DS-3000 Frequently Asked Questions

Question number FAQ-0724

Unit calibration in the absence of an acoustic calibration device for MI series measurement microphones.

If you don't have an acoustic calibration, we will explain how to calibration simply by finding the coefficient k from the microphone sensitivity and preamp gain values available in the catalog.

To be precise, use a standard acoustic calibration and refer to the operating manual (PDF file) below to perform the unit calibration.

"Operation Manual for Acoustic Analysis Using MI Series Measurement Microphones" (PDF)

Here, it is explained with the assumption that the MI-1433 is used as a measurement microphone and the MI-3111 is used as a microphone preamplifier.

from the catalog

● Sensitivity representative value of MI-1433 microphone	−29 dB Re. 1 V／Pa
● Representative gain value of MI-3111 preamplifier	−2.0 dB

From here;

= 0.02818 V.
When the sound pressure is 1 Pa, it becomes 0.02818 V.

calibration Setting values

In the "Configuration" window, click [I/O Settings]→ [Units calibration], → [Open]. The "calibration Settings" dialog box will open.
Check "EU" under "CH1" in the "calibration Settings" dialog box.
In the "calibration Settings" dialog box, set the [EU Type] for "CH1" to "V/EU."
Set the '0 dB reference value' to '2E-05'. (See the blue arrow)
In the "calibration Settings" dialog box, enter "0.02818" in the [EU Value] field of "CH1".

With that, the unit calibration is complete. Microphone sensitivity and preamp gain vary slightly for each individual. Therefore, this method is for rough measurement. Correctly, perform calibration with an acoustic calibration.

[Supplement]

The voltage output at a sound pressure level of 94 dB is lower than -31 dB; converting -31 dB to voltage.

than

"It can be understood that the output is 0.028184V (RMS) at a sound pressure level of 94 dB. Similarly, the true value A that corresponds to 94 dB is;"

Therefore, the coefficient k (EU/V) is;

The voltage output at a sound pressure of 1 Pa is -29.0 dB - 2.0 dB = -31.0 dBV.

Last updated: 2007-03-19