[sdiy] VCO - sine output - why bother?

[Donald Tillman]

> On Aug 26, 2016, at 1:52 AM, Oakley Sound <oakleylist at btinternet.com> wrote:
> 
> You can add (or subtract) the sine waveform to your other chosen waveform to create more (or less) powerful sounds. Again sine seems to work better for this - or at least gives you more predictable results.

This is great technique... except for a problem to beware of.

Subtracting the sine waveform only works as intended when the phase of the sine wave is aligned with the fundamental component of the other chosen waveform.

But the standard way of deriving a triangle and sine wave from a sawtooth core (ie., an absolute value circuit) leaves the phase of the triangle and sine 90 degrees from the sawtooth.  So one can't actually subtract out the fundamental in that situation.

Other than my own designs, I don't know of any VCOs where the sawtooth and triangle/sine are correctly phase aligned.

  -- Don

--
Don Tillman
Palo Alto, California
don at till.com
http://www.till.com