As “left over” from the synthesizer experiments in my youth I still had a finished PCB of the Elektor Formant 12 dB VCF. It should fit to the TTSH electronics and as such I have created a module from it, fitting into my TTSH case.
Front panel and mounting construction were done very similar to the Midi2CV module.
A first test, connecting one of the TTSH VCOs to the Formant VCF, shows (on the oscilloscope and by audio) that things are working. But, I think that quality can be improved. I will consider to replace the various VCF components, that are about 30 years old, with newer and better ones.