 He expanded the SEM concept, and again enlisting the expertise of Dave Rossum and Scott Wedge of E-mu Systems, combining the SEM with a digital keyboard, created the Oberheim 2-Voice and 4-Voice synthesizers, the first commercially available polyphonic music synthesizers.By combining more single-voice synthesizer modules together, Oberheim expanded the concept to the Oberheim 8-Voice synthesizer, introduced in 1976.Realizing that programming the 4-Voice on stage was impractical, he designed the Polyphonic Synthesizer Programmer, an integrated circuit memory for storing the synthesizer's sound settings, another industry first.