Extras and WIP
Please note the materials below are concerning v1 Gecho (made in 2018 and earlier).
Schematics, Diagrams & Blueprints
This extension will allow you to connect with various music gear, like keyboards, synthesizers, drum machines and other and either control Gecho by external devices, or control those devices by Gecho.
Enclosure plans and dimensions
If you want to make your own box, here are blueprints and hints that you might find useful, mainly if you want to do it ahead and don't have the board at hand yet.
A peek into inner workings of Subtractive Synthesis block
This is a functional block used by most basic channels - those which play background chord progression with melody or arpeggiator. There is 8 Resonant Low-pass Filters per channel and control logic. Just a sketch - work in progress, will need to redraw it again and add detailed explanation.
UPDATE - Redrawn schematic:
Full Circuit Schematic
Making of Synth
An article explaining motivation behind this project and early prototyping work.