BRUEL & KJAER 4111 - Sound Pressure Measurement Guide

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Support 4116 is used on the analyzers simply for keeping the rod in
position. Figs. 9 and 10 show complete set-ups for both Microphone
Amplifier 2601 and Analyzer 2105, together with the accessories men-
tioned. The arrow in fig. 10 indicates the support 4116.
The Condenser Microphone 4111 is usually delivered in a case with
place for both microphone and extension rod.
MEASUREMENTS OF SOUND PRESSURE LEVEL
With precision measurements of sound pressure, care must be taken
that the microphone is placed in the sound field remote from any dis-
turbing reflecting objects, and the microphone membrane should be
directed towards the sound source, as its adjustment curve is based
on the sound waves striking the membrane perpendicularly. If it is
believed that the microphone amplifier or analyzer itself has a dis-
turbing effect on the sound field, it is recommended to use the Micro-
phone Stand type 4112 or the Extension Cable 4114, with a length of
10 metres.
The Microphone Amplifier 2601 is primarily meant as an amplifier
for the High Speed Level Recorder 2304 for recording noise levels,
frequency characteristics, measurement of sound insulation, rever-
beration time, etc. The instrument is therefore not equipped with
an indicating meter, although a VT Voltme~er, e. g. type 2407, can be
used for this purpose by connecting it to the output. The dynamic range
of the microphone amplifier is kept high for these measurements by
having the amplifier tubes d. c. heated. Sound levels can be recorded