PILOT 99BE 1/4" CCP Free-field Standard Microphone Set

Freq. range: 4 Hz to 80 kHz
Dyn. range: 35 dBA to 160 dB
Sensitivity: 4 mV / Pa
Use: For general acoustic diagnostics
  • PILOT 99BE 1/4


Through a close cooperation with our customers, we know that data-safety is highly important because the costs related to unsuited and unreliable sensors may determine whether your project turns into a success or not.

For our users, data safety translates directly into requests for easier microphone selection, simple system configuration and reduction of measurement errors.

To meet these requirements, we invented the microphone set concept. It is simple, reliable and robust and consists of a microphone cartridge and preamplifier combination, which is calibrated as one unit. This eliminates errors because there is only one sensitivity value to account for and the risk of contaminating the interface is eliminated. Combine this with our unique and proven design and you have the most reliable measurement microphone sets available in the industry today.

Typical applications and use

The 46AE is a free-field microphone set and as such optimized for all acoustic applications, where the location of the main sound source is known and the microphone can be pointed directly at it ensuring 0° incidence.

However it should be noted that the small size of the 1/4” microphone body and diaphragm also enables pressure and random-incidence (diffuse field) measurements up to 20 kHz without removing the protection grid or need for further compensation. This all-use feature is very useful if you are not able to point out the nature of your sound field.

The medium frequency range makes it ideal for general acoustic diagnostics.

The high cut-off frequency makes it ideal for ultra-sonic diagnostics and impulse measurements, where minimum distortion and high resolution are obtained by the small size and fast response of the diaphragm.

The microphone set can be used in temperatures up to 60 °C / 140 °F. Should higher temperatures be required, we recommend using the G.R.A.S. probe microphones where the microphone and preamplifier can be isolated from the hot source.


The G.R.A.S. 46BEX is a high-performance  standard microphone set. In our clean-room environment the set is assembled and sealed with a label. However, the microphone set can be dismounted, if  you wish to use the components separately.

The microphone cartridge is the high-quality IEC  61094 WS3F standardized G.R.A.S. 40BE 1/4" Prepolarized Free-Field Microphone designed for long-term reliability in multiple environments.

The preamplifier is the G.R.A.S. 26CB 1/4" CCP Standard Preamplifier with Microdot Connector, and based on our well-known circuit board substrates. In the industry these are famous for their low self-noise, wide frequency and excellent slew rate performance.


To perform as specified the G.R.A.S. 46BEX microphone set requires a constant current input module that can deliver 4 mA and 24 V unloaded CCP voltage supply. If the  constant current supply is lower, the capability of driving long cables is reduced and consequently the upper frequency is reduced. If the voltage supply is lower it will influence the upper dynamic range.

The microphone set is terminated with a Microdot 10/32. Coax cables with connectors of various types and lengths are available in standard as well as customized lengths.

The 46BEX is IEEE 1451.4 TEDS v. 1.0 compliant. If your measurement platform supports Transducer Electronic Data Sheets you will be able to read and write data like properties and calibration data.

System verification

The functionality of TEDS is very useful to determine which microphone is connected to which input channel. However, it is not a check of whether the microphone is within specifications or not. For daily verification and check of your measurement setup, we therefore recommend using a sound source like the G.R.A.S. 42AB Sound Calibrator.

For proper sensitivity calibration we recommend using a reference sound source like the G.R.A.S. 42AP Intelligent Pistonphone.

Service, Calibration and Warranty


Should you by mistake damage the diaphragm on a G.R.A.S. microphone we will in most cases be able to exchange it at a very reasonable cost and short turn-around time. This not only protects your investment but also meets your quality assurance department since you do not have to worry about new serial numbers etc.


When leaving the factory, all G.R.A.S. 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: G.R.A.S. Traceable Calibration and G.R.A.S. Accredited Calibration.

G.R.A.S. 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 G.R.A.S. microphones are subjected to at the final stage of their production.

Learn more at gras/calibration.

G.R.A.S. Accredited Calibration is performed by the G.R.A.S. 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/calibration.

Quality and warranty

G.R.A.S. microphone sets are made of components from our proven standard portfolio and are all manufactured of high-quality material and branded parts that were chosen and processed to ensure life-long stability and robustness.

All parts are manufactured and assembled at the factory in Denmark by skilled and dedicated operators in a verified clean-room environment. The microphone diaphragm, body and unique protection grid are made of high-grade stainless steel and make the microphone set resistant to physical damage as well as corrosion caused by aggressive air or gasses. This, together with the enforced gold-plated microphone terminal guarantees a highly reliable connection.

Thanks to the high quality, our warranty against defective materials and workmanship is 5 years.

Frequency range (±1 dB) Hz 10 to 40 k
Frequency range (±2 dB) Hz 4 to 80 k
Frequency range (±3 dB) Hz 4 to 100 k
Dynamic range lower limit (microphone thermal noise) dB(A) 30
Dynamic range lower limit with G.R.A.S. preamplifier dB(A) 35
Dynamic range upper limit dB 166
Dynamic range upper limit with G.R.A.S. preamplifier @ +28 V / ±14 V power supply dB 168
Dynamic range upper limit with G.R.A.S. preamplifier @ +120 V / ±60 V power supply dB TBD
Dynamic range upper limit with G.R.A.S. CCP preamplifier dB TBD
Set sensitivity @ 250 Hz (±2 dB) mV/Pa 4
Set sensitivity @ 250 Hz (±2 dB) dB re 1V/Pa -48
Output impedance Ω <50
Output Voltage Swing, min. @ 24-28 V CCP voltage supply Vp ± 8
Power supply min. to max. mA 2 to 20
DC-offset, min., single suppy V 26CB
DC-offset, max., single suppy V 26CB
DC-offset, balanced supply V 26CB
Microphone venting Rear
IEC 61094-4 Compliance WS3F
Temperature range, operation °C / °F -30 to 60 / -22 to 140
Temperature range, storage °C / °F -40 to 85 / -40 to 185
Temperature coefficient @250 Hz dB/°C / dB/°F -0,01 / -TBD
Static pressure coefficient @250 Hz dB/kPa -0,013
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 60
TEDS UTID (IEEE 1451.4) 27 v. 1.0
Connector type Microdot 10/32
CE/RoHS compliant/WEEE registered Yes/Yes/Yes
Weight g / oz 8 / 0.282

Included items

G.R.A.S. AA0008 3 m
G.R.A.S. AA0035 BNC to BNC 50 Ω extension cables


Optional items


G.R.A.S. CA0001 Traceable Calibration of Microphone
G.R.A.S. CA0029 Traceable Calibration of Microphone Set
G.R.A.S. CA2001 Accredited Calibration of Microphone
G.R.A.S. CA2300 Accredited Calibration of Microphone Set