 A demonstration of the ACD system led to Meyer Sound creating a subwoofer for film director Francis Ford Coppola’s use with the custom, quadraphonic sound system that toured with the original 70 mm release of "Apocalypse Now".This was the first loudspeaker to use a dedicated processing unit to provide crossover, amplitude and phase correction, along with driver protection.Also in 1979, the company developed the UM-1 UltraMonitor, which led to a long association with the band Grateful Dead.