The A-137-2 is another version of a wave multiplier. In contrast to the A-137-1 Wavemultiplier, the A-137-2 generates four phase-shifted copies of a VCO signal applied to the audio input. The four shifted signals are added to the original signal to obtain a fat sound similar to five independent VCOs. The phase shifting is made by a simple circuit that works only for sloped signals like sawtooth, triangle or sine, but not for rectangles or pulses.
The audio input signal (typically a sawtooth, triangle or sine wave from a VCO) is compared with a slowly varying control voltage (CV Shift In). The output of the comparator is a rectangle wave with variable pulsewidth. If the output of the comparator is added to the input signal with the correct level relation between both signals, a phase shifted waveshape is achieved.
The module has four manual shift controls and four control voltage inputs with attenuators for the four internal shifting circuits. Typical sources for these inputs are LFOs, VCLFOs, random voltages, envelope generators, sequencers or other control voltage sources. Internally eight single outputs are available at single pins: the four shifted signals and in addition four rectangle outputs.
The audio input is equipped with an attenuator to adjust the level for the right summation of the original and the comparator signal