Case Study: The Ceremonies Audio System Design At The London 2012 Olympic Games

Venue Geometry
The venue is relatively simple in its shape and remains consistent. There are three design features which interrupt the consistent upper and lower bowl profile; the north and south video screen locations and the west side middle bowl.

The basic approach was to use consistent flown and stacked arrays throughout the design to avoid variations in vertical pattern control.

This approach suited two thirds of the stadium perfectly, however I expected that the west middle bowl would require unique processing to deal with change in the profile. This would be dealt with during the tuning and commissioning process.

Flown Line Length
To achieve a consistent listening experience throughout the upper bowl each array required 10 V-DOSC elements. At over 4.5 meters long, this quantity of V-DOSC also provided the line array length required for useful low frequency pattern control.

The vertical consistency can be seen, which was duplicated at all array positions around the stadium. The screen shot below shows the vertical consistency of the upper and middle bowl from the V-DOSC array.

Selecting 22 arrays allowed us to provide the best balance between providing a stereo listening environment and avoiding too much overlap and damaging intelligibility. The number of arrays also worked with the geometry of the tension ring system.

(click to enlarge)


L-Acoustics SOUNDVISION
With all 22 V-DOSC arrays designed the athletics requirements needed to be addressed. The V-DOSC provided excellent coverage for the upper bowl and for the upper and middle bowl on the west. The flown arrays required extending to provide lower bowl coverage.

We had planned to run the V-DOSC with a more full range preset for the athletics given the lack of subs, and perhaps change the system EQ to extend the frequency response. This approach provided plenty of 40 Hz to 80 Hz for the lower bowl so the downfill could be a two-way product which helps in terms of amplifier count and total system weight.

Conveniently, at approximately the same time, L-Acoustics launched the ARCS II constant curvature line source that both had the power we needed and provided the coverage required with only a pair of cabinets. The addition of a pair of ARCS II cabinets to the flown systems provided excellent down fill coverage for the entire lower bowl.

Stacked Arrays
The ground stacked arrays, pictured below, consisted of four KUDO and four SB28 each. KUDO is low profile enough to fit four elements in an acceptable vertical height.

The design intent behind the long horizontal line of SB28’s was to create an array with horizontal pattern control. Controlling the vertical pattern was not of interest, the goal was to minimize the number of sub-bass sources audible at any listening location to improve the impact and clarity of the system. The approach was very successful and one that I will definitely be using again.

Filling The Gaps
The loudspeaker system is designed around the venue geometry, yet inevitably there are parts of the overlay such as staging, camera platforms and scenery that creates acoustically shadowed audience areas. The original design predicted this, and eight 12XT loudspeakers were available to be deployed as required for each Ceremony.

System Installation
The rigging method and suspension concept for the system was devised by Jeremy Lloyd (technical manager, staging and design). All 22 arrays were installed over a four-day period.

The custom rigging for the V-DOSC and the ARCS II down fill consisted of a bumper, a vertical spine, lighting ladder and ARCS attachment. All parts locked together to form a rigid structure which supported the V-DOSC from top to bottom.

Testing the LA8 amp/controllers prior to the games. (click to enlarge)

Amplifier Installation
The London Olympic Stadium has a catwalk just above the edge of the roof which runs the full circumference of the roof.

Various rooms were built over the catwalk to house technical facilities such as automation control, power distribution and audio network nodes.

The placement of the amplifiers was loosely based around the network node layout, but the most important factors were minimizing the loudspeaker cable lengths whilst ensuring weather protection of the amplifier racks.

Ultimately all speaker cable lengths for the flown arrays were 50 meters and all amplifiers were well protected from the daily London downpour.