Discrete Core Ladder VCF

The ACL Discrete Core Ladder VCF is a classic transistor ladder filter with a fully discrete, low-noise, low-distortion audio path. Its four stages each have a buffered output, for 6, 12, 18 and 24 dB/octave slopes that can be used separately and at once; each stage is 90° out of phase with the previous one, so mixing them, some inverted, gives other slopes and filter types. BOOST restores the low frequencies a ladder loses as the resonance rises, and the filter self-oscillates down to below 1 Hz. The Q LIN switch chooses whether the resonance stays independent of the cutoff or falls with it. Three mixed audio inputs, 1V/OCT and two attenuated CV inputs for the cutoff, and a CV input for the resonance complete it; the cutoff is temperature stabilised.