BOSS RC-505 audio interface

Hardware
1

Hi,
I want to use a headless zynthian setup with my trusty, crusty old RC-505 as audio interface. That way, I could use a usb midi keyboard, an RPi and the RC-505 for live use, and get to keep my analog inputs free to plug in other intruments. It feel very excited about trying out this setup.
Problem is that I cannot get it to work reliably. So I am wondering if anyone else got it up and running?
Little more detail:
I used the 23-06-03 version on a RPi 4. This kernel (5.10.103?) does not recognize the RC-505 audio interface, so I added the VID/PID as a “quirk” in pcm.c and recompiled the kernel and modules. I have also tried compiling a more modern kernel with similar results.
Now it recognizes the interface, and can input and output audio, but it crackles roughly every second, and sometimes get xruns/freezes a while as well. It is setup as a Generic USB soundcard, with plenty buffers (up to 1024), -n 3 , -r 44100 and format S32_LE.
Appreciate any input or suggestions,
P

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2

Update: when running patchboxOS instead, RC-505 works flawlessly out-of-the-box. It has a later kernel, and perhaps different scheduler?

uname -a
Linux patchbox 5.15.36-rt41-v7l+ #1 SMP PREEMPT_RT

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3

Hi @pajen !

Welcome to zynthian community!

Scheduler on zynthian is the same PREEMPT_RT.
We will release a bullseye- aarch64 image very soon. Perhaps this solve your issues.

Regards

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4

I had pretty good results at one point with a Boss GP-10, very similar to your RC-505 in most respects.

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5

I suspect I perhaps did not configure PREEMPT_RT when I did my kernel rebuild… Looking forward to trying the new aarch64 image, although PatchboxOS seems to scratch my itch for the headless use case, and I am rather happy with it.
What kernel version will be used for the new aarch64 image?

6

We always use official kernel from repository.

Regards,

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7

I installed kdoren’s Low-Latency PREEMPT kernel 5.15.65-llat for Raspberry Pi, and that works. There are changes in the usb audio between 5.10 and 5.15 that enables a bunch of sound cards apparently.

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8

We are now working on 64bit image that uses kernel 6.1. It should be out in a few weeks.

Regards,

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