The Voltage Modular Synthesizer Expander Module is an emulation of the classic Oberheim Synthesizer Expander Module, aka the "SEM." Originally released in 1974, the keyboardless, mono SEM module was intended as a companion to the Oberheim DS-2, one of the earliest digital sequencers. Though it was a simple, barebones monosynth, the SEM sounded fantastic, and had a tone quality very different than the common fuzzy, fat Moog sound, thanks to its 12 dB/oct state-variable filter. With lowpass, bandpass, highpass and notch modes, this flexible filter was the star of the show. We've precisely recreated it here with a detailed emulation programmed by award-winning synth designer, Mark Barton (MRB). The design is similar to the "patch panel" reissue SEM's released in the 2000's; these were basically identical to the 70s versions but added an extensive patch panel for modular synth flexibility. Because this a polyphonic module, the majority of the patch panel jacks are poly jacks (mono jacks are used where appropriate).