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

The 46BL has been optimized for high sensitivity and low noise. The diaphragm is slightly larger than usual for a ¼" microphone, and the protective grid has been modified accordingly.

The 46BL can be used for applications where a ½" microphone would be the natural choice, but the advantages of a smaller microphone are desired. The small dimensions of the 46BL means that its presence in the sound field has minimal influence in the audible frequency range. It can be used to measure frequencies up to 20 kHz. 

Its high sensitivity and low noise make it ideally suited for all applications with low to moderate sound levels.

It complies with the specifications IEC 61094: Measurement Microphones, Part 4: Specifications for working standard microphones, except that the upper limit of the useful frequency range is 20 kHz.

46BL is individually factory-calibrated and delivered with a calibration chart stating its specific open-circuit sensitivity and pressure frequency response.

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.


The 46BL uses a Microdot connector, which requires an input module that supports this technology. Our 1/4" rain protection cap and nose cone do not fit.

System verification

For daily verification and check of your measurement setup, we recommend using a calibrator like G.R.A.S. 42AB Sound 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. microphone sets are made of high-quality materials that will ensure life-long stability and robustness. The microphone sets 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. microphone sets are calibrated as a unit in a controlled laboratory environment using traceable calibration equipment. The sets are delivered with calibration charts including sensitivity values and frequency response graphs for the complete set. You can use the sensitivity value directly in your system setup.

Depending on the use, measurement environment, and internal quality control programs, we recommend recalibrating the microphone set at least every second year.

TYPE (Microphone features) P
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. 42AA

Pistonphone, Class 1

G.R.A.S. 42AP

Intelligent Pistonphone, Class 0

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. AA0070

3 m Microdot - BNC Cable

G.R.A.S. AA0073-CL

Customized length Microdot - BNC Cable