Service Manual
AT235
26
CALIBRATION OF DD45
Fig. 42
Equipment needed for DD45 calibration
•
Measuring amplifier
•
Acoustical IEC 60318-3 (IEC 303) coupler
•
Frequency counter
•
Correction values for coupler
From the AUD menu, select
Transducer Calibration
.
Place the transducer on the 6cc IEC 60318-3 (IEC 303) coupler
Adjust the slider until the calibration level is obtained on the measurement amplifier
(i.e. 90 dB SPL).
Fig 43
Check the frequency accuracy with a frequency counter. The accuracy has to be better than ±1%.
When the intended calibration level is obtained, use
‘Enter’
to get the next frequency.
Repeat until all stimuli are calibrated, for both the left and right transducer.
NOTICE
Do not forget to add or subtract the correction for your microphone
