PlanetZ forums - scopeusers.com

Posted: **Sun Nov 06, 2005 9:00 am**

Try a lowcut at 20 Hz. This should eliminate the zipper noise. A (fast) volume change with low frequencies is always .. ummh, well .. "problematic".

cheers
Wolfgang

Posted: **Sun Nov 06, 2005 2:13 pm**

well, a 20hz filter will not help much with a 250hz sine...

but that's exactly the point:
the zipping seems restricted to sines, and of course if the sine is routed back to an analog or digital input, then the external port shows the zipping as well.

This might also explain my tests without zipping (when I changed the graphic parameter): by pure chance I could have picked a frequency where the zipping happened to match the zero crossing of the waveform

cheers, Tom

Posted: **Sun Nov 06, 2005 4:19 pm**

it appear as an aliasing issue.....

Posted: **Mon Nov 07, 2005 4:36 am**

you're partly right as a sine suffers from aliasing by nature, but that's not restricted to the CWA mixers

I was able to reproduce the same effect within a native application that had a sine generator built in.
Moving the corresponding fader caused zipping.

cheers, Tom

<font size=-1>[ This Message was edited by: astroman on 2005-11-07 04:38 ]</font>