[PD] Anti-aliasing filter

Johannes Taelman j0 at advalvas.be
Tue May 18 23:00:50 CEST 2004

Al Riley wrote:

> I've got an additive synth which generates some very
> high frequency partials and hence aliasing distortion
> occurs when the fundamental is high enough.

Just mute the osc's that are above 22050Hz. That's the normal solution.

> I tried to fix this by using a low pass (lop~) filter
> before the dac. This didn't fix the problem and I
> suspect that lop~ only filters up to about 22kHz.

There is no signal above 22050Hz (assuming 44.1kHz sampling rate). 
Nothing to filter out anymore. The aliasing is already inseparatable 
from the intended signal at that point.


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