WOK's new BFS-1 is a VST emulation of the famous Bode frequency shifter. The original unit was available as an expensive module for the Moog™ modular system. Here's all the details from WOK...
The frequency shifter is not a pitch shifter, which changes frequencies by a multiplikation. Instead it shifts all frequencies/harmonics by adding a fixed amount. The sound reminds to a ring modulator, but unlike this, it is possible to get the upshifted and downshifted signal seperately.
Unlike a ring modulator, the frequency shifter is also capable of changing the signal by a low amount, e.g. 1 Hz, to obtain effects known as "Barberpole flanging".
This plugin has some additional features like delays for each section, an LFO (all host synced), an envelope with MIDI trigger and an envelope follower to modulate shift and/or volume. Pricing and Availability: