A most congenial place
Nov 1, 2000 12:00 PM, Joyce Jorgenson
Sophisticated, flexible audio solutions come to the Victorian Arts Centre's Melbourne Concert Hall.
When the Melbourne Concert Hall was built in 1982 at the Victorian Arts Centre, its interior was created by John Truscott, a native of down under whose set design for the film classic Camelot earned him an Academy Award. Then, 14 years after the concert hall opened, John O'Donnell came to the Victorian Arts Centre as its resident sound designer and brought with him the notion that audio in the room should be every bit as sublime as Truscott's inspired surroundings. The 2,800-capacity venue, however, with its three-tiered balconies, 80 ft (24 m) ceilings and cement walls, presented a disenchanting mix of acoustical problems that eventually proved to be too much for the facility's aging sound system.
"The speaker clusters had been hung from the ceiling, 40 feet (12 m) above the stage floor, and simply weren't big enough, rolling off at 160 Hz," said O'Donnell. "This resulted in massive cancellation from reflections off the ceiling, which rendered the overall sound muddy and indistinct. In addition, the walls added a tremendous amount of low reflection, but did very little to bring sweetness to the sound."
As a way of remedying the situation, O'Donnell launched a $700,000 quest in 1997 to produce a technically excellent sound system that could handle the broad-ranging musical requirements of contemporary pop, rock and roll, classical, opera and symphony orchestral performances.
"First and foremost," said O'Donnell, "the goal was to achieve the highest level of audio quality. Secondly, we wanted to provide our visiting artists with virtually everything they needed in terms of equipment, so they could essentially arrive here from anywhere in the world without having to worry about packing a single piece of gear."
As one of the five main venues managed and operated by the VAC currently under O'Donnell's care (his domain includes three theatre venues and the 15,000-seat Sidney Myer Music Bowl), the Melbourne Concert Hall has long been one of its biggest attractions, renting out at $12,000 per day and drawing acts ranging from Elvis Costello, Joe Jackson, George Benson, Jethro Tull, and k.d. lang to the Australian Chamber Orchestra. With the new sound system in place, it is expected that even more artists will be charmed into using the venue, resulting in a significant increase in revenue for the VAC.
Bringing the room's acoustics under control is credited in no small measure to the meticulous design of the main left/right and orchestral loudspeaker systems penned by Roger Gans, who specified a wide assortment of high-quality, self-powered loudspeakers from Meyer Sound Labs. In 1997, O'Donnell visited the United States to meet with several designers experienced in large concert venues, one of whom was Gans, who had served as sound designer on world tours for Pavarotti and other famous tenors, and has retained the title of resident sound designer for the San Francisco Opera House for the past 20 years.
When O'Donnell first met with him, Gans' sound system design for the San Francisco Civic Center had just been implemented. It was an experience for O'Donnell that confirmed the viability of amplified classical music. "Although the San Francisco Civic Center is a bigger venue than ours, it is similar in that it has some very difficult acoustical challenges to contend with," O'Donnell said. "Based upon his work there, I felt that Roger was definitely the person to help us achieve the same high level of sound quality at the Melbourne Concert Hall."
1998 marked the year in which Gans was officially commissioned by the VAC to provide the conceptual design of the left/right and orchestral loudspeaker systems for the Melbourne Concert Hall. At the same time, Bob McCarthy, a specialist skilled in the use of Meyer Sound's SIM System, was also enlisted to manage system tuning chores upon completion of the installation.
Taking into consideration the room's acoustical shortcomings, there were two main objectives at the outset of the design process. One was to project the low frequencies into the room rather than allow them to excite the cavernous space above the 49 ft (15 m) stage. For this, Gans specified Meyer Sound's PSW-6 cardioid subwoofers. Second was to distribute the high-frequency energy evenly throughout the room, for which he designated delay clusters consisting of Meyer CQ-1, CQ-2 and PSW-2 subwoofers. Situating the subwoofers on a delay 66 feet (20 m) downstage allowed the sub-bass to reach the tops of the balconies.
Primarily used for contemporary and amplified concerts, the main left/right loudspeaker system is composed of high-powered arrays flown above the stage. Each of the two arrays uses four Meyer MSL-4s, 1 CQ-1, two DS-4Ps and two Meyer PSW-6 subwoofers flown in sub-bass positions.
The orchestral loudspeaker system consists of a central loudspeaker cluster, outside delay clusters and one central delay cluster. The central cluster uses three Meyer MSL-4s, two CQ-1s, two UPA-1Ps and two UPA-2Ps, all of which are flown above the stage. The MSL-4s form the top tier with a 30ø splay between each box. Below that are the two CQ-1s splayed at 70ø and down-tilted to provide even coverage of the room.
