
full size "PCB for Jim Patchell's Vocal Filter" "The 100-1003 is now in the public domain. This filter was designed to simulate the vocal tract of a human. To do this, there are three resonant filters that will be tuned to different frequencies. To make it so that the phonems can be selected via voltage control, there are three CV shapers on the board. These will allow you to make a more or less arbitrary function to control the filter frequencies." More details on Jim Patchell's site.