Right next door to Nellis, a group of Las Vegas entrepreneurs decided to pour about $200 million into constructing the world's largest (and costliest) auto racing complex: the Las Vegas Motor Speedway (LVMS). When completed, the 1800-acre facility will comprise 24 tracks to accommodate everything from BMX bicycles to Formula One Grand Prix cars. The crown jewel of the complex, a 1.75-mile tri-oval with grandstand seating for 102,000, made its debut with a 300-mile Indy Racing League event in September of 1996. The inaugural race thrilled fans speeds up to 229 MPH, and chilled them with 10 of 28 cars crashing on the fast track.

That same day, the powerful, computer-controlled sound system at the LVMS tri-oval produced levels up to 117dB SPL. It did not crash. But the race to get it designed, tested and installed was a suspenseful story in itself - complete with unprecedented performance expectations, difficult working conditions, and a frenzied construction pace typical of Las Vegas mega-projects.

Initial sound system design was assigned to Ron Sauro of Northwest Audio and Acoustics (Tacoma, WA.), who had referred LVMS owners on the basis of a system he had designed for the Hollywood Park horse track. Once presented with the basic requirements for the system, Sauro realized that he would need help in order to complete a full system design spec in the required time. He decided to concentrate on challenging specifics of loudspeaker coverage, turning over the task of overall systems integration to Brian Gross of A-Com (Chantilly, VA). In the early stages, Gross called on his friend Neil Shaw of Menlo Scientific Acoustics (Topanga, CA) to serve as a key technical advisor. After A-Com was awarded the contract to supply and install the system, Gross enlisted the aid of Josh Thompson of Point Source (Las Vegas and Nashville) to serve installation supervisor, with Chris Potter working as primary on-site coordinator. (Owners and Great Expectations.) The sprawling LVMS complex is the brainchild of owner/operator Richie Clyne, with financial backing from owners of two prominent Las Vegas casinos. In Las Vegas the line between sports and entertainment is a fuzzy one at best, so it's no surprise that the LVMS owners insisted on "concert quality" sound as a prerequisite for all spectator areas of the track. That previously unheard-of requirement eliminated the traditional approach of using large, limited bandwidth horn arrays.

Also, ever mindful of income sources, the ownership wanted a system that could be heard throughout the entire race, so commercial announcements could be clearly audible even when the race was going full bore - something virtually impossible at most other tracks. Since the ambient noise level in the grandstands at an auto race approaches 115dB, the system (even with optimum equalization and processing of the source) must be capable of uniform coverage at the same levels or higher. One more detail: the owners didn't like the way loudspeakers and light poles obscured spectator sight lines at other racing facilities. So, for most main grandstand areas at the LVMS tri-oval, all light poles and speakers would have to be placed BEHIND the spectators - which means the sound must be thrown even further because of the reverse slope of the seating area.

Other Things Considered Several other complicating factors had to be considered early in the design phase. Cable runs would be very long, with the extreme end loudspeakers for the tri-oval as much as 3/4 mile from the main control booth. Ambient on site temperatures during the summer of 115 to 120 degrees F are not uncommon. Winds gusts of 60 to 70 MPH are regular occurrences, making wind loading on speaker mounts an overriding concern. And frequent windstorms churn up the surrounding desert floor, depositing layers of dust and sand on anything not sealed against the elements. To further complicate matters, no landed electrical power was available on the construction site, and there would not be any until a few hours before the inaugural race. Finally, to design, supply and install the system for the main tri-oval only, covering 102,000 spectators plus pits, garages, concession areas, corporate pavilions, luxury suites and the backstretch RV park - the owners had budgeted $1.5 million. Money was tight, and the schedule even tighter. Could it be done?

Yes. In the early morning hours of September 17, 1996, landed power arrived at LVMS. Finally the entire sound system - previously tested piecemeal using generators - could be fired up and tested for a race that was only hours away. The MediaMatrix computer came to life, mixing and processing audio sources before routing them to the appropriate fiber optic interfaces. A second computer running Crest NexSys came on-line, configuring the system, setting levels and monitoring key amplifiers and speaker parameters.

