Built for the 2004 Men's World Ice Hockey Championships, the O2 Arena is home to the HC Slavia Praha and HC Lev Praha ice hockey teams and also hosts a range of other sporting and corporate events and concerts.
The venue needed to replace its existing PA system installed 10 years ago, a point source system that was, by the venue's own admission, under-specified and under-powered. The brief required a complete new PA/VA system to provide information and emergency announcements as well as music: also the new system needed to integrate easily into the Arena's existing systems, and to represent good value for money.
"We looked at the best technology around the world," says Jan Plihal, head of media technology at the Arena, finally choosing a Nexo Geo system with a total of 72x Geo S12-ST specialist long-throw cabinets and 24x RS18 subs.
Supplied and installed by Nexo's Czech distributor MusicData, the Geo S12-ST cabinets are flown from a central 'cube', carrying large screens on each side, which descends from the ceiling for sporting, congresses and corporate events. When the cube is lowered, it is still 24m from cabinet to the floor, and this is where the Geo S12-ST's long-throw capability comes into its own. The compact two-way ST cabinets have been developed from the standard Geo S12 design offering the high SPL and enhanced speech intelligibility required for stadium and arena applications.
The 24x RS18 subs - also flown - enhance events such as motor sports, BMX championships and the Davis and Federation Cup tennis matches. "These days, events like this are more and more a show," says Plihal. "It's not just about the sports, we have to think about commercials as well." Although a typical level for an ice hockey match is 90-94dBA, an SPL of 106dBA is possible in the Arena. The system is driven by 16x NXAMP4x4 TDControllers situated in rack cases in the roof, providing 256KW of power.
The arena has also installed a new fibre optic cabling infrastructure to carry an EtherSound ring network for the audio. Auvitran network devices deliver the signal from control room to racks with full double redundancy, while an option to switch to analogue offers even more backup. If any amplifier should fail, the system will automatically switch to another one.
As the Arena team requires a degree of control over every element of the system, MusicData sat down with Plihal to design a custom network interface, which runs on iPads connected to Wi-Fi. This displays highly visual information required for day-to-day operation, such as the ability to switch on and off each of the Arena's 24 different zones set over three levels including the pitch. The interface also displays the voltage on the output of the amps, giving a complete visualisation of the signal travelling through the system.
The O2's new PA system perfectly meets Plihal's motto, "to be prepared for all". "We have one of the best arena acoustics, with a reverb time of less than two seconds," he says. "The Nexo cabinets have been positioned to minimise the small reverberation problems we get from the glass-fronted VIP boxes. We expect excellent audio for speech and music, and the implementation of the emergency system is the most important thing."
(Jim Evans)
