I wanted to try some digital signal processing on the Arduino/AVR for some time.
This project started a breadboard-build of a circuit based on the pedalSHIELD by electrosmash, just to see if it was even half-way decent.
When that worked out, I put it on protoboard and did a bit more work on the software (refactored the core routines into an AudioDspDriver library).
Along the way I also got the genuine kit from electrosmash.
As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub