amplifier distortion is toggled using the "cln/dist" button. The character of the distortion can be changed with the "semi/hvy" button. Semi-distortion behaves much like the "edge" setting is described to, in the Rockman and X100 product. The Bass Ace has the most spartan controls, including mid and treble boost buttons. Rockmodules The Rockmodules are a line of professional-quality, rack-mount guitar effects, introduced in 1986. There are roughly three categories of Rockmodules, the amplifier simulators, the sound processors and the control devices. Amplifier simulators The amplifier simulators include the Sustainor and Distortion Generator. They are the basic building blocks for creating a Rockman system. Systems built from the Sustainor or Distortion Generator are primarily intended for direct connection to a full-range PA system. The Sustainor was first released in 1986. The Sustainor includes a preamp/compressor, a noise gate, distortion and filters, along with a cabinet simulation. Another feature is the auto-clean circuit that allows controlling the guitar distortion by adjusting the guitar volume knob. The Distortion Generator is a related product that was released in 1987. The Distortion Generator includes compression, distortion and cabinet simulation circuitry. Compared to the Sustainor, the Distortion Generator lacks the noise gate and external loop, but includes a three-band pre-distortion EQ. Sound processors The sound processors include the EQ, Compressor, Smart Gate, Chorus, Echo and Stereo Chorus/Delay. The Stereo Chorus/Delay was released first in 1986. It can be used as either a chorus or delay. The chorus effect can be mono or stereo. The Chorus/Delay is used for doubling, slap-back and reverb-like short echoes. Combining the Stereo Chorus/Delay with a Sustainor provides a complete system for recording guitar. 1987 brought the Instrument EQ, Stereo Echo and Stereo Chorus. The Instrument EQ was specifically designed for use with the Sustainor and Distortion Generator. The EQ frequencies were tailored for use with musical instruments, putting an emphasis on the mid-range frequencies. Its intended place in a Rockmodule lineup is after the Sustainor or Distortion Generator, but before the chorus and echo effects. It can also be used as a pre-distortion EQ, when placed in the Sustainor effects loop. The Rockman Stereo Echo is an analog delay. It can be used to provide "slap back" echo when no feedback is used. Increasing the delay time and adding feedback provides standard echo effects. It has stereo inputs, or a mono input if only the left input is used. One possible