The A-137-1 is a four-fold waveshaper (kind of four simplified A-136es in one box?).
Technical details can be found on Doepfer’s Homepage:
The example uses a single A-111 VCO (triangle output) which is controlled by an A-155 Sequencer. The A-137-1 has four modulation inputs: number of multiples, folding (distortion) level, symmetry of folding (i.e. positive and negative amount) and harmonics (additional harmonic created). Three LFOs (a slow, a medium and a fast one) and a S&H (synced to the sequencer) are used via A-138m matrix mixer to modulate the Wave Multiplier.
Here we go:
Here’s another A-137-1 example, together with an A-143-1:
The A-143-1 is the sound source, its mix out goes directly into the A-137-1, which is modulated by 4 LFOs from an A-143-3 Quad LFO. Until 1:40, I’m just playing around with the Wave Multiplier and its modulation. After this, I’m changing attack and decay settings on the A-143-1 as well. All A-143-1 units are in LFO mode.
There’s some reverb added, no filter, no VCA.