BRUEL & KJAER 4220 Instructions And Applications

Pistonphone Type 4220
The Pistonphone is a compact battery-operated
precision sound source, designed to enable quick
and accurate overall calibration of sound measur-
ing equ ipments. It produces a sound pressure
level of 124 dB at the microphone diaphragm, at
a frequency of 250 Hz.
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BRUEL&K.'-'AEA
NA:.RUM, DENMARK. Teleph.: 80 OS 00. Cable : BRUKJA. Telex : 5316. COPENHAGEN
BB 4220- 0300053