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JBL Gets Into Tweeter Center

Pro Sound Service has installed new JBL VerTec line arrays and AE Series loudspeakers at the Tweeter Center in Mansfield, Mass. The Tweeter Center is a 19,900-seat outdoor venue with a covered, roofed section of about 7,500 seats with the balance in an open seating area. A wall at the back of the seating area separates it from the community.

Until installation of the new system, there had been an ongoing noise-complaint issue from the neighborhood located behind the back wall of the facility. A 16-foot-high wall barrier had been erected to alleviate noise complaints after the town established a maximum allowable SPL of 95 dB at the back wall. Sound levels are continuously monitored via a real-time calibrated measuring system with mics located at the top of the wall. Minute-by-minute SPL readings are printed for review by town officials and a high priority is placed on containment of sound within the venue.

“During the system installation and commissioning,” says Charles Tappa, Pro Sound Service president, “we found that we were able to measure a full 10dB difference between the measurement mics at the top of the wall and the SPL at ground level. This we absolutely attribute to the tight vertical pattern control of the JBL VerTec line array system.”

Tappa and crew took detailed measurements of the facility, including the existing speaker-mounting cluster locations in the fascia, as the budget constraints would require the use of existing speaker locations. It was determined that VerTec line arrays would provide the required coverage and output power within the seating area while maintaining control of SPLs at the boundaries of the audience coverage area.

The final design specified that each of four existing cluster locations would contain five VT4888 enclosures, with two additional locations each housing VRX932LA compact constant-curvature line arrays and a single AM6212/95 cabinet as “fringe fill.” The total system includes 20 VerTec VT4888 midsize line array elements, two AM6212/95s and six VRX932LAs. Additionally, the system included 11 Crown I-Tech 4000 amplifiers and 10 I-Tech 8000s, with two dbx 2231 dual 31-band graphic equalizers. The company’s VerTec Line Array Calculator software allowed the team to accurately predict not only coverage patterns, but SPL at various locations in the lawn area along with rigging details.

“During system commissioning,” Tappa continues, “with the system running at 95dB SPL at the back wall, a handheld meter was taken into the neighborhood to check sound pressure levels. We made a phone call to verify that the sound system was still on because it could not even be heard in an area that was previously a problem spot in the neighborhood. This was truly a testament to the highly effective, as-advertised pattern control of the VerTec system.”

The new system is one of the first lawn-delay systems in the nation to use Harman Professional’s HiQnet networking protocol and System Architect Software. According to Tappa. “HiQnet gave us a level of system control and flexibility not previously available. The HiQnet-compatible Crown amplifiers allow for individual DSP on each amp channel. Along with the DSP, we have load monitoring and error reporting so that we can get automatic system reports of any small problems before they become big ones. HiQnet allows for global changes of all 42 DSP processors in the various amplifier channels through easy-to-build control screens. The HiQnet remote control and monitor system was a major selling feature to the customer, who immediately realized the full potential of this advanced system.”

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