Easy to build eduactional DIY VCF

es x mki.EDU DIY VCF is a resonant low pass diode ladder filter that sticks to super basic and widely available components. On top of that, the architecture is as approachable as possible by avoiding the tricky diff-pair setup classic ladder filters rely on.
It’s arguably the beating heart of any subtractive synth – adding character, dynamics, and a good deal of retro-futuristic oddness to your patches.

https://www.ericasynths.lv/shop/diy-kits-1/edu-diy-vcf/