DS-3000 Frequently Asked Questions

Question number FAQ-0724

Unit calibration when an acoustic calibration is not available 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.

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

This explanation assumes the use of the MI-1433 as the measurement microphone and the MI-3111 as the microphone preamplifier.

From the catalog

● Typical sensitivity values for the MI-1433 microphone	−29 dB Re. 1 V／Pa
● Typical gain values for the MI-3111 preamplifier	−2.0 dB

From here on;

= 0.02818 V.
When the sound pressure is 1 Pa, the voltage is 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 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】

If the voltage output at a sound pressure level of 94 dB is -31 dB, then converting -31 dB to voltage would be:

twist

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

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

At a sound pressure of 1 Pa, the voltage output is -29.0 dB - 2.0 dB = -31.0 dBV.

Last updated: 2007-03-19