Reviewing The Calibration Settings; Understanding Calibration Stability - Larson Davis SoundAdvisor Reference Manual

5.1.3 Understanding Calibration Stability

5.2 Reviewing the Calibration Settings

SoundAdvisor Model 831C
Overload Level
When using a microphone having a sensitivity of 50 mV/Pa, the input
overload may occur approximately as shown in Table 5.1.
Table 5.1 Input Overload Levels
Input Gain, dB
Under Range Level
The Under Range level is the higher of the following levels:
1. Noise Floor plus 9.14 dB (under range shown when self noise con-
tributes ≥ 0.5 dB to the readings).
2. Actual point where the log-linearity exceeds maximum permitted
value. Except for very low noise level microphones, the under range
level is usually determined by the noise floor plus 9.14 dB.
For more information about measurement range, noise floor,
LEARN MORE
linearity range, and max peak levels as they relate to different
microphones and Gain settings, see
(Nominal Values) on page
The 831C maintains a stable value of sensitivity over long periods of
time. Significant changes in sensitivity, or a pattern of small but regular
sensitivity changes, are indicative of problems with the measurement
system. To assist you in identifying these situations, the 831C provides
2 notifications:
1. Calibration History Table: Data and date/time of the 10 most recent
calibrations
2. Large Change Notifications
During calibration, the meter makes an automatic comparison
between the sensitivity determined by the calibration and the previous
value. A warning appears when the difference between these two
values exceeds 3 dB.
On your 831C, go to Tools  Calibrate.
831C calibration settings display on the following 4 tabs:
• 5.2.1 Calibrate Tab

Reviewing the Calibration Settings

0
20
Table A.2 SLM Performance
A-2.
Overload Level, dB Peak
143
123
5-2