18th October 2000 - Technical Visit to the Millenium Dome

About 25 AES UK members met at 09:45 at North Greenwich tube station eagerly anticipating an interesting Dome visit; we were not disappointed. Roland Hemming, the audio director for the New Millennium Experience Company, came to meet us and began a very interesting tour. He started with some statistics: 15,000 dome visitors every weekday, 35,000 on Saturday and Sunday. This is rather more than visit Paris Eurodisney. The sound installation has over 800 items of BSS Audio Soundweb equipment, and over 8000 loudspeakers. The Dome sound system is the largest Soundweb installation anywhere.

We then visited the audio nerve centre, which was behind an unmarked door down an unmarked corridor. Apparently, this is to deter any potential thieves! There are 15 zones in the dome. Each one has its own local Soundweb based digital audio network. Each of the zone networks is itself attached to a backbone network which is set under the floor in the dome. The control room has a giant diagram on the wall which shows the whole system. This reminded me of the kind of diagram one can see at power station control rooms or train network control rooms. From the control room computers, any sound source can be "connected" to any loudspeaker. During opening hours, there is always one or two audio engineers on call in the control room. The engineers form a rapid response team to fix any audio problems very quickly.

Each zone has a rack of audio equipment consisting of a Soundweb network interface, one or more removable hard disk recorders, amplifiers and other equipment. Most zones have audio tracks associated with each exhibit. These audio tracks either repeat over a specified time, or have some interaction with the viewer of the exhibit. The sound tracks were provided by the creator of the zone, and then edited by the dome audio engineers to create the final sounds you hear today.

One of the zones is called "Our Town". Unlike most zones, this changes every day. 250 towns in the UK have been chosen to create a performance on the "Our Town" stage. The performance has to indicate the past, present and future of the town. Some performances are musical, others are plays. The big audio challenge here is that each town gets a video of their performance. This is professionally done, however the performers are amateurs, usually from local schools in the featured town. So the audio engineers have to be very flexible, with each day being different.

There are also two identical radio studios. These are sound-proofed, and have separate interview and control rooms. They are used by local radio stations which can broadcast from the Dome. This is especially useful when a particular town is performing on the "Our Town" stage. Often, the local radio station will run the entire day's programming from the Dome.

The central show is the highlight of a dome visit. There is an enormous central, moving, loudspeaker stack, along with a ring of loudspeaker stacks set just behind the audience. Even further behind the audience is another ring of loudspeaker stacks to provide ambience. Each of these loudspeaker stacks is digitally connected to the central show Soundweb network. The loudspeaker cabinets are made from a special moulded material which is light and very stiff. The low weight is needed because of the weight limitations on items suspended from the Dome roof. Each loudspeaker stack has its own D/A converters, along with PWM and conventional amplifiers.

In most public facilities, the emergency announcement system is separate from any other audio system. In the Dome, the emergency announcement system uses the same loudspeakers and networks as the rest of the audio. This is to minimise the visual distraction of having separate emergency announcement loudspeakers. To satisfy safety rules, the loudspeakers and network system has to be fully autonomous, even during a power failure. Each audio equipment stack has its own battery powered backup supply system. This is capable of keeping the audio system up and running in the event of a power failure.

I think all the attendees had a most enjoyable morning, and hopefully enjoyed the Dome for the rest of the day. I was very impressed by the professional approach and enthusiasm of Roland and his team and I would like to say a big thank you to them for giving us an excellent tour.

Steven Harris