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At the Smithsonian, They Let the Music Play

The McEvoy Auditorium originally opened in July 2006 as part of the massive renovation project. Led by Hartman Cox Architects of Washington, D.C., the renovation added architectural features like curving staircases and vaulted galleries, as well as four new public-use facilities: the McEvoy Auditorium, the Lunder Conservation Center, the Luce Foundation Center for American Art, and the Kogod Courtyard.

CHALLENGE: Enhance the acoustics of a purpose-built lecture auditorium to better accommodate musical performances and surround-sound film presentations.

SOLUTION: To save on equipment and labor, install an acoustic enhancement system that integrates with the existing audio and digital processing systems.

As the world's largest museum complex, the Smithsonian Institution offers a diverse array of public programming, from lectures and films to dance and music performances. Venues like the new 346-seat Nan Tucker McEvoy Auditorium, which is shared by the Smithsonian American Art Museum and National Portrait Gallery, must serve multiple audiences yet maintain the high standards expected of an international cultural institution.

The McEvoy Auditorium originally opened in July 2006 as part of the massive renovation project. Led by Hartman Cox Architects of Washington, D.C., the renovation added architectural features like curving staircases and vaulted galleries, as well as four new public-use facilities: the McEvoy Auditorium, the Lunder Conservation Center, the Luce Foundation Center for American Art, and the Kogod Courtyard.

A LARES Associates enhancement system warms the acoustics in the Nan Tucker McEvoy Auditorium at the Smithsonian Institution.

A LARES Associates enhancement system warms the acoustics in the Nan Tucker McEvoy Auditorium at the Smithsonian Institution.

New York–based Cerami Associates served as the AV consultant for the original project and was responsible for the systems' overall capabilities and layout. Robert Slye Electronics, an integrator in Arlington, Va., installed the original systems and was called to assist in enhancing the space's acoustics in 2007.

“The auditorium was created for presentations and lectures, with 35-mm film projection and AV presentation systems. During the design phase, wooden acoustical slats were chosen for the side walls to maximize intelligibility; the room acoustics are fairly dry,” says Stephen Slye, the integrator's president. “Once the Smithsonian began using the new space, they discovered that chamber orchestra groups and solo musicians liked the intimate size of the room, but the acoustics were not warm enough for music performances.”

NOT SUITED TO MUSIC

The McEvoy Auditorium looks like a basic auditorium, with an elevated stage and rows of cushioned theater seats. “It's a typical room built for lecture and media presentation. It is small enough so the spoken word can be heard at the rear seats without amplification, and the acoustics are dry enough for both film and amplified speech reinforcement,” says Steve Barbar, president of LARES Associates, an acoustic enhancement systems design and manufacturing firm in Belmont, Mass. “But with a reverberation time of 0.7 seconds, the acoustics are contrary to the needs of music.” LARES Associates joined the project after Slye Electronics evaluated several options and technologies that could improve the acoustical response. Budgetary constraints and the room's packed schedule were also important factors in the final decision.

“LARES was chosen because they were willing to work with the existing Peavey MediaMatrix system. [Its] technology would add a minimal number of new speakers to the space and would also minimize the need to deconstruct or reconfigure the current installed audio system,” says Slye.

The audio system installed in 2006 included 20 Tannoy CMS-801 ceiling speakers for speech reinforcement that were installed 8 feet apart in the room's suspended ceiling clouds over each row of seating. A separate left-center-right audio system, consisting of three JBL AM6215 speakers for the center cluster and two JBL AL6125 subwoofers on each side, was used for film playback on the two Kinoton FP-38es 35-mm film projectors. Audio for the film projection system was handled by a Panastereo CSP-1200 stereo sound processor, one Dolby Digital DA-20 adaptor, and one Sony DTS-60 adaptor.

Despite the robust audio system, something was missing when the space was redesigned. Because of the wooden slats on the side walls, any attempt at surround sound for film playback fell short.

“The slats on the side walls did not allow for surround speakers so ‘surround sound' came from the ceiling speakers. While functional, the surround audio was far from optimal,” Slye says. “The original plan was to have the slats motorized to change the acoustics of the room, but somewhere along in the process they were installed at a fixed angle.”

Barbar notes, “The side walls have two inches of absorptive material plus an air gap behind the slats. The angle of the slats is throwing sound towards the back of the room and the walls are absorbing lots of sound energy.”

LAYERING ACOUSTICS

Installing the equipment needed for the LARES system to work properly required a multipronged approach. The first challenge: the placement of the additional loudspeakers without compromising the room's aesthetics and function. Barbar added eight LARES 440 loudspeakers near the stage area. “On stage, musicians needed the system to carry the reflected energy back to the stage for a more natural acoustical experience,” he explains.

“By adding that additional energy to the stage, it adds to the comfort of the performing musicians. It is a more natural sounding environment for them,” Slye says.

Barbar also added another eight Tannoy CMS-801 ceiling speakers in the auditorium “because some of the original speakers were spaced too far apart [for even coverage],” he says. Unlike the original ceiling speakers, these eight were installed from below the ceiling clouds rather than above. This required Slye and his crew to scaffold the seating area, a task that is never fun or easy.

To add both true surround-sound capability for film playback, as well as lateral envelopment for music, the room needed side wall speakers that could integrate into the existing wooden slat structure of the side walls. Fourteen slats were replaced by custom fabricated LARES 448 vertical loudspeakers, which were mounted every 12 feet down each side of the room. The vertical loudspeakers were the same cubic volume as the LARES 440s, but had reconfigured electronics and a custom cabinet made specifically to fit the slat holes.

“Their placement provides an encompassing soundfield for the audience. In a larger hall, sound comes from all around you,” says Barbar. “If the ceiling speakers were used exclusively, your neurology would detect that the sound energy is coming primarily from above and not all around you and it doesn't feel, or sound, correct.”

The second challenge was integrating the new hardware and acoustic enhancement functionality into the existing MediaMatrix 760NT digital processing mainframe and existing AMX control system. “We significantly reduced the cost of both additional equipment and labor by using the existing DSP to distribute LARES signals,” says Barbar. “It was also fortunate that the original ceiling speakers were wired the right way. The 20 original ceiling speakers had dedicated amplifier and processing channels, which enabled us to readily integrate LARES processing.”

According to Slye, the ceiling speakers were wired as individual home runs to allow the left and right surround channels to be fed to the appropriate ceiling speakers. This configuration also allowed the speech reinforcement audio to be adjusted for the change in elevation from the front of the auditorium to the rear, relative to the audience seats.

For the side wall speakers, Slye added an AES digital audio I/O card to the MediaMatrix system “and then programmed the surround channels to send to the new pieces from LARES,” he says. “Conversely, because the existing ceiling speakers were already processed by the MediaMatrix, we had to route the new reverberant channels back into the ceiling speakers.”

For integration into the existing AMX control system, Slye's AMX programmer worked closely with Barbar to add a new control page that could source select, recall the LARES presets, and adjust the LARES system volume remotely from the operator position in the rear control room. The physical integration was done using the RS232 and MIDI connections on the LARES system and connecting the appropriate pieces into the AMX system.

“The end result was that we completely retuned the film system with dramatic results. The existing system had enough hardware and Dolby processing for good surround imaging but the original tuning was severely hampered by the lack of lateral sound. Once that problem was resolved, the experience was significantly improved,” Barbar says.

Linda Seid Frembes is a freelance AV journalist and frequent contributor to PRO AV. She can be reached at www.frembes.com.



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