GRAS 46BC Multifield Microphone Set High Sensitivity User Manual
- June 15, 2024
- GRAS
Table of Contents
GRAS 46BC Multifield Microphone Set High Sensitivity
Product Information
Specifications:
- Model: GRAS 46BC
- Microphone Type: 1/4 CCP Multifield Microphone Set
- Sensitivity: 20 mV/Pa
- Frequency Range: 4 Hz to 20 kHz
- Dynamic Range: 24 dB(A) to 145 dB
Product Usage Instructions
Technology
The GRAS 46BC 1/4 CCP Multifield Microphone Set is designed for use in
pressure, free-field, or random-incidence environments where the sound field
is ill-defined or changing. Its small dimensions and enhanced high-frequency
content make it ideal for in-cabin measurements or scenarios requiring
measurement in a random incidence environment. The microphone can accurately
measure in any field or combination of defined fields (pressure, free field,
or random incidence), and it is compliant with IEC 61672 Limits for all sound
fields and angles of incidence.
Microphone Set Concept
The GRAS 46BC microphone set concept ensures data safety, simplified
microphone selection, easy system configuration, and reduced measurement
errors. The set consists of a microphone cartridge and preamplifier
combination calibrated as one unit. This eliminates errors and reduces the
risk of interface contamination.
The design of the microphone set, combined with its reliability and robustness, makes it one of the most reliable measurement microphone sets available in the industry.
Typical Applications
The GRAS 46BC microphone set is suitable for various applications,
including:
- Pressure, free-field, or random-incidence measurements
- In-cabin measurements
- Scenarios requiring measurement in random incidence environments
Compatibility
The GRAS 46BC microphone set requires a constant current input module that
can deliver 3.5 mA and 24 V unloaded CCP voltage supply to perform as
specified. Lower constant current supply may reduce the capability of driving
long cables and the upper frequency range. Lower voltage supply may 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.
The 46BC microphone is IEEE 1451.4 TEDS v. 1.0 compliant, allowing for reading and writing of data like properties and calibration data if your measurement platform supports Transducer Electronic Data Sheets (TEDS).
FAQ:
- Q: How long should the microphone be powered on before starting a measurement?
- A: To achieve optimal performance, the GRAS 46BC microphone should be powered on for at least two minutes before starting a measurement.
- Q: How does positive pressure affect the output voltage of the 46BC microphone?
- A: Unlike other CCP microphones, a positive pressure on the 46BC diaphragm generates a negative output voltage.
Technology
GRAS 46BC multifield microphone
46BC is a true multifield microphone for use in pressure, free-field, or
random-incidence environments or any scenarios where the sound field is ill-
defined or changing. The design of this microphone takes advantage of the
microphone’s small dimensions and slightly enhances the high-frequency
content, which results in the perfect microphone for in-cabin measurements or
any scenarios where measuring in a random incidence environment is needed.
Sound fields have historically been defined in microphone standards as pressure, free field, or random incidence. Multifield microphones can accurately measure in any field or in any combination of the defined fields. In all situations, sound fields, and angles of incidence, 46BC is compliant with IEC 61672 Limits.
46BC protection grid
Unlike other ¼″ microphones, 46BC is optimized for use with the protection
grid. This feature ensures protection during in-cabin measurements.
NOTE : The protection grid creates a resonance that will occur around 35 kHz. This resonance is in the order of magnitude of + 6 dB.
Microphone set concept
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 users, data safety translates directly into tools that allow for
easier microphone selection, simple system configuration, and reduction of
measurement errors.
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 small size and optimized frequency response make 46BC ideally suited for
applications where the sound field is ill-defined or changing. This is due to
the combination of size and optimization, which reduces the influence of the
angle of incidence of source positions and reflections. The result is a
reduction in measurement uncertainty in applications such as in-cabin noise,
architectural acoustics, and outdoor measurements. GRAS 46BC is also well
suited for general acoustic measurements where high sensitivity and low noise
are required.
Instruction Manual: RA0399 H-shaped holder for 6-unit microphone array
NOTES:
- To achieve optimal performances 46BC must be powered on for at least two minutes before starting a measurement.
- Unlike other CCP microphones, a positive pressure on the 46BC diaphragm generates a negative output voltage.
Compatibility
To perform as specified, the GRAS 46BC microphone set requires a constant
current input module that can deliver 3.5 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 46BC is IEEE 1451.4 TEDS v. 1.0 compliant. If your measurement platform supports Transducer Electronic Data Sheets (TEDS), 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
46BC has a diaphragm that is slightly larger in diameter than is standard for
¼″ microphones. This does not affect sensitivity calibration, but for
frequency calibration, you need a RA0236 Adapter. 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 which 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 instead of the default factory calibration, specify this when ordering. Learn more at calibration.