Miles of fiber optic cables lit up, carrying muxed audio signals via Telecast Fiber Systems interfaces and NexSys data through Fiber Options boxes. Finally, 77 Crest CKS/CKV Series amplifiers delivered 171,000 watts of power potential to 129 Renkus-Heinz CoEntrant loudspeakers. Up in the control booth, A-Com's Brian Gross popped a Rolling Stones CD into the player, cued "Start Me Up," pressed play, and brought up the levels in MediaMatrix. It was time to fine tune the system. Out in the stands, Point Source and A-Com personnel reported the results back via two-way radios. Everything was up, and the sound was clear, full and undistorted. Whew. Success. But it had been a wild and wooly ride since Ron Sauro received his first phone call ten months earlier.

EASEing Into It Because of the owners' insistence on clear sight lines, Sauro's design employed speakers mounted behind the grandstand seats, except in the "B" stands where (to the owners' chagrin) the light poles had to be put in front in order to get enough light into the backstretch of the Legends Track (a small oval integrated into the larger tri-oval). Sauro quickly realized no single loudspeaker cabinet could do the job. He would need a very high Q long throw cabinet to throw sound to the front rows, a lower Q cabinet to cover the closer back rows, and a separate low frequency cabinet to supply the bass octaves. Using the EASE electro-acoustic simulation software, Sauro modeled dozens of different approaches using a variety of loudspeaker cabinet combinations at various spacings and articulations. "I could not have done this job without EASE," he maintains. "I had enormous areas to cover with dozens of speakers, and I needed to know precisely what the interference patterns would be. Also, I had to take into account the fact that such powerful speakers would project sound over great distances, and I needed to know precisely where we would need to delay the sound, particularly in the pit areas, but even all the way across the track in the backstretch RV area." Sauro soon discovered that speaker combinations from only two manufacturers met the requirements for bandwidth and SPL. "The basics were dictated by the distances we were throwing and the levels required," says Sauro. "We had to get above the levels of the cars, and with NASCAR races we actually did measurements at Charlotte and Daytona and we were getting levels of 115 dB in the stands. To throw that power from a distance, we needed a speaker with a vertical pattern of about 20 degrees, and either a 60 or 90 degree horizontal pattern. Only a few companies had large format, powerful boxes with that kind of tight pattern control." However, other considerations narrow the options even further. Although roughly half the speakers would be mounted on the front fascia of the skybox suites overlooking the grandstands, the others would be mounted on the light poles. "Now we were getting into power-to-weight ratios," notes Sauro, "and we also had to look at size. The engineer for Musco, the lighting contractor, told us we had a limited amount of space, weight and wind loading to work with. Basically, he said the speakers could not be larger than a certain defined volume and surface area, and the limited weight could extend out more than a certain distance from the pole." In the final analysis, maintains Sauro, the only loudspeaker systems able to meet the stringent specifications were the CoEntrant models from Renkus-Heinz, which employ multiple drivers coupled to a common horn throat to achieve very high broadband power within precisely defined coverage patterns. Sauro's final design, for the main spectator areas only, employed 51 Renkus-Heinz CEMH62-3D 60x30 long-throw cabinets, 51 CEMH94-1D 90x40 short-throw cabinets, and 27 CE-3T low frequency cabinets. The speakers were laid out in "pods" of five, with a low frequency cabinet hung with alternate long-throw cabinets at the upper pole or fascia position, and the short-throw cabinet at the lower position. Renkus-Heinz X24 electronic controllers provide crossover, parametric EQ and limiting functions. Sauro then used EASE modeling to tweak the design for optimum coverage and intelligibility, and to minimize interference patterns. Essentially, the speakers are laid out so that all significant cancellation effects fall into the aisle stairways, with full bandwidth and SPL maintained in virtually all seating areas. "Frankly, I amazed myself," admits Sauro. "When you stand in a walkway, the two patterns combine, but move a foot one way or the other and you are in the field of the nearest cluster. Those speakers work like laser beams." Brian Gross concurred wholeheartedly with the loudspeaker specification: "One of the wonderful things about the CoEntrant technology is that you are getting pattern control over the full bandwidth at very high SPL. The image is virtually the same no matter where you are in the direct field." To keep within the budget, the wide-bandwidth Renkus-Heinz speakers specified for main audience seating areas only. Other areas covered by the overall system - pit row, garages, concession areas, backstretch RV park - would receive high intelligibility but more limited bandwidth coverage from a total of 116 Atlas/Soundolier and University horns.

