[sdiy] Continuously variable waveshaping (was Behringer Neutron)

[Ian Fritz]

Good discussion.  Wave shaping has been my favorite method for timbral variation from the very beginning. Lots of examples and info at my site and also several commercial implementations.

I would point out that waveshape variation by distorting/bending is quite a different matter from simple dynamic mixing of two or more waveforms.  For example, the Saw/Tri tilter I mentioned earlier sounds quite different from just mixing the two waveforms. And as a source for driving other shapers its continuous variation is a big advantage. For example I love driving my 5Pulser from it and modulating the tilt.

Clearly I could go for pages about all this, and equally clearly 
I shouldn't.  :-)

Ian



> On Apr 7, 2018, at 3:44 AM, Tom Wiltshire <tom at electricdruid.net> wrote:
> 
> 
> 
>> On 7 Apr 2018, at 10:08, Olivier Gillet <ol.gillet at gmail.com> wrote:
>> 
>> If you did it under CPU control, you could probably dump the requirement for VCA linearisation too (compensate in software), which reduces the hardware by one VCA and two op-amps per channel. You can do a 4 waveform mixer with just a 2164 and a quad-channel DAC fed to a single I-to-V op-amp stage.
>> 
>> As a bonus, you could also control the output level, assuming you had enough DAC resolution - just turn down all four waveforms at once by simple subtraction from their DAC values (don’t you love log control?!).
>> 
>> I had the same idea and made the "Frames" module :)
> 
> Very nice, Olivier. I was just reading your schematic! I like the stored “frames” idea - very flexible.
> 
> I notice you used a 12-bit DAC. Assuming 100dB range on the VCA, that gives you roughly 0.024dB/bit accuracy!
> 
> Presumably that’s how you were able to implement Lin/log CV control and different easing curves in software. That wouldn’t have worked so well with less resolution.
> 
> Tom
> 
> 
> 
> 
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