[sdiy] VCO tuning philosophy re-visited

[Scott Nordlund]

> Ah! I AM going to build a dual slider-based VCO (15 or 31 sliders each -- I
> haven't decided yet) for myself -- that's what I'm going to do with the
> humongous slider board (or boards) I bought cheap from Electronics Goldmine
> last month. However, I'm thinking about a wavetable based VCO in Euro mode
> from a "business" perspective. Plus, I'm kinda looking forward to messing
> around with digital stuff (SRAMs and such) just to learn more about it, and
> the idea of an analog-digital hybrid VCO appeals to my twisted sensibilities
> as a bona fide Techno-Luddite.

Just a thought, if you make it similar to a step sequencer (clock driven 
counter and analog multiplexer) and buffer the slider voltages, you can get
multiple (polyphonic or detuned or whatever) outputs from a single set of 
sliders. And if you add some low level switching or patching between the 
counters and the multiplexers, you can make several different variations-
split the slider "ROM" into multiple parts, play them in a different order,
etc... and of course external signals can be patched in too.

If you want to be really cool you can make a wavetable oscillator that 
simultaneously puts out sinusoidal waveforms at different harmonics, using 
the sliders to mix the harmonics. If it's low resolution (you can easily
add switches to drop address bits) it will be essentially like the RMI
Harmonic Synthesizer (though this actually used Walsh functions). Use a
VCA or multiplying DAC per harmonic and you can have arbitrary voltage 
control.