Control on ice
Jan 1, 2000 12:00 PM, Bruce Borgerson
Audio systems at a new sports/wellness complex in Denver benefit from innovative loudspeaker cluster design and user-friendly computer control.
The University of Denver's new $70 million sports and wellness complex has proven a most welcome addition to campus life. In particular, the gleaming new hockey arena, the centerpiece of the complex, was long overdue. From 1947 to 1996, the school's Pioneer hockey teams played their home games in a war surplus aircraft hanger that had been hauled piecemeal to Denver from a decommissioned naval base in Idaho. That veteran venue offered a rink, about 4,000 seats, a hodge-podge of audio equipment accumulated over the decades and little else. In recent years, as the Pioneers moved up in the national NCAA Division I rankings, university officials and alumni became increasingly frustrated with the WWII-era hangar. It had to go, and the building was scheduled for demolition.
After demolition crews cleared the site, the university launched the single most ambitious construction project in its 133-year history-the Daniel L. Ritchie Center for Sports and Wellness. The new construction covers more than 400,000 ft superscript 2 (37,000 m superscript 2) and encompasses the showcase Magness Arena along with the Hamilton Gymnasium, El Pomar Natatorium, Joy Burns Community/Practice Rink and Coors Fitness Center. Also integrated into the new complex were two existing facilities-the Stapleton Tennis Pavilion and the Gates Field House. In addition to providing first-class facilities for the university's 19 NCAA Division I teams, the Center is open to the Denver community and currently hosts more than 30 youth and adult recreation programs.
Architects for the Center's new construction were the Davis Partnership and Sink, Combs, Dethlefs. Acoustic design and original audio system specifications were assigned to Boner Associates, Austin, TX, and a design-build contract for all new audio systems in the complex was awarded to Electromedia, Arvada, CO.
NHL impact, collegiate budget
The Magness Arena seats 6,200 in theater-style seats for hockey games, 7,200 for basketball and more than 8,000 in concert seating configurations. It shares many spectator-friendly characteristics common to other newer facilities, including steeply raked seating areas for a feeling of intimacy, clear sightlines from all seats and a state-of-the-art audio system. Delivering quality audio in the venue, however, proved to be a challenge because of the hard reflective surfaces (steel, ice and hard seats) and a relatively low ceiling with a high scoreboard hang. Also, although adequate, the budget left no room for over-engineering to be on the safe side in terms of SPL. Unlike professional sports arenas into which teams often pour in millions for glitzy sportainment effects, collegiate facilities face much tighter budget constraints when it comes to A-V systems. This puts the squeeze on system designers because collegiate fans also have come to expect a high-impact, music- and effects-laden experience.
"With the original budget as submitted to the consultant, we could have come close to an NHL-class system," said Electromedia Senior Engineer Mark Graham, the system's primary designer, "but when all bids came in high for the basic iron and cement type of work, the audio budget was cut back substantially. We had to do some basic value engineering. We had to do away with bells and whistles and focus on getting good coverage at respectable volume. We couldn't do the 110 dB peaks of new pro arenas, but we set a goal in the upper 90s in nearly all seats with a -6 dB point at about 45 Hz."
The consultant's original specification called for an extensive distributed system, which would have produced superb results, according to Graham, but with the lower overall budget, Electromedia had to find some way to get substantially equivalent results using fewer loudspeaker cluster locations.
Icing boom buildup
Fewer clusters cut costs, but making them run at higher levels and throw further raised potential problems with inconsistent mid-high coverage as well as bass buildup, the nemesis of modern, full-range arena systems. Scoreboard sightlines imposed further restrictions because loudspeaker clusters could not hang more than approximately 4 feet (1.2 m) below the lowest red iron beams. Essentially, Graham set out to create a design that could fill the room, maintain broad bandwidth pattern control (preferably to 100 Hz and below) and do it all with only eight clusters, each no more than about 4 feet high.
