SPL: Inconsistencies between Windows 7 and Linux

linuxonly

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Hi,

Context:

I'm using REW beta.
Same computer (dual boot) therefore same sound card.
Same REW settings: Linux parameters exported and reimported in Windows.
Sound card is ASUS Xonar D1, analog output.
Mic is UMIK-1
Measurements at 48kHz SR using Java.
The 6 channels are set to the same volume level both in windows and in linux. It's easier to do on linux.
No effects whatsoever, no EQ, etc.

Problem:

Because of differences between the linux drivers and the windows drivers, I determined it's best to make windows measurements to create convolution filters tailored for windows instead of using the filters generated when using linux. They're not 100% compatible, particularly audible differences in SPL between channels (6) creating unbalance. One could always use the linux filters on windows but would require to adjust each channel gain separately to recenter the phantom image. It's doable with 2 channels but more complex with 6. Hence the idea to generate filters for linux on linux and filters for windows on windows.

When I make measurements on Linux, I set the SPL at 75 dB. I'm very used to it. I can tell just hearing it, I've been doing this for 2-3 months, the reported SPL is correct.

On windows, I have to crank the volume control on the AVR to just reach 60 dB for my measurements but the problem is, the real SPL is clearly at or very close to the pain threshold level: I have to get out of the room. I take 18 measurements, 3 for each channel so it's not tolerable for such a large amount of time. Additionally REW SPL meter reports around 40dB instead of 100-110 which is probably closer the real SPL.

Is there something I missing, or an issue?
 

John Mulcahy

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On windows, I have to crank the volume control on the AVR to just reach 60 dB for my measurements but the problem is, the real SPL is clearly at or very close to the pain threshold level: I have to get out of the room
Never raise the volume above a comfortable listening level. Clearly the displayed SPL figure is wrong on the Win7 installation. That might be related to the Windows input volume setting, check what it is set to for the UMIK. REW's input volume compensation might also be wrong for Win7 with current UMIKs, that OS is so old now it has been many years since REW was tested with it.
 

linuxonly

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Joined
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108
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Preamp, Processor or Receiver
Logitech Z906
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AMD FCH Azalia
Computer Audio
SPDIF output with alsa, pipewire, wireplumber on Fedora 40
Streaming Equipment
Kodi
Front Height Speakers
33 in
Middle Height Speakers
30 in
Rear Height Speakers
57 in
Video Display Device
X11/VGA + X11/DVI
Never raise the volume above a comfortable listening level. Clearly the displayed SPL figure is wrong on the Win7 installation. That might be related to the Windows input volume setting, check what it is set to for the UMIK. REW's input volume compensation might also be wrong for Win7 with current UMIKs, that OS is so old now it has been many years since REW was tested with it.
Thanks, John. I understand that. I've forgotten that fact.
 

linuxonly

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Thread Starter
Joined
Jul 27, 2024
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108
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Preamp, Processor or Receiver
Logitech Z906
DAC
AMD FCH Azalia
Computer Audio
SPDIF output with alsa, pipewire, wireplumber on Fedora 40
Streaming Equipment
Kodi
Front Height Speakers
33 in
Middle Height Speakers
30 in
Rear Height Speakers
57 in
Video Display Device
X11/VGA + X11/DVI
Wondering if the culprit could be that untickable 'control input volume'...
 

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John Mulcahy

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The input volume shouldn't be active in WASAPI Exclusive mode, but you can adjust it via the Windows audio properties for the input.
 

linuxonly

Member
Thread Starter
Joined
Jul 27, 2024
Posts
108
More  
Preamp, Processor or Receiver
Logitech Z906
DAC
AMD FCH Azalia
Computer Audio
SPDIF output with alsa, pipewire, wireplumber on Fedora 40
Streaming Equipment
Kodi
Front Height Speakers
33 in
Middle Height Speakers
30 in
Rear Height Speakers
57 in
Video Display Device
X11/VGA + X11/DVI
The input volume shouldn't be active in WASAPI Exclusive mode, but you can adjust it via the Windows audio properties for the input.
Thanks John, It's at 100% by default.
 
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