Getting UMM-6 mic to work on Ubuntu Linux laptop

[ameucci8]

I'm trying to get my Dayton UMM-6 working properly with REW on Ubuntu (REW 5.40 beta 104) but running into several issues.
Main problem - device selection error: When I try to select the UMM-6 as input device, I get: "UMM6 [plughw:3,0] does not have any lines supporting PCM_signed 48000 Hz, 16 bit, stereo, 4 bytes/frame, little endian. Try a different sample rate." I'm already at 48kHz and tried other sample rates - same error. I ended up creating an ALSA virtual mono device as a workaround since the UMM-6 seems to require stereo at the driver level on Linux.
Calibration file issue: When I load the calibration file (2580168.txt), I get: "The cal file has a Sens Factor entry but the input is not a recognized USB mic. The Sens Factor entry will not be used."
System info:
Ubuntu Linux, REW 5.40 beta 104
lsusb shows: ID 0d8c:0147 C-Media Electronics, Inc. UMM-6

Side note: Even without calibration files, the same room gives wildly different readings - Windows shows ~22 dB, Ubuntu shows ~55 dB. Maybe I'm just doing something wrong here.
Everything works fine on Windows. Has anyone successfully gotten the UMM-6 working on Linux? Any tips or workarounds?
Thanks!

 

[phofman]

Main problem - device selection error: When I try to select the UMM-6 as input device, I get: "UMM6 [plughw:3,0] does not have any lines supporting PCM_signed 48000 Hz, 16 bit, stereo, 4 bytes/frame, little endian. Try a different sample rate." I'm already at 48kHz and tried other sample rates - same error.

Since you are using plughw:X device (i.e. using the alsa plug plugin), any format is always available. My 2 cents your device is enabled in pulseaudio/pipewire and used by that sound server, thus blocking out the direct alsa access by java in REW.

Always disable a device in PW/PA if you want to use it via alsa directly (such as by REW/java). Disabling is via audio-settings GUI of your specific desktop environment or via pavucontrol/pactl

Disable/Remove Audio Source (PulseAudio)

In Windows, as a comparison, one can disable audio sources, so that when wanting to switch between them, one receives a shortened list of available audio sources to choose from. To my understandin...

unix.stackexchange.com

Entirely disable audio devices from sound settings?

That they don't show up not. But I know a Way to disbale them. For that You can use PulseAudio control. To install it. open the Terminal and type sudo apt install pavucontrol and when it is installed, open it. When You have it open got to the last Tab called Configuration. There You should see...

forum.zorin.com

 

[ameucci8]

Thank you for replying, however the Windows SPL readings and my Ubuntu Linux laptop SPL readings still differ by a considerable amount. I was able to successfully connect the UMM-6 mic to my laptop without getting any errors, but in a quiet room for which the Windows SPL reads 39 dB(A), my laptop is reading 46dB(A). Same microphone, same calibration file, same environment same everything. Both are being used exclusively by REW. Same sample rate, both are treating 32 bit data as 24 bit, both have save buffer, sweep level, and input volume. Why?

If 39 to 46 dB(A) wasn't a surprising enough change, I also tried it with a different UMM-6 mic, in the exact same room, also with the same environment and everything. On the Windows desktop this second mic showed a reading of 41 dB(A) for a quiet room. For my laptop? 56. Five six. I've been trying to diagnose this for the past few days and have arrived at no reasonable conclusion in the slightest. For such big difference you would think I'm missing something very obvious, but I've tried everything I could think of. Any help would be greatly appreciated.

 

[sam_adams]

but in a quiet room for which the Windows SPL reads 39 dB(A), my laptop is reading 46dB(A)

Have you disabled all audio enhancements for the microphone (Disable Audio Enhancements - Microsoft.com)?

 

[ameucci8]

Yes, there are no Audio Enhancements being done on the Windows side, and Linux/Ubuntu doesn't have it like Windows does by default

 

[phofman]

The hardware works the same way on linux and windows. But the hardware configuration can be different.

My 2 cents - there is some gain USB control in your USB capture device which gets set differently in windows and linux. IIUC REW itself operates this control, if the checkbox "control input volume" is enabled. It's quite common for the numerical values of volume control to differ on windows and linux, because these are not the actual values sent to the usb device feature, but undergo complicated conversions.

You can disable that checkbox and control the gain feature via windows mixer or alsamixer/amixer in linux.

 

[John Mulcahy]

When I load the calibration file (2580168.txt), I get: "The cal file has a Sens Factor entry but the input is not a recognized USB mic. The Sens Factor entry will not be used."

That's because the device name isn't in a format REW recognises. UMM-6 used to appear in device lists as "UMM-6". Later it started appearing as "UMM_6" so I added that. Now it seems we also have "UMM6", so I'll add that in the next build. It would be nice if they could stick to one name. Since REW doesn't recognise the mic it can't use the Sens Factor entry so you have to calibrate the mic yourself using the SPL cal process.