At the end of November 2014 at VDNKh (the former site of the USSR Exhibition of Economic Achievement, long-since dismantled - Ed) the world's largest ice-rink was opened. The total area of ice on this artificial rink covers more than 20,000 square metres. The shape of the rink traces a fairy golden key, and covers the entire central area of the VDNKh site near the Central Pavilion. Ice tracks run around the Friendship of Peoples fountain complex, right up as far as the Stone Flower fountain. The acoustic systems for the rink were designed and installed by the Moscow company Prioriti. Our correspondent Denis Dubrovsky talked to the head of Prioriti Denis Afanasyevabout the specifics of this sound system installation.
Denis Dubrovsky: Can you tell me, what the technical challenge here involved?
Denis Afanasyev:At this ice-rink we had to arrange three sound zones, so that each could have its own separate music simultaneously for events, with no cross-over. The first zone is an ice area with tracks for extreme skating. The second and third zones are a children's rink, and a hockey rink. The system had to be extremely simple to operate, so that no training would be needed for whoever was operating it. It had to be usable with any kind of sound source attached to it, or any microphones. We also had to set up several quick-start sound regimes – speech, background music behind speech, and music. Of course, the system has to be very durable and resistant to very low temperatures, while delivering top-quality sound, and looking good too!
Denis Dubrovsky: So, the sound system for the main ice rink, plus zones for extreme skating too – that must have been the hardest job?
Denis Afanasyev:That's right. There are 109 loudspeakers installed in this zone, at an average distance from each other of 20 metres. It took nearly two kilometres of cable to connect them all. Some of it goes above ground in special hosing for electrical cables, while some of it goes under the ice. We had to create a seamless sound-zone with no 'acoustic drop-out' zones, or reflection or delay – the listener should always been in the 'sweet zone' for listening.
Denis Dubrovsky: What loudspeakers did you use in this project?
Denis Afanasyev: We used all-weather speakers from American manufacturers Bose Panaray series, guaranteed to operate in a temperature range from -30 to +60 Celsius. Panaray 402 a 120-watt system supplying the sound on the main ice rink and the extreme-skating tracks. These speakers have a fixed output gradient of 120 degree horizontally, and 60 degrees vertically. We angled them pretty sharply upwards, so there wouldn't be any sound reflection off the building. The loudspeakers are sited four metres off the ground, and we angled them roughly 30 degrees upwards. There are eight Panaray 802 speakers at the children's rink.
Our choice of the brand of speakers was pretty-much decided ahead of the start, because we'd had excellent experience with their performance in extremely low temperatures. In addition they have active equalization, which enables the engineer to adjust the frequency response with little difficulty. They are very easy to install. And another plus point is aesthetic – they look great, and customers like them, And of course, they give a comfortable and balanced sound.
Denis Dubrovsky: Are there any problems with sound bouncing off the ice?
Denis Afanasyev: No, there aren't. Well, of course there is sound reflection - but it's not a critical problem in the listening area. It's simply not discernible.
Denis Dubrovsky: What computer program did you use for designing the sound system?
Denis Afanasyev: We did the acoustic analysis using Bose Modeler. We uploaded the project, and then tested a whole library of loudspeakers until we found the right solution.
Denis Dubrovsky: What amplifiers and processors are used in the project?
Denis Afanasyev: Bose PowerMatch 8500 eight-channel amplifiers, 8 x 500 watts. We created 14 lines per 1000 watts. The amplifiers for the hockey field, the big skating area and the extreme-skating zone are in the main hardware, but the amplifiers for the children's rink are in a second unit. All the amps are linked to the local network and can be operated from a central control-board.
We've got two sound-processors Вose ControlSpace ESP-00 and Вose ControlSpace ESP-880 in the system. The first one is highly scalable, and has the facility to install extra expansion cards – while the second one is a more budget option. All the sound plugs are analogue, while the outputs that connect to the amps are 8-channel optic.
Denis Dubrovsky: What were the hardest things when setting up this project?
Denis Afanasyev:Well, the biggest difficult was the huge central skating area and the Friendship of Peoples fountain – there are lots of buildings around, which means a lot of reflected sound. Another is the main rink which is very long, and this means long communication lines, big distances between the loudspeakers. And the second problem, of course, was the extremely short time-frame in which everything had to be done. In all we had a month to do everything.
The third problem was that there was a huge number of contractors working on the site, and quite a few of them happily ignored the work the rest of us were doing. For example, they sliced-off our cables quite a few times, or put self-tapping screws right through our cables. It meant that we had to do emergency repairs to solve completely unnecessary problems and restore the operability of our system. But all our guys are highly qualified, and we managed to get everything done on time.