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 five 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 | 0 V / CCP | |
|---|---|---|
| Frequency range (±1 dB) | Hz | 10 to 10k |
| Frequency range (±3 dB) | Hz | 4 to 20k |
| Set sensitivity @ 250 Hz (±2 dB) | mV/Pa | 20 |
| Set sensitivity @ 250 Hz (±2 dB) | dB re 1V/Pa | -34 |
| Output impedance | Ω | <50 |
| Output Voltage Swing, min. @ 24-28 V CCP voltage supply | Vp | 8 |
| Power supply min. to max. | mA | 3.5 to 10 |
| DC bias voltage, typ. | V | 14 |
| Microphone venting | Rear | |
| IEC 61094-4 Designation | WS3F | |
| Temperature range, operation | °C / °F | -20 to 80 / -4 to 176 |
| Temperature range, storage | °C / °F | -40 to 85 / -40 to 185 |
| Temperature coefficient @250 Hz | dB/°C / dB/°F | -0.02 / -0.012 |
| Static pressure coefficient @250 Hz | dB/kPa | –0.01 (typical value) |
| Humidity range noncondensing | % RH | 0 to 90 |
| Influence of axial vibration @1 m/s² | dB re 20 µPa | 60 (typical value) |
| TEDS UTID (IEEE 1451.4) | 27 v. 1.0 | |
| Connector type | Microdot 10/32 | |
| CE/RoHS compliant/WEEE registered | Yes / Yes/Yes |
Dynamic range lower limit with GRAS preamplifier
|
dB(A)
| Max 24
Typical 23.5
Dynamic range upper limit with GRAS CCP preamplifier
|
dB
| 142 RMS
145 Peak level
Dynamic range| dB| 120
Typical frequency response (with protection grid)
Free-field and Random-incidence corrections
⅓-octave noise curve, linear
⅓-octave noise curve, A-weighted
Narrow-band FFT (1 Hz bandwidth)
GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.
Dimensions
- Weight (g / oz) 8 / 0.282
- Dimensions in mm Length : 53
- Height : 7
Ordering Info
Optional items
| GRAS AA0070 | 3 m Microdot – BNC Cable |
|---|---|
| GRAS AL0029 | ¼″ Microphone Holder, POM |
| GRAS AL0013 | ¼″ Microphone Holder, Stainless Steel |
| GRAS AL0005 | Swivel head |
| GRAS AL0006 | Tripod |
| GRAS AM0071 | Windscreen for ¼″ Microphones |
| GRAS 12AL | 1-channel CCP Power Module with A-weighting filter |
| GRAS 12BA, BB, and BE | **** 1-, 4- and 2-channel CCP Power Modules |
| 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 RA0236| Adapter for frequency calibration of 46BL (also fits 46BL-1, and
46BC)
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.
GRAS Worldwide
Subsidiaries and distributors in more than 40 countries
HEAD OFFICE,
DENMARK GRAS SOUND & VIBRATION Skovlytoften 33 2840 Holte Denmark Tel :
+45 4566 4046www.grasacoustics.com
gras@grasacoustics.com
USA
GRAS SOUND & VIBRATION 5750 S.W. Arctic Drive Beaverton, OR 97005 Tel :
503-627-0832 Toll – Free :
800-231-7350
www.grasacoustics.com sales-
usa@grasacoustics.com
UK
GRAS SOUND & VIBRATION Unit 115, Gibson House, Ermine Business Park,
Huntingdon, Cambridgeshire, PE29 6XU Tel : +44 (0) 7762 584 202
www.grasacoustics.com sales-
uk@grasacoustics.com
CHINA
GRAS SOUND & VIBRATION Room 303, Building T6 Hongqiaohui, 990, Shenchang Road
Minhang District, Shanghai China. 201106 Tel : +86 21 64203370
www.grasacoustics.cn
cnsales@grasacoustics.com
About GRAS Sound & Vibration
GRAS is a worldwide leader in the sound and vibration industry. We develop and
manufacture state-of-the-art measurement microphones and related equipment for
industries where acoustic measuring accuracy and repeatability are of the
utmost importance. This includes applications and solutions for customers
within the fields of aerospace, automotive, audiology, consumer electronics and
other highly demanding industries. GRAS microphones are designed to live up to
the high quality, durability and accuracy that our customers have come to
expect, trust and require. GRAS Sound & Vibration is represented through
subsidiaries and distributors in more than 40 countries and is part of
Axiometrix Solutions, a leading test solutions provider comprised of globally
recognized measurement brands. Read more at www.grasacoustics.com
References
- 声学测试麦克风 传声器 | GRAS 声学与振动测量 - 官网
- GRAS Sound and Vibration
- GRAS 12AL 1-Channel CCP Power Module with A-weighting filter
- GRAS 12AQ 2-Channel Universal Power Module with signal conditioning and PC interface
- GRAS 42AP Intelligent Pistonphone, Class 0
- GRAS AM0071 Windscreen for 1/4" Microphones
- GRAS AL0006 Tripod
- GRAS AL0005 Swivel head
- GRAS AA0070 3 m Microdot - BNC Cable
- GRAS AL0013 1/4" Microphone Holder, Stainless Steel
- GRAS AL0029 1/4" Microphone Holder, POM
- GRAS 42AG Multifunction Sound Calibrator, Class 1
- 12BA , 12BE and 12BB CCP Power Modules with USB Connection
- Calibration Service
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