BRUEL & KJAER 4131 - 10 Influence of Ambient

4135 • 41~ - DESCRIPTION
during more than 10 minutes will not damage the microphones but will
produce a permanent change in characteristics.
For example after one hour at 220°C and return to 25° C, a 4135 cartridge
showed a sensitivity which was increased by 3.6 dB in the flat part of the
frequency response and 1 dB in the range 20-80 kHz.
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Pressure
FreQuency
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tempprnt,,rps
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Fig. 1.20. Influence of temperatur e on the frequency response of the 4135.
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Fig. 1.21. Influence of temperature on the Frequency response of the 4136.
10. Influence of Ambient Pressure.
The microphone sensitivity will vary less than- o.1 % for + 10% variations
in ambient pressure. For important changes in ambient pressure the fre-
quency response of the microphone will be modified, especially towards
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