The right direction
Nov 1, 1998 12:00 PM, Rod Sintow and Stan Hutto
A national passion, NFL Football is a sport that feeds on impact, and thefans expect high-impact audio with it. Gone are the days when sound systemswere designed for a lone announcer who squawked out downs, names andscores, his voice rising barely above the crowd noise. True, voiceintelligibility remains essential, but today's NFL stadium systems mustalso deliver full-fidelity music and convincing sound effects at levelsexceeding 100 dB SPL. Nothing less is appropriate for the vast videoscoreboards with their dazzling displays.
Affectionately known in the industry as "sportainment," nowhere is thisphenomenon more apparent than in the new Raymond James Stadium (named forthe sponsoring financial services firm) in Tampa, FL. The new facilityhosts world-class soccer as the home of the Tampa Mutiny pro soccer team,and it is also the home of the University of South Florida football team,but the primary tenant is the NFL's Tampa Bay Buccaneers.
In addition to a new Meyer Sound self-powered loudspeaker system, thestadium has been outfitted with two electronic scoreboards (about 2009 x609 or 61 m x 18.3 m) plugged into a full-blown video production andcomputer effects studio. In-house production and broadcast studios arebecoming an integral part of sport venue system designs as a result of theneed to generate entertainment for patrons of the stadium throughin-stadium broadcasting. Numerous video screens strategically placedthroughout the facility allow for film clips and generated montages to bebroadcast as patrons enter or exit the facility. In many cases, these videomonitors promote an orderly exit from and entrance to the facility andoffer advertising opportunities for sponsors. The NFL has already selectedthis showcase facility to host Super Bowl XXXV in 2001.
Built at a total cost of $168 million, the new 65,000-seat stadium is ownedby the Tampa Sports Authority (TSA). Sporting facility architects HOK Sportof Kansas City, MO, supervised overall design with Wrightson, Johnson,Haddon and Williams (WJHW) of Dallas assigned to develop the audio systems.The Miami-based firm, ProSound, was contracted directly by TSA to provideand install all audio, distributed video, surveillance and broadcastinterface systems.
The new Tampa facility is typical of the new generation of non-domed NFLstadiums. It is large and spacious, with minimal overhang on the threetiers of seating. This architectural style virtually rules out adistributed main system; a rear-firing system poses acoustic placementobjections, and front-mounted loudspeakers of the size required would blocksight lines. Consequently, as with most recent similar installations, themain system for the stadium bowl would have to be a single end-zonecluster. Although less costly than a distributed system, the single-clusterapproach is fraught with inherent difficulties, most notably delivering thesound to all seating areas while directing sound away from the playingfield and reflective surfaces. High-Q pattern control is crucial.
The demand for high-quality sound extends beyond the stadium bowl into therestrooms, the concourses (to support the 600 TV monitors) and the clubareas. The Tampa stadium specification called for clean, full-bandwidthsound at high SPL to all points in the facility.
As is often true in the systems installation business, anything can be doneif price is no object. The reality, however, is that most new NFL stadiumsare public/private partnerships supported by tax dollars and are subject tocareful financial review. Budgets, although normally adequate, are notunrestricted.
These problems were familiar to Gary White of WJHW, who had previouslydesigned systems for NFL stadiums in Charlotte and Jacksonville.Nevertheless, when contracted for the Tampa job, he was determined to pushthe envelope and take his previous single-cluster designs to the next levelof performance even though he was faced with similar architecturalacoustics and comparable budget restraints. In particular, he wanted tocreate a system able to project a higher sound pressure level with improvedhigh-frequency response at the opposite end of the stadium, in this case adistance of up to 700 feet (213 m).
The only practical main loudspeaker location was above the scoreboard atthe south end, about 150 feet (46 m) above the ground. The cluster isenclosed in a metal structure about 50 feet (15 m) wide by 20 feet (6 m)high mounted on a concrete slab with the front side covered by only a wiremesh metal screen emblazoned with the Buccaneers' logo. Although a roofoffers overhead protection, the rain accompanying Tampa's manythunderstorms often leans toward the horizontal. Heat and humidity areprevalent, and central Florida gets more than its fair share of lightning.
