C-4 824 Reference Manual 9/29/09
Storage temperature: -10°C to 60°C
Humidty: ± 0.5 dB error
between 30 and 90%
relative humidity at
40°C
Equivalent mic
impedance:
18 pF for Larson Davis
1/2” microphone
Range level error: < ±0.1 dB relative to
the reference range
Calibration procedure: Using a Larson-Davis CAL200 or
equivalent calibrator, insert the microphone fully into the
calibrator. Set the calibrator to 114 dB SPL. On the 824 press
the tools
Tkey, arrow down to “Calibration” and press the
right arrow
rkey. From the calibration menu use the down
arrow
d key and highlight “Change”. Press the check c
key to initiate the calibration. The 824 will prompt you to turn
the calibrator on with “Calibrator Active?”. Select “Yes” after
turning the calibrator on and press the check
c key. The 824
performs the calibration change.
Effect of Magnetic
Field:
80 A/m ( 1 Gauss) @
60 Hz produces a
change of < 0.3 dB
SPL - passes Class 1
according to IEC
61672
Vibration Sensitivity:
(worst case)
73.7 dB with linear-
weighting at 1.0 m/
sec
2
referenced to 58.1 dB
Warm-up Time: 45 sec
Digital Display Update
Rate
Four times per second
(0.25 sec between
updates). First display
indication is available
0.25 seconds after
initiation of a
measurement.
Effect of an extension
cable (EXAxxx) on
calibration:
none (up to 500 feet)
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