to the B zone and then recall a POP (population) group containing Robert's vocal and effects into the B zone meant that Roy had his own section.
"This in turn provided me with access to the remaining two bays and the VCA (variable control association) section to mix the band. The 'a/b' headphone solo busses were invaluable as I could be using one while Roy used the other."
A preproduction Klark Teknik DN9696 high-resolution live hard disk recorder was on hand during rehearsals, allowing the engineers to 'virtual soundcheck', working on the sound and effects from the live recordings and using the settings to create automated scenes for each song.
During full production rehearsals, the band ran through the entire show twice.
These sessions were also recorded on the DN9696 to further develop the mix and provide a time reference for the lighting and video crews.
The band was then able to watch the whole show from an audience perspective, and also use the recordings to assess their live performances.
The extra capacity provided by the DN9696 proved invaluable, Hughes says.
Onstage, a Midas Heritage 3000 handled the band's monitor duties under sound engineer Dee Miller.
Ultimately, Led Zeppelin's performance was hailed as a revelation by critics, with landmark songs including Stairway to Heaven and Whole Lotta Love praised for their sheer power, virtuosity and relevance, more than 30 years on from when they were first performed.
The production crew undoubtedly deserves much of the credit for the quality of the sound on the night, having developed a thoroughly modern platform that highlighted the intricacies and at times subtleties of the band's most-loved songs.
"It was an honour and privilege to participate in this iconic event," says Major Tom MD Lars Brogaard.
"There was a lot of pressure but it's always reassuring for us to know we're working with the best sound equipment in the business."
"The entire crew from the engineers to the guys running the PA did a tremendous job."