Inside the Target Field Install
Apr 12, 2010 2:32 PM, By Dan Daley
Communication saves the build at Target Field.
The Learning Curve
For Parsons Electric—which was hired by Mortenson Construction as an integrator of voice/data, audio/video, broadcast, security, and other systems—there was more at stake than just meeting deadlines by coordinating with other vendors. “Part of out mission here was to become a player in the large-scale sports venue sector,” says Michael Couture, Parsons’ project manager on the job, who noted that Parsons acquired a local security company to buttress those skillsets and partnered with TSI Global for audio/video cabling and to help implement WJHW’s PA system design. “We literally geared up for this job,” he says, “researching other stadium projects to determine what skills we needed to beef up and augment. Anyone can run cable; it was our knowledge of the various system requirements that we were improving.”
Parsons brought on other partners, including Siemens to help develop the security systems and Infinity Scaffold to help them rig the hoists to lift loudspeakers into place. But as an electrical contractor, Parsons was certainly familiar with interaction between trades, and that took place to a large extent as they coordinated cable pathways with Gephart Electrical’s installation crews. “The most important thing for any cabling contractor to be able to meet its deadline is to have that pathway ready for you,” he says. “Mortenson and Gephart did a great job of that to help us achieve our timeline and our budget.”
Target Field’s aesthetic design dictated the location of many AV elements, perhaps most notably the distributed audio system. A design that called for a retractable roof was scuttled since it would have added another $100 million to the stadium’s price tag. Instead, a huge metal canopy extends out over the upper deck seating, offering fans some protection from the elements. For both aesthetic and practical purposes, it was determined that the canopy also hold loudspeakers between its upper and lower metal skins to cover the upper reaches of the stadium. However, while toward the center the canopy’s interior was as high as 20ft., with its own internal catwalk, its airplane wing-like shape—tapered severely at each end—made integrating loudspeakers into those areas a challenge. The lower skin is made from thin, 12’x6’ panels of perforated steel. The 3’x4’ custom loudspeaker boxes, loaded with JBL Control series loudspeakers, required custom brackets fabricated by TSI Global to attach the boxes to the structural steel, both for sturdiness and to keep the loudspeakers at a uniform 6in. above the perforated sheets that act as giant grilles. The brackets also had to meet state code, which in Minnesota means being able to withstand up to a 2lb. load per square inch of ice and snow. Altogether, 16 clusters of boxes—PD43347 WRX cabinets custom-made by JBL each loaded with a 12in. woofer aimed outward toward the seating area bowl and a 6in. horn firing directly down—fill the canopy. The 380lb., anvil-shaped boxes were hauled up to the canopy by an electric winch, which held them in place as they were bolted to the brackets before the underskins were installed.
“This was a very different installation configuration than we had experienced before at large stadiums,” says Steve Higgenbotham, project manager for TSI Global, the PA systems designer and integrator. He referred to Anheuser Busch Stadium in St. Louis and the Mets’ Citi Field in New York, where TSI installed the uppermost PA loudspeakers in the open. Several JBL PD5200/43 WRX loudspeakers that are attached to beam-mounted light bars and are painted to match the grayish background created by the canopy and visually fade into it. Six additional JBL PD5322/64WH loudspeakers are mounted on the custom Daktronics 101’x57’ (LxH) HD display, the fourth largest of any MLB stadium. The weather-resistant boxes—“half the size of a Hyundai,” as Higgenbotham describes them—are welded to the display’s frame and are tuned for long throws to centerfield, grandstand, and upper-deck seating.
Audio is networked throughout the stadium on a CobraNet system, allowing it to connect with the IPTV system that distributes audio and video to the club levels and concessions areas. There are five clubs total, each with local control of its AV systems, which include Sony BDP-S200ES Blu-ray players, Crown CTS-600 amplifiers, and Creston Pro2 processors in dedicated rooms racks, and either Sunlight or Sony LCD displays. This high degree of local control, using Crestron TPS-4000 control panels, extends to the stadium’s bar areas, as well. However, every audio system and display is also under the control of the central control room. “Essentially, the IPTV system lets the Twins control the video as though it was a computer on a LAN,” Higgenbotham explains. “They can turn any set on or off, change channels, or change content, which makes it a type of digital signage, as well.”
The audio system also plays a role in Target Field’s reported intent to apply for LEED certification as a green building. If certified, the ballpark would be only the second LEED-certified professional sports stadium in the United States, after the Nationals Park in Washington, D.C. All of the Crown CTS 600, CTS 1200, CTS 2000, and CTS 3000 amplifiers are run on the 20-amp house circuit and all the bowl, which Higgenbotham says offers a high degree of energy efficiency and thermal distribution.
Parsons and TSI worked together to install the stadium sound system. At one point, a structural change on the canopy’s underskin resulted in several points where solid metal sheets would be used in place of the perforated ones, rendering them opaque to sound. As a result, several loudspeakers had to be relocated; this also required that they be re-aimed, based on calculations supplied by acoustical consultant WJHW, using a combination of lasers and inclinometers. The coverage of the 168 external loudspeakers that comprise the bowl distributed system was plotted as a single huge zone, and intended to keep all of the sound in the bowl, not letting it leak into the surrounding residential neighborhood. “That was accomplished by a combination of precisely aiming each speaker and tuning specific frequencies that affect their throw distance,” Couture says.
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