This is a physical modeling synthesis algorithm designed to replicate the sound of plucked, vibrating strings – although it has also proven useful for some percussion sounds as well. A short sample – originally noise, although it can be a high frequency chirp or other sound – is sent to both the output, and to a delay line. The output of a delay line is connected to a filter – originally a one-pole low pass filter; changing the filter has a huge effect on the character of the sound – and then back to both the main output and the input of the delay line. A few modules implement Karplus Strong synthesis, although it is an interesting challenge to patch yourself and play with the results.
