Doepfer

> Does the A-137 Wave Multiplier also rectify somewhat, via the
> "Symmetry" setting, or am I understanding it wrong?

Yes, it does. The waveform is 'folded' about two levels, the sum and 
difference of the 'symmetry' and 'folding' settings, and this folding 
is essentially 'rectification'. This 'rectified' signal is then 
multiplied by a gain determined by the 'harmonics' setting, and mixed 
back into itself: this whole process is then repeated four times, so 
that what comes out at the end looks nothing like rectification at all.

Both the A-136 and A-137 I feel are difficult modules to get grips 
with: even knowing how the circuits work from the schematics, it is 
difficult to abstract to simpler levels and summarize what they do. The 
alternative method is not to worry about this, and just listen to what 
they sound like, and decide what works for you, and what doesn't!

Tim