Larson Davis SoundAdvisor 831C Reference Manual page 234

h) Electrical Insert Signals
The electrical design of the input device to insert electrical signals into the preamplifier is a series 12pF ± 5%
capacitor. The Larson Davis ADP090 is used for this purpose. The ADP090 is also use for noise floor
measurements by attaching the included BNC short on the front of the ADP090.
i) Self Generating Noise in Low Level Sound Field
Table B.7 SLM Noise Levels
Self Generated
Electrical Noise
Weighting
Self Generated Total
Weighting
Note: Combination of the electronic noise and the thermal noise of the 377B02
microphone at 68 °F (20 °C) measured in a sealed and vibration isolated cavity
with an averaging time of 60 seconds. Electronic noise of the instrument with an
ADP090 (12 pF) in place of the microphone highest anticipated self-generated
noise.
j) Highest Sound Pressure Level
The highest sound pressure level the Larson Davis 831C is designed to accommodate at the level of overload is
140 dB. The maximum peak-to-peak voltage is 28 Vpp input through the ADP090.
k) Battery Power Voltage Range
The battery power supply voltage range for which the 831C conforms to this standard: 16.8 Volts maximum.
The 831C shuts down if the battery is below 4.0 Volts when used with alkaline batteries. Therefore, from 4.0 to
16.8 Volts is the usable range of battery voltage. The instrument will shut off to ensure that no data is taken that
would not meet the requirements of IEC 61672.
l) Typical Stabilization Time
The typical time interval needed to stabilize after changes in environmental conditions:
• For a temperature change of 5 °C, then 30 minutes are required.
• For a static pressure change of 5 kPa, then 15 seconds are required.
• For a humidity change of 25% (non-condensing), then 30 minutes are required.
m) Field Strength > 10 V/m
The 831C was not measured for field strengths greater than 10 V/m.
SoundAdvisor Model 831C
Typical (dB)
A
C
Z
Noise
Typical (dB)
A
C
Z
0 dB Gain
Max (dB)
10 12
13 16
22 25
0 dB Gain
Max (dB)
16 19
17 20
23 26
20 dB Gain
Typical (dB) Max (dB)
6 9
12 15
22 25
20 dB Gain
Typical (dB) Max (dB)
16 17
16 19
23 26
B-11