How to calibrate the unit of the MI series measurement microphone when there is no sound calibrator

This is a simple method to perform unit calibration by obtaining the coefficient k from the values of the microphone sensitivity and preamplifier gain described in the brochure, when you do not have a sound calibrator. This method is based on the condition of using the MI-1433 as the measurement microphone and the MI-3111 as the microphone preamplifier.

 

From the values described in the brochure,

●Representative sensitivity value of the MI-1433 Microphone −29 dB Re. 1 V/Pa
●Representative gain value of the MI-3111 Preamplifier −2.0 dB

 

From the above, followings can be said;

The voltage output when the sound pressure is 1 Pa: −29.0 dB−2.0 dB=−31.0 dBV

When the voltage output is -31.0 dB, 10-31/20 = 0.02818 V (1 Pa becomes 0.02818 V)

Setting of calibration value

1. In the [Configuration] window, click [Input/ Output setting] > [Unit /Cal setting] > [Open] in this order. [Cal setting] dialog box is opened.

2. Put check mark to [EU] of [CH 1] in the [Cal setting] dialog box.

3. Select [EU type] of [CH 1] as [V/EU] in [Cal setting] dialog box.

4. Use the key button to input the coefficient value of 0.02818 to the [EU value] of the [CH 1] in the [Cal setting] dialog box.

 

 

The unit calibration is now complete. Each microphone or preamplifier has a small difference in the sensitivity or gain. Therefore, above operation method is for the approximate measurement. To make precise calibration, please use the sound calibrator.

Revised:2007.03.19

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