G.R.A.S. 46BL 1/4" CCP Pressure Standard Microphone Set, High Sensitivity

Freq range: 4 Hz to 20 kHz
Dyn range: 25 dB(A) to 147 dB
Sensitivity: 18 mV/Pa


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

46BL is ideally suited for production line testing of portable communication devices, such as cell phones, laptop computers, tablets, GPS receivers and similar devices using microspeakers.

It is also well suited for general acoustic measurements when high sensitivity and low noise are required.

Regarding temperature range, see the specifications. Should higher temperature limits be required, we recommend the G.R.A.S. probe microphones, where the microphone and preamplifier can be isolated from the hot source.


To perform as specified, the G.R.A.S. 46BL 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 10/32 Microdot female connector. Ready-to-use coax cable assemblies of various types and lengths are available in standard as well as customized lengths.

The 46BL 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.


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 as an integral part of our quality assurance.

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/calib.

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.


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.

Frequency range (±1 dB) Hz 10 to 10 k
Frequency range (±2 dB) Hz 4 to 20 k
Dynamic range lower limit with G.R.A.S. preamplifier dB(A) 25
Dynamic range upper limit with G.R.A.S. CCP preamplifier dB 147
Set sensitivity @ 250 Hz (±2 dB) mV/Pa 18
Set sensitivity @ 250 Hz (±2 dB) dB re 1V/Pa -35
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
Microphone venting Rear
IEC 61094-4 Compliance WS3P
Temperature range, operation °C / °F -30 to 70 / -22 to 158
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 95
Humidity coefficient @250 Hz dB/% RH –0.001
Influence of axial vibration @1 m/s² dB re 20 µPa 55
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


Typical frequency response (without protection grid)

Free-field corrections for different angles of incidence

Optional items

G.R.A.S. AA0070

3 m Microdot - BNC Cable

G.R.A.S. AA0073-CL

Customized Length Microdot - BNC Cable

G.R.A.S. AA0087-CL

Customized Length Microdot - Microdot Cable

G.R.A.S. AL0029

1/4" Microphone Holder, POM

G.R.A.S. AL0013

1/4" Microphone Holder, Stainless Steel

G.R.A.S. AL0005

Swivel head

G.R.A.S. AL0006


G.R.A.S. AM0071

Windscreen for 1/4" Microphones

G.R.A.S. 12AL

1-Channel CCP Power Module with A-weighting filter

G.R.A.S. 12AQ

2-Channel Universal Power Module with signal conditioning and PC interface

G.R.A.S. 42AB

Sound Calibrator, Class 1

G.R.A.S. 42AP

Intelligent Pistonphone, Class 0

G.R.A.S. CA0029

Traceable Calibration of Microphone Set

G.R.A.S. CA2301

Accredited Calibration of Microphone Set