Poor sound when paging through soundcard

Hi all,
I am trying to setup paging through soundcard on my trixbox v2.6.1.13 following this guide
voip-info.org/wiki/view/Sett … sound+card

I get no errors, but during paging voice comes out incredibly low and totally distorted. I played with alsamixer but couldn’t improve quality.

The soundcard was installed after trixbox installation, can it be that i have to recompile asterisk in order to have the proper chan_oss.so module?

Thanks for your help