Gemini 2412

Two independent vintage SEM style state variable filters, with FET buffers, low pass, band pass and high pass outputs and a vary output that fades from low pass through notch to high pass, all usable at once. A central mixing bus for audio and frequency CV combines them: in dual mode the input of VCF 1 feeds VCF 2 in parallel, optionally inverted against it; in cascade mode VCF 1 feeds VCF 2 in series; the audio mix crossfades between them to the D-OUT output, for a 24 dB SEM filter, vocal formants and more.