Mercersburg Academy: New Sound System for Historic, Gothic-Style Chapel
Mar 17, 2005 3:45 PM
"Replace a 50-plus-year-old sound reinforcement system in an historic stone chapel without disturbing the architectural integrity of the interior, and allow for expanded use of the space for lectures and, temporarily, concerts."
The general project description is not unusual, even to the multi-use request that seems to push against the primary demand of an architecturally unobtrusive system. But behind every superficially similar project description is a very specific architectural structure—and a solution, if it really works, that's site-specific.
Founded in 1893, Mercersburg Academy in Mercersburg, Penn. has a co-ed student body of approximately 450. The Academy Chapel, dedicated in 1928 to the memory of Mercersburg alumni killed in World War I, was designed by Ralph Adams Cram (1863-1942), the foremost Gothic revival architect in the United States. His work is represented on a number of campuses, including Sweet Briar College, Rice University, and West Point. But he is most closely associated with Princeton, where he served as Consulting Architect from 1907 to 1929. Among Cram's churches are the nave and exterior of the Cathedral of Saint John the Divine in New York.
In the Spring of 2004, Mercersburg Academy's performing arts center, Boone Hall, was scheduled for demolition and reconstruction. As a temporary solution to the loss of Boone Hall, the school looked toward their historic chapel for hosting performing arts concerts, as well as for their scheduled lecture series. The school contacted Audio-Video Group of Frederick, Md., concerning the 50+ year old Chapel sound system. Audio-Video Group is a full-service, systems design-build company that also offers compete lines of sound and video presentations systems for rent.
Architectural concerns make a central cluster loudspeaker system unworkable, says Audio-Video Group systems designer and sales executive, Charles Cassell. "We decided to take a distributed speaker system approach," he says. "From day one, the primary focus for this system was speech intelligibility, with a secondary emphasis on full range capabilities. But implementing this design presented many challenges because of the chapel's architecture and construction."
Audio-Video Group's solution was a seven-zone system of independently controllable loudspeakers, all from Community: 14 Community STS26 and two STS28 loudspeakers. STS26 and STS28 are full-range loudspeakers with a ferrofluid-cooled, high-frequency driver and dual matched 6-1/2in. and 8in. low-frequency speakers, respectively. Both loudspeakers have 120 degrees H X 60 degrees V dispersion patterns. Three QSC CX404 amps power the Community products.
"By using seven zones of independently controllable loudspeakers," says Cassell, "we were able to minimize the volume produced in each zone and maintain very consistent coverage throughout the nave, transepts, and balcony." The Chapel is approximately 180ft. in length, with a 46ft. wide nave and a 50ft. high ceiling.
"All of the processing for each zone is handled through the Biamp AudiaFLEX frame [with six IP2 and OP2 cards]," says Cassell. "This allowed us to set relatively low output levels in each zone, thereby minimizing reflections."
Ten Community loudspeakers cover the nave. A pair ST28s cover the nave from the front of the chancel steps to the first R-L pair of four sets of delays. The upper and lower transept galleries are covered by two pair of STS26s, and pair of STS26s covers the balcony area at the rear of the chapel.
"We chose the Community STS series product," says Cassell, "for their relatively small size and their good voice articulation over a large coverage area from fairly close proximity. The whole goal was to use a distributed system and not have to turn up the volume in any one area. The Community product helped us achieve this."
Actually, Audio-Video Group created a dual-purpose system for the Chapel. The school can use the automatic mixer for speech reinforcement, no operator required. Or for more full range applications, such as concerts and drama presentations, they can roll in the portable dual 15in. sub, plugging in to one of two custom connection plates integrated into the chancel flooring, and run the system in manual mode with an Allen & Heath PA28 console and an operator. "The school can switch between automatic and manual mixing modes" says Cassell, "by selecting one of two presets in the Biamp AudiaFLEX."
Mercersburg Academy Minister Peter Dietz, who was responsible for overseeing the project, comments: "Making this type of upgrade to a Gothic, stone, cathedral style building is a huge challenge. Maintaining the integrity of the environment and limiting any noticeable changes to the building were some of my non-negotiable issues. Audio-Video Group met and exceeded my expectations."
The Mercersburg Chapel spire, a replica of St. Mary the Virgin at Oxford, contains one of 163 traditional carillons in the United States, and provides weekly (unamplified) concerts.
