G.R.A.S. Sound & Vibration
Pistonphone Types 42AA/42AA-S1 - Page 4
1. General Description
The G.R.A.S. Pistonphone (Fig. 1.1) is a battery-operated, precision sound source for accurate
and reliable calibration of measurement microphones, sound level meters and other sound
measuring equipment.
• Type 42AA includes barometer type ZC0002K.
• Type 42AA-S1 includes barometer type RA0168.
Otherwise, there is no difference between the two types.
1.1 Operating Frequency
The Pistonphone type 42AA and type 42AA-S1 operates at a frequency of 250Hz.
1.2 Calibration Level
With a microphone inserted in the Pistonhone’s coupler and the Pistonphone and switched on,
the nominal calibration level is:
• 114 dB
1
re. 20 µPa
• 105.4 dBA re. 20 µPa (with A-weighting applied)
At a static ambient pressure of 1013 hPa, no further correction factors need be applied. An indi-
vidual calibration chart is delivered with each Pistonphone.
* True centre frequency of a 250 Hz ⅓-octave band lter
1
114 dB is equivalent to 10 Pa
Fig. 1.1 Pistonphone
The Pistonphone is an extremely stable laboratory-standard sound source which can also be
used for eld calibrations - it retains its high accuracy even under hostile environmental conditions.
The Pistonphone complies with all the requirements of IEC Standard 942 (1988) Sound Calibra-
tors Class 1 when corrected with barometer ZC0002K as well as Class 0 when corrected with
barometer RA0168. Type 42AA includes ZC0002K and Type 42AA-S1 includes RA0168.
To Next Page
Loading...