Casella CEL CEL-450 - Manual (Page 60)

9. Record about 30 seconds of the calibration signal.
A calibration signal with known level is inserted via the sound
level meter and recorded, so that when replayed, it gives an
indication of the record/replay characteristics of the tape.
10. Switch the calibrator OFF and remove it from the microphone.
When the VU reading is estimated (which it usually must be at
these levels), repeatability from one series of recordings to
another may suffer. Therefore, either keep the Record Level
control in the same position for ALL recordings, or perform a
new calibration for EACH series of measurements.
11. Without touching the Record Level on the recorder, if required,
change the measurement range of the instrument to
accommodate the noise signal.
12. Make a note of the range used for measurement.
13. Proceed with recording the noise signal.
5.5.2 Replay
The following guide lines are suggested for replaying sound signals.
Figure 6: Bottom panel of the instrument
Page 60 - CEL-450/490 Operators Handbook
Operation