Jul 20, 2019

KS-20 Filter

My interest in the MS-20 style filter was sparked by videos from Look Mum No Computer, who built a DIY low pass version. This filter makes great basslines, with both strong bottom end which is not reduced at high resonance, and gnarly sound due to a nonlinear resonance path. Clearly I needed such a filter in my system, and the result of that is this module which I tackily named the KS-20.


Mar 4, 2019

Dual VCA

You can never have enough VCAs, a common meme in modular synthesis declares. While this module certainly cannot fill that infinite gap, it does provide two handy voltage controlled amplifiers. They are linear, DC coupled VCAs, suitable for both audio and CV processing.

Oct 17, 2018

ASR Envelope

My first envelope was a traditional ADSR envelope, adapted from Yusynth's design which uses a (7)555 timer as the core logic element. That design works great, but I originally made it only on prototyping board. Recently, in need of more envelopes, I decided to make a proper PCB layout, and revisit the envelope design in the process.

I realized that in typical uses of an ADSR envelope, I tend to set the Decay and Release controls to roughly the same value. This gives the decay and release portion of the sound the same time constant, which often sounds natural to me. I decided that it would be handy to have some envelope generators where the Decay and Release time combined in a single knob, and the result is this module which I called ASR envelope.

Jul 8, 2018

Transistor ladder filter

When I started with synth DIY, I knew little about how transistors work, and the famous Moog transistor ladder filter just looked like magic. Intrigued, I stared long at the schematics posted by Yusynth, and worked my way to the very detailed and mathematical analysis by Tim Stinchcombe.

Jul 5, 2018

Avalance VCO

Thanks to Look Mum No Computer, a super simple oscillator circuit has been popular lately based on the reverse avalance breakdown effect in normal transistors. I decided to experiment with this idea myself, and in particular see if I can add basic V/Oct control to it.