GRAS 46BC Multifield Microphone Set High Sensitivity User Manual

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

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

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 [email protected]

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- [email protected]

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- [email protected]

CHINA
GRAS SOUND & VIBRATION Room 303, Building T6 Hongqiaohui, 990, Shenchang Road Minhang District, Shanghai China. 201106 Tel : +86 21 64203370 www.grasacoustics.cn [email protected]

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

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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