Pushing the Envelope of Stadium Audio:
Innovations at Tampa's New NFL Stadium Push Technology's Limits, but Without Going Out on a Limb.
S&VC Magazine - November, 1998
by Rod Sintow and Stan Hutto
Baseball may be the national pastime, but NFL football is the national passion. It's a sport that feeds on impact, and the fans expect high impact sound to go with it. Gone are the days when sound systems were designed for a lone announcer who squawked out downs, names and scores, his voice rising barely above the crowd noise. True, excellent voice intelligibility remains an essential requirement, but today's NFL stadium systems also must deliver full fidelity music and convincing sound effects at levels over 100 dB SPL. Nothing less is appropriate for those vast video scoreboards that erupt into dazzling displays to fill the slow moments between plays.
Some have dubbed it "sportainment," and nowhere is this phenomenon more apparent than in the new Raymond James Stadium (named for the sponsoring financial services firm) in Tampa, Florida. The new facility hosts the University of South Florida football team and the Mutiny pro soccer team, but the primary tenant is the NFL's Tampa Bay Buccaneers. In fact, to bolster home team spirit, the stadium sports a full-scale replica of a pirate ship surrounded by a rustic "Buccaneer Village" boardwalk.
In addition to a revolutionary new Meyer Sound self-powered loudspeaker system, the stadium has been outfitted with two massive electronic scoreboards (about 200' x 60'), plugged into a full-blown video production and computer effects studio. (What else would you expect next door to the theme park capital of the world?) The NFL already has already selected this showcase facility to host Super Bowl XXXV in 2001.
Built at a cost of $168 million, the new 65,000-seat Raymond James stadium is owned by the Tampa Sports Authority (TSA). Renowned sporting facility architects HOK Sport of Kansas City supervised overall design, with Wrightson, Johnson, Haddon and Williams (WJHW) of Dallas assigned to develop the audio systems. Our Miami-based firm, ProSound, Inc., was contracted directly by TSA to provide and install all audio, distributed video, surveillance and broadcast interface systems.
In many ways, the new Tampa facility is typical of the new generation of non-domed NFL stadiums. It is big, open and spacious, with minimal overhang on the three tiers of seating. This architectural style virtually rules out a distributed main system: a rear-firing system poses psychoacoustic objections, and front mounted speakers of the size required would block sight lines. Consequently, as with most recent similar installations, the main system for the stadium bowl would have to be a single end zone cluster. Although generally less costly than distributed system, the single cluster approach is fraught with inherent difficulties, most notably delivering the sound to the all seating areas while directing sound away from the playing field and troublesome reflective surfaces. High Q pattern control is crucial.
The demand for high quality sound extends beyond the stadium bowl into the restrooms, the concourses (to support the 600 TV monitors) and most certainly in the club areas. In sum, the Tampa stadium spec called for clean, full bandwidth sound at quite high SPL at every point in facility, and that translates into an extremely powerful and complex system.
Of course, anything can be done if the price is right. Unfortunately, most new NFL stadiums are public-private partnerships supported by tax dollars and therefore subject to careful financial review. Budgets, though normally adequate, are not unrestricted.
All these problems were familiar to Gary White of WJHW, who previously had designed systems for NFL stadiums in Charlotte and Jacksonville. Nevertheless, when contracted for the Tampa job, he was determined to "push the envelope" and take his previous single cluster designs up to the next level of performance-even though he was faced with similar architectural acoustics and comparable budget restraints. In particular, he wanted to create a system able to project higher SPLs with improved high frequency response at the opposite end of the stadium, in this case a distance of up to 700 feet.
The only practical main speaker location was above the scoreboard at the south end, about 150 feet above the ground. The cluster is enclosed in a metal structure about 50' wide by 20' high mounted on a concrete slab, with the front side covered by nothing more than a wire mesh metal screen emblazoned with the Bucs logo. Although a roof offers overhead protection, the rain accompanying Tampa's many thunderstorms often leans toward the horizontal. Heat and humidity are everywhere, and central Florida is the lightning strike capital of the United States.
With these familiar environmental hazards in mind (Jacksonville is not that far away), White first designed a high power, high Q system based on Meyer Sound MSL-10 cabinets powered by 34 Crest amplifiers. Although certainly capable of producing the desired results, all bids based on that first round came in over the allowed budget. After White reworked the specification along more conventional lines employing lower cost loudspeakers, at ProSound we suggested that he consider a system based on the new Meyer Sound Self-Powered Series-including the revolutionary SB-1 Sound Beam parabolic transducer and the new PSW-6 directional subwoofer, neither of which had yet been permanently installed in the United States, indoors or out!
