Model

Oberheim SEM

Semi-modular analog synthesizer voice module

The Oberheim SEM (Synthesizer Expander Module), introduced in 1974, was Oberheim's first product: a compact semi-modular single-voice analog synthesizer module with two VCOs and a distinctive two-pole multimode voltage-controlled filter offering low-pass, high-pass, band-pass, and notch responses. Stacked SEMs formed the basis of the Two Voice, Four Voice, and Eight Voice instruments, and its filter character was later revived in the OB-X8.