Morphing SVF

The E430 is a faithful re-creation of the classic Oberheim SEM 12dB/oct state-variable filter with 3 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 includes 2 FM inputs (FM1 is a reversing attenuator) and user-programmable LED color for the Morph switch (see the video in the DEMO section).

The 18HP wide E430 has a MSRP of $339, which includes FREE domestic shipping. This production run is limited to 210 modules, due to parts constraints.

SPECS
Height 3U (128.5mm)
Width 18hp (91.4mm)
Depth w/power cable 35.6mm
Power 10-pin Eurorack (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
PANEL CONTROLS
Frequency Sets the initial filter frequency
Input 1 & 2 Level knobs for the two audio inputs
Resonance Sets the initial filter resonance
FM 1 Level Inverting attenuator for the FM CV inputs
FM 2 Level Secondary FM in
Filter Morph Sweeps between LP-selected=HP filter outputs
LED pushbutton OFF (unlit) - Bandpass is selected for Morph ON (lit) - Notch is selected for Morph
INPUTS AND OUTPUTS
1V/Oct 1 volt per octave control for the filter frequency
FM 1 and FM 2 Filter frequency modulation
RES CV input for Resonance
In 1 & 2 Audio signal inputs
LP Out Lowpass filter output
BP Out Bandpass filter output
NOTCH Out Notch filter output
HP Out Highpass filter output
MORPH Out Morphing filter output
M CV Morph CV input