BRUEL & KJAER 2204 - Technical Description

Frequency
Range
Tolerances
Tolerances
Hz
L.30°
Incidence
90° Incidence
dB
dB
31.5- 1000
+o.5
-o.5 +1
-1
1000- 2000
+o.5
-o.5
+1
-2
2000- 4000
+o .5
-1.0 +1
-3
4000- 8000
+o.5 -1.5 +1
-6
8000-12500
+ 0.5 -2.0 +1
-10
Table 2.1. Permissible variation of sensitivity with angle of incidence.
is easily portable, battery driven and completely self-contained for ordinary
sound level and vibration measurements. Used in conjunction with a suitable
filter set e. g. the B & K Octave Filter Set Type 1613, the instrument becomes
a handy and easily operated frequency analyzer.
There are no requirements s, tated in the IEC Draft Specification regarding
dynamic range, but the B & K Type 2203 covers the range 18 to 134 dB
(or 39 to 148 dB using a 1/~' microphone) and as will be seen from Table 1.1
this covers most sound levels which need to be measured. All three weighting
networks (A, B and C) are included in the instrument as well as a linear
characteristic and means for connecting external filter circuits for further
shaping of the frequency characteristic if necessary.
From instrument serial No. 82939 the Sound Level Meter complies with the
American Standard for General Purpose Sound Level Meters, ASA S 1.4-1961.
Technical Description.
A block diagram of the inslrument is given in Fig. 2.2.
The instrument can be divided into the following main parts:-
1. Condenser microphone and source follower.
2. Input amplifier with input attenuator.
f6(686
Fig. 2.2. Block diagram of Type 2203.
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