G.R.A.S. 47AX User manual

www.gras.dk
LI0063 – 29 May 2015
Instruction Manual
G.R.A.S. 1/2”, 1/4”, and 1/8”
CCP Flush-mount microphone sets

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LI0063 – Revision 29 May 2015
Revision History
Any feedback or questions about this document are welcome at [email protected].
Revision Date Description
1 27 August 2014 First publication
2 29 May 2015 Section about dismounting added.
Copyright Notice
© 2014-15 G.R.A.S. Sound & Vibration A/S
http://www.gras.dk
Any technical documentation that is made available by G.R.A.S. is the copyrighted work of
G.R.A.S. and is owned by G.R.A.S.
The content in this document is subject to change without notice. G.R.A.S. Sound & Vibration A/S
is not liable or responsible for any errors or inaccuracies that may appear in this document.
Trademarks
Product names mentioned in this document may be trademarks or registered trademarks of their
respective companies and are hereby acknowledged.

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Contents
Introduction.................................................................................. 4
The Scope of this Manual ........................................................................... 4
Brief Description ........................................................................................ 4
General Handling Rules for Flush-mount Microphones.................................... 5
Delivered items and Accessories ....................................................... 6
Delivered Items ......................................................................................... 6
Optional Accessories – Mounting.................................................................. 7
Optional Accessories – Calibration ................................................................ 7
Mounting and Removal................................................................... 8
General Information.................................................................................... 8
Mounting without Adapters ......................................................................... 8
Mounting with Adapters.............................................................................. 8
Removal of 1/2 inch and 1/4 inch Flush-mount Microphone ......................... 12
Powering & Connection – CCP ........................................................ 13
General Information.................................................................................. 13
Connection .............................................................................................. 13
Extension Cables...................................................................................... 13
Calibration ................................................................................. 15
Periodical Calibration ................................................................................ 15
How to Perform Sensitivity Calibration........................................................ 15
How to Perform Frequency Calibration........................................................ 15
Specifications ............................................................................. 16
Calibration, Warranty and Repair .................................................... 16
Calibration............................................................................................... 16
Warranty................................................................................................. 16
Service and Repairs.................................................................................. 16

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Introduction
The Scope of this Manual
This manual describes how to mount the G.R.A.S 1/2”, 1/4” and 1/8” flush-mount microphone
sets, how to connect them, and how to perform sensitivity and frequency calibration.
Two mounting options are described:
• Mounting with Adapter
An adapter for each microphone size is available. The adapters are made from a non-
conductive plastic material that provides electrical insulation between microphone and test
object. The microphone set is attached to the adapter with an O-ring. This makes installation
and removal of the microphone set easy.
• Direct Mounting
The measures you need to make your own mounting solution are provided, without the use of
a G.R.A.S. mounting adapter.
Brief Description
Venting
The microphone is front-vented for air pressure equalization. This is realized through a tiny
hole that is visible when the microphone grid is removed. It is important that the