G.R.A.S. 46AP 1/2" LEMO Pressure Standard Microphone Set, High Sensitivity

Freq range: 3.15 Hz to 10 kHz
Dyn range: 18 dB(A) to 149 dB
Sensitivity: 50 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 application and use

The 46AP is a pressure microphone set and as such optimized for acoustic measurements of the sound source in a closed coupler or the measurement of sound pressure at a boundary or wall; in which case the microphone forms part of the wall and measures the sound pressure on the wall itself.

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


The G.R.A.S. 46AP 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 WS2P standardized G.R.A.S. 40AP 1/2" Ext. Polarized Pressure Microphone, High Sensitivity, designed for long-term reliability in multiple environments.

The preamplifier is the G.R.A.S. 26TK Preamplifier which is inclusive TEDS 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. 46AP microphone set requires a power module or an analyzer input which can supply the preamplifier with power as well as 200 V polarization. If the power 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 7-pin LEMO connector. Ready to use cable assemblies with LEMO connectors of various types and lengths are available in standard as well as customized lengths.

The 46AP is IEEE 1451.4 TEDS 27v. 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.

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 12.5 to 7.5 k
Frequency range (±2 dB) Hz 3.15 to 10 k
Dynamic range lower limit with G.R.A.S. preamplifier dB(A) 18
Dynamic range upper limit with G.R.A.S. preamplifier @ +28 V / ±14 V power supply dB 142
Dynamic range upper limit with G.R.A.S. preamplifier @ +120 V / ±60 V power supply dB 149
Set sensitivity @ 250 Hz (±2 dB) mV/Pa 50
Set sensitivity @ 250 Hz (±2 dB) dB re 1V/Pa -26
Output impedance Ω 75
Power supply min. to max. (single/balanced) V 28 to 120 / ± 14 to ± 60
DC-offset, min., single suppy V 0.5 x Vs - 1
DC-offset, max., single suppy V 0.5 x Vs + 4
DC-offset, balanced supply V -1 to 4
Microphone venting Rear (Front on request)
IEC 61094-4 Compliance WS2P
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 100
Humidity coefficient @250 Hz dB/% RH -0.001
Influence of axial vibration @1 m/s² dB re 20 µPa 62
TEDS UTID (IEEE 1451.4) 27 v. 1.0
Connector type 3 m 7-pin LEMO
CE/RoHS compliant/WEEE registered Yes / Yes/Yes
Weight g / oz 42 / 1.482

Typical frequency response

Free-field corrections for different angles of incidence

Optional items

G.R.A.S. AA0008

3 m LEMO 7-pin - LEMO 7-pin Cable

G.R.A.S. AA0020-CL

Customized Length LEMO 7-pin - LEMO 7-pin Cable

G.R.A.S. AL0008

1/2" Microphone Holder, POM

G.R.A.S. AL0012

1/2" Microphone Holder, Stainless Steel

G.R.A.S. AL0005

Swivel head

G.R.A.S. AL0006


G.R.A.S. RA0020

1/2" Nosecone

G.R.A.S. AM0069

Windscreen for 1/2" Microphones

G.R.A.S. RA0131

Rain-protection cap for 1/2” microphones

G.R.A.S. 12AA

2-Channel Power Module with gain, filters and SysCheck generator

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