Freeware - Cherry Audio Synthesizer Expander Module VSTi Plugin

https://cherryaudio.com/products/synthesizer-expander-module

Synthesizer Expander Module is a free emulation of the classic Oberheim® self‑contained synthesizer module of the same name. Originally released in 1974, the keyboardless, mono module was intended as a companion to the one of the earliest digital sequencers, the Oberheim DS-2. Soon thereafter, Oberheim linked multiple Synthesizer Expander Modules to an early digitally scanned keyboard to create some of the first polyphonic synthesizers, used by legendary artists including Joe Zawinul, Toto's Steve Porcaro, Styx, and Jan Hammer. Though it was a simple, barebones monosynth, the Synthesizer Expander Module possessed a unique tone quality, courtesy of 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 filter section and Phasor effect programmed by award-winning synth designer Mark Barton (MRB). Best of all, it's absolutely FREE!