For me it's worth the price of this pedal just for the awesome graphic of the virtual rotors within its built-in display. The spinning lights show the audio-rotation characteristics of the RT-20 with the center of the display, illuminated in red light, representing the virtual bass speaker. The outside ring, illuminated in blue, displays the rotation of the virtual horn. I had to kick myself out of a trance a couple of times staring at this Stargate vortex.

With the RT-20, COSM is used to simulate classic rotary characteristics in stereo via its two outputs, allowing the (impossible with a real Leslie® speaker) virtual horn and bass speaker to be independently adjustable while you play. This unit will accept either guitar level or keyboard/synth levels--just use the Drive Type switch to optimize the effect.

You can add the BOSS FV-500H/-500L expression pedal to control parameters such as rotation speed from slow to fast while you play. For more information, contact Roland Corporation U.S. at: 323-890-3700 or visit www.BossUS.com/.