While waiting for the PCB’s of the Elektor Formant VCO rebuild, NGF VCA DC uno and the Vocoder project, I started the rebuild of the Elektor Formant 24dB VCF. I have already an modified version of the original. Now I want to rebuild the original with easily available parts with better specs and better overall performance. I will add the features of my modified version as well. The features are: Voltage controlled Q, voltage controlled linear slope controll, better ENV controll for the HP with “gender changer”, simple level control. To start with I just put up one 6dB Filter cell on breadboard to verify some part values.

Elektor Formant VCF 6dB filter cell on breadboard

Four of this cells makes the core of the 24dB Elektor Formant VCF rebuild. You can add two more to go for 36dB as well. Let’s see.

Elektor Formant 24dB VCF – 6dB filter cell