BRUEL & KJAER 4188 - Frequency Response

Chapter 8 —
1
/
2
" Microphone Preamplifier Type 2669
Frequency Response
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Microphone Handbook
Brüel & Kjær
8
−
4
8.2 Frequency Response
The frequency response of the preamplifier depends on the capacitance of the micro-
phone connected to its input, and the capacitive load (for example, extension cables)
connected to the output.
The low frequency curves in Fig.8.3 show the low-frequency response of the pream-
plifier for various capacitances typical of 1",
1
/
2
" and
1
/
4
" microphones. Note, they do
not show the lower cut-off frequencies of the microphones.
The effects of various capacitive output loads (cables etc.) on the high frequencies
are also shown. All curves shown in Fig.8.3 apply only for low signal levels where
the limitations shown in Fig.8.5 and Fig.8.6 have no influence.
Fig.8.3 Typical frequency response as a function of input (transducer) capacitance at low frequen-
cies and as a function of capacitive loading at high frequencies
1 10
– 12
0.1
– 5
dB
0
– 10
100 k20 20 k
2
941021e
Frequency (Hz)
47 pF
15 pF
6.2 pF
10 nF
3 nF
3 m Standard Cable
30 nF