Here's the story. A notorious analog aficionado and active performer (whom we'll call David) pointed out a minor deficiency in our 200 Series catalog -- NO BARBER POLES! Beside ourselves with embarrassment, we snuck into our long mothballed design studio, and working feverishly around the clock, repaired this deficiency with not one, but TWO new barber pole modules. Now don't get too excited and see this as Buchla resuming production of 200 Series analog synths. We are simply filling in a gap that we inadvertently overlooked some 25 years ago. After all, whoever heard of an analog synth with no barber poles?

Now just what is a "barber pole" module? A barber pole, used in a bygone era to identify haircutting saloons, is a spiral (resembles a candy cane) that slowly turns around a vertical axis. The actual movement is rotational and horizontal; the perceived movement is vertical, but illusory. The term has been applied to processes in which movement is perceived to occur continuously in one direction, but ultimately there is no net movement (in that direction). We don't know the origin of the association with hair-cutting, bur neither do any barbers we've talked to.

The first of our new barber pole modules is the Model 260 Duophonic Pitch Class Generator. The term "barber pole" refers to an auditory illusion that can be readily produced by this module. Called the Shepard tone paradox (after its inventor, Roger Shepard), one's perception is that each note in a forever on going series of notes is higher in pitch than the preceding note. The illusion works in reverse also, with each note perceived to be pitched lower than its predecessor. M. C. Escher's "Ascending and Descending" is occasionally cited as a visual equivalent of the auditory paradox.

Our second barber pole is the Model 297 Infinite Phase Shifter. We've all heard the output of those little stomp-boxes called phase shifters. By mixing an unprocessed signal with a phase shifted version, they create a type of comb filter, and if the degree of phase shift is cyclically varied, the filter peaks move up and down at a user-specified rate. "Infinite phasing", in which these peaks move continually in one direction, was first introduced in 1981 by the Bode Sound Company, but very few devices were manufactured and the idea has since been abandoned. Seemed interesting (and challenging) to us, so we designed one.