Gary was open and frank in his skepticism. First, he was concerned that the self-powered speakers would not be able to produce the higher SPL levels he sought, and he also was understandably nervous about placing crucial amplifier and processing electronics in a semi-exposed metal shed 150 feet up in Tampa's damp and often turbulent air.
It took some convincing arguments on our part, along with a trip to the Meyer factory in Berkeley, to quiet his doubts. Gary is respected in the industry for designing bulletproof systems, so we knew he would never compromise reliability for the sake of being on the "bleeding edge" of technology. After examining the weatherproofing techniques employed by Meyer and evaluating our extremely low failure rate with similar products, he relented and, in consultation with Meyer's technical services department, he worked up a new cluster design employing all Meyer self-powered components. Although the powered speakers themselves were certainly more expensive, we were (obviously) able to eliminate all costs for amplifiers and the associated processing, racks and wiring. But the most significant savings were realized in labor costs, since both installation and final system alignment could proceed at a much quicker pace. Plug in line level audio and you're done: internal driver alignment and equalization is a given.
The main cluster as installed employs a total of eight Meyer Sound MSL-6 cabinets, eight PSW-6 cardioid subwoofers, and four SB-1 parabolic loudspeakers for "spotlight" long throw, plus two MSL-4 and three CQ-2 loudspeakers for side and down fill coverage at the south (cluster) end of the stadium.
The MSL-6 is a high power, high Q system containing three 4" diaphragm compression drivers, two 12" low frequency drivers, matched class AB/H MOSFET amplifiers for each driver (2480W burst power total) and all associated protection and control electronics. The -6 dB points are 30 degrees horizontal and 25 degrees vertical, enabling precise aiming at the desired spectator seating areas.
Though a 25 by 30 pattern is considered high Q by most standards, over a distance of 700 feet that can translate into a fairly broad area. The far corners are always difficult to cover in large stadiums, and particularly so at Tampa where each corner has large reflective surface areas. With conventional technology, all the options have a down side. You can simply let it slide and accept lower levels and reduced HF response in these areas, or you can add more horns and more power with inevitable bleed onto the field and nearby reflective surfaces, or you can install an expensive additional delay system at great cost and with probable impaired sight lines from some seats.
At Tampa Bay, new technology offered a better alternative. The Meyer SB-1 Sound Beam (patent pending) is a revolutionary transducer that uses a parabolic reflector rather than a conventional horn to project a coherent beam of mid and high frequencies (500 Hz - 15 kHz) over long distances with a beamwidth of an astonishing 10 degrees. Unlike conventional free field transducers, a parabolic device is not subject to the inverse square law, so SPL decrease is as little as 3 dB with each doubling of distance. In the Tampa system, two SB-1 systems are employed on each side of the main cluster to spotlight the problematic far corner areas, giving these seats equal (if not better) high frequency coverage. As a bonus, these seats seem less subject to disturbances from wind effects: waves propagated by a parabolic reflector apparently maintain more coherency even when the air is in motion. The perceived effect is that the sound source is much closer than it actually is.
NFL franchises also expect lots of "thump" in their systems, and this demand for extended bass response generates its own set of problems in single cluster designs. Since conventional subwoofers are effectively omni-directional, placing them inside a cluster enclosure such as the one at Tampa can generate narrow band cancellation effects, not to mention spilling unwanted energy back into the parking lot-and beyond-where it is not needed and might be unwelcome.
Once again, the Tampa system breaks new ground with the first installation of the PSW-6 powered directional subwoofer. Enclosing two 18" and four 15" drivers (two facing the rear), the PSW-6 employs the sample principle used in cardioid directional microphones, only this time in reverse, to provide a front-to-back projection ratio of better than 15 dB from 30 Hz to 125 Hz. This enabled mounting of the PSW-6 subwoofers co-planer with the MSL-6 cabinets for a seamless low frequency transition with no cancellation effects from the surrounding enclosure.
The first phase of the cluster installation was somewhat nerve-wracking, as it involved hoisting all the loudspeakers 150 feet up in the air on a crane and then maneuvering them into place inside the enclosure. During the process, several cabinets received damage to the exterior weather protection. Meyer Sound responded quickly with all the parts and materials needed to restore all the cabinets to factory fresh condition, much to Gary White's relief.
Aiming is critical in any high Q system. For the Tampa installation, ProSound constructed a custom hanging track assembly which allowed precise adjustment of the suspended cabinets in both the horizontal and vertical axes. However the SB-1 dishes sit on the concrete deck, and employ their own highly precise integral aiming mechanism.
As we expected, final installation of the self-powered systems proceeded very quickly. In fact, if we had opted for a conventional system, final commissioning might have been delayed for weeks because the amplifier room (used here only for distributed systems in concourses, restrooms etc.) had not yet been finished. But with the self-powered cluster fully up and running, we were able to start on aiming and alignment nearly four weeks in advance of the Bucs home opener against the Bears on September 20.
When we first turned on the system to confirm all components were up and working properly, we were immediately struck by the power and clarity of the sound, even with no equalization or signal alignment delays. We put on CDs and walked around the stadium, having a ball just listening. On the next day, we were in our trailer outside the stadium, about 900 feet away from the cluster, and we could clearly hear every song that was playing.
The sound quality went up another notch when Gary and Bob McCarthy (formerly of Meyer, now an independent consultant) came in to do final aiming, time alignment and equalization using Meyers SIM® (Source Independent Measurement) System II. Much of their time was spent in delicate adjustment of the high Q speakers which (like football) comes down to a game of inches.
By the time we had installed the main cluster, the stadium interior was sufficiently complete to concentrate more effort on installing the remaining 590-odd speakers (from CDK, EAW, Soundolier, Turbosound and University) in the 70V systems for concourse areas, restrooms, and clubs. With thirty amplifiers in three far-flung locations (not counting the monitor amp in the main control room), one of our primary concerns was amplifier control and monitoring. We needed the ability to easily check for existing or potential failures, as well as quickly make gain adjustments for various zones without resorting to walkie-talkies and manual knob twisting. To accomplish this task we chose the PC-based QSControl 2 system, both for its program flexibility and the bulletproof reliability of the QSC amplifiers.
A second PC computer in the main control room is dedicated to Meyers RMS (Remote Monitoring System) for the main speaker cluster. RMS is a software/hardware solution that allows engineers to remotely monitor the real-time conditions of Meyer self-powered speakers. It delivers to the operator extensive status and system data including amplifier voltages, limiting activity, power output, temperature, and fan and driver status.
Although both the QSControl 2 System and RMS could run on the same CPU, we chose to keep them separate to provide redundancy. However, should either or both computers fail, the audio signal would not be affected in any way: only monitoring and control functions would be lost until computer functions were restored.
Since the first commandment of a Gary White-designed system seems to be "THOU SHALT NEVER LOSE AUDIO," the balance of the system front end relies on proven and more conventional technologies. The front end utilizes an analog DDA CS-8 console, with an Ashley MM508 in the rack ready for quick patching in as backup. For front end signal processing, White specified parametric equalizers from Klark Teknik and Symetrix, dbx compressor/limiters, a Symetrix vocal processor, and digital delays from Klark Teknik and Peavey. Discrete boxes were favored over a computer-controlled DSP system because you can patch around a failed unit; if your CPU or DSP core fails the results can be, well, most unwelcome.
So although the Tampa system incorporates pioneering advancements in high SPL, extended bandwidth stadium audio, it does so without compromising fundamental reliability. It's still too early to accurately gauge the success of the system (the Bucs home opener is a week away from this writing), but all indications are that the Raymond James stadium will establish a new benchmark for audio quality and power in the NFL circuit. The installation certainly marks a high point in the history of our company, and the authors would like to particularly thank Sean Miller, ProSound's installation supervisor, who was instrumental in making sure the work was done right and right on time.
One final note: The main Meyer cluster did cause to some minor installation delays-but in the secondary distributed systems installed later! Every time we put music on the main cluster, our installers (along with painters, plumbers, electricians, dry wall hangers etc.) would be drawn out into the bowl to listen and gawk and say, "Boy this sure sounds better than my stereo at home." To get them back to work we would have to turn off the system. Successful design has its benefits, but also its distractions.
Rod Sintow is CEO of ProSound in Miami. Stan Hutto was ProSound's project director for the Tampa installation. The authors would like to thank Bruce Borgerson of Wavelength Communications for his help in preparing this manuscript.