With these environmental hazards in mind, White first designed ahigh-power, high-Q system based on Meyer Sound MSL-10 cabinets powered by34 Crest amps. Although certainly capable of producing the desired results,all bids based on that first round came in over the allowed budget. AfterWhite reworked the specification along more conventional lines with lowercost loudspeakers, ProSound suggested a system based on the new Meyer SoundSelf-Powered series. This system comprises the SB-1 Sound Beam parabolictransducer and the new PSW-6 directional subwoofer, neither of which hadyet been permanently installed in the United States, indoors or out.
White was open and frank in his skepticism. First, he was concerned thatthe self-powered loudspeakers would not be able to produce the higher SPLlevels he sought, and he was understandably nervous about placing crucialamp and processing electronics in a semi-exposed metal shed 150 feet (46 m)up in Tampa's damp and often turbulent air.
It took some convincing arguments from ProSound and a trip to the Meyerfactory in Berkeley, CA, to quiet his doubts. After examining theweatherproofing techniques employed by Meyer and evaluating the low failurerate with similar products, he relented, and in consultation with Meyer'stechnical services department, he worked up a new cluster design employingall Meyer self-powered components. Although the powered loudspeakersthemselves were certainly more expensive, all costs for amps, associatedprocessing, racks and wiring were eliminated because of the self-powereddesign. Significant savings were realized in labor costs because bothinstallation and final system alignment could proceed more quickly. Addline-level audio, and the install is ready for testing because internaldriver alignment and EQ is a given.
The main cluster as installed employs a total of eight Meyer Sound MSL-6cabinets, eight PSW-6 cardioid subwoofers and four SB-1 parabolicloudspeakers for spotlight long throw, plus two MSL-4 and three CQ-2loudspeakers for side- and down-fill coverage at the south end of thestadium.
The MSL-6 is a high-power, high-Q system with three 4 inch (102 mm)diaphragm compression drivers, two 12 inch (305 mm), low-frequency drivers,matched class AB/H MOSFET amps for each driver (2,480 W burst power total),and all associated protection and control electronics. The -6 dB points are30 degrees horizontal and 25 degrees vertical for precise aiming at thedesired spectator seating areas.
Although a 25 degrees x 30 degrees pattern is considered high Q; at adistance of 700 feet (213 m) from the source, it still translates into afairly broad coverage area. The far corners are always difficult to coverin large stadiums, particularly at Tampa, where each corner has largereflective surface areas. With conventional technology, all the optionshave a down side. One approach is to accept lower levels and reduced HFresponse in these remote areas. Another way is to add more horns and morepower, which will virtually guarantee bleed onto the field and nearbyreflective surfaces. Yet another option (although expensive) is to installadditional delay systems and risk the impaired sight lines from some seats.
At Tampa Bay, new technology offered a better alternative. The Meyer SB-1Sound Beam (patent pending) is a transducer that uses a parabolic reflectorrather than a conventional horn to project a coherent beam of mid and highfrequencies (500 Hz to 15 kHz) over long distances with a beamwidth of 10degrees. Because of the unique focused dispersional characteristics of thisdevice, sound pressure level reduction is as little as 3 dB with eachdoubling of distance. In the Tampa system, two SB-1 systems are employed oneach side of the main cluster to spotlight the problematic far cornerareas, giving these seats equal (if not better) high-frequency coverage.Luckily, these distant seats seem less subject to disturbances from windeffects in this stadium. The parabolic reflector seems to maintain morecoherency even when the air is in motion, allowing a perceived effect of acloser sound source.
NFL franchises also expect lots of "thump" in their systems, and thisdemand for extended bass response generates its own set of problems insingle-cluster designs. Because conventional subwoofers are effectivelyomnidirectional below 100 Hz, placing them inside a cluster enclosure suchas the one at Tampa can generate narrow band cancellation effects and spillunwanted energy back into the parking lot and beyond. This problem wasthwarted by the installation of the PSW-6 powered directional subwoofer.Enclosing two 18 inch (457 mm) and four 15 inch (381 mm) drivers (twofacing the rear), the PSW-6 employs the same simple principle used incardioid mic transducers to provide a front-to-back projection ratio ofbetter than 15 dB from 30 Hz to 125 Hz. This enabled mounting of the PSW-6sub-woofers co-planar with the MSL-6 cabinets for a seamless low-frequencytransition with no cancellation effects from the surrounding enclosure.
The first phase of the cluster installation was somewhat nerve-wrackingbecause it involved hoisting all the loudspeakers 150 feet (457 m) in theair on a crane and then maneuvering them into place inside the enclosure.Several cabinets received damage to the exterior weather protection. MeyerSound responded quickly with all the parts and materials needed to restorethe cabinets.
Aiming is critical in any high-Q system. For the Tampa installation,ProSound constructed a custom hanging track assembly that allowed preciseadjustment of the suspended cabinets in both the horizontal and verticalaxes. The SB-1 devices sit on the concrete deck and employ their ownprecise integral aiming mechanism.
As expected, final installation of the self-powered systems proceededquickly. If a more conventional system had been chosen, final commissioningmight have been delayed for weeks because the amp room (used here only fordistributed systems in concourses and restrooms) had not yet been finished.With the self-powered cluster fully functional, aiming and alignment wasstarted nearly four weeks in advance of the Buccaneers' home opener againstthe Chicago Bears on September 20, 1998.
When the system was first energized to confirm all components were workingproperly, the impact of the power and clarity of the sound was startling,even with no EQ or signal alignment delays. While testing with recordedmusic the next day, sound was clearly heard outside the stadium some 900feet (274 m) away from the cluster.
The sound quality went up another notch when White and Bob McCarthy(formerly of Meyer, now an independent consultant) came in to do finalaiming, time alignment and EQ using Meyer's SIM (Source IndependentMeasurement) System II. Much time was spent in delicate adjustment of thehigh-Q loudspeakers, which, like football itself, is a game of inches.
By the time the main cluster was installed, the stadium interior wassufficiently complete to concentrate more effort on installing theremaining 590 other loudspeakers (from CDK, EAW, Soundolier, Turbosound andUniversity) in the 70 V systems for concourse areas, restrooms and clubs.With thirty QSC amps in three far-flung locations (not counting the monitoramp in the main control room), one of the primary concerns was amp controland monitoring. The need to check for existing or potential failures andmake quick gain adjustments for various zones without resorting towalkie-talkies and manual knob-twisting is abundantly clear in situationssuch as these. To accomplish this task, the PC-based QSControl 2 system waschosen both for its program flexibility and the reliability of the QSC amps.
A second PC computer in the main control room is dedicated to Meyer's RMS(Remote Monitoring System) for the main loudspeaker cluster. RMS is asoftware/hardware solution that allows engineers to monitor the real-timeconditions of Meyer self-powered loudspeakers remotely. It delivers to theoperator extensive status and system data, including amp voltages, limitingactivity, power output, temperature, and fan and driver status.
Although both the QSControl 2 system and RMS could run on the same CPU, thechoice was made to keep them separate for redundancy. Should either or bothcomputers fail, the audio signal would not be affected in any way becauseonly monitoring and control functions would be lost until computerfunctions were restored.
Because White's first commandment seems to be "Thou shalt never loseaudio," the balanceof the system front end relies on proven and moreconventional technologies. The front end uses an analog DDA CS-8 consolewith an Ashly MM508 in the rack ready for quick patching in as backup. ForFOH main signal processing, White specified parametric EQs fromKlark-Teknik and Symetrix, dbx Professional compressor/limiters, a Symetrixvocal processor and digital delays from Klark-Teknik and Peavey. Discreteboxes were favored over a computer-controlled DSP system because one canpatch around a failed unit.
Although the Tampa system incorporates pioneering advancements in high-SPL,extended-bandwidth stadium audio, it does so without compromisingfundamental reliability. It is still too early to gauge the success of thesystem accurately, but indications are that the Raymond James Stadium willestablish a new benchmark for audio quality and power in the NFL. Theinstallation certainly marks a high point in the history of ProSound, andthe authors would like to thank Sean Miller, ProSound's installationsupervisor, who was instrumental in making sure the work was done right.