NexSys: Power Under Control Sauro's design now had scores of power-hungry loudspeakers spread along an arc nearly a mile long. Powering in direct drive (low impedance) mode from a central amplifier location would be impossible, but a 70V distributed system would either require massive transformers or compromise fidelity, most likely both. The only workable solution was to distribute amplifier racks around the track, placing amplifiers as close as possible to the loudspeakers. The final design specified 24 amplifier sites, with the worst case run of 12-gauge cable less than 160 feet. With dozens of amplifiers scattered at multiple locations around the facility, computerized control and monitoring became an essential design element. The final specifications focused on the Crest NexSys system, with all control and monitoring circuitry integrated into Crest's new CKS/CKV amplifiers. "We were set on NexSys because of the kind of topography it offered," says Brian Gross, who was principally responsible for the amplifier spec. "First, we wanted a Windows-based system that would be complementary to MediaMatrix, and at that time NexSys was the only serious contender using Windows. Also, we wanted a parallel-based architecture to protect the network if one node goes down. The final factor in our decision was the willingness of the people at Crest to jump on the bandwagon, particularly the way they took the initiative in adapting NexSys to operate over a fiber optic token ring, something which had never been done before." "We went through a whole process of evaluating approaches to computer control," says Sauro, who consulted on the decision. "Crest came to the forefront because it was the only system that had the networking capabilities we needed and that could support the number of nodes we had in our system. Essentially, NexSys was the only computer control system capable of handling the job." As configured for LVMS system, NexSys control features include amplifier sequential power on/off, input level setting, and real-time monitoring of temperature and clipping for each channel. The LVMS system also incorporates the optional Load Monitoring, a feature that performs remote and automated analysis of the connected loads by plotting impedance curves and then checking at intervals for any deviations that could indicate potential problems. "NexSys is extremely powerful in the way it lets you set normal criteria for each amplifier," says Gross. "It polls each amplifier as it wakes up and goes to an assigned volume, then checks the speaker impedance and sets off an alarm if the impedance drops below the danger threshold. It's the ideal system for preventive maintenance, because in our extensive system it would be very difficult to tell if any one of the thousands of individual drivers out there has failed or is about to fail." In addition, the NexSys "snapshot" feature allows very fast reconfiguration of the audio system to accommodate different racing events. The main tri-oval also incorporates four racing configurations, each of which may utilize different seating arrangements. With NexSys, the operator simply clicks a mouse to select the appropriate audio system configuration, automatically turning on and setting levels for amplifiers that are required for the event and turning off those not needed.

Watts In The Fridge? Yes, and yes. In the central grandstands--those backed by skybox suites and press boxes--the amplifier racks were placed in the centrally located audio control booth and also in small enclosed spaces inside restroom facilities spaced across the rooftop. All of these rooms, of course, are air-conditioned.

