The Buchla programmable complex waveform generator model 259 is a very flexible and complex oscillator. It contains 2 oscillators, several waveshapers, a modulation matrix and a phase locked loop. It is capable of a very broad range of sonic timbres.
I wanted to built something similar to the Buchla 259 based on two 258J oscillator boards I already built. It would not be a clone of the original module but I wanted to try to built some core functionality of the original into my version so it would behave, for those things implemented, close to the real thing. To connect the two oscillators I’m using a modulation index section based on the 292C VCA and the timbre section of the Buchla 259. For this timbre/modulation index section I designed a PCB to make building it easier. The block diagram for my mutant complex waveform generator looks like this.
The signal from the modulation oscillator is fed into the modulation index where you can select the modulation destinations. Timbre can be modulated and the principal oscillator can be FM and AM modulated. All modulation types can be selected independent of each other. So, it is possible to use AM, FM and timbre modulation simultaneous.
This is the prototype front panel design. The front panel really is stuffed with controls. There is no more room to add anything else. The switches in the modulation index section are not the final switches. I used what I had and these will be replaced by switches with a rounded lever, like the other four on the panel.
For the modulation oscillator the following mods will be implemented:
– hi/lo switch for selecting LFO or normal frequency range
– waveshape switch for switching between ramp and square wave
– sine output
– triangle/square output (depending on position waveshape switch)
– cv output (for with in LFO mode)
For the principal oscillator the following mods will be implemented:
– waveshape switch for switching between ramp and square wave
– sine output
– triangle/square output (depending on position waveshape switch)
While redesigning the mutant timbre/mod section PCB I added an additional offset control for the modulation index, resulting in a new front panel design. I also added an extra pot I forgot in the timbre section. The front panel is now completely stuffed. No more room for anything else…
Here is the Front Panel Designer layout: mutant_complex_waveform_generator_v23.fpd
Notice: Unfortunately I never completely finished this project and after I lost some design files to a disk crash I abandoned the project as at the time there were actual Buchla 259 clone PCBs available.