Synthesizer innovator Robert A. Moog, Aug. 21 Robert A. Moog, whose self-named synthesizers turned electric currents into sound and opened the musical wave that became electronica, died at his home in Asheville, N.C. on Sunday, Aug. 21, 2005. He was 71. As a Ph.D. student in engineering physics at Cornell University, Moog -- which rhymes with vogue -- in 1964 developed his first voltage-controlled synthesizer modules with composer Herbert Deutsch. By the end of that year, R.A. Moog Co. marketed the first commercial modular synthesizer. The instrument allowed musicians, first in a studio and later on stage, to generate a range of sounds that could mimic nature or seem otherworldly by flipping a switch, twisting a dial, or sliding a knob. The arrival of the synthesizer came just as the Beatles and other musicians started seeking ways to fuse psychedelic-drug experiences with their art. The Beatles used a Moog synthesizer on their 1969 album, Abbey Road; a Moog was used to create an eerie sound on the soundtrack to the 1971 film A Clockwork Orange. Keyboardist Walter (later Wendy) Carlos demonstrated the range of Moog's synthesizer by recording the hit album Switched-On Bach in 1968 using only the new instrument instead of an orchestra. The popularity of the synthesizer and the success of the company named for Moog took off in rock as extended keyboard solos in songs by Manfred Mann, Yes and Pink Floyd became part of the progressive sound of the 1970s. ``The sound defined progressive music as we know it,'' said Keith Emerson, keyboardist for the rock band Emerson, Lake and Palmer.