VCO idea

Philip thelab at
Fri Jul 31 11:20:13 CEST 1998

Martin Czech wrote:

> I don't want to discourage you, but ... I toyed arround a lot with hand
> made waves and wavetables for the Waldorf Microwave I (No, I won't swap
> it against a Microwave II or XT) and came to the conclusion that in a
> lot of cases the results are not very exciting, certainly there are
> differences in sound, but I expected something to knock me off my
> chair, and this really happens, but not very often.

Original Idea:

> Why not have a repeating waveform that has (say) 4 "lines" of which the 
> slope and duration can be adjusted, either by a control knob or voltage 
> control.

I agree with Martin, spectral changes over time are needed to make
periodic waveforms sound interesting on their own, the VCO with the 4
variable sloped steps would sound much like playing single waves in a
Microwave. But by adding modulation control of the "slopes" and "steps"
of your design, it would sound far more interesting. AND it would
certainly sound more interesting than a simple sine, tri, sqr or ramp
osc so I feel it is interesting and worth persuing.

Maybe you could get hold of a MW or Nord Modular for experimentation? I
wrote a simple piece of software for the MWI that morphs two .wav files
(heck it will do any file too...ever hear autoexec.bat to config.sys :)
I find it very powerful even with no modulation routings other than the
wavetable morph from one .wav to the other. (VCF wide open). It is
really weird to hear such a variety of these nice sounds come from a MW
with no filter or modulations!! It is akin to additive synthesis where
filters are not really needed.

Anyway, a chain of cascading one shot ramps with polarity would do the
trick for the osc, I'm not sure of the details of scaling their time
constants via a CV however? Call its a "COS0" Cascaded One Shot
Oscillator :)


Philip Pilgrim                  The Lab Audio Works
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