Flown beside the CQ-1 on either side is a UPA-1P and UPA-2P. The UPA-2Ps fire perpendicularly to the MSL-4s to cover the section of the balcony that is closest to the quasi-wraparound stage, while the UPA-1Ps cover the choir seating area on either side of the stage. Within the central cluster, one matrix mix goes to the MSL-4s and CQ-1 and CQ-2s, while a second matrix mix goes to UPA-1Ps and UPA-2Ps, allowing them to be switched off if the choir and balcony seating areas are not in use.
Each outside delay cluster uses one CQ-2 stacked atop a single PSW-2 subwoofer, while the center delay is made up of one CQ-1 and one PSW-2. The CQ-1's 80ø dispersion works well to distribute the sound to the balcony's wide center seating area, while the CQ-2's narrower 50ø pattern allows the sound to hit the walls as obliquely as possible to avoid time-delay errors while providing ample coverage to the outer seating sections.
"This was the premise of the entire design - to maintain specific coverage from each speaker and keep the sound away from the walls," said O'Donnell. "In this fashion, direct energy levels remain high while reverberant energy was kept at a minimum."
Within the orchestral loudspeaker system are three rings of eight UPM-1Ps positioned at stage front, under the lower balcony, and under the upper balcony, which serve as delay speakers to fill-in areas shadowed by balconies. There are also two Meyer PSW-6 subwoofers providing discrete sub-bass that are flown left and right at the same height as the central cluster.
Recounting his initial visit to the site in 1998 to survey the situation, Gans said that to achieve such a broad range of audio requirements, there were a number of aesthetic, financial and acoustic issues to address. The most practical way to go - and the one he is most fond of these days - is to encourage people to become more empowered by thinking of the sound system as a tool.
"It's more valuable to the client if I train him to deal with the system in terms of fine tuning and aligning it, so he can continue to receive the most of what it has to offer," Gans said. "Critical to this concept, of course, is his knowledge of the Meyer Sound SIM system. I prefer to take this approach rather than come in, design the system, then lock it up and leave.
"Once the house audio staff has a comprehensive working knowledge of the system, if a visiting production crew wishes to use a rear-projection system, and cluster heights need to be changed, or they want to add larger side stacks, hanging clusters, or integrate their own production equipment within the concert hall, they can easily deal with these changes themselves. Rather than guess, they're be able to realign the system themselves for optimal performance.
"Using the Meyer self-powered loudspeakers and highly-focused EQ, they can build onto the system and continue to experiment and refine it with different arrays, clusters, and coverage angles. I've found this to be a philosophy that clients embrace, one that allows them to become self-sufficient in running the venue."
Within the concert hall's input scheme, in addition to the FOH console, all mics are patched into a rack of BSS active mic splitters which lead to a Harrison 32-channel in-line broadcast console found in an Australian Broadcast Commission studio located within the venue. Another isolated feed of all mics is sent to O'Donnell's own dubbing suite for multitrack recording and mixdown. The last feed winds up at a Midas monitor mixer for the stage monitoring system.
The FOH console is a 56-channel AMEK Recall by Langly that features eight Rupert Neve modules, four stereo line input modules, virtual dynamics on all channels, Showtime 5.3 software, and dual linear power supplies with diode switch-over. Two ancillary racks are located adjacent to the AMEK. The console and racks can be moved to accommodate three different mix positions - the enclosed control room overlooking the venue (when noise isolation is a critical issue), the rear of the center seating area for contemporary, rock and other high-level shows, or to the rear of the dress circle seating area. The latter is a good position for lightly reinforced performances, requiring the removal of only 10 seats for reduced financial impact on the promoter.
Other gear kept at hand includes the venue's notable collection of Neumann U-47, U-48 and U-67 vintage mics, each worth upwards of $10,000, plus a number of other Neumann, AKG and even several Octavia mics from Russia, which O'Donnell describes as quirky and interesting. For outboard processing, there is a wide range of high-quality Lexicon, TC Electronic, Roland, dbx Professional and BSS products from which to choose. For recording and playback, the concert hall stocks a Sony PCM 2700 DAT machine, Sony MDS-E11 Minidisc, Sony CDP-D11 CD player and a Tascam 122 MKIII cassette deck.
From the outputs of the FOH console, signals travel to the first outboard rack and then terminate at an XLR patch field which facilitates processing of the PA. The second outboard rack at the FOH position houses effects, compressors, and dynamics control.
Distributing processed audio on a systems-wide basis was a job left to a Sound-web network implemented by VAC sound engineer Patrick Shek. Using a PC and Soundweb Designer software, Shek programmed all system devices and routed the audio signals.
Each single rack-space Soundweb unit has eight analog inputs and eight analog outputs as well as a digital Ethernet buss. Each provides its own processing power, so adding DSP power to the system is as easy as simply linking another unit. Processing for devices can be started on one Soundweb and finished on another, the result being unlimited DSP, which can be configured to suit the application at substantial cost savings. With the Soundweb network in place, the house PA can be controlled via computer from the control room or any point in the room with a Soundweb 9010 remote.
