Martin Van Dijk, partner and director of Toronto consultants Engineering Harmonics, who has been involved with Roy Thomson Hall for many years as an aficionado of the symphony, sound engineer, and consultant, knew that what he had been hearing during amplified performances just wasn’t right.

“I could hear predominant acoustic anomalies in that room, but I needed to do a proper survey to determine exactly what they were from a scientific and engineering point of view,” Van Dijk recalls.

Engineering Harmonics has designed performance sound systems for acclaimed concert halls around the world, including the Margot and Bill Winspear Opera House at the AT&T Center in Dallas, Kansas City’s Kauffman Center for the Performing Arts, and Koerner Hall in Toronto.

“We set the bar very high for what we do,” says Engineering Harmonics’ partner and director Gary Tibshirani. “In designing a sound-reinforcement system for any room that has been created to be an essentially acoustic space, it is imperative that we undertake a thorough acoustical analysis before we start down the road to design and specify a sound-reinforcement system. Our goal as consultants is to create a great marriage of acoustics and performance sound, and, like a good marriage counselor, we strive to understand the underlying issues and the tensions that exist between them, as well as those that may arise when they are driven to extremes.”

A square peg in a round hole

“In designing the cluster, we had taken the size of the opening into account from the drawings, but we found, when we went up to the canopy to inspect it, that the doors don’t operate fully open, and the full aperture is not available,” Van Dijk recalls. “Somehow, we had to find a way to squeeze the cluster into a smaller form factor.”

Working with Andy Foord, designer at project contractor and installer Westbury National Show Systems, the team redesigned the cluster through a number of successive iterations to fit the opening. Van Dijk notes, “This was a mechanical 3-D jigsaw rigging puzzle that Andy and his team approached with diligence, resulting in a great solution.”

In the final design, the cluster comprises nine JM-IPs, six UPQ-1Ps, and three UPA-1P cabinets, all arranged in three angled tiers for complete 360° coverage of the hall’s multiple seating levels. In order to fit through the opening, how ever, the wrap of JM-1Ps has been staggered: The faces of the front three share the same arc; the faces of the next pair on each side lie on an arc about 4″ toward the center point of the cluster; and the remaining cabinet toward the rear of each side is rigged a further 4″ in toward the center point, leaving about 4″ of clearance on all sides through the open doors.

“We adjusted the time delay to the front three JM-1Ps in the 0.3ms – 0.4ms range to account for the side speakers being tucked back about 4″,” McCarthy says. The geometry has been further altered in that the two side pairs are each angled downward about 7° and the single units on each side of the cluster are angled down about 12° to follow the line of staggered seating pods around the hall.

“Geppetto would be proud of this design,” McCarthy says. “It retains enough flexibility so that we were able to aim it a few degrees here and there during the tuning when we worked to sort out the real 3-D of this thing, which was quite fascinating. All of the loudspeakers were very tactically planned for their target zones, yet there was enough flexibility that, when it came to the final step of optimization, we were able to turnbuckle and move just a few parts of the structure to get everything to fall where it needed to fall.

“The result is a really fascinating puzzle that gets all the way around 360° and targets all of the vastly irregular shapes that are presented as you move around,” McCarthy continues. “We have every seat covered. The tuning proceeded in a really orderly fashion. From the top center, we wrapped all the way around and got the top row done, and then we moved down to the next level and made the next ring, and then stitched the upper ring and the middle ring together, and then mixed in the lower ring and it just came together like the pieces of the puzzle that we wanted it to be. It was tons of fun. I love a tough one.”

Replacing the original passive loudspeaker system with active units increased the load significantly, and while most of the existing loft blocks could be reused, the drum motors for the winch had to be upgraded and the winch platform reinforced to handle the heavier load.

“The ceiling structure is somewhat like the hub of a wagon wheel, and the challenge is that we’re trying to drop the cluster right through the center of the hub, which didn’t have any spot to get through,” says Doug Wildeboer, Westbury’s project manager. “Instead, we had to create a device in the structural ceiling above the reflector that would bring those loft blocks and the lines around the center hub and back down to the point where we needed them to get it to drop down through that center hole in the reflector.”

Twelve AC circuits were added for the power amplifiers in the active loudspeakers. The original Socapex cabling that had been used to transport the speaker-level signals was reused for power distribution, and a new 12-pair audio snake was installed to feed line-level signals to the individual cabinets. The basket on top of the cluster was redesigned to receive the cabling as the cluster is retracted through the opening.

In addition to the retractable center cluster, left and right stage-mounted loudspeaker systems, each consisting of four JM-1Ps and two 700-HP subs on dolly frames, can be wheeled out from storage backstage and deployed as required.

“Mixers all want a left-right system,” McCarthy says, “so you give them enough of a left-right system to be able to cover the seating area on the floor, and it’s set up to bring the image down and provide a better fill in those areas. It’s not 100% mandatory; technically, you could just about cover everything without it, but it provides some power down to the floor that all mixers are happy to have, and gives them some capability to adjust the ratio of left-right coverage to center coverage. However, once you reach the second floor level and above, as well as the wraparound behind the stage, you’re in the coverage area of the center system.”

Van Dijk explains that when the left-right stage system is deployed, certain loudspeakers in the center cluster are turned off, “to avoid overlapping cancellation. There are presets in the Meyer Galileo 616 loudspeaker management system to select various configurations. For example, the deck loudspeakers alone can be used when the venue is not sold out, since there is no point in energizing other parts of the hall when there are no patrons there.

“Similarly with the center cluster, if there’s an orchestra with a master class, for example, with people only on the orchestra level, then the bottom part of the cluster is turned on and the upper part, which addresses the balconies, is turned off using another preset. If they want to have the image down onstage, they can roll out the deck fills.”

In his site assessment, Van Dijk noted, “The rear area of the orchestra level requires small loudspeakers to fill in the sound coverage that is not directly covered by the center cluster. The current loudspeaker complement is insufficient, resulting in uneven coverage. The coverage could be improved, particularly along the sides, with a greater number of loudspeakers.”

By tripling the number of Meyer UPM-1P underbalcony loudspeakers, he not only improved the coverage, but achieved better localization of the sound source. Each loudspeaker has its own unique processing channel, so delays can be set appropriately for the output of each underbalcony loudspeaker to fall within the Haas fusion zone and integrate properly with the output from the center cluster. The target level of the system is 105dB SPL, A-weighted.

“We used an Optocore fiber optic backbone for signal transport between the front-of-house control area and the Galileo loudspeaker management system, and it’s all AES,” Van Dijk says. “We’re essentially digital right to the output of the speaker processing, where it’s converted to analog.”

Via Optocore, any channel can be routed to any device on the network, and exported as many times as required to any destination, although in practice it is used to deliver performance sound from the Yamaha PM1D front-of-house console to the Galileo processors.

Wiring challenges

A further difficulty facing Van Dijk was that, because this was a renovation and not new construction, “detailed engineering drawings are really a waste of time, because as soon as you get on site and open up a wall to change a cable or conduit path, you may have to do a complete rework. You often don’t know what you’re going to find until you open up that part of the building and take a look.”

What they found was a number of wiring anomalies resulting from the physical renovation of the hall in 2002 when the acoustic reflector was installed over the stage. “When they did that renovation, there was an enormous amount of destruction wreaked on the original sound system signal path,” Van Dijk says. “They literally took sawzalls through conduits containing microphone lines and communications lines, which were later spliced together in junction boxes placed ad hoc throughout the area. We cleaned all that up and pulled new lines for comms and microphones.”

The original backstage and lobby paging system dated from the early 1980s, so an upgrade was included in the current renovation. The original system was, in fact, the emergency evacuation system for the hall, which under current code requirements, must be separated from the house paging system.

“They can be integrated together, but only people with the proper certification can actually touch anything, and there are virtually no AV or sound people with fire alarm certification who have the skill sets needed to manage a real sound system. It’s a very unusual skill set, and certainly the fire alarm people don’t understand the complexity of a modern sound system,” Van Dijk says. He was able to reuse most of the existing loudspeakers in the paging system, while dividing some of the larger zones into smaller areas and adding new microphones, amplification, and a Rane HAL digital distribution system that allowed him to condense two full racks of equipment down to about half a rack.

“The HAL system has a unique capability in that it can run an AES audio I/O interface 500′ on Cat 5 cable, along with serial data,” Van Dijk says, “That allowed us to deploy the very long cable lengths that were necessary in order to get audio and paging into the lobby areas. The building is essentially a concrete bunker, and finding a path for cabling out to the lobby areas that ring the hall is sometimes very difficult.”

A Crestron control system was integrated into the paging system, with touch panels backstage and in the front-ofhouse manager’s office, offering presets for control of routing, audio levels, and paging recall times in the various backstage and lobby areas.

In addition to paging, the front-of-house manager also has been given the ability to program different events in the lobby spaces. Supplementary cabling was required for permanently installed sound systems in two small adjunct performance spaces in the north and south sides of the lobby. Routing that cabling and integrating it into the whole facility presented additional challenges, and because there are only minimal spaces available to route cables to the outer ring of the circular building, cable lengths grew excessive.

When it comes to the appreciation of performance sound systems in symphony halls, expectations are usually very much like the mail – no news is good news. “If nobody says anything, that typically means it’s really good,” Van Dijk says. In this case, however, the renovation has received nothing but praise.

“The newly installed system has made an incredible difference in terms of coverage, power, and fidelity,” says Doug McKendrick, production manager for the Corporation of Massey Hall and Roy Thomson Hall. “It has been well received by both touring sound engineers and audience members alike. The quality of the equipment and install has been rock-solid for us.”

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