I have no idea what makes this gadget tick but this shit is magic! it can do true vibrato as well as univibe phasing type vibrato.... it can also sound like a chorus or a fake leslie... or even a broken record or warbly old dictaphone tape. This is THE vibe pedal to put on a digital piano when you wanna play Ashes to Ashes. The big drawback is, of course, the shitty DOD switch! I dock it 1 star for that and the mediocre buffer.