A-137.1 is a voltage controlled Wave Multiplier. The idea which is to multiply the waveform of an incoming signal within one period of the waveform. This leads to additional harmonics of the incoming signal. The period and consequently the pitch of the signals remains unchanged. The A-137.1 works as a kind of "inverse low pass filter", i.e. it adds a lot of harmonics to a signal that contains none or only a few harmonics (e.g. sine or triangle waveform). Consequently the best results are obtained in combination with input signals poor in harmonics (e.g. sine or triangle). The A-137.1 can be used with signals rich in harmonics too (e.g. saw) but the effect is not as effective as for triangle or sine waves. For rectangle signals none or only little effect is achieved. The A-137.1 is a very sophisticated wave multiplier that offers much more features, more controls and more waveform manipulations than other wave multipliers available so far. In addition all parameters are both manually adjusted and controlled by external voltages. The Multiples parameter (manual and ext. CV) defines the number of basic wave multiplications within one period. With the Folding Level and Symmetry parameter (both manual and ext. CV) the upper and lower clipping levels of the wave folder units are controlled. The Harmonics parameter (manual and ext. CV) adds some harmonic content by sharpening the waveform edges and adding overshoot peaks. It works a little bit like the resonance control of a VCF. The module is fully DC coupled, i.e. even control signal can be processed with the modules.