With a varied calendar of sporting and entertainment events, the audio requirements at France’s national stadium are particularly stringent, writes Paddy Baker.
Just about any stadium these days has to perform a wide variety of functions – and the fifth-largest in Europe is no exception. Opened in 1998, the 80,000-seat Stade de France hosts around 25 events each year. It’s used for major domestic and international football and rugby matches as well as for athletics tournaments, concerts and live events.
Architecturally, the stadium has at least one quirk: the roof seems to float above the stands, without touching them; it is supported on pillars instead.
The stadium’s audio installation is equally interesting: different types of event have different crowd configurations, and therefore different audio requirements. But even football and athletics don’t have the same audio coverage patterns in the Stade, as some of the lower-level seating sections can be removed to reconfigure the arena for athletics.
When the decision was taken to completely replace the audio system, the requirements were suitably stringent; excellent audio quality and audio comfort for all spectators in every stadium configuration, best possible speech intelligibility and conformity to security standards, full control and optimisation of audio levels everywhere in the arena and finally permanent audio level measurement in and out the arena to facilitate real-time control.
Two companies put in bids for the contract. Winning integrator Melpomen, led by project manager Sylvian Brottes, chose to install a line array system, with all audio equipment connected and controlled via an EtherSound network. The network is carried on a fibre-optic loop running round the stadium at roof level, providing redundancy in the event of a break in the fibre.
Melpomen’s design – which was created using both EASE software and Nexo’s GeoSoft package – uses a single audio system for PA and voice alarm functions. While there are equipment savings to be made by having a single integrated system, the life-critical nature of the system added two further requirements: there must be full redundancy at all levels, and there must be full control, and visibility of status, of all audio equipment from the control room.
There is a total of 11 amplifier racks in the stadium, nine of which are dedicated to audio within the bowl. These nine racks contain a total of 51 Nexo NXAmp amplifiers; each rack has an amplifier channel for each level of seating (high, medium and low-level seats, plus the field) and a back-up amplifier, which is switched in automatically in the event of an amplifier failure. These feed the audio out to clusters of Nexo line array speakers, passing through a special power switching box designed by Melpomen.
Forty clusters of Nexo Geo S1210 cabinets are flown from the roof: 20 of them contain seven S1210s and are aimed at the high- and mid-level stands, while the other 20 clusters, aimed directly at the lower levels, each contain six of these speakers. Add in another 32 cabinets positioned at ground level, and that’s a total of 292. Also flown are 27 Nexo RS18 subwoofers – the first time Nexo has supplied sub-bass units in a stadium install.
Some of the long distances involved (the high-level speakers are 45m above the ground), mean the S1210s are actually a special variant: they have been fitted with a speaker driver with a +3dB treble boost.
The other two amplifier racks look after sound reinforcement in 30 rooms inside the stadium complex, and stageboxes for visiting concerts and productions to use to hook up to the system.
Work on the project began in March 2010, with the installation starting at the beginning of September. PSNE’s visit in June 2011 coincided with a brief period of overlap, with the new system running alongside the Nexo Alpha system it is replacing; our photographs show the two sets of speakers hanging side by side.
Real-time monitoring of the status of the NXAmps in each of these racks is carried out by an AuviTran AVNF49-ES supervisory device. The amplifiers can communicate information about parameters such as an unexpected impedance level on a channel, or a temperature limit overrun. Another useful feature, adds Budnik, is the ability for visiting productions to make use of the sound reinforcement system high up in the stands.
He explains: “If a company is setting up a stage production in the stadium and they want to use the sound reinforcement in the arena, we can get the signal back from one of the stageboxes connected to the network, realign all the delays on the speakers if needed, choose the zones we want to address and without adding any other speakers in the roof we can have a high-level sound reinforcement system, directly accessible.”
The Nexo-AuviTran pairing is spreading its wings beyond France. Two further stadium installations in Morocco have made use of the technology: in Marakesh (with integrator Encom) and Tangier (with SGM). So while the French national football team may not be doing so well on the international stage at present, its audio technology is doing rather better.