GRAS 40BE 1/4" Prepolarized Free-field Microphone
Freq range: 4 Hz to 80 kHz
Dyn range: 30 dB(A) to 168 dB
Sensitivity: 4 mV/Pa
Technology
Introduction
It is a high-precision condenser microphone made according to IEC 61094-4 requirements. Its dynamic range makes it suitable for high-frequency or high-level measurements, as well as acoustic transient measurements. It is extremely robust and reliable and can measure sound pressure levels up to 168 dB in the range of 4 Hz to 100 kHz.
40BE is individually factory-calibrated and delivered with a calibration chart stating its specific open-circuit sensitivity and pressure frequency response.
NOTE: At low frequencies, protection grids are acoustically transparent; however, around 20 kHz and above, protection grids can act as resonators and influence the frequency response. So for higher frequency measurements, ¼″ and ⅛″ microphones have been optimized for use without the protection grid. Please remove the protection grid when measuring.
Typical applications and use
The 40BE is ideal for sound measurements at very high frequencies and levels, as well as acoustic transient measurements. It is suitable for general purpose measurements in open acoustic fields.
The 40BE is included in the GRAS 46BE ¼” free-field microphone set
Compatibility
The 40BE 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 42AG Sound Level Calibrator.
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.
Quality and warranty
All GRAS microphones are made of high-quality materials that will ensure life-long stability and robustness. The microphones are all 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 high-grade stainless steel, which 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 5 years warranty against defective materials and workmanship.
Service
If you accidentally damage the diaphragm on a GRAS microphone, we can—in most cases—replace it at a very reasonable cost and with a short turn-around time. This not only protects your investment, but also pleases your quality assurance department because you don’t have to worry about new serial numbers, etc.
Specifications
Typical frequency response (without protection grid). Upper curve shows free-field response for 0°, lower curve shows pressure response.
Free-field corrections for different angles of incidence
GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.
Dimensions
Ordering info
|
GRAS CA0001 |
Traceable Calibration of Microphone |
|
GRAS CA2001 |
Accredited Calibration of Microphone |
GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.
