Casella CEL CEL-414 - Manual (Page 37)

14. If the recording levels are lower than
90 dB, record the 114 dBsignal from
the calibrator as described in step
11. Then without touching the
record level on the tape recorder,
move the 80-50-20 Switch on the
sound level meter (not CEL-493/3) to
“50" for signals in the range 50 to
110 dB, or ”20" for signals between
20 and 80 dB.
When these signals are replayed, 30
or 60 dB respectively must be sub-
tracted from the values indicated by
the sound level meter to obtain the
true level.
15. Record about 30 seconds of the
calibration signal.
16. Switch the calibrator OFF and remove
it from the microphone.
17. Adjust the A-L-FA-FL/A-C-FA-FL
switch on the sound level meter
(and the frequency of the filter set)
to the settings required for the
particular recording task.
18. Proceed with recording the noise or
vibration signal.
If the recorded material is to be used
for frequency analysis, it is recom-
mended that each tape be calibrated
individually by using a suitable
generator to produce signals at the
required (centre) frequencies.
Octave or third-octave filtered
output signals from a CEL-213
Random Noise Generator may be
used for this calibration.
When replayed and analysed, these
signals will give an indication of the
record/replay frequency character-
istics of the tape.
7.4.2 Replay From a Tape
Recorder
These guide lines are recommended for
replaying sound or vibration signals with
a CEL sound level meter.
1. Prepare the sound level meter (and
filter set if connected) for use as
detailed in Chapter 4.
2. Using a suitable acoustic calibrator,
perform a field accuracy check on
the sound level meter (and filter set)
as described in Chapter 5.
3. Connect the sound level meter with
the tape recorder as shown in Figure
17 for replay.
4. Set the sound level meter controls as
follows:
P-I-F-S F (Fast),
A-L-FA-FL or
A-C-FA-FL L (Linear), C (C-weighted)
or A (A-weighted) if no
filter is to be used,
UHER 4000
CEL-216
C3526/2
920011
CEL-316
Figure 17: Connection with a tape
recorder (Uher 4000) for replay
General CEL Sound Level Meters Handbook - Page 33