1/2″ Ext. Polarized Free-field Microphone GRAS 40AN 0.5Hz~20kHz

Introduction

• GRAS 40AN is a high-precision condenser microphone made according to IEC 61094-4 requirements. The 40AN’s design is based on the similar GRAS 40AF ½” free-field microphone, but optimized for low-frequency measurements. The cut-off frequency is as low as 0.5 Hz and obtained by modifying the equalization.
• 40AN is individually factory-calibrated and delivered with a calibration chart stating its specific open-circuit sensitivity, pressure, and corrected free-field frequency responses.

Typical applications and use

• The low-frequency property combined with its high sensitivity and robust design make 40AN the obvious choice for infra-sound measurements—a fast growing discipline following the need for monitoring and reducing low-frequency noise from, for example, power and production plants and the increasing number of wind turbines.

Compatibility

• The 40AN requires a standardized ½” or ¼” LEMO preamplifier and an input module that supports this technology with a 7-pin LEMO connector.
• Note that to benefit from 40AN’s low frequency capabilities, it is important that the microphone preamplifier, analyzer input module, or sound level meter is designed to match 40AN.

System verification

• For daily verification and check of your measurement setup, we recommend using a calibrator like GRAS 42AG Sound Level Calibrator.
• For proper sensitivity calibration, we recommend using a pistonphone like GRAS 42AP.

Calibration

• When leaving the factory, all GRAS microphones have been calibrated in a controlled laboratory environment using traceable calibration equipment. Depending on the use, measurement environment and internal quality control programs we recommend that the microphone is recalibrated at least once a year.
• We offer two kinds of calibration as an optional after-sales service: GRAS Traceable Calibration and GRAS Accredited 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.
• GRAS Accredited Calibration is performed by the GRAS Accredited Calibration Laboratory that has been accredited in accordance with ISO 17025 by DANAK, the Danish Accreditation Fund.
• If you want a new microphone set delivered with an accredited calibration in stead of the default factory calibration, specify this when ordering.
• Learn more at gras/calib.