"My starting point was to get some vertical control of the low frequencies," said Graham, "because the room has a pretty nasty reverb time around 100 Hz, over four seconds. The classic way to deal with this problem is with a horizontal line array, but we didn't have enough height allowance to do it in a straight line. So we used two custom JBL three-way cabinets in a horizontal array with dual 14 inch (357 mm) low-frequency drivers in each box. As installed, with the two boxes angled down at 15 degrees and 50 degrees, the four drivers line up to form a curved vertical line array. In each cluster, the top and bottom bass drivers take a common feed off one output of the Peavey MediaMatrix, and the two middle loudspeakers are fed from another output. So, by introducing small amounts of delay on the ends, we can use beam steering to generate about 100 degrees of vertical pattern control. That helps the system maintain relatively flat, defined bass in the audience area without overloading the room."
The loudspeaker cabinets were designed by Andrew Rutkin, director of custom product engineering at JBL, following Graham's concept and performance specifications.
"What we created is essentially a two-box system made up of a wide horizontal coverage module and a narrow coverage module," said Rutkin. "The top module has 60 degree horizontal mid- and high-frequency horns for the longer throw to the top seats, and the bottom module has a 90 degree pattern to cover the lower seats close underneath. The horn-loaded 10 inch (254 mm) mid-range drivers are interesting in that they are symmetrical horizontally but asymmetrical vertically, so when stacked at the proper splay angle, they couple to create a symmetrical vertical pattern. They have a practically coincident point of origin in this frequency band because the two drivers have only the cabinet thickness between them."
The result of this collaboration is an innovative cluster design uniquely suited to arena applications. "When you project this cluster's coverage on the typical seating area," said Rutkin, "you get more of a rectangular shape, not the pie shape typical of single pattern clusters. This makes it much easier to eliminate hot spots and dead spots when covering adjacent seating areas."
Rutkin says that the cluster modules are not currently in the JBL product line, but they can be supplied by the JBL Custom Shop as models CSM4364H (60 degrees) and CSM4395H (90 degrees) on only a few weeks' notice because major components are identical to those in JBL's current Venue series product.
The completed Magness system uses seven of the dual-box line array clusters with four additional single cabinets employed at the north end where severe height restrictions (due to concert rigging steelwork) did not allow two-high clusters. Eight additional high- frequency hockey horns (JBL 2447H driver/2353 60 degrees infinity 40 degrees horn) are aimed straight down to provide high frequency fill to shadowed seats immediately behind the Plexiglass dasher boards. Six JBL Sound Power SP212A cabinets, hung from the scoreboard, cover the playing surface with the high-level, music-quality reproduction needed for such events as figure skating competitions. All arena loudspeakers are powered by a complement of 22 QSC MX3000a, MX2000a and MX700 amps.
MediaMatrix control
Like many other multi-use facilities, the Magness Arena uses a Peavey MediaMatrix system for general signal processing and electronic reconfiguration to accommodate different events. In this installation, Graham chose a MiniFrame 208 with four bobs for a maximum 32infinity32 in/out capacity.
"We're using the MediaMatrix for all our drive processing, cluster delays and output matrixing," Graham said, "so we have it pretty much maxed out. We used very few outboard boxes for some miscellaneous needs, such as a Peavey IDL1000 delay for the JBL Control 5 control room monitors to get them in sync with the main clusters."
The MediaMatrix system is pre-programmed with presets for all common uses, including hockey, basketball and special events. In the latter configuration, middle- and south-end clusters are delayed, referenced to a zero point at the north end stage location. Also, a bitmap screen graphic allows operators to turn individual clusters on and off within a preset by mouse-clicking on cluster icons. The primary use of this feature, said Graham, is to turn off clusters over empty seating areas during events with limited attendance. Electromedia Associate Engineer Josh Beaudoin devoted the better part of three days to the design an attractive interface screen that would be as simple to use as possible.
"You have to plan for those times when a regular operator calls in sick and some substitute comes in," Beaudoin said. "We imported a bitmap of the arena layout, but it doesn't have a lot of detail, so we had to be very careful about color selection and color balancing so that the operator can tell immediately which buttons affect which areas of the arena."
Flexible support systems
To accommodate a wide variety of possible uses, Electromedia installed an extensive network of tie lines and provided dual split boxes to accommodate broadcast requirements. A 16infinity4 multipin connector is located at both center ice and at the stage end, which connects to a supplied snake for running out to a video truck at the dock.
"That facility will take care of multiple mic feeds for a network-type production," said Graham, "but we also have eight permanent tie lines to the dock for less demanding requirements. Again, it's a matter of value engineering. Using the snake takes care of an infrequent requirement at a fraction of the cost of installing a permanent split and much bigger patchbays."
