Sound and Vibration Instrument Hire and Calibration
Norsonic 1252 Sound Level Calibrators
The Nor 1252 has been withdrawn as most customers prefer the
Nor 1251 or a
B&K 4231 class 1 calibrator. The following details are retained for information
Nor 1252 : Sound Calibrator - Class 2
A small battery operated sound calibrator complying with IEC 942 class 2 for calibration of microphones and sound measuring equipment
Output level is 114 dB re 20 µPa or 10 Pascal
RMS @ 1000 Hz, corresponding to 100 bar
Due to the principal of operation, the calibration level is virtually independent of ambient conditions i.e. temperature, atmospheric pressure and humidity within the specified range of operation.
The calibrator is intended for 1/2" measurement microphones and sound level meters equipped with such microphones. Smaller microphones may be calibrated with suitable adaptors - not included.
Most 1/2" free-field microphones, as defined by IEC 651 have a pressure response that is 0.2 dB lower than their free-field sensitivity at 100 Hz. Therefore for a 1/2" free-field microphone the level should be adjusted to 113.8 dB
Half-inch microphones designed for flat random incidence response, normally require no correction and should be adjusted to 114.0 dB
Effective Microphone Front Volume
Various types and makes of microphones may have different effective front volumes. Due to the patented working principle of the Nor 1252 sound calibrator, the coupler has a large effective volume.
The variations in sound pressure due to variations in the effective front volume for different microphones is therefore less important for most applications