In January 2009, Katy Guetta contacted us to create a design for the UNIGHTED party featuring David Guetta.
I chose to do the Stade de France in L.Acoustics. This event has been held for three consecutive years, the last edition having taken place in Nice, with David Guetta among others.
The configuration included a central stage, 40,000 clubbers on the parterre and part of the first bleachers, with the exception of the corners, which remained unoccupied.
Sound design concept
Why 2 tours at the Stade de France with l.acoustics
It would have been easy to imagine four towers with four stereo broadcasts, but this solution didn’t seem satisfactory for achieving a truly “big sound”. The real challenge lay in the 40-160 Hz frequency range.
To minimize phase cancellations and lobes caused by step differences between sources, it was essential to limit their number. The idea was to group them together as much as possible to create a single source per side – otherwise the very notion of a scene would disappear.
Engine management
This grouping involved optimizing the motor points to position the bumpers so that the last V-DOSCs, located at the bottom of the line, were very close to each other, only 50 cm or 1 m apart. The result: 60 V-DOSCs, 10 SB28s and 12 dV-DOSCs per lap!
So I reduced the system from four to two sound towers. But this posed a dilemma with regard to stereo, as it would have to be largely sacrificed for a majority of listeners. In the end, I came up with a loss-limiting solution: the four source lines on each side alternated left and right channels, a L-R-L-R arrangement.
SUBWOFER acoustics design
Why subwoofers in cardio
Once the layout had been defined, all that remained was to organize the subs. I was determined to position some of them high up, but the first problem came from the bumpers, which could only support eight caissons – not enough. To get around this limitation, I used two bumpers per side, placed one under the other thanks to a clever trick: the first bumper was hung at a single central point, while the second was suspended below at two points, its motor chains passing on either side of the first six subs.
Stade de France in L.Acoustics – After the theory, the practice
In all, there were 13 Motors hanging 15 m high from a metal frame built for the occasion, and for which I had calculated and drawn the position of each motor point.
13 motors: 3 for the Sub, 2 for the 2 inner systems and 3 for the 2 outer systems, as I had used Delta to adjust the angles.
Subwofer management
That left the subwoofers on the floor … the problem here was the risk that, by arranging the subwoofers around the Round Stage, the DJ would be overwhelmed by the low frequencies … don’t forget that there were also 24 x SB28 …. in the air, hence the idea of making 6 packs of 8 subwoofers in cardio mode to ensure good rejection in the center and therefore at the turntables.
Cardio mode with the SB218s meant 2 x 4 subwoofers separated by 50cm. So we used the sub carts that Potar had to prepare 6x (2x4SB218) separated by 2 cleats of 50 cm, and therefore perfectly mobile, which proved to be a great help in allowing the other teams around the stage to work undisturbed. Once the space was clear, it was a simple matter of moving the 6 packs back into place and wiring them up.
The first year, there was a dance floor at the top of the first bleachers at each end of the stadium, so I added 6 Dvdosc and 2 subwoofers per side to clarify this area.
Course of the assembly day
We arrived at 6 a.m. and after a slight delay due to the absence of hooks at the end of the engine chains….. a detail ….? by 9am, work had begun in earnest and by 4pm everything was in the air. Time enough to test all the boxes ….. 120 Vdosc 44 DVdosc … 74 sub … we began a series of measurements, but I was already reassured: all the boxes were there, all the amp racks (around 20 per side) all the wiring (we needed the right lengths to put the amps under the stage). After a quick test, I knew my design would work.
Conclusion
It worked so well that I reproduced it identically the following 2 years (I just slightly reduced the amount of V for Nice).
Here’s a time lapse of the 1st montage:
Setting
As the design is perfectly symmetrical, the initial objective was to check each quarter of the stadium by taking ten or so measurements per zone, then to deduce a local average and finally a global average to adjust the system accordingly. To do this, I used an HF system, as pulling 200 meters of cable was clearly not an ideal option.
One of the major technical challenges was to phase the subs, both on the ground and in the air, with the V-DOSCs. The right compromises had to be made. In the end, ground subs were filtered at 100 Hz, with a low-pass filter that limited their bandwidth to 93 Hz, a decision that provided a real advantage.
For the record, I use WinMLS for my analyses, and since that experience, I’ve definitely adopted HF systems. It’s an incredibly practical and ultimately affordable solution, but it deserves an article of its own.
2023 I now use REW
Management
As for the control room, which has remained virtually unchanged over the three editions, I had a PM1D console for its exceptional dynamics, a Mutec iClock clock (undoubtedly one of the best), a DA PSX100 Apogee – Special Edition converter, and a Chandler Curve Bender. The signal was then passed through two Al.So Dynax2 compressors, which drove three Dolby Lake Processor LP4D12:
- One for filtering V-DOSC and dV-DOSC from indoor systems,
- Another for outdoor systems,
- And the last one is dedicated to subs, since it should be remembered that there were only LA8s for the SB28s installed in the towers.
Note for experts:
As Le Lake has 12 outputs, I used 10 of them for the V and dV in stereo (3 outputs for the V, 2 for the dV, i.e. 5 on each side). This left 2 outputs, which I assigned to the V-DOSC bass. This ensured a similar impedance between bass, midrange and treble. Otherwise, given that there were two amps for bass versus one for midrange and treble, the Lake’s bass output would have seen twice as many amps as those for the other registers.
To achieve this result, I carefully selected each cable in the control room (I know it may make you smile?), whether it was the power cables (the famous Shuko), the digital cables or the word clock (because there was a digital clock).
For wiring diagrams, there’s now Sketch
A little anecdote
A little anecdote: as soon as I could actually send out sound, as the stadium manager was joining me, I immediately noticed that the sound was reflecting off empty seats, in areas that weren’t normally supposed to have sound. The mix between direct and reflected sound was far from optimal.
So I called my assistant and asked him to mutate the mids and highs of the first three boxes… and then of the first six. The result was that all six boxes were now bass-only, an approach that could almost have been christened V-DOSC Sub, like today’s KSub.
?
Many thanks to: Matthieu Marionneau my assistant Face, efficient ++ , Yves Galliot (the Buzz killer …), Gilles Vautier, Gérald Desjardin, Benoit Malhomme … and all the little hands …
For team management, there’s BookingTech
