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Aliasing problem in generating a sawtooth wave via additive synthesis w cycle~


9
January 18, 2010 | 10:41 pm

Hello,

I was playing around with additively creating a sawtooth wave by summing cycle~’s with the appropriate relative freq and amp to get the saw.

It’s all fine and dandy except I am getting aliasing when my partials exceed 20k. I tried using lores~ but didn’t work? I can seem to find a viable filter in msp. Any suggestions?

Also was wondering, I couldn’tfor the life of me get scope~ to show the saw summing as I was adding my partials – it looked like a funny pulse thing, but I checked in the spectroscope and it’s positively a saw.

here’s the patch

– Pasted Max Patch, click to expand. –

thanks!


Christopher Dobrian
January 18, 2010 | 11:26 pm

For a band-limited sawtooth wave, try saw~. Adding sinusoids to get a sawtooth will only look "correct" (sawtoothy) in the scope~ if the sinusoids all have the same phase offset, but it’ll still sound like a sawtooth even if they’re out of phase.


Chris Muir
January 19, 2010 | 12:02 am

I have an example, called "Partial Workshop," that I wrote _many_ years ago to illustrate creating waveforms out of partials. It can be found here: http://xfade.com/max/examples/


Roman Thilenius
January 19, 2010 | 12:37 pm

 
have you tried using a somewhat bandlimited version of the waveform?

instead of a perfect sawtooth, use a 1. 0.5 0. transition and one point and
see if there is a difference.

-110
 

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