[SOLVED] Distorted audio with usb soundcard

[SOLVED] I suppose that this is a bit of a noob problem to have, but I’ll leave the post up in the hope that it helps someone else in the future… I was able to to fix the issue by ignoring the recommended value of 128 and increasing the buffer size to at least 512 in the Jack configuration settings.


Hi all,

I just installed patchbox os (console only mode) for the first time, and I’m having some strange issues with the audio output. When I generate a 440 Hz sine tone in Pd and output it from a (cheap) usb interface, it comes out as what sounds like about 220 Hz square wave mixed with a noisy “zipper” sound. The same thing happens when I run the sine-module directly from patchbox. EDIT: sometimes the result is a 440 tone, but still mixed with the noisy zipper tone.

I’ve tried 3 different usb interfaces - one of the cheap white dongle ones, and two different multichannel (5.1 & 7.1) ones, I think they’re all made with the CMedia chipset - and they all make the same sound. I know that the sound cards work because I was able to verify all of the outputs using speaker-test -t wav -c6 -Dhw:1,0 on a standard version of raspberry os lite (but the doesn’t work on patchbox). I can also address the output individually from Pd by changing the arguments to [dac~], but the result always sounds garbled…

Does anyone have any idea what could be causing this, or what I could do to fix it? I had a look around the forum and didn’t see any mention of a similar problem.

EDIT: it may be worth noting that when i start Pd, I get the following message in the console:
opened alsa client 132 in:1 out:1


We do recommend 512 for USB audio cards. :slight_smile: https://blokas.io/patchbox-os/docs/setup-wizard/