In the sound booth, front-end equipment includes a 24-input Yamaha GF-24 console. In addition to 24 mic level patch points, signal inputs to the Yamaha include two Sony UHF wireless mics, a Tascam cassette deck and Tascam CD player. A patchable Symetrix 528E voice processor is provided for the announcing mic, a headworn Crown CM311. Incidental music and sound effects come from a laptop computer not supplied as part of the contract.
To meet assisted listening requirements, Electromedia installed a Phonic Ear 550T with a remote antenna installed over center ice. Production intercom needs are fulfilled by a two-channel Clear-Com wired system with 15 remote stations, supplemented by a wireless Clear-Com system.
"Wireless systems are much more expensive," said Graham, "but using them avoided running lines at the spectator level and also gave us a portable system for the adjacent gymnasium where there was no budget for any intercom at all."
The Magness Arena system was commissioned a few hours before the Pioneer hockey team's home opener for the 1999 season. Mark Graham admits to being somewhat apprehensive about the system's performance, but after a few hours of system tuning using a SMAART system, his fears were allayed. The curved line arrays seemed to be behaving exactly as predicted in the EASE modeling.
"We were able to get a clean, punchy bass," Graham said. "The system is amazingly musical considering the surroundings, and we have excellent intelligibility at all seats."
A wired complex
Although the Magness Arena showcases the most innovations (and consumed the majority of the budget), Electromedia also supplied audio systems for the complex's new gymnasium, natatorium, fitness center and alumni lounge/meeting room. The Hamilton Gymnasium was particularly challenging, again because of budget restrictions. Not willing to compromise basic quality, Graham designed a high-quality system to cover all seating areas using six JBL Sound Power SP222 two-way cabinets with two additional cabinets covering the floor area. All operate with passive crossover with one channel of a QSC MX2000A amp assigned to each. Zoning control is handled by a Peavey MediaMatrix X-Frame in conjunction with a custom pushbutton panel, which allows selection of "Game" or "Stage" presets along with individual muting of bleacher areas and floor systems. For most typical uses, mics connect via permanent input panels to a Peavey A/A-8P preamp and auto mixer. For special events, an X-Frame preset selects a Mackie 1604VLZ mixer with inputs normalled to a 16-channel multipin snake connector. To prepare for future needs while holding to current budget, Electromedia ran cable for a second floor box as well as for recommended JBL SP212 loudspeakers to cover the upper concourses, but neither were included in the first-round installation.
In the Coors Fitness Center, the weight room keeps them pumping with 16 JBL Control 26CT two-way ceiling loudspeakers, augmented by six Control 19CST ceiling subwoofers. Sources for the EVI Audio ELX-1A mixer include a TOA AM/FM tuner, Marantz CD/cassette combo, and custom mic/line input panel. Power is supplied by a QSC CX-6T amp. The dance and aerobics rooms are each equipped with seven of the JBL Control 26CT two-way speakers and three Control 19CST subwoofers. For these rooms, all other equipment (save the automatic fire override system) is contained in a roll-around rack. Each rack contains the same mixer and CD/tape units as the weight room but also offers a Sony WRR800 UHF wireless receiver and Shure DFR11 feedback controller. Power comes from a QSC MX1500a amp. Three of these racks were provided in the contract because they can also connect to existing or proposed systems in the practice ice rink, tennis pavilion and field house.
Finally, there is a particularly pleasant system for those folks who were instrumental in making it all happen-the alumni. The Pioneer Room system uses an Ivie 784 mixer to select from the available sources: audio-from-video, TOA AM/FM tuner, Marantz CD changer or mic inputs. The sound comes out through 11 JBL Control 26CT, seven Control 24CT and four Control 19CST subs, the entire contingent is powered by a pair of QSC 302V amps.
According to Graham, the overall Ritchie Center installation proceeded smoothly and involved (in his words) "nothing particularly new or unusual." Nevertheless, he suspected that the innovative cluster co-developed with JBL marks an incremental step forward in engineering cost-efficient, high-level arena systems.
"The concepts behind it are well known," he said, "but we may have come up with a new wrinkle in this particular cabinet configuration. It will be interesting to see if this particular approach finds wider application in other similar systems in the future."
Acceptable Use Policy blog comments powered by Disqus
