SSM2040

The SSM2040 is a four pole VCF IC with the cutoff frequency exponentially voltage controlable. Designed by Dave Rossum of E-mu Systems and used in the first 2 versions of the Sequential Circuits Prophet 5. "This SSM 2040 VCF is widely acknowledged as one of the best filter chips ever put in an analog synthesizer." Early SSM chips were often defective, and having to pay royalties led Sequential to switch to Curtis ICs in later versions of the Prophet 5.

Synthesizers using the SSM2040

 * Digisound 80-7
 * RSF Kobol Expander I
 * Sequential Circuits Prophet 5 Rev. 1 & 2
 * SRM Synthesizer Octave Cat
 * Steiner EVI

Synthesizers implementing a SSM2040 clone

 * Division 6 Filtare SEIII
 * HM2040
 * Jürgen Haible 4-pole filter, with VC resonance.
 * Mattson Mini Modular FV1-B], based on the SSM2040 designed by Jim Patchell
 * Synthesis Technology MOTM-440
 * Tiptop Audio Z2040