The Union, founded in 1823, is Britain's second oldest Debating Union. The Chamber itself was designed by Alfred Waterhouse in 1878, and today it has a Grade II* listing. With a seating capacity of 450, for the first time it recently took delivery of a Harman Pro integrated sound system, provided by local multimedia specialists, City AV.
Their MD, Peter Gunn, has been providing the Chamber with temporary PA equipment for these high profile events for many years. But as Bursar Lindsey Warne points out, with its growing commercial use, and increasing requests to stage corporate, conference, exhibition and wedding events, it made sense to have a permanently installed system.
In designing the sound system, CAV's team were confronted by numerous challenges - not least being that they needed to meet the Listed Buildings Consent requirements. "Acoustically, the building is an interesting shape," notes Gunn, "and this affects the seating. Downstairs at the front, the benches are facing each other, while at the back they are front facing - whereas up on the balcony there is an audience wrapped around all four sides. The geometry couldn't be more difficult.
"Also, the technical solution had to go hand-in-hand with one that was visually acceptable to the listed building people." Part of that meant that the speakers had to be hand painted to blend invisibly into the rich colour of the walls and not impact on the woodwork, which had to remain a feature. The enclosures also had to be positioned at a height where the line array would be effective but equally unobtrusive.
City AV were supported by Hugo Burnard from Sound Technology's Project Team, who conducted a site visit and conducted EASE measurements. "We worked on several different options but the final option was tweaked to satisfy all the Building requirements," notes Peter Gunn.
The eight CBT50LA speakers wall mounted downstairs are in four clusters of two down each flank, whereas up on the balcony a further eight CBT50LA are spaced individually around the perimeter. It is a generous complement of sound reinforcement tools, but as Peter Gunn says, with so much inherent echo and room reverberation, they are able to drive these at low level from the Crown XLS 1000 amps and minimise any reflections. Standard JBL brackets were used to fix direct onto the masonry.
The package also includes a BSS Soundweb BLU-100 network, featuring fixed format 12-in/8-out. This contains two different presets and has been set up for standard usage by non-skilled personnel. Guest speakers requiring a microphone are given a choice of AKG WMS470 Presenter Set and two GN155 (155cm tall) floor standing gooseneck mics (fitted with CK33 capsules).A further four AKG tie-clip mics will also be added so that roving speakers, wishing to wander into the audience, will be well catered for.
Summarising the installation, Peter Gunn says that the facility now enjoys a lot of flexibility - including a Soundcraft EPM-8 mixer in the portable rack for manual mic mixing and two 4-aux inputs, one on either side of the bench, running Cat 5. "Oxford Union is learning that the system can actually do a lot more than they anticipated," he said, "and that's because we have a lot of experience and knowledge of this particular facility."
(Jim Evans)