The real problem concerned the "B" and "C" grandstands, stretching out on both sides. No suitable enclosed spaces were available anywhere nearby. The only possible solution was to place the amplifiers inside "environmental housings" at the foot of each pole. The enclosures (devised by Brian Gross) consist of a sealed NEMA 4-rated Hoffman rack cabinet with powder-coat finish, each equipped with a compact 3500 BTU air-conditioner. Each enclosure contains a fiber optic LIU (light interface unit), demuxers for audio and NexSys network data, a loudspeaker controller, and the requisite Crest CKS amplifiers. "They tested these enclosures at A-Com in Virginia on a 98-degree day in August," says Chris Potter of Point Source. "They drove the amplifiers flat out, but the internal temperature stayed at 65 degrees." But what if the AC fails? "We open the door and put a fan on it," says Potter. "We've found that the Crest amplifiers will take a lot of heat and abuse. When we first rigged up the system for testing, we had no AC in the main racks until four hours before race time. The amps did fine despite the very high ambient temperatures." The rooftop amplifiers were also thoroughly coated with drywall dust (the amps went in before the walls) and desert grime before the opening race. All fan filters were permeated with dust, but no amplifier failures were experienced as a result.

Light Up the Network The only feasible way to carry the audio signal to the distant amplifiers was on fiber; conventional copper lines would cause unacceptable deterioration and would also be prone to RF interference and lightning-strike damage. Fortunately, like any new state-of-the-art sports facility, LVMS is interconnected by a web of fiber optic communication lines. The multimode fiber backbone carries data, telephone communications, video and audio--not just around the tri-oval, but to and from all tracks (present and proposed) throughout the LVMS complex. In most cases, the audio system "piggybacks" on existing fiber cables, though in some cases special fiber runs were specified. Four strands are dedicated to audio throughout the system: one for network data send, one for data return, one for audio, and one for a spare. LVMS audio utilizes a separate mux/demux unit for audio and NexSys network data, with audio handled by Telecast Fiber Systems´ 16-channel units. The audio goes through a simple daisy-chain arrangement, with the assigned audio channel dropped out at each node, with each amplifier comprising a node. The signal is then refreshed and passed along to the next node. Since each fiber carries up to 16 channels of full bandwidth audio, each amplifier can be assigned to any one of sixteen available "virtual zones" by simply selecting a channel with a selector switch on the fiber interface box for that node. In combination with MediaMatrix mixing and routing, this feature of fiber optic distribution opens up intriguing system configuration possibilities that have yet to be fully utilized at LVMS. The NexSys network is a two-way system operating with a distinctly different protocols. At LVMS, for the first time anywhere, NexSys rides on fiber optics in a multiple token ring topology. Once again, the sprawling size of the system demanded a fresh approach to familiar problems. "There was no way we could afford to have separate fiber run back and forth from each amplifier location as you would with a star topology," says Gross. "Fortunately, Fiber Options and Crest jumped to the plate and helped us develop this elegant token ring topology. The system goes out, finds the proper node, talks to it, then sends the signal along in a designated packet, and at the end of the loop it all comes back to the NexSys hub. We have about 80 different nodes broken down into five rings.

The Rush To The Race The preceding is a simplified summary of the system as presented to the LVMS architects in an 84-page design document early in 1996. The subsequent solicitation resulted in five competitive bids - all in the $1.5 million neighborhood - with a spread of only 6.5% between the high and low figures. Unquestionably, all bidders understood exactly what the specification required.

In April of 1996, Brian Gross was given a verbal commitment to proceed as primary supplier of the sound system. "Sometimes you have to be careful what you wish for," muses Gross, "because you just might get it." Even before the signed contract was in hand, A-Com started ordering equipment essential to meet the September deadline. All equipment, with the exception of speakers and mounting brackets, would be assembled and pre-tested at A-Com's Virginia facility before shipment (in eight semi-trailers) to Las Vegas. Conduit work and wire pulling was assigned to the primary LVMS electrical contractor, since A-Com was not a licensed Nevada contractor. Summer arrived, and the heat was on. Literally and figuratively, "Change it? Again? Tonight?" One of the biggest problems we faced was that the overall facility design had not been completed by the time we needed to finalize our design," laments Gross. "Rooms designated to house amplifiers suddenly disappeared. Or we would get word that they needed conduit layouts that night because they would be trenching for it the next morning. It was a very aggressive pace, and we had to do a lot of engineering on the fly. It was absolutely insane for about three months." As the summer blazed on, the steel skeleton of grandstands, luxury suites and press boxes gradually emerged from the desert floor--weeks behind schedule. As soon as the 40-foot long prefabricated concrete fascia panels were in place, Point Source started the speaker mounting procedures. For safety margins, each of the three hanging points was designed to hold 10 times the weight of the speaker. The mounting brackets were engineered to hold at least 3300 pounds (the Renkus-Heinz cabinets weighing in at about 200 lbs. each). Suspension brackets for the fascia speakers were mounted to the concrete with eight Hilti chemical expansion bolts, which had to be kept in an ice bucket to set properly. "Each bolt has a pullout rating of 10,000 torque pounds," says Gross, "so these speakers are never coming down unless the whole fascia comes with them."

