Quantity: 1
Ken Stone’s CGS 29 Wave Multiplier:
The idea for this project came from the fabled middle section of the Serge wave multipliers. … The circuit I came up with I would describe as a “reflector”, and is ingeniously simple. Going on it’s performance, I would guess it to be very close to Serge’s original design.
In addition to this multiplier, there is a second simple multiplier created by adding lag to the feedback path of an op-amp. The results are reminiscent of a well known tube modulator.
For the primary multiplier, the “folder”, connect the input to the triangle wave output of a VCO. Connect a LFO, envelope generator or even a DC voltage to the folds input. The result will be a harmonically rich signal at the “FOLD” output. A second input based on a lag circuit allows square waves and other hard-edged waveforms to be used as the signal source.
There is also a “PULSE” output available, with “pwm” inputs to further vary the possibilities.
To use the second multiplier, the “grinder”, feed the input from the output of a VCO. Adjusting the “drive” and “lag” pots will give variation to the output signal.
Obviously both multipliers can also be used to mangle control voltages, the outputs from LFOs etc.
Modifications:
Stooge Panel
Some parts changes:
- At IC4a change 47K to 100K to double the PWM CV sensitivity.
- At IC4b pin 7 use a 3K3/1K8 divider to change the PULSE OUT level to +/-5V.
- At IC2b pin 6 change 100K to 33K for FOLD CV input to increase sensitivity.
- At IC1a add a 100pf capacitor between pins 1 and 2 to eliminate parasitic oscillation in the GRINDER.
- Add a 1K resistor to ground at GRINDER OUT to cut the amplitude in half, as it can clip at the power rails.
Hello richard, I would be interested to know how this compares to the oakley Discontinuity module,or what you understand about that module? Wave folders and the like intrigue me but Im never quite sure what the theory is behind these circuits or what they are doing and there are many variations. Is there a way to kluge something using basic modules to get an idea?
I don’t have the Oakley Discontinuity and really can’t compare it with the CGS wave multiplier. Suggest looking at the CGS site for Ken Stone’s description and explanation of how it works. In any case the sound of Ken’s circuit is distinctive and can produce a wide variety of timbre changes, depending on the waveforms going in. I use it more often than some of my filters.
I guess you have a v1 PCB as in v2 IC4 is the 3080/13700. I think on v2 this is IC5 and there is already a divider but with different values (1K8/1K).
I have a v1 PCB myself but didn’t decide yet if I go your way with a minimized frontpanel or the fullblown way aka Bridechamber (but without the ring mod jacks).
Yes, my CGS 29 board is version 1.
CGS 29 Wave Multiplier V1
My panel is an original Stooge panel, probably from about 2004. I don’t know who designed it.
Hey Richard,
How would you compare the CGS wave mult and the serge wave mult? Do you use one more than the other [I see you’ve built both].
Hi XNOR,
I would compare the CGS and the Serge wave multipliers by saying that they’re both excellent timbre modifiers. The Serge is currently my favorite of the two, but I’ve made plenty of use of the CGS design and will continue to use it. I like the Serge so much, I plan to build another one to use in a new stand alone synthesizer I’m working on.