# SPL Calibration File Numbers Question



## RoundChiTown (Dec 31, 2009)

I may just be thinking about this the wrong way but I am a little confused as to what the numbers mean in the calibration file. From what I have noticed the calibration file is not automatically applied to measurements. Disregarding any inherent inaccuracy of the cal file itself, what I am wondering is if a value such as "20.0	-9.05" means that what REW shows for a measurement is 9.05 too high or 9.05 too low.

Example
REW measurement shows 76.50db at 20hz
Assuming the cal file is correct, is -9.05 telling me that the corrected db is 85.55 or 67.45.

I would assume the latter but looking at the curve for the cal file it shows I keep wondering if what I want to be doing is trying to overlap my measurement with the curve, which would mean it was the former, i think...

If anyone can understand that or if there is a way to apply the cal file to measurements automatically I would appreciate any :help:


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## Wayne A. Pflughaupt (Apr 13, 2006)

Welcome to the Forum, Round!



> ...what I am wondering is if a value such as "20.0 -9.05" means that what REW shows for a measurement is 9.05 too high or 9.05 too low.


The value means that the meter is -9.05 dB at 20 Hz. That tells REW how much to increase at 20 Hz.




> If anyone can understand that or if there is a way to apply the cal file to measurements automatically I would appreciate any


 Once you load the calibration file under Settings, Mic/Meter tab, REW does everything automatically from that point. The frequency response graph that’s generated after measuring is the corrected response.

Regards,
Wayne


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## RoundChiTown (Dec 31, 2009)

Thankyou very much for the welcome and the help


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