[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/

Raspberry Pi 4 (4Gb) + USB sound card SSL2 + Patchbox, 44100, 512, 3, as recommended, which is unusable at all but wanted to try - sound distorted. Occasionally the sound cleans up for a couple of seconds and then goes distorted again. The sound is distorted no matter what I do. Tried also different buffers setting and it always distorted.

However, the same sound card works perfectly fine without any xruns on 32 samples buffer with Guitarix on Manjaro system (intel, not a Raspberry Pi).

Raspberry Pi + SSL2 + Manjaro + Guitarix plays without xruns on 128 samples.

Im having the same issue now with a MobilePre usb card .
Having a hard time guessing where does it come from , as it seems to come and go .