1/4″ Prepolarized Pressure Microphone GRAS 40BD 4Hz~70kHz

Introduction

• The 40BD is an IEC 61094 WS3P ¼” prepolarized pressure microphone with rear-venting. Read about the externally polarized equivalent [40BP]
• It is a high-precision condenser microphone made according to IEC 61094-4 requirements. Its low sensitivity makes it ideal for sound measurements at high frequencies and high sound pressure levels of up to 174 dB. Its small size reduces the effects of diffraction and reflections around the microphone, resulting in a frequency range that extends up to 70 kHz.
• 40BD 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 40BD is ideal for sound pressure measurements, as well as high frequency and high level pressure measurements. It is suitable for general purpose acoustic measurements in couplers and at boundaries. 40BD is included in the GRAS 46BD ¼” Pressure microphone set.

Compatibility

• The 40BD requires a standardized ½” or ¼” CCP preamplifier and an input module that supports this technology with a BNC, SMB, or Microdot connector.

System verification

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