Megasound

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Megasound was the name of a movie theater sound system created by Warner Bros. in the early 1980s. It was used to enhance the premiere engagements of a handful of Warner features, including Altered States (1980), Outland, Wolfen and Superman II (all 1981).

Theaters equipped for Megasound had additional speakers mounted on the left, right and rear walls of the auditorium. 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.

The system worked in a similar manner to MCA/Universal's SENSURROUND Special Effects System, but unlike SENSURROUND, no discrete control tones on the soundtrack were used - instead, the Megasound control system was triggered by low bass below 50Hz on the soundtrack... a slightly modified Aphex Sub-Harmonic Synthesizer was contained in every Megasound system to extend the bass recorded on the soundtrack down into the infrasonic range. The modification of the Aphex was needed because in its normal state, the Aphex would only synthesize bass down to 25Hz, which wasn't deep enough to create the sensation of movement. A 16Hz low frequency cut-off was used in both SENSURROUND and Megasound because, during system development, MCA's engineers had discovered that the majority of theaters resonated around 5 Hz (and none had significant resonance above 10Hz), so by making sure that the systems had virtually no output below 16Hz, any risk of physical damage to the theater would be eliminated. Like SENSURROUND, Megasound played the low frequency bass at a level of 110-120db. In many Megasound installations, MCA/Cerwin-Vega engineered SENSURROUND horns were used. This was because the SENSURROUND horns were custom designed for very low frequency, high level bass reproduction in theaters and there were no other commercially available speakers that could be used. Quite a number of theaters kept the horns in place after the Megasound runs and wired them into the main system, thus patrons experienced 70mm films such as "Close Encounters Of The Third Kind" with very deep bass.

Unlike MCA's SENSURROUND, Warner Brothers never attempted to market Megasound to other studios as a general purpose, high-fidelity, sound system like Dolby Stereo.

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It should be noted that the bass experienced with SENSURROUND and Megasound cannot be compared to digital sound reproduction in theaters today. SENSURROUND and Megasound had vastly louder and deeper bass that simply can't be duplicated in today's cinemas. No subwoofer currently in use in theaters, not even in IMAX installations, comes close to what the Cerwin-Vega SENSURROUND horns could do or the thrilling audience participation effect they could create.