The VCF 30 combines 3 different versions of a ladder-filter that you can use in steps of 6, 12, 18, 24 and 30 dB. Every version has its own charcterisitics, so overall sound can behave differently. As usual you have knobs to set Cutoff frequency (OCTAVES), ENVelope, resonance (Q) and OUTput. And the obligatory IN and TM (Timbre Modulation) inputs.