Larson Davis Spartan 821 - Page 108

Spartan 821/721 Manual IEC 61672-1 Section 9.3 B-19
The following sections f) through o) are applicable for the PRM821 preamplifier.
f) Linear Operating Range
g) Linear Measurement Starting Point
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 adapter (ADP090) is used for this purpose.
i) Self Generating Noise in Low Level Sound Field
TABLE B.9 SLM Self-Generated Noise Levels
The following self-generated noise levels represent the highest anticipated self-generated electronic noise of
the instrument with an adapter ADP090 (12 pF) in place of the microphone.
TABLE B.10 SLM Self-generated Noise Levels
The following self-generated noise levels represent a combination of the electronic and thermal noise of the
377B02 microphone at 68 °F (20 °C) measured in a sealed, vibration-isolated cavity, with averaging time greater
than 30 seconds.
TABLE B.7 Linearity Range (Nominal Values)
Weighting 31.5 Hz 1 kHz 4 kHz 8 kHz 12.5 kHz
Lower Upper Lower Upper Lower Upper Lower Upper Lower Upper
A
24 100 24 140 24 141 24 138 24 133
C
28 137 27 140 27 139 27 136 27 131
Z
38 140 37 140 37 140 37 140 37 140
C Peak
50 140 50 143 50 142 50 139 50 134
TABLE B.8 Linear Measurement Starting Point
31.5 Hz 1 kHz 4 kHz 8 kHz 12.5 kHz
Level (dB) 74.5 114 115 112.9 109.7
Freq Weighting Typical (dB) Max (dB)
A 12 15
C 14 17
Z 22 25
Freq Weighting Typical (dB) Max (dB)
A 17 20
C 18 21
Z 25 28