A very simple implementation of a Shepard filter
This is a very simple implementation of a Shepard filter which uses equidistant bandpass filters with ascending or descending center frequencies to simulate a filter effect version of Shepard tones (also known as Risset tones). The effect is similar to Sean Costello's Barberpole Phaser, although it is accomplished by different means. The number of voices determine the number of equidistant bandpass filters.
v. 2.0: added control for width of the Shepard filter
v. 3.0: is now stereo