Cannot Calibrate REW with UMIK-2

[4donutsYx]

I'm using a UMIK-2 and none of the readings match up. Am I not understanding the REW SPL meter correctly? What does the dB(C) S window represent vs the dBFS in window?

With other mics, I could manually calibrate the mic ,dB(C)S, to the reading on the phone, but with the UMIK, it does not allow you to do it. Also, if I connect the UMIK to the front panel USB (external drive), I get about 10dB more noise vs the rear panel on the motherboard. Note, yes the 90 deg cal file is loaded.

 

[John Mulcahy]

You need to select the input device and input corresponding to the UMIK-2 in the REW soundcard preferences and load the cal file, which includes information on sensitivity which REW uses to show correct SPL. To do that it needs to know the volume setting, to get that it needs the device selections to be made, they cannot be left as default.

dB(C) S = SPL in dB, C-weighted, Slow.

 

[4donutsYx]

John, yes I believe I did the steps you mentioned, shown in the pics (in Linux). Doing that did not fix the mismatch between the phone and umik. However, I lowered the OS mic volume to get it to match. Does this resolve my issue?

But in Windows, the mic volume is too low even though the OS input volume is 100%. So I'm not sure I can do anything to resolve the mismatch because I cannot increase past 100%.

 

[John Mulcahy]

Do not use default, select the named device and input for the mic. The volume level is fine.

 

[4donutsYx]

I get the same results with Default and the named default, but I'll use the named input going forward. However after restarting REW, I have to adjust the OS input volume by a different amount than I previous set it. There's something else throwing it off. I'll have to check Windows again.

 

[John Mulcahy]

I don't know what you mean by "named default", but if "default" appears anywhere within the device name or input name REW cannot access the volume control to correctly show SPL.

 

[4donutsYx]

'named default' must be a linux thing since it uses general drivers.

 

[4donutsYx]

Here's a screenshot of Windows. In Windows the SPL meter is higher than the phone. There's no way for me to reduce it to match the phone. I tried the HyperX Quadcast 2 usb mic and that gave me the option to use the 'Calibrate' button to match the phone.

 

[John Mulcahy]

You can adjust the mic cal file SENS_FACTOR figure to alter the calibration if you feel it is incorrect, but I wouldn't have expected a phone to be a reliable class 1 reference. If you have a mic calibrator that would be a better check.

 

[4donutsYx]

thanks. I don't expect the phone to be reference but I'm just looking for close enough rather than 5 or 10dB.

 

[4donutsYx]

btw, the mic for the AVR, the phone and the HyperX Quadcast 2 all show 75dB based on the results of the AVR's room correction. So I use that as cross reference to show some trust in the phone as being good enough.

 

[John Mulcahy]

My UMIK-2 is within 0.5 dB on my class 1 calibrator at 94 dB.

 

[4donutsYx]

I hear you, but if the OS or other device is inducing noise or is off for whatever reason, it renders the UMIK unreliable and I still need to adjust for it by using the other microphones as reference.

An example of noise via USB is the front panel (external usb drive) has more noise than the rear panel ports direct from the motherboard.