How can I calibrate my system with a microphone calibrator?

[tcoor8325]

I would like to calibrate my microphones to dBSPL using a mic calibrator, inside of REW
I have a GRAS 45CA Ear Simulator that I am using to make headphone measurements. The device comes with a GRAS 42AA Pistonphone Microphone Calibrator, which produces 114 dBSPL (linear) at 250 Hz.
Before switching to REW, I was using the Audiomatica CLIO 12, which allows me to calibrate my microphone by setting a calibration level to expect, and then calculates a sensitivity by recording the signal when the calibrator is on and inserted over the microphone (See image below).

My question is, how can I do this within REW? My 1st thought is that my sensitivity will have to be in dBFS instead of dBV. I could perhaps measure the waveform when the calibrator is on with the Scope. I'm also not sure if I should make a cal file, because they appear to measure sensitivity w.r.t. 94 dBSPL.
My current rough calibration has been the standard method for room measurements using an SPL Meter and the replacement method.

My system is as follows: GRAS 45CA Left and Right Microphones -> Preamplifier -> Focusrite Scarlett 2i2 -> Thinkpad X1; Ubuntu 22.04.5 LTS; REW V5.31.3

Thanks for any guidance!

 

[John Mulcahy]

Follow the Calibrating the SPL reading help, selecting "External signal" at the relevant point and entering 114dB as the level.

 

[tcoor8325]

Thanks, this solved it. My procedure for those wondering:

1. Open up the ear simulator to access the left microphone
2. In REW, under SPL Meter->Calibrate, set reference to 114dBSPL and hit start
3. turn on pistonphone and place over microphone
4. REW records measurement
5. Under Preferences->Mic Cal Files->Settings, REW has already calculated the dBFS @ 94dBSPL. Record this for future use (REW should save this value by default)
6. Repeat for Right Ear

 

[John Mulcahy]

REW should save this value by default

The values are automatically saved as part of the cal data for that input. Make sure the option for separate cal for each input is selected.

 

[ClaireGarcia]

Thanks, this solved it. My procedure for those wondering:

1. Open up the ear simulator to access the left microphone
2. In REW, under SPL Meter->Calibrate, set reference to 114dBSPL and hit start
3. turn on pistonphone and place over microphone
4. REW records measurement
5. Under Preferences->Mic Cal Files->Settings, REW has already calculated the dBFS @ 94dBSPL. Record this for future use (REW should save this value by default)
6. Repeat for Right Ear
   
   
   
   
   
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Thanks for the steps.

 

[lillieryan]

Thanks, this solved it. My procedure for those wondering:

1. Open up the ear simulator to access the left microphone
2. In REW, under SPL Meter->Calibrate, set reference to 114dBSPL and hit start
3. turn on pistonphone and place over microphone
4. REW records measurement
5. Under Preferences->Mic Cal Files->Drift Boss, REW has already calculated the dBFS @ 94dBSPL. Record this for future use (REW should save this value by default)
6. Repeat for Right Ear

Good guide.

 

[fedele]

this is a my old video.

 

[fedele]

Just produced a new one

New Video
𝐑𝐄𝐖 - 𝐒𝐏𝐋 𝐂𝐚𝐥𝐢𝐛𝐫𝐚𝐭𝐢𝐨𝐧 𝐏𝐫𝐨𝐜𝐞𝐝𝐮𝐫𝐞 𝐮𝐬𝐢𝐧𝐠 𝐚 𝐦𝐢𝐜 𝐂𝐚𝐥𝐢𝐛𝐫𝐚𝐭𝐨𝐫
In English.

There are different methods to calibrate in REW (like in other softwares). Here... I will show you the basic steps to calibrate your system using an external calibrator. Please... refer to the videos on my YouTube channel to learn more about the theoretical concepts... such as levels, SPL measurements, and Sound Level Meters. You will also find detailed explanations on LAeq... and all the specific parameters that characterize S-P-L measurements.