Behringer x32 + PipeWire + LinuxMint 22 (Ubuntu 24.04)

Hi everyone!

I have a Behringer x32 compact (32 channels in / 32 channels out) which I'm trying to use as a sound card from the USB interface with REW.

The LinuxMint 22 / Ubuntu 24.04 ships with PipeWire. Jack has been deprecated and removed.

I need to have the RTA mic on channel 30, the stereo output on channel 31 and 32, but I cannot get the remapping working.

In Preferences > Soundcard, I select
- Output device: "PCM: Pipewire"
- Output: "Default Ouput" | "L"

Then I click "Set Output Channel Mapping", and I set
- Channel 1: Hardware Channel: 31 - Name: L
- Channel 2: Hardware Channel: 32 - Name: R

Then:
- Input Device: "PCM Pipewire"
- Input: "Default Input" - Channel 30

Then I click "Calibrate soundcard", start the wizard. I see the Out meter at -12dBFS and In -484.66dBFS so no signal coming. Then I installed qpwgraph and from that graph I can see that regardless of the remapping settings I configured, Out gets routed to playback channel 0 and 1 and the In is taken from capture channel 0 and 1.


Should the remapping be working with Pipewire or did I get something wrong?

Thanks

To use REW with PA mixing console, your best bet would be to stick with one of the standard REW equipment recommendations:

• USB mic -> laptop computer -> computer audio out -> mixing console input
• Measurement mic with XLR connection -> USB audio interface with phantom power -> Interface audio output -> mixing console input

Regards,
Wayne

• Measurement mic with XLR connection -> USB audio interface with phantom power -> Interface audio output -> mixing console input

Click to expand...

This is what I'm after: Behringer ECM8000 + calibration file, connected to x32 using phantom power, x32 is detected as a 32/32 sound card.

In order for this to (maybe) work, the console needs a USB output -> laptop -> laptop audio output -> console.

I don’t think it will work.

Regards,
Wayne

@lfdm: I wonder why the pipewire GUI shows only 2ch for the Pipewire Alsa connections, eventhough the REW/java alsa interface should open the alsa PCM pipewire device (= alsa plugin https://gitlab.freedesktop.org/pipe...sa/alsa-plugins/pcm_pipewire.c?ref_type=heads) at 32 channels . That's where I would focus attention at to solve the issue of your chain.

However, the question is why pipewire is involved in your chain in the first place. IMO if you do not need any pipewire facilities like some DSP, the measurement chain should avoid any non-bitperfect components if possible. I.e. disabling your 32ch soundcard in pipewire (to avoid being blocked by PW and thus not being available to any other alsa application) and use direct alsa java interface in REW. Then you will not need to handle any routing.

Your current chain:

soundcard ADC -> alsa usb-audio driver -> alsa API -> pipewire -> alsa API -> alsa pipewire plugin -> alsa API -> java/REW
java/REW -> alsa API -> alsa pipewire plugin -> pipewire -> alsa API -> alsa usb-audio driver -> soundcard DAC

IMO the correct chain for measuring:
soundcard ADC -> alsa usb-audio driver -> alsa API -> java/REW
java/REW -> alsa API -> alsa usb-audio driver -> soundcard DAC

I do not have pipewire on my machines yet, so I cannot tell you how to disable a device in GUI. Wireplumber method is e.g. https://blog.zenlinux.com/2022/08/how-to-disable-audio-devices-in-pipewire-wireplumber/