GRAS 40AU-1 1/2" Ext. Polarized Reference Pressure Microphone

Introduction

GRAS 40AU-1 is an IEC 61094 LS2aP ½" externally polarized reference microphone. The microphone is rear-vented and delivered with a dust and scratch protective cap.

The microphone has a front cavity according to IEC 61094-1 that makes it suitable for primary method calibration (reciprocity) and for precision sound pressure measurements in general.

The microphone is made of carefully selected high-grade metals and materials in combination with tight tolerances and dedicated workmanship to ensure a reliable and stable measurement. 

GRAS 40AU-1 microphones are individually calibrated, and each is delivered with a calibration chart stating its specific open-circuit sensitivity pressure response (actuator response).

Typical applications and use

GRAS 40AU-1:

• Is intended for sound pressure measurements of the highest attainable accuracy.
• Can be used for reciprocity measurements according to the specifications in IEC 61094-2.
• Is suitable for measurements in couplers, ear simulators and enclosures where pressure measurements are to be performed.

Caution: To ensure optimal stability, stable conditions and special care must always be taken into account when handling a reference microphone.  

Compatibility

The 40AU-1 requires a standardized ½" LEMO preamplifier and an input module that supports this technology with a 7-pin LEMO connector.

System verification

For frequency calibration the dedicated electrostatic actuator RA0014-S1 (optional) must be used. The RA0014-S1 actuator allows for frequency calibration without removing the front volume ring. The front cavity ring is fixed.

Be aware that any attempt to remove the front cavity ring will cause damage to the microphone.

RA0014-S1 can be ordered separately.

Calibration 

40AU-1 is delivered with a traceable calibration, including calibration chart that documents the following: 

• Specific open-circuit sensitivity
• Pressure frequency response (by actuator Type RA0014-S1)
• Temperature coefficient

All GRAS microphones leave the factory  calibrated in our controlled laboratory environment using traceable calibration equipment.

Depending on use, measurment environment and internal quality control programs, we recommend that the microphone is recalibrated at least once a year.

For reference measurement purposes, we recommend make a Primary calibration, which ensures the highest precision calibration.

GRAS Traceable Calibration is a traceable calibration performed by trained personnel under controlled conditions according to established procedures and standards. This is identical to the rigorous calibration that all GRAS microphones are subjected to as an integral part of our quality assurance.

Learn more at calibration-service.

Quality and warranty

All GRAS microphones are made of high-quality materials that ensure life-long stability and robustness. The microphones are assembled in verified clean-room environments by skilled and dedicated operators with many years of expertise in this field.

The microphone diaphragm, body, and improved protection grid are made of carefully selected high-grade metals and materials. This makes the microphone resistant to physical damage, as well as corrosion caused by aggressive air or gasses.

This, combined with the reinforced gold-plated microphone terminal, which guarantees a highly reliable connection, enables GRAS to offer a five-year warranty against defective materials and workmanship.

Included items

Optional items

GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.