GRAS Acoustic Calibrators
| GRAS 42AA |
Pistonphone Calibrator - class 1 |
£ 6 a day * |

Battery operated for field checks of complete systems.
Laboratory calibration of measurements microphones
114 dB at 250 Hz or 105.4 dBA.
For use with 1/2" and 1/4" microphones, includes a barometer with correction values.
Certification traceable to NPL.
GRAS 42 Manufacturer's Specifications
| GRAS 51AB |
Sound Intensity Calibrator |
£ 8 a day * |

For phase and level calibration of both 1/2" and 1/4" sound intensity microphone pairs. The 51AB may be used for residual intensity testing, level and the particle velocity calibration as specified in BS EN 61043.
The calibrator consists of a sound source which supplies a well defined sound pressure field simultaneously to both measurement microphones, so the resulting phase difference can be expressed as the Pressure Intensity Index.
For sound intensity and particle velocity calibration a phase shifting element is inserted between the source and the receiving part of the calibrator, resulting in a phase shift similar to that found in a free field.
GRAS 51AB Manufacturer's Specifications
Needs an external generator producing white, pink or sine waves via a BNC connector, which is included in the Nor 840 analyser.
* Our standard hire charges are based on a 4-day minimum period,
details other options.
Gracey & Associates 01933 624212 hire@gracey.com
British Standards accreditation for noise and vibration instrument hire and calibration
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