The Heart of Brisbane Pumps with EV XLD
May 17, 2006
Brisbane City Hall was constructed during the 1920s at a cost of 980,000 pounds. The building was officially opened on 8th April 1930 and at the time was considered to be amongst the great structures of the Commonwealth, ranking second only to the construction of the Sydney Harbour Bridge. The heritage-listed City Hall is seen as the heart of the City of Brisbane. The interior of City Hall has been refurbished and is used for an array of community and commercial activities. The main auditorium is a popular venue for various cultural and business events. It can seat up to 1500 guests theatre style and 850 banquet style. It is the largest room in City Hall with an area of 849 square meters. Its circular design with large fluted columns is based on the Pantheon of Ancient Rome.
In April 2005, the project to upgrade the auditorium’s sound system went out to tender. Scientific Acoustics’ Peter Patrick managed the process. “We had around eight tenderers. There were submissions put together from all points of the compass,“ commented Patrick.
“The new sound system delivers very good speech intelligibility over more than 85% of the audience and excellent fidelity over all of the audience. The coverage is even as might be expected with no hot’ spots.”
Brisbane City Hall’s cylindrical shape produced a number of focal points and some interesting challenges in terms of acoustic design. “It was very difficult to hang heavy equipment in the building due to the ceiling construction,“ Patrick reported. “This made it impossible to hold a shoot-out, so I set holding the first shoot-out in a 3D software model. As soon as my spec hit the designer’s tables I started getting phone calls telling me “this is impossible!’. It turned out that the loudspeaker data I’d used as a benchmark was faulty so the complaints were correct! I not only had to re-look at the whole specification but also sift through all the tenderer’s information to eliminate bad data.“
The performance criteria were very specific. The intended uses of the room ranged from theatrical performances through to jazz and orchestral events. Most importantly, clarity of speech and quality of sound were the prime objectives that needed to be fulfilled. “The goal was to deliver high quality sound to every seat, but such an acoustically-challenged room presented many issues,“ commented Bryan Davidson from APAC Audio. “We worked with the EV Tech Support team in Burnsville, Minnesota to address them precisely. The initial LAPS (Line Array Prediction Software) designs we worked out to rough-in aiming angles were imported into an EASE model, where further intense calculations were performed over the ensuing weeks.“
“The application called for a compact line array, and it just so happened that Electro-Voice had released their XLD Compact Line Array system at that time. APAC Audio launched the XLD in Melbourne and I was so excited by the system that I took measurements on axis, underneath it and to the rear of it, finding that typically the differences between the front and rear of the line array were in the order of 10 dB,“ enthused Davidson. “These tests, combined with the results of the EASE simulations, reinforced that the XLD system was the best solution for this project.“
The next difficult task was to convince the consultant-by way of the simulations-that the XLD system would do exactly as predicted. “We supplied total SPL and direct SPL maps at various frequency bands, including the stage area,“ Davidson added. “This was very important, as we had to make sure that we were at least 6 dB down on stage, which we were. The key to the success of the XLD system is in the way the Americans have designed it. Basically there are two eight-inch drivers in the cabinet, with a hydra high-frequency aperture in the center. But unlike most other ’me-too’ line arrays that are out in the market, each woofer has its own crossover section and then the high-frequency attached to that. The second woofer then becomes like a steering woofer and also helps to reinforce the low frequency energy.“
The tender closed in May 2005, and it was Peter Patrick’s job to sort through the submissions. “There were a couple of things about the EV that I liked,“ commented Patrick. “One was its articulation, another was its small size. Plus it delivered the best results. We needed two things in the line array, (a) wide dispersion and (b) good articulation at the hinges. The EV was the best compromise that I could see from the data! There were others with wider dispersion and even some with greater angles available, but the EV’s small height per cabinet, wide and very even dispersion, and 10-degree hinge limit, all factored in the decision. It was a very difficult process but well worth the effort in the end.“
The design was completed with Electro-Voice Precision Series Remote Control amplifiers. Ten Electro-Voice P3000 RL’s and one P900 RL were used, each with full DSP on board allowing the system to be remotely monitored and controlled.
AudioVision Pty Ltd (formerly DR Audio) was the successful contractor selected to install the system. “The new Electro-Voice line array speaker system provides major improvements in dispersion and sound quality over the audience seating (in the balcony and main floor) and being able to provide stereo to a large percentage of the audience is a bonus. The amplifiers provide DSP system setup and constant monitoring of the speaker performance which is beneficial for maintenance,“ commented David Riddell, Managing Director of Audiovision Pty Ltd.
Extensive testing post-installation has been carried out and the following is an extract from Peter Patrick’s commissioning report: “The new sound system delivers very good speech intelligibility over more than 85% of the audience and excellent fidelity over all of the audience. The coverage is even as might be expected with no “hot’ spots. The physical articulation of the [Electro-Voice XLD] arrays and the accompanying sound dispersion characteristics make full advantage of a low altitude suspension height. The lower suspension height has eliminated the need for under balcony fill speakers and minimized echoes from building architecture reaching the listening areas.“
A number of functions have been held in the main auditorium since the upgrade and the feedback has been excellent. “It’s so much better than what was there before and everyone’s quite pleased with it,“ commented Terry O’Sullivan, Brisbane City Hall’s Engineer.
22 x Electro-Voice XLD 281
4 x Electro-Voice XS 212 subs
4 x Electro-Voice XLD grid
2 x Electro-Voice C-Beam
10 x Electro-Voice P3000RL remote control amplifier
1 x Electro-Voice P900 RL remote control amplifier
1 x Electro-Voice UCC1 control interface
5 x Electro-Voice Xi1082 loudspeaker
5 x Electro-Voice MB1082 mounting bracketshttp://www.scientific-acoustics.com.au/ http://www.audiovision.net.au
Electro-Voice (EV), is a professional audio brand of Telex Communications, Inc., a leader in the design, manufacture and marketing of sophisticated audio, wireless, multimedia, aircraft, broadcast and communications equipment for commercial, professional and industrial customers. Telex Communications markets its products in more than 80 countries under the brands EV, Telex, RTS, Dynacord, Midas, Klark Teknik and others.
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