COTA VCF

Cascaded OTA Filter

This is a four pole multimode filter capable of -24dB/octave low pass, -12dB/octave low pass and +/-6dB/octave bandpass outputs simultaneously. The filter core is based on four identical cascaded current controlled integrators. This is similar to the topology found on the filters in the SH series of monosynths as well as the CEM3320, IR3109 and SSM2040 filters of the classic polyphonics.

At high resonance, we call it 'feedback', the COTA VCF will oscillate well over the whole of the audio band with a clean sinewave. Its temperature compensated too. The module also features a feedback input. This is similar to the one we introduced in the groundbreaking Multiladder module. In conjunction with the 24dB/octave output this input allows the resonance signal path to be split. This means that additional modules can process the resonance loop independentally. This allows a large variety of new timbres to be created. And it also allows for voltage controlled resonance with the use of an extra single VCA module.

http://oakleysound.com/cota.htm