The Synthesis Technology e430 is a faithful re-creation of the classic Oberheim SEM 12db/oct state-variable filter with added features:

Individual filter outputs: low-pass, bandpass, notch, and high-pass

Voltage-controlled morph output: sweeps between lp-bp-hp or lp-notch-hp via panel switch voltage-controlled resonance

The original SEM circuitry was not "improved" or updated. Great care was spent through measurements and beta testing to duplicate the SEM's unique sound. The design incorporates 40 year old circuits such as:

LM301 audio input op amp, LM741 resonance op amp, RC4558 audio summing op amps, discrete jfet current buffers between filter sections, CA3080-class OTAs, no self-resonance unless patched externally

Other features include 2 FM inputs (FM1 is a reversing attenuator) and user-programmable LED color for the morph switch (see the video demo).

Specs-

Width: 18hp

Depth (w/power cable): 35.6mm

Power: 49ma from +12v, 34ma from -12v

CV input range: 10vpp (-5v to +5v), dc to 8khz

Audio Input: 50k nominal input impedance, 10v pk-pk

Audio Output: 12vpp (-6v to +6v), 10hz to 18khz frequency range