MK:427 Environmental Noise Microphone
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3.
Attach the microphone grill to the microphone capsule
4.
Connect the acoustic calibrator and select the 94dB level.
5.
Adjust the calibration level using Calpot R1 for the output current given in the table below.
This provides a reference calibration level so that the current output is now proportional to the
noise level. The current will depend upon the range of the instrument.
Range
Calculation
Current for 94dB Calibrator
74 – 144 dB
dB = (10 x I ) + 30
6.4mA
64 – 134 dB
dB = (10 x I) + 20
7.4mA
54 – 124 dB
dB = (10 x I) + 10
8.4mA
44 – 114 dB
dB = (10 x I)
9.4mA
34 – 104 dB
dB = (10 x I) – 10
10.4mA
24 – 94 dB
dB = (10 x I) – 20
11.4mA
