12
Insert the ½ inch microphone to the hole of ST-120 sound calibrator, turn on the power
supply. Press key. The meter automatically starts calibration. The sound pressure
level is displayed after "Current SPL". This sound pressure level is approximately equal
to the calibrator’s sound pressure level minus free field correction. The sensitivity level
is displayed after "New Sensiti.".
During calibration, a number is displayed on the bottom
right corner of the screen, which changes from 0 to 21 and
then stops. Then the user presses key, the new micro-
phone sensitivity level will be saved.
If the newly calibrated sensitivity level differs from the last
saved sensitivity level by over 4dB, the meter will prompt
"As the sensitivity level difference exceeds 4dB, it can’t be
saved. Please check whether the calibration is correct.".
The user should check whether the microphone is
damaged. If the user doesn’t press key, the meter will
still use the original microphone sensitivity level.
5.3 Directly input sensitivity level
If no calibrator is available, the user can also directly input the microphone’s sensitivity
level. Press key, and press or key to move the cursor to "New Sensiti.", and
then adjust the value by or key until it arrives the expected value. At last, press
to save the Calibrator SPL.
ST
-25D