O'Donnell pointed out that an added advantage of the Soundweb in the Melbourne Concert Hall design is that it enabled them to place two units in the ceiling to control the center delay loudspeakers. Via 656 feet (200 m) of Ethernet cable, the digital signal travels to the ceiling units where they are converted to analog before going to the loudspeakers.
"It's a much nicer way of distributing audio over long distances," said O'Donnell, "providing us with a 300 m capacity of 48K, 24-bit digital audio with 1.5 km driving capacity between each Soundweb unit.
"Because the Meyer loudspeakers are all self-powered, we're running line-level audio to each loudspeaker. The chance of picking up noise when traveling 300 m is quite high, so running a total of 16 digital channels is a major advantage. From the perspective of cost, it's much more effective to use 16-way multi-cord rather than pulling multiple cables. From a purist view, it's much nicer to break it out to analog at the speakers, which produces a much cleaner sound."
As an example that further illustrates the system's flexibility, the left/right console output driving the main and right loudspeaker systems is sent to a Klark-Teknik 1/3-octave EQ to give visiting sound engineers the option of doing their own equalization of the system. From the K-T EQ, the signal goes to a Meyer LD-1A line driver where it is split and routed back to the first Soundweb module for specific time alignment and equalization of each and every pair of loudspeaker enclosures in the main left and right arrays.
The eight matrix outputs of the console drive the orchestral system, which consists of the central cluster, the three delay clusters and the rings of fill loudspeakers. Again, all have their own Soundweb path, going to various units depending upon their specific function requirements and each Soundweb unit's available memory capabilities. All matrix outputs are patched through a SIM System II interface, which has its own dedicated Soundweb. The delay and EQ settings from this Soundweb are then copied to the other Soundweb modules and permanently programmed with specific parameters for their respective loudspeakers.
O'Donnell noted that what was important here was that virtually every loudspeaker has its own delay, EQ and amp because it is self-powered. "As a concept, it's as good as it gets," he said. "Our ultimate goal was to obtain plus or -3 dB coverage in the entire room. With the large variation of SPLs, it was our driving force to make it even throughout."
All loudspeaker arrays were hung using Meyer FlyWare rigging. Each one, including the small delay clusters, has its own 1,000 pound (450 kg) load-style motor, each of which was designed and patented by VAC Structural Engineer Ian Mesner. Installed in the ceiling space, the motor never leaves its position, only the chain, which is attached to the Meyer FlyWare. The rigging system actually takes the weight of the motor off the chain, so the cluster is no longer relying in any way on the motor for support. Controlled via a radio remote control device, the motors can be serviced in the ceiling without having to remove them.
SIM alignment was performed by Bob McCarthy, who began the positioning, EQ, level and delay process by checking the final loudspeaker locations, height and aim points. First, the loudspeakers were measured in their original positions, and then determinations were made as to what worked most optimally until all positions were fine-tuned. The next step was equalization of each individual sub-system, followed by respective level settings to obtain the most uniform response from top to bottom of the hall. Finally, all delays of the individual sub-systems were set to ensure that transition points between the loudspeaker positions were as seamless as possible.
McCarthy said that it was actually a five-part process in total; however, the first part involved changing the architectural acoustics of the room. "In a symphony hall, that's an option you don't have," he said. "The outstanding thing about this particular installation is that the sound system offers us just the right amount of flexibility to allow the loudspeakers to be repositioned to optimal positions for virtually any application, and we have enough electronic control to separate every part of the system and then perform separate equalization and delay settings. The unique rigging of the clusters also made it easy to remotely reposition the speakers vertically and horizontally within 15 minutes."
McCarthy went on to say that the system as originally installed would have far exceeded the quality standards for comparable venues. "Already running 90% of its potential," he said, "the SIM alignment process allowed us to get that very challenging last 10% out of the system."
The moment of truth came on the evening of April 29, 2000 when the Melbourne Concert Hall presented the Australian Chamber Orchestra. Narrated by Peter Garrett (of Midnight Oil), the program included the text and images of Michael Leunig and a palette of sounds from the works of Prokofiev, Saint-Saens, Bryars, Grainger, and Steve Reich.
"Under normal circumstances, this small orchestra onstage wouldn't have had a chance of making it to the back of the hall with a single-string bass," McCarthy said, "but sitting behind the last row of the balcony, that string bass was right there in my lap. A thinking person would look at the instrument 120 feet (37 m) away and reason `this can't be happening', but it was. That's very impressive."
"We are very happy with the outcome and proud of the fact that there wasn't one single wiring error in the entire system," O'Donnell said. "When one of the Australian Broadcast Commission engineers heard the sound, he was amazed at the quality. The ovation goes to Roger, Bob and the entire VAC staff, who worked so hard to make it so. All things audio considered, this is indeed a most congenial place."