Trial by Nightfly In mid August, as soon as the first complete "pod" of speakers was in place, Point Source rented some Crest amplifiers in Las Vegas, powered them with a generator, and hooked up a CD player. The LVMS architects and owners were invited out to the site for a preliminary audition. "They came out in 118 degree weather to hear it," Gross recalls. "We started by playing Donald Fagen's "Ruby, Ruby" from The Nightfly at about 108dB. It wasn't just shock or amazement, they were grinning from ear to ear. It sounded like a huge home stereo. Richie Clyne even said it sounded better than the showroom downstairs [at the Imperial Palace]. They got back in their limos and went away satisfied that their money was well spent." A good omen, but the final laps would push the limits of everybody's endurance. The inaugural race was only weeks away and the audio control room was merely a frame of metal girders, the fascia wasn't complete, and most poles were still flat on the ground. But somehow it came together. With bare metal roof overhead and temporary flooring underneath, the audio control room was assembled. "Every piece of equipment was burned in, tested, wired, crimped and ready to go," says Gross. "We were confident that when it all landed five days before the race, it would go up on the roof and it would work. It had to. Clark County would not allow a race of this size to go on without a working PA system." There was also no landed power, so the system was tested zone by zone using generators. All equipment cooked in unair-conditioned confinement, continually assaulted by the drifting grit of frenzied last-minute construction. When full power was finally available, the A-Com team had only a few hours to do a temporary commissioning of the system. "There was no time to do any kind of sophisticated analysis and measurement," Gross admits. "Fortunately we had a crew of people with experienced ears. They went out with radios and reported back while I did equalizing on the fly. I brought up the long throws, short throws and bass and got them all balanced, all of which went a lot faster thanks to NexSys control."

The crowds arrived, the stands filled, and the system made its debut. By all accounts it performed flawlessly, with clearly intelligible sound delivered to every spectator. The owners were suitably impressed, and decided to install similar Renkus-Heinz systems at the 1/4-mile dirt oval (completed in October) and at the dragstrip. Chris Potter surmises that more systems of that nature will be contracted as future tracks emerge from the barren desert floor.

"I expect this facility will drive changes at many other racing facilities around the world," predicts Ron Sauro. "Once race fans hear the LVMS system, they aren't going to be happy with anything less than the best quality sound. And I think the facility owners will have to respond. What we have created, I believe, is a forerunner for the way audio systems will be designed both for new speedways and for retrofits of existing facilities." A-Com's Brian Gross plans to continue A-Com's development of sound systems at LVMS and some other venues under discussion. For now he's pleased that the initial phase of LVMS job is complete, with performance meeting or exceeding all expectations. "I've never been so proud of a team," he says. "Everybody involved did a magnificent job--Ron, Neil Shaw, Point Source's Josh Thompson, Chris Potter, Danny Walker, Keith Davies and Jerry Neff--plus all the vendors and Dru Srnecz and Bob Garrison here at A-Com. Considering what we went through in a three month period, it was a Herculean effort. I had heard some horror stories about Vegas projects, about how if you're not ready they will eat you alive. But I knew if we brought in the best guns, we could make it happen."

Text by Bruce Borgerson of Wavelength Communications, Ashland, Oregon.