Old Crow's Synth Shop: The Synth-Tan Project: Oberheim 4-Voice

No classic synthesizer collection would be complete without a contribution from Tom Oberheim, who designed several polyphonic (multiple notes at once) synthesizers that have become well-known for their rich sound. Prior to the advent of the low-cost microprocessor--in 1976 a Z-80 microprocessor was $300.00; in 1980 it was $10.00--efforts to create polyphony without a CPU were challenging. Yamaha managed it by throwing several thousand parts at the problem, repeating a circuit as many times as needed. Oberheim took a more modular approach. He built the SEM, a "synthesizer expander module," and designed instrument cabinets that allowed one to install from one to eight SEMs with each one added permitting a new note of polyphony. Each SEM had its own control panel, and the base unit's keyboard had an 'assigner' that could route sections of the keyboard to specific SEMs, thus allowing one to dial up for example a bass isntrument, a chord isntrument, and a lead instrument all in one synthesizer.

1976 was a pivotal year in the evolution of synthesizers, as rock bands grew more accustomed to using them on stage as well as in the studio. Keyboardist Dennis DeYoung of the band Styx was an expert at using the Oberheim, as heard here in their famous track Come Sail Away.

--Crow