Forsyth Barr Stadium


Forsyth Barr Stadium Forsyth Barr Stadium

"Due to the interesting architectural features of this venue the audio design had to be carefully modified to work in with the architects vision."

CASE STUDY: STADIUM AUDIO SYSTEM


On 9 August 2006, a proposal was announced that would see Carisbrook (branded with the name "The House of Pain", due to its reputation as a difficult venue for visiting teams) retired and a 30,000 capacity covered stadium built in Dunedin North, close to other major sporting facilities such as Logan Park and the University Oval. Construction and ownership of the new $198 million stadium, officially named the Forsyth Barr Stadium at University Plaza, was overseen by the Carisbrook Stadium Trust.


After a rigorous tender process Strawberry Sound was given the green light on the Sports Lighting Control, Television Distribution and, of course, the sound. Mike Pearce company director states "This is a big task and one we are extremely proud to be involved with. For more than 25 years Dunedin has been home base for Strawberry Sound and we look forward to spending the next 25 years here, supporting Otago and the Highlanders. Watching the game under the lights and enjoying the show.”


Forsyth Barr Stadium is the world's only permanently covered stadium to boast a natural turf playing field, designed by leading architects and incorporating a space-age transparent roof. The roof does not degrade under ultraviolet light or atmospheric pollution, and its perfectly smooth surface is ‘self-cleaning' and dirt is unable to stick to it and is washed away by rainwater.


But enough about the roof, what about the sound you are asking.


The consultant specification for Dunedin Stadium was very specific with the system design covering four stands, five lounges and 21 corporate suites. The PA/AV system had to provide a main sound system covering all public spectator areas. This system had to support public address functions, sound reinforcement for a small band with one or more vocalists and playback of music and other programs. It needed to have good uniformity of direct SPL and frequency response and of course very good speech intelligibility. Crowd ambiance to be fed to enclosed boxes and suites. The PA system needed to feed an official scorers and media area. A distributed sound system which can selectively relay the main sound system out to concession areas, member areas, function rooms and other public areas. The signal processing was to be distributed using the industry standard CobraNET protocol. This audio specification was eventually scaled back to the North and South stands only due to budgeting constraints.


The final design included a mixture of the JBL PD5212-95 Series loudspeakers and the smaller AE Series AM7215-95 cabinets as they both supplement each other. The PD5000 Series loudspeakers deliver high power and constant coverage in a low profile form and feature the 24 x 24” PT™ Progressive Transition mid-frequency rotatable waveguides that offer excellent pattern control with low distortion and extremely natural sound character. BSS Soundweb BLU-160 Signal Processor and BSS BLU-120 I/O expander for all audio processing, and Crown CTs2000 and CTs1200 amplifiers with IQ3PIPLITE cards for network control of the amplifiers. Shane from Strawberry Sound was very impressed with Soundweb "The boxed worked first time when plugged in. Obviously there was complex programming involved but from a networking perspective it was very straight forward."


Jpro learnt that regular jet-spray water blasting to clean the underside of the roof was to be carried out therefore it was deemed prudent to change to the WRC version of loudspeakers (WRC = Weatherised for Covered use outdoors), which carries an IP-55 rating per IEC (referred to as "jetspray-proof”), and includes stainless-steel hardware.


The architect preferred the speaker clusters to be aligned with the main roof trusses, which was different to the original specification and meant reducing the amount of clusters. However the coverage of the sound system could not be affected. So further acoustic modelling was carried out to check the impact of relocating the main bowl loudspeakers on the North and South Grandstands.


The North stand was originally specified with 8 x clusters of single loudspeakers, to accommodate the architect request this was re-designed with 5 x 2 speaker clusters using JBL AM7215-95-WRC boxes. The clusters were mounted directly to the lighting bars using custom brackets. The internal roof height and a dizzying 37 metres and was designed to allow plenty of room for rugby balls to be kicked and all kinds of high-flying action to take place underneath. Shane from Strawberry comments "The trickiest part of the whole install was installing the speaker clusters in the north stand. We had to hoist over 100kgs of speakers more than 30m in the air and then secure them in place”.

INTEGRATOR

Installed and programmed by Strawberry Sound: Strawberry Sound has been involved in commercial contracting for over 20 years. Working on most major building projects in the South Islands recent history including Christchurch Woman's Hospital, AMI Stadium, the Queenstown Aquatic Centre, Dunedin Airport, and the Dunedin Stadium to name a few.