Electro-Voice XLD system for McMahon Stadium, Calgary
September 23, 2008
The new speaker systems are mounted inside a circular enclosure suspended by four steel ropes 107’ above the center of the playing field. Dave Harrison of E.K. Sound described the installation, and how the XLD provided the ideal balance of compact size and high performance:
“We serviced and operated the original system for almost 20 years,“ says Harrison, “beginning when we re-coned the original speakers after the Calgary Winter Olympics, the first of several times. The old system comprised 24 front-loaded 15“ woofers, upper and lower boxes in a 12-segment circle, with 36 two-inch compression drivers on short lenses. There was no weatherizing on the original boxes, so the elements took their toll. Since weather treatment and another re-coning would have only given these speakers another four or five years of life, it was more cost-effective and pro-active to replace them with something new. The original amplification was also over 20 years old, so switching those out was also seen as a maintenance upgrade.“
“The stadium staff are very impressed with the system’s coverage and the quality of the speech sound-the primary application for this system”
Harrison and colleague Darcy Klumpp carefully observed a particular client prerequisite when specifying the system: they needed to use the existing infrastructure, including all the existing cabling and the speaker enclosure itself; to replace the central enclosure would have meant changing the support towers-at a cost of several million dollars.
“With these factors in mind, our challenge was to find a loudspeaker solution that would fit in the enclosure without any modification, one that we could weld to the existing internal bracing structure,“ Harrison adds. “I looked at pretty much every manufacturer under the sun to see what was available, what would fit, and what would provide the necessary SPL at that size to cover the grandstand area.
“Seating capacity at the stadium is around 36,000, split primarily between the east and west stands. For special events like the Grey Cup, they build temporary seating out of scaffolding in the north end-zone, increasing the capacity to around 45,000. One of the requirements was to provide for coverage in this area for larger events. These criteria narrowed my search quite dramatically. The only box that I came across that I really felt could do the job was the XLD281; the performance was there and the size was there.
“We demo’d a ground-stacked array of eight boxes and the combination of sound quality and price was exactly what the client was looking for. Robert Deyarmond (Tech Support Engineer, EV) came up with initial EASE and LAPS (Line Array Prediction Software) designs. These designs were slightly modified to better fit the enclosure while maintaining optimal performance. For the main systems, we installed four arrays of nine weatherproofed XLD281 boxes, each covering a quadrant of the stadium. An additional array of eight boxes is installed at a much shallower angle-about one or two degrees per box instead of three or four-shoots towards the end-zone on the north end, used for temporary seating during events like the Grey Cup. In addition to the arrays aimed east and west, three center-mounted FRX+660 boxes down-fire over the field, used primarily during amateur sporting events for public address and background music, turned on when the stands aren’t full, but when controlled audio coverage is required on the field.
Tour Grade TG-7 amplifiers with RCM-26 modules provide the power and processing for the system, cutting down on hardware while offering the accuracy and performance of IRIS-Net remote control and FIR filters. “The amps run off the existing electrical system,“ Harrison explains; “rather than re-wire the entire amplifier room with higher gauge mains cabling, we converted the 120-volt system to feed the amps at 208-volts single phase-the TG-7s are fully auto-ranging and run very well at 208. This allowed us to use the same wiring while giving the amplifiers adequate supply current. The original system took up eight equipment racks; the new TG-7 amps only take up three sparsely populated racks-we use far fewer amplifiers and have greater output power. The TG-7s are loaded with RCM-26 modules, so all the processing is internal; we did away with all our distribution amplification and the outboard time delays. Running IRIS-Net, we have real-time monitoring capabilities. And, most importantly, these amps sound excellent-a considerable improvement. Like the rest of the system, the TG amps contributed to a reduction in infrastructure upgrade costs.“
Using EV’s versatile factory flying hardware as a basis, Harrison devised a custom mounting solution to ensure stable performance in unstable conditions “When the winds whip up, the enclosure bobs around like a cork on the water,“ he says. “This meant we couldn’t go with standard install mounting practices-the speakers needed to be mounted rigidly to the structure. I attached aluminum blocks to the factory bumpers, using the shackle holes to bolt through into these aluminum blocks. These blocks then bolt up into pieces of three-inch heavy channel that we welded into place in the enclosure. I needed to get as much height as possible, as I had a finite amount of vertical space-we ended up being about an inch away from the expanded metal screen at the bottom of the enclosure. I then used factory rigging pins and custom support block to hold the array rigidly at the desired angle-the LAPS showed there was no rear pull-back support needed. The blocks and pins don’t actually take any weight; they simply prevent sway, keeping the high frequencies focused.“
“The stadium staff are very impressed with the system’s coverage and the quality of the speech sound-the primary application for this system,“ he adds. “For my part, I was very impressed by the level of support we received from EV, from our rep Mark Kulas (PAG Canada), from EV Tech Support, Sales Support, and Manufacturing. This project had a 30-day turnaround from the signing of the PO to the commissioning of the system, which might be a world record! It went in on time and exactly as spec’d on EASE and LAPS, and it sounds fantastic.“
4x XLD grid array bumpers
23x TG-7 power amplifiers with RCM-26 IRIS-Net modules
1x UCC-1 USB to CAN bus interface for IRIS-Net control
1x Midas Venice 240
Klark Teknik 500 series limiters
The EK team-Dave Harrison, Darcy Klumpp
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