G.R.A.S. 40AM 1/2" Prepolarized Free-Field Microphone, High Frequency Date 10-06-2013. Page 1 of 5 G.R.A.S. 40AM 1/2" Prepolarized Free-Field Microphone, High Frequency Sensitivity: 14.5 mV/Pa Freq resp: 3.15 Hz to 31.5 kHz Dynamic range: 20 dBA to 146 dB The 40AM is an IEC 61094 WS2F classified ½” prepolarized free-field, wide-frequency microphone with rear-venting. It is a high-precision electret condenser microphone made according to IEC 61094-4 requirements. Introduction The 40AM is an IEC 61094 WS2F classified ½” prepolarized free-field, wide-frequency microphone with rear-venting. Read about the externally polarized equivalent [40AC]. It is a high-precision electret condenser microphone made according to IEC 61094-4 requirements. The electret technology for microphones was introduced in the beginning of the 1960’s and has been continuously improved over the years. At G.R.A.S., we have developed and refined our own techniques. This guarantees that our prepolarized microphones are as stable and robust as our traditional, externally polarized versions in daily use scenarios. Learn more about our prepolarized microphones. The 40AM’s design is based on the original reference ½” externally polarized pressure microphone, but is optimized for free-field measurements. This results in a doubling of the upper 3 dB frequency limit. All other parameters remain unchanged, making 40AM the perfect free-field complement to the G.R.A.S. 40AO ½” Prepolarized Pressure Microphone.

G.R.A.S. 40AM 1/2" Prepolarized Free-Field Microphone, High Frequency Date 10-06-2013. Page 2 of 5 40AM 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 compact design and low sensitivity make 40AM very robust and stable. This, combined with its wide frequency range, makes it an all-round free-field microphone suitable for both field-work and laboratory measurements. Compatibility The 40AM requires a standardized ½” or ¼” CCP preamplifier...

G.R.A.S. 40AM 1/2" Prepolarized Free-Field Microphone, High Frequency Date 10-06-2013. Page 3 of 5 Before leaving the factory, all G.R.A.S. microphones are calibrated in a controlled laboratory environment using traceable calibration equipment. Depending on the use, measurement environment, and internal quality control programs, we recommend recalibrating the microphone at least once a year. Learn more about G.R.A.S.’ calibration services. Specification Open-circuit sensitivity @ 250 Hz (±2 dB) Resonance frequency Dynamic range lower limit (microphone thermal noise) Dynamic range upper limit...

G.R.A.S. 40AM 1/2" Prepolarized Free-Field Microphone, High Frequency Date 10-06-2013. Page 4 of 5 Influence of axial vibration @1 m/s² CE/RoHS compliant, WEEE registered Weight

G.R.A.S. 40AM 1/2" Prepolarized Free-Field Microphone, High Frequency Date 10-06-2013. Page 5 of 5 Tradition Since the establishment in 1994, G.R.A.S. have been 100% dedicated to developing and manufacturing high-quality measurement microphones and related acoustic equipment. Founded by the Danish acoustics pioneer Gunnar Rasmussen who for more than 60 years has contributed to the world of sound and vibration with his unique ideas and designs. From the first reproducible 1” condenser measurement microphone that enabled quality measurements and instrumentation for acoustic calibration, Mr. Rasmussen’s...