Inspired by the old-yet-innovative rotary speaker systems, like the old  Maestro Revolver, Leslie, and mostly the “Doppolas rotary speaker” made  by Mr. Gilmour & Mr. Taylor, with the DOPPOLER, we wanted to make a  pedal that really reproduce the rotary effect in a physical way, just  missing the mechanical parts. in fact, the Doppoler is NOT a “rotary  simulator” but the brain of a system that in his best setting is made of  two cabinets, positioned at 180° from each other, to let the Doppoler  handle it reproducing what happened to signal when the speaker is  rotating. We paid a lot of attention, measurement, tests, to exactly  understand and reproduce what happens to the signal coming to our ears  with a rotary speaker. This meant to apply eq filters, phase changing,  volume changing, and calculate how reflections reacts and affect all of  this.. Indeed, the signal coming out from Front and Rear speaker are  quite different from each other, cause they are already made to do their  job in the correct position. Speed sets the speed of rotary effect, and  can also be set by the TAP tempo foot switch.