Sep 2, 2009 12:00 PM, By Trevor Boyer
Designing and implementing stadium audio systems for the 2009 MLB season.
The seating is just one section of the stadium; for the purposes of the AV system, there’s also the back of house (concession, clubs, bathrooms) and broadcast (camera positions, press interview facilities, etc.). More than 90 JBL Contractor Series Control 29s cover the stadium’s private suites and certain fill areas near home plate and in the “home run porch” in left field; and Tannoy CMS6 and Di6 DCT loudspeakers are installed in bathrooms and concession areas.
The bulk of the power for Citi Field’s loud¬speakers is supplied by Crown CTs 3000 amplifiers, which serve mainly the front-firing horns of the EAW AX series units. CTs 2000 amplifiers power the rear-firing components of those custom boxes. From the audio sourcea Yamaha M7CL 48-channel digital mixer drives the system from the control room over home plateto the amplifier closets, audio travels as CobraNet over Cat-5; from the closets out to the loudspeakers, it’s over copper wire.
At the same time as the company was designing Citi Field’s audio system, WJHW was also at work developing the new Yankee Stadium’s system. For both stadiums, a new hybrid BSS signal-distribution scheme was used for the respective DSP systems that made them much more fault-tolerant than was previously possible. Beaudoin describes a “distributed” DSP design. “At both those stadiums, we used smaller DSP processors that were linked together via both CobraNet and the BSS digital audio bus,” he says.
CobraNet runs on Cat-5 through network switches; it originates at the control room over home plate. That signal runs to each of three amplifier rooms above first base, third base, and center field. There’s also an analog audio backup running to these rooms in case CobraNet fails. From these rooms, a digital audio bus links the BSS London BLU DSP boxes to each other in two directions via Cat-5. The boxes essentially form a ring. “That’s how you get that redundancy,” Beaudoin says. If one box fails, the DSP signal switches directions and there’s no break in audio.
WJHW designed and TSI Global integrated more than just the audio system for the New York Mets’ new stadium in Queens, N.Y. For one thing, TSI Global designed and assembled all the Middle Atlantic equipment racks for Citi Field’s AV systems in its Missouri facility.
The stadium also has more than 800 video monitors throughout the facility in concourses, restaurants, club spaces, and an adjoining 200,000-square-foot event space. Provided by Sharp, these Aquos LCD HDTVs display both the live game (via four inhouse channels) and dozens of local and satellite channels. Inhouse channels are produced in full 1080 HD.
TSI was not responsible for the hanging of the actual Sharp sets, but it was tasked with supplying a signal to each of the hundreds of monitor locations, as well as infrastructure to facilitate mounting, electricity, and a cable drop. Passing these HD signals around such a large building was a challenge, according to Dave Potts, senior field engineer with TSI, because all the channels had to travel down a single fiber out to relay locations. “We’re not just distributing an RF signal,” Potts says. “We’re distributing the entire complement of DirecTV down that pipe also.” From one rack room, the signals are distributed to a series of equipment closets, for signal relay out to the displays. Balancing the signals traveling on that single fiber was a challenge for the integration team.
Inhouse channels, such as the stadium’s video replay, are generated as full 1080-line HD signals and encoded to MPEG using four Adtec Digital MediaHub-HD Pro encoders. The system then modulates the MPEG stream to an ASI stream. That stream enters a modulator, which converts it over to a QAM signal for over-the-air distribution.
TSI also integrated the cabling and connectivity for all the stadium’s broadcast locations, such as camera positions, interview locations, and broadcast truck docks. (This broadcast “connectivity” required the building of several dedicated racks.)
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