1/4″ Ext. Polarized Free-field Microphone GRAS 40BF 4Hz~100kHz

Introduction

• It’s a low sensitivity microphone that is ideal for high-level and high-frequency measurements. It can measure high sound pressure levels of up to 166 dB due to its low sensitivity. Its frequency range reaches up to 100 kHz due to its small size.
• 40BF is individually factory-calibrated and delivered with a calibration chart stating its specific open-circuit sensitivity and pressure frequency response. 

Typical applications and use

• The 40BF is typically used for high frequency and high-level measurements, and acoustic-transient measurements.
• 40BF is included in GRAS 46BF-1 ¼” Free-Field Set.

Compatibility

• The 40BF requires a standardized ½” or ¼” LEMO preamplifier and an input module that supports this technology with a 7-pin LEMO connector and polarization and supply voltages for microphone and preamplifier.

System verification

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

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.