Casella CEL CEL-450 - Manual (Page 59)

4.5.1 Recording
DAT recorders have a typical dynamic range of 70 dB, while analog
recorders often have less. To ensure the maximum dynamic range for
recording while avoiding overload, the 60 to 70 dB range of the recorder
must be arranged to accommodate only the top or bottom 60 to 70 dB
portion of the 140 dB output from the sound level meter. This is
achieved by selecting an AC output signal to match the level used to
calibrate the sound level meter. The following guide lines are suggested.
1. Use a CEL-110, CEL-284/2 or CEL-282 Calibrator to perform an
acoustic calibration check of the sound level meter at 114 dB or
94 dB, as described in Section 4.
2. Display the Configure screen, accessed from the Main screen as
described in Section 2.1.
3. Select and display the AC Output screen.
4. Select Hi or Low to match the calibration level used in Step 1,
i.e. Use Low range with a 94 dB calibration,
Use Hi range with a 114 dB calibration.
5. Connect the input of the recorder to the instrument OUT terminal.
6. Select broadband L ZF measure mode on the sound level meter.
7. Switch the recorder ON and start it operating in record mode.
8. For accurately repeatable recordings, adjust the Record Level
control on the recorder until the calibrator signal gives a reading
of -12 dB on the tape recorder VU meter.
Now the top of the recording range on the tape (= 0 VU) will
occur in the same place as overload on the sound level meter
(140 dB or 98 dB depending on the calibration used).
Selected output range
CEL-450/490 Operators Handbook - Page 59
Operation