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Project Notes

#239 AudioDSP/SuperCrunch

AudioDSP crunchy symmetrical Schetzen distortion effect based on the pedalSHIELD.

waveform

Notes

SuperCrunch.ino is a crunchy distortion effect from the pedalSHIELD examples. The pushbuttons control the volume of the output signal.

Core algorithm:

  • distortion is derived on a symmetrical clipping system based on Schetzen formula

Schetzen Formula for symmetrical soft clipping is as follows:

         { 2*x                for  0  <= |x| <= 1/3  }
f(x) =   { (3-(2-3*x)^3)/3    for 1/3 <= |x| <= 2/3 }
         { 1                  for 2/3 <= |x| <= 1   }

Performance

A vast improvement on the asymmetrical Crunch, and a much warmer fuzz than the simple clipping of Distortion.

Delivers quite a warm crunch with pretty good frequency response, although the upper registers of the guitar are a bit beyond the capability of the Arduino.

AudioDspDriver Library

This example uses a private AudioDspDriver library that contains my refactoring of the core algorithms for driving the board. I may split this out as a stand-alone library at some point.

Construction

Breadboard

The Schematic

Build

Credits and References

About LEAP#239 AudioArduinoDSPOpAmp
Project Source on GitHub Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is my personal collection of electronics projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.