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Calibration Equipment

GRAS Acoustic Calibrators.

Gras Pistonphone type acoustic calibrators.

Code	Description
Gras-42AA	General Purpose
The Pistonphone Type 42AA is a precision sound source for calibrating microphones. It is battery operated and produces a constant sound pressure level of 114 dB re. 20µPa (equivalent to 10 Pa) at 250 Hz, or 105.4 dBA re. 20µPa. Each Type 42AA is within 0.1 dB of the nominal value and is delivered with an individual calibration chart and a barometer for Class 1 static pressure corrections. For Class 0 static pressure corrections, a precision barometer is required.
Gras-42AC	General Purpose
The Pistonphone Type 42AC is a precision sound source for calibrating microphones. It is battery operated and produces a constant sound pressure level of 134 dB re. 20µPa (equivalent to 100 Pa) at 250 Hz, or 125.4 dBA re. 20µPa. Each Type 42AC is within 0.1 dB of the nominal value and is delivered with an individual calibration chart and a barometer for Class 1 static pressure corrections. For Class 0 static pressure corrections, a precision barometer is required.
Gras-42AP	General Purpose
The G.R.A.S. 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. It 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.
Gras-42AE	Low Frequency Calibrator
The G.R.A.S. Low-Frequency Calibrator Type 42AE permits microphone calibration at frequencies down to 0.01 Hz for both front and rear-vented microphones. It produces a constant sound pressure level down to very low frequencies. The two-port configuration allows the actual sound pressure in the coupler to be monitored by a reference microphone simultaneously with the microphone under test. The built-in DC-coupled power amplifier enables the calibration to be used for swept-sine, broadband and step function investigations.