The Wright Brothers may have soared into history at Kitty Hawk field in North Carolina, but New York has an equally strong claim to having been the birthplace of modern aviation. The site of the first unmanned powered glider flight back in 1896 and the launching point of Charles Lindberghs famed nonstop transatlantic flight, Long Island was also the longtime home of Grumman Corporation, manufacturer of cutting-edge aircraft ranging from World War II Navy fighters to the Lunar Module that landed man on the moon.
The recently refurbished and reopened Cradle Of Aviation Museum, located near famed Mitchel Field in Uniondale, pays homage to the men and machines that freed us from the bounds of gravity. The 130,000-square-foot complex houses two hangars filled with vintage aircraft (including the last operational lunar lander, earmarked to fly the canceled Apollo 18 mission), as well as a large-scale IMAX dome equipped with a state-of-the-art 6.1-channel surround sound system provided by Sonics Associates of Birmingham, AL.
Installation of the sound system was, in the words of Sonics project manager Chuck Dowd, quite an unusual process, and much more drawn-out than what we usually see. Initial architectural design work by Edward Durell Stone and Wiedersum Associates began in the late 1980s, with onsite acoustical measurements by consultant R. Kring Herbert of Omergaard Associates done in 1989. But fundraising problems and budgetary constraints imposed by local authorities put the project on hold for many years, and construction did not actually begin until 1997. As a result, Dowd says, we had to double-check to make sure that the newer equipment we were installing was going to fit in properly with the older design. Fortunately, apart from some interfacing difficulties with the house dimming system, few equipment problems were encountered.
Other issues proved to be far more challenging. For one thing, New Yorks busy JFK Airport is only some 15 miles away, and, unfortunately, the museum is located directly in the SST flight path. As a result, massive 12-inch concrete walls and a 6-inch concrete roof had to be constructed. The interior utilizes a room-within-a-room design, using gypsum board walls and ceiling with a hefty air space allowing for both acoustic damping and the installation of ventilation ducting.
Acoustically, IMAX domes are very unusual spaces in that they have perforated interiors, Herbert points out. The requirement was for a very short reverberation time over a broad range of frequencies, so we had to develop a special detail of 4-inch black-faced fiberglass to apply on the walls and the ceiling behind the perforated metal. While dome size may vary somewhat, the channel locations are standardized: left screen, center screen, right screen, left rear, right rear, and top screen (which carries height information), as well as a subbass channel. In conjunction with the wide spacing between speakers, this configuration allows for unusually intense panning movements that perfectly complement the NASA-commissioned big-screen action that often places the viewer inside (or even outside) the space shuttle or International Space Station. The suspended speaker arrays are all manufactured by Sonics (not surprisingly, the company is wholly owned by IMAX), utilizing their Proportional Point Source technology that is specially designed to eliminate positional variations in volume and sound quality in a stadium seating environment. Sonics-branded amplifiers (manufactured to their specifications by Bryston) provide 800 watts of power to the main channel woofers and the subbass channel, and 600 watts to the channel mid and high frequencies.
The audio brain of the IMAX system is a Sonics DTAC (Digital Theater Audio Controller) an integrated hardware/software all-in-one package that includes a mic/line mixer and 16 channels of 16-bit 44.1 kHz digital-to-analog conversion (the additional channels allow for alternate languages, headset feeds, and booth monitoring). The audio portion of IMAX presentations is delivered in non-compressed PCM format on DVD-ROM, and is then dumped to a pair of redundant 16-GB hard drives for real-time playback.
Operating under Windows NT, the proprietary control software not only enables multiple audio streaming, but gives onsite staff the ability to construct custom shows with locally created preshows and walk-in and walk-out music, as well as trailer selection. Ive been involved in this field for about 15 years now, says museum theater and A/V services manager Greg Merigliano, and the sound originally came in on 35 mm mag, with reel-to-reel as a backup. As a result, youd have to do physical splices to put a show together. By comparison, doing it in software is a piece of cake.
For more information, contact the Cradle of Aviation Museum at 516-572-4111 or go to www.cradleofaviation.org.
