Module A-187-1 is a DSP based effects module. Four parameters of the selected digital effect are voltage controlled. The main effect (e.g. reverb, delay, pitch-shifter, equalizer) is selected by the two small buttons effect up / down. The upper row of the display shows the effect that is currently selected. In the lower row the four parameters are shown as well as a small bar left from the abbreviation that displays the current parameter value. Each parameter can be adjusted manually (upper potentiometer row) and modified by external control voltages (lower row of the potentiometers and upper row of the sockets). The lower row of the sockets contains the two audio inputs and outputs.

Another button (bypass) is used to turn the effect on / off. When bypass is chosen the upper line of the display shows in turn "BYPASS" and the name of the pre-selected effect. In the bypass mode another effect can be pre-selected and called-up by pressing the bypass button again. Even the effect parameters can be adjusted and are displayed with the bar graphs. But they become effective not before the bypass mode is left.

The module is equipped with two audio inputs and two audio outputs because the DSP board features stereo audio processing. The audio inputs can process usual A-100 signal levels without clipping / distortion. For higher levels external attenuators (e.g. A-183-1) or VCAs may be used.

A ready-made DSP board is used inside the A-187-1 module. Consequently, only these effects and parameters are available that are supported by the DSP module. Some parameters can be changed only in steps or with audible artefacts. The DSP board has 20 Bit DA and AD converter with 32 kHz sample rate available. The inter sound processing uses 24 Bit.