[chuck-users] Using biquad...

Tomtom girodt at gmail.com
Thu Feb 17 03:33:24 EST 2011


I did something a bit similar recently. My approach was to simply to apply a
decreasing exponential function on an input value to control the gain of a
sample and simulate distance.

Math.exp(-param * coef) will give you 1 for param=0, and progressively decrease
at a speed controled by coef.

Based on this, I guess all you have to do is to find the proper coefficients to
transform your decreasing parameter into a decreasing frequency for your

by the way, if you want to progressively cut the high frequencies, wouldn't it
be simpler to use a LPF filter ?


Excerpts from Wolfgang Gil's message of jeu. févr. 17 08:02:54 +0100 2011:
> Hey guys
> i'm working on a sampler that uses a simple equation system to determine
> parameters of reverb, volume and pitch filtering. The goal is to emulate
> 'depth' using the idea that if a sound's source moves away from our ears, we
> will perceive it as quieter and more diffused, with its high-pitch content
> less present.
> Motivated by this, I started to read about the biquad ugen, but i haven't
> figured out how to deal with its coefficients so I can make something
> interesting out of it.
> My question is, how can i make a high cut filter that gradually reduces the
> high-pitched content of the sound signal's spectrum, based on an input of
> 0-100?
> (0 = no filtering, 100 = no high-pitch content)
> thanks!

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