Casella 620 Series - Linearity Measurements Starting Point; Electrical Input; Self-Generated Noise; Highest Level

620 Series
29
Weighting
31.5Hz
1 kHz
4kHz
8kHz
12.5kHz
A
30 to 100
30 to 140
30 to 141
30 to 138
30 to 134
C
32 to 137
32 to 140
32 to139
32 to 136
32 to 132
Z
38 to 140
38 to 140
38 to 140
38 to 140
38 to 140
CPeak
65 to 140
65 to 143
65 to 142
65 to 139
65 to 135
f) Linearity Measurements Starting Point
The starting point for measuring level linearity errors is 114dB.
g) Electrical Input
The input device to apply electrical signals to the pre-amplifier is a series 18pF +/- 5% capacitor.
The CEL-516-02 can be used for this purpose. The electrical self-generated noise can be
measured with the supplied shorting plug attached to the CEL-516-02.
h) Self-Generated Noise
Combination of CEL-251 microphone thermal noise and meter electrical noise.
Weighting
Electrical
Typical dB
Electrical
Max dB
Microphone
Thermal dB
Combined
Typical dB
Combined
Max dB
A
18.0
20.0
16.0
20.0
22.0
C
21.0
23.0
16.8
22.0
24.0
Z
28.0
30.0
16.8
28.0
30.5
Note: The CEL-252 microphone has a thermal noise of typically 20dBA – the combined typical
and max noise levels will be 1.5dB higher than above.
i) Highest Level
The highest sound pressure level designed to be measured by the CEL-62X sound level meter
when fitted with a 50mV/Pa microphone is 140dB. The highest peak to peak voltage that can
be applied to the pre-amplifier input via the CEL-516-02 is 28.5V.