[sdiy] analog oscillators with non-standard waveforms

[James Patchell]

Well, anything is posible...although, I am not sure how much you would gain.

When it comes right down to it, you really need only an adjustable 
pulse.  With a 50% duty factor, you get odd harmonics.  Now it gets hard, 
lets test my memory...25% duty factor, you get the 1st, 2nd, 3rd, skip the 
4th, and etc...10% duty factor generates another set of harmonics...

The point is, in the steady state, one set of harmonics pretty much sounds 
like another.  Having different waveforms only gives you a different set of 
harmonics.  Probably one of the reasons you don't see a lot of analog 
oscillators like you described is because the gain you make is probably not 
justified by the amount of work that is required.

However, that being said, I have the solution you need (and actually a few 
other people as well).  You need a wave shaper.

http://www.oldcrows.net/~patchell/synthmodules/shaper.html

If you start with either a ramp or a triangle, you can create pretty much 
any waveform you want.  So, while not exactly a special VCO, it does get 
you what you want...although, be warned, you will not notice much sonicly, 
for the reasons I gave above.

You would do better with more filter animation.

I personally like this filter:

http://www.oldcrows.net/~patchell/synthmodules/vocalfilter.html

With three band pass filters doing different things to the same oscillator, 
you can get some really interesting sounds.


At 10:40 PM 3/11/2005 +0000, Milo Barrowclough wrote:
>hi all
>
>i've been wondering, is it possible to build an analog oscillator that 
>produces waveforms that are different from the standard waveforms i.e. 
>square, triangle, sawtooth ?
>
>      it would be interesting to have the variety of waveshape of a 
> digital oscillator combined with the tonal characteristics distinct to 
> analog oscillators i.e. warmth, fullness.
>        i guess you can do FM sounds with analog oscillators, but that 
> uses sine waves anyway.
>or maybe analog oscillators are limited to primitive (but good none the 
>less) waveforms because of the components used i.e. a capactor charging up 
>and down produces a traingle wave.
>
>
>
>
>
>Send instant messages to your online friends http://uk.messenger.yahoo.com

         -Jim
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