Digital VCO

The traditional waves as triangle/squares/saw are becoming more and more boring to me. I actually started the modular synth to go to something wilder, noiser and more psychedelic. Obviously there’re some very interesting modules out there but most of all are far from my reach in terms of price (at the moment, maybe i’ll become richer one of a glory day). Having a stock of AVR I decided to give it a try and the result is interesting.

I’ve used waveforms from the electro druid digital VCO (you can find the waves at the bottom of the ASM file) just for fun and try things out. It turned out that it is very useable. I wish to build  a wicked nasty thing which will incorporate bitwise operator communly known as bit_reduction (AND, FLIP, OR), sampling rate reduction, and a morphing. The DAC is built with a shift register driving a R2R ladder, followed by a 2 pole low pass filter.

The morphing is maybe the more interesting of all and I still don’t know how to incorporate it in terms of interface. The idea is to mix two waves at the output, the portion of each being variable via a potentiometer (or CV).  Ideally both waves could be selected but this obligates to have more hardwares. Here’re a few pictures of it in action (although the following video shows really well the process of morphing):


you can find video where the Iphone wanted to partially participate (no sound but great show on the morphing process)

and sound :

note that any of the bit_reduction nor sampling rate have been used for that soundclip (to much crap on breadboard) and some noise are introduced by the stray capacitance of the breadboard spreading the SPI clock all around. The VCO is passing through a WASP filter.

electric druid :



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