Doepfer A-127 Triple Resonance Filter example

This is a very unusual filter. It consists of three separate bandpass filters with resonance control, each having a built-in LFOs for filter frequency modulation. A similar concept had been used in the Korg PS 3100. Details can be found at Doepfer’s Homepage:

I’ve put the usual three A-110 VCOs (sawtooth wave) into the A-127 filter, then each of the three individual outputs into an A-138m Matrix mixer. Here I assign the first and second filter to a first VCA (panned left) and the second and third filter to a second VCA (panned right).

The filters were controlled by their internal LFOs at first, later I plug in outputs of an A-143-9 VC Quadrature LFO for audio frequency filter modulation.