The RPM-1 uses a tube pre-amp for the front end of this Leslie®-type rotary speaker emulator. You get tube "warmth" as well as all the tube overdrive by cranking up the front panel Drive control. To insure a good replication of the old '50's cabinets, the RPM-1 even uses the same crossover and slope frequency as those old systems.

Modern technology takes over from here because the RPM uses two digital pitch shifters to emulate separately both the upper horn and the lower rotor speakers. The two speakers can change speeds at different rates since the front panel controls Horn Speed and Rotor Acceleration imitate the same functions as choosing different pulleys on the original cabinets. The Spread control virtually changes electronically the position of the microphones that would be used to record a rotary speaker. In this way you control the stereo width of the rotary sound from a wide stereo down to a punchy mono. There are also Speed (fast/slow), Brake (for instant stop) and Bypass buttons. A standard volume pedal will continuously change the speed of rotation for "live" playing.