level of difficulty:
This is a project for the guitar electronics geek. Traditionally guitar effects pedals used analogue circuits made up of clever combinations resistors, capacitors etc. Digital signal processing chips now allow analogue effects circuit to be simulated in software. This project shows the a prospective pedal maker how to build a guitar pedal with an Arduino for lo-fi digital signal processing..
This type of effects pedal digitises the guitar signal when it enters the pedal and converts it back to analog when it leaves the pedal for the amplifier. The quality depends on many bits you use to digitise the signal (quantization noise), this project uses 10-bits (CD audio uses 16 bits for each channel). This project is realistic about the loss in signal quality, it is meant to be Lo-fi pedal after all. The speed of the processing chip is also important (if it is too slow there will be noticeable delay) The project doesn't use a specialist DSP chip, but uses the widely available and open source Arduino system. Some suggestions for speeding up the effects unit are adding a dedicated analogue to digital convertor, to take some of the pressure of the Arduino.