E440 Discrete OTA VCF

The synthesis technology e440 is a lowpass voltage-controlled filter with 3 simultaneous outputs. the input is any audio source (can be from line level to synth level) and the output is via the different slopes of the filter: 2pole (-12db/oct), 3pole (-18db/oct) and 4pole (-24db/oct). there are 3 cv inputs to control the cutoff frequency plus a separate cv input for the resonance. the e440 will self-oscillate at high resonance and can be used for a sine vco (each output is phase shifted 45 degrees from the prior one) with 1v/oct tracking (trimmable) over a 4-octave range. this response is also temperature-compensated. an external audio mixer module can be used to blend the 3 outputs into “in-between” slopes and by inverting them relative to another, different frequency responses.