Larson Davis SoundTrack LxT, User Manual

Page: 98 / 307

LxT Manual Acoustic Calibration
7-5
Frequency Weighting
The LxT automatically switches to C frequency weighting
and Fast detector response for calibration. This permits 250
Hz and 1000 Hz calibrators to be used. The Fast detector
response reduces the stabilization time required before
calibration.
After calibration, the LxT returns to the original frequency
and time weighting set by the user.
Calibrator
The Calibrator section of the Calibrate tab includes an
area to enter information about a calibrator and a list of
calibrators. The user may select a calibrator from the list or
enter new information about a calibrator.
Recommended Calibrator
Table 7-1 'Recommended Calibrators for Use with LxT1 and
LxT2' lists the sound level calibrators which Larson Davis
recommends for calibrating the LxT1 and LxT2.
When using a 1/4” microphone, the adaptor ADP024, a 1/4”
microphone adaptor for the 1/2” opening in the CAL150 and
CAL200 calibrators, is also required.
Calibrating the LxT1 and 377B02 microphone
The CAL200 provides a nominal pressure level of 94 dB or
114 dB. The exact levels are printed on the Larson Davis
calibration sheet that came with the calibrator. When using a
free-field microphone, the pressure level at the microphone
diaphragm is slightly different. Thus, a free field correction
of -0.12 dB (0.03 dB uncertainty at 95% confidence level)
should be applied to either of these levels. Pressure and
random incidence microphones do not require this
correction. If the calibrator and instrument are near room
Calibrator Instrument
Calibrator
Precision
Output Frequency
CAL200 LxT1, LxT2 Class 1 94/114 dB 1 kHz
CAL150 LxT2 Class 2 94/114 dB 1 kHz
Table 7-1 Recommended Calibrators for Use with LxT1 and LxT2