G.R.A.S. 40AN 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.
The 40AZ’s design is based on the similar G.R.A.S. 40AE ½” free-field microphone, but optimized for low-frequency measurements. The cut-off frequency is as low as 0.5 Hz and obtained by modifying the equalization.
40AZ 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 low-frequency property combined with its high sensitivity and robust design make 40AZ the obvious choice for infra-sound measurements—a fast growing discipline following the need for monitoring and reducing low-frequency noise from, for example, power and production plants and the increasing number of wind turbines.
The 40AZ requires a standardized ½” or ¼” LEMO preamplifier and an input module that supports this technology with a 7-pin LEMO connector.
To benefit from 40AZ’s low frequency capabilities, it is important that the microphone preamplifier, analyzer input module, or sound level meter is designed to match 40AZ.
For daily verification and check of your measurement setup, we recommend using a calibrator like G.R.A.S. 42AB Sound Level Calibrator .
For proper sensitivity calibration, we recommend using a pistonphone like G.R.A.S. 42AP Intelligent Pistonphone.
Quality and warranty
All G.R.A.S. 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 G.R.A.S. to offer 5 years warranty against defective materials and workmanship.
If you accidentally damage the diaphragm on a G.R.A.S. 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.
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.
|Frequency range (±1 dB)||Hz||1 to 10 k|
|Frequency range (±2 dB)||Hz||0.5 to 20 k|
|Dynamic range lower limit (microphone thermal noise)||dB(A)||14|
|Dynamic range lower limit with G.R.A.S. preamplifier||dB(A)||17|
|Dynamic range upper limit||dB||146|
|Dynamic range upper limit with G.R.A.S. CCP preamplifier||dB||134|
|Open-circuit sensitivity @ 250 Hz (±2 dB)||mV/Pa||50|
|Open-circuit sensitivity @ 250 Hz (±2 dB)||dB re 1V/Pa||-26|
|Microphone cartridge capacity, typical||pF||20|
|Temperature range, operation||°C / °F||-40 to 120 / -40 to 248|
|Temperature range, storage||°C / °F||-40 to 85 / -40 to 185|
|Temperature coefficient @250 Hz||dB/°C / dB/°F||-0,01 / -0,006|
|Static pressure coefficient @250 Hz||dB/kPa||-0,008|
|Humidity range non condensing||% RH||0 to 100|
|Humidity coefficient @250 Hz||dB/% RH||-0,001|
|Influence of axial vibration @1 m/s²||dB re 20 µPa||62|
|CE/RoHS compliant/WEEE registered||Yes / Yes, Yes|
|Weight||g / oz||9 / 0,317|