The AJH Synth MiniMod VCF is a recreation of the 24dB/Oct low-pass transistor ladder filter used in the classic Moog Model D synthesizer. It features a three-channel input mixer, dedicated filter cutoff knob, and both 1/3” and 2/3” CV ins that faithfully emulate the original Model D’s VCF switches. There’s also a variable CV input offering additional modulation possibilities.
In addition to a manual Emphasis control, there is now a vactrol-controlled CV input for voltage controlled resonance. Since the input features a vactrol, it can reach audio rates, allowing the filter to self-oscillate for use as a sine wave oscillator.
This is the SILVER version of the MiniMod VCF.
MiniMod VCF Features
Eurorack Replica of the 24db/octave Low Pass Transistor Ladder Filter used in the early Moog Model D Synthesizer
3 Channel Input Mixer
1 Filter Signal Output
1V/OCT Input: Changes the filter cutoff at the rate of 1V per Octave, or if the filter is in full self-oscillation (Emphasis Control fully CW) it will control the pitch of the resulting sine wave at the rate of 1V/OCT (When compared to the Model D this emulates having “Keyboard Control” switches 1 and 2 “ON”)
Frequency CV Input
1/3 CV Input: Changes the filter cutoff at the rate of 333mV per Octave (When compared to the Model D this is the equivalent of having “Keyboard Control” switch 1 “ON” and switch 2 “OFF”)
2/3 CV Input: Changes the filter cutoff at the rate of 666mV per Octave (When compared to the Model D this is the equivalent of having “Keyboard Control” switch 1 “OFF” and switch 2 “ON”)
Emphasis CV Input: ±5V
Emphasis CV Input Level Control: 0% to 100% (Manual Emphasis Level Control is still active and acts as an offset control)
Emphasis Level Control (Resonance Level Control): Self-Oscillates between positions 8 and 10
Filter Cutoff Control
Frequency CV Level Control: 0% to 130% (Greater range than the 1V/OCT Input so over-modulation effects are possible)