The GRAS Pistonphone type 42AP is a battery-operated, precision sound source for accurate and reliable calibration of measurement microphones, sound level meters and other sound measuring equipment.
Pistonphone type 42AP has a built-in precision barometer and a thermometer. Via its display and RS-232 interface, the user can read the actual corrected sound pressure level, as well as the calibration temperature and ambient static pressure.
With a microphone placed in the coupler of the pistonphone, the calibration level and frequency is:
- Nominally 114dB re; 20µPa at either 250Hz or 251.2Hz
The actual sound pressure level, corrected for static ambient pressure, is shown on the display of the Pistonphone.
The display can also show the A-weighted sound pressure level after correcting it for using an A-weighting filter. An individual calibration chart is delivered with each Pistonphone.
The Display can be switched to show any of the following:
- Actual corrected sound pressure level in decibels
- Static air pressure in hPa
- Calibration temperature in ºC or ºF
The type 42AP is a stable laboratory standard sound source which can also be used for field calibrations, it retains its high accuracy even under hostile environmental conditions (- 10°C to + 55°C).
Batteries used are 4 x AA alkaline or external power of 6V DC 125mA with a weight of 437g.
The type 42AP complies with all the requirements of IEC Standard 60942 (2003) LS.
Available accessories include: adapter for 1” microphones, two-port calibration coupler for ½” microphones, Octopus couplers for calibrating up to 8 microphones simultaneously.
Metromatics represents GRAS in Australia and New Zealand.
