BRUEL & KJAER 4111 - Page 25

22
should have such frequency characteristics that the low and very high
frequencies be depressed in a manner corresponding to fig. 13. In
practice it is sufficient to have three different characteristics each ef-
fective in their own level range. In Europe the characteristics set
down in DIN 5045 are used, and in America the slightly divergent stan-
dards set down in ASA Z 24. 3. The standards set down also contain
requirements for the sound level meter' s dynamic characteristics,
frequency addition and overload safety factor. All these requirements
are satisfied within the permitted tolerances in Microphone Amplifier
2601 and Analyzers 2105 and 2109 when equipped with a Condenser
Mic rophone type 4111.
fO
lin
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---
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--
0
db
-fO
60-f30
phOfh;;#
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~-60,
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v
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phon
.. :
v
~
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.
.:I'
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~~
~
~/"
v
v /;,~
below
A
~Ophon
~'l
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ilf .
-20
-30
-+0
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'
v/
-so
-60
'4
3 .f s
fO~
2
3
• 5
to
4
c..~.s 2
~
+ s
----2fOS
------- 2fQ9
-·-·-·- 260f
'"
8
Fig. 14b. Frequency responses of the weighting networks as employed
in Microphone Amplifier 2601 and Analyzers 2105 and 2109.