GRAS 46BP-1 1/4" LEMO Pressure Standard Microphone Set

Freq range: 4 Hz to 70 kHz
Dyn range: 39 dB(A) to 172 dB
Sensitivity: 1.5 mV/Pa

Technology

Introduction

46BP-1 is typically used for sound pressure, high frequency, and high level pressure measurements. It is suitable for general purpose acoustic measurements in couplers and at boundaries.

The microphone in the 46BP-1 is very versatile when connected to the RA0086 Transmitter Adapter for 1/4" Microphones. The 46BP-1 becomes a high-impedance sound source when the RA0086 takes a calibration signal directly from the signal generator and makes the microphone behave like an electrostatic loudspeaker. When used for calibrating an acoustic coupler, this gives a frequency response that is as good as when the 46BP behaves like a microphone.

A front-vented version is available, 46BP-1-FV 1/4" LEMO Pressure Microphone Set, Front Vented

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

Design

The GRAS 46BP-1 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.

Microphone
The microphone cartridge is the high-quality IEC  61094 WS3F standardized GRAS 40BP 1/4" Externally Polarized Pressure Microphone, designed for long-term reliability in multiple environments.

Preamplifier
The preamplifier is the GRAS 26AC-1 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.

Compatibility

To perform as specified, the GRAS 46BP-1 microphone set requires a power module or an analyzer input which can supply the preamplifier with power as well as 200 V polarization voltage for the microphone.

The microphone set is terminated with a 5-pin mini-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 46BP-1 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 GRAS 42AG Sound Calibrator.

For proper sensitivity calibration we recommend using a reference sound source like the GRAS 42AP Intelligent Pistonphone.

Calibration

When leaving the factory, all GRAS 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: GRAS Traceable Calibration and GRAS Accredited Calibration.

GRAS 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 GRAS microphones are subjected to as an integral part of our quality assurance.

GRAS Accredited Calibration is performed by the GRAS 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.

GRAS HALT

When our R&D team develops a measurement microphone, it must undergo the most demanding tests to prove that it can withstand our customers' daily test conditions. Using a series of Highly Accelerated Lifetime Tests (HALT) we ensure that our microphones live up to the high quality and precision that our customers have come to expect and trust. Our HALT tests actively accelerate the lifetime of a microphone by simulating the handling and use it is exposed to in real life situations.

For more about HALT, see http://www.gras.dk/halt.

Quality and warranty

GRAS 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.

Service

Should you by mistake damage the diaphragm on a GRAS 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.

Specifications

Polarization/Connection
200 V / Traditional
Frequency range (±1 dB)
Hz
10 to 25 k
Frequency range (±2 dB)
Hz
4 to 70 k
Dynamic range lower limit with GRAS preamplifier
dB(A)
39
Dynamic range upper limit with GRAS preamplifier @ +28 V / ±14 V power supply
dB
169
Dynamic range upper limit with GRAS preamplifier @ +120 V / ±60 V power supply
dB
172
Set sensitivity @ 250 Hz (±3 dB)
mV/Pa
1.5
Set sensitivity @ 250 Hz (±3 dB)
dB re 1V/Pa
-56.5
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
IEC 61094-4 Designation
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 90
Humidity coefficient @250 Hz
dB/% RH
-0.0013
Influence of axial vibration @1 m/s²
dB re 20 µPa
55
TEDS UTID (IEEE 1451.4)
27 v. 1.0
Connector type
5-pin LEMO 00
CE/RoHS compliant/WEEE registered
Yes / Yes/Yes
Weight
g / oz
10 / 0.353

 

Typical frequency response (without protection grid).

 

Free-field corrections for different angles of incidence


GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.

Dimensions

Ordering info

Optional items

GRAS AA0091

3 m LEMO 5-pin - LEMO 7-pin Cable

GRAS AA0092-CL

Customized Length LEMO 5-pin - LEMO 7-pin Cable

GRAS AL0029

1/4" Microphone Holder, POM

GRAS AL0013

1/4" Microphone Holder, Stainless Steel

GRAS AL0005

Swivel head

GRAS AL0006

Tripod

GRAS RA0022

1/4" Nosecone

GRAS AM0071

Windscreen for 1/4" Microphones

GRAS RA0127

 Rain-protection cap for 1/4” microphones

GRAS 12AA

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

GRAS 12AK

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

GRAS 12AQ

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

GRAS 42AG

Multifunction Sound Calibrator, Class 1

GRAS 42AP

Intelligent Pistonphone, Class 0

GRAS CA0029

Traceable Calibration of Microphone Set

GRAS CA2301

Accredited Calibration of Microphone Set

GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.

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