The new Prophet-5 “Rev 4” is Dave Smith's timely return to the analog poly synth that changed the world. It’s “the best of all Prophet-5s” because it embodies all three revisions of the legendary synth—Rev1, Rev2, and Rev3—through the use of genuine Curtis analog VCOs and filters (as in the Rev3) as well as new 2140 low-pass filters designed by Dave Rossum, the modern equivalent of the 2040 filters he designed in the original Rev1 and Rev2. A Rev switch lets you choose between the two filter designs.