Yamaha IG000156, vcf


The first synthesizer I ever used was a Yamaha CS-10 (or perhaps CS-15). Recently I looked at the specs and noticed that the filter is a Yamaha 16 legged DIP circuit named IG000156, which seems to be used in several Yamaha models from the 70’s . I googled the part without success, I only found a reference to the CS-15 service manual that indicates that the LP-mode has a 12 dB slope which might indicate that it is a 2-pole internal construction? I’m curious, does anyone know anything more about this filter circuit? :slight_smile:



Given that the IC has LP/HP/BP outputs, and only two caps, it looks like it is a SVF. Maybe you can try breadboarding this or TubeOhm’s upcoming thing, and tweak the gains / non-linearities to give it the character of the CS-15?

Thank you! :slight_smile:

I also found a document with Yamaha circuit documentation, the IG000156 is described on page 37:


The Block & Schematic diagram looks similar to the description of the Shruthi SVF here: