1/8″ Prepolarized Pressure Microphone GRAS 40DD 6.5Hz~70kHz

Introduction

• The 40DD is an IEC 61094 1/8″ prepolarized pressure microphone with rear-venting. Read about the externally polarized equivalent GRAS 40DP
• It is a high-precision condenser microphone made according to IEC 61094-4 requirements. Its tiny size allows it to be used for measuring very high frequency sounds without disturbing the sound field. It can measure sound pressure levels up to 174 dB in the range of 6 Hz to 140 kHz.
• 40DD is individually factory-calibrated and delivered with a calibration chart stating its specific open-circuit sensitivity and pressure frequency response.
• A front-vented version is available, 40DD-FV 1/8” Prepolarized Pressure Microphone, Front Vented.

Typical applications and use

• The 40DD has a low sensitivity making it perfect for sound measurements at high frequencies and very high level pressure, as well as impulse noises.
• The 40DD is included in the 67SB Blast Probe Microphone because of its wide-frequency response.

Compatibility

• The 40DD must be used with an adapter for mounting a 1/8″ microphone onto a 1/4″ preamplifier.

System verification

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