Megasound

Megasound was the name of a movie theater sound system created by Warner Bros. and was officially deployed during the early 1980s. Warner Bros. used it to provide deep-bass enhancement to premiere engagements to only a handful of their features, including:

Theaters equipped for Megasound had an additional battery of speakers, consisting subs and horns; usually all were placed on the stage, behind the screen. This system also came along with extra power-amps and specialized processing equipment. Megasound selected soundtrack events with lots of low-frequency content (thuds, crashes, explosions, etc.) were directed to these speakers at very high-volume, creating a visceral-effect intended to thrill the audience. Megasound has been best remembered for its infrasonic rumble capability.

Megasound was similar to MCA/Universal's Sensurround. However, unlike Sensurround, Warner Bros. never attempted to market Megasound to other studios as a high-fidelity, high-impact bass enhancement sound system.

In 1977, Dolby debuted the 70mm "Baby Boom" format and used the same 70mm format as Todd-AO with a reconfiguration of its original six-track sound. The new setup utilized speakers leftover from old 70mm Todd-AO engagements. There were three screen channels, one surround channel and two dedicated boom channels that utilized frequencies > 250 Hz. Encoding Dolby A-type NR (Noise Reduction) on prints meant that each of the six magnetic tracks had less tape hiss.

Warner Bros. Superman (1978) was the first film to use the 70mm "Split Surround" as a beta-test project. The surround was split into left and right. The left/right high frequencies were recorded left-center/right-center, while sharing these tracks with the booms, which were recorded at lower frequencies. Lower frequencies for the stereo surrounds were recorded on track 6, the former mono surround track. A new filter then split the boom tracks on channels 2 and 4 from the stereo treble surround tracks. The surrounds were limited > 450 Hz and the booms < 250 Hz. Some Megasound installations added additional speakers; one which a near-future Megasound driven array of subs and horns could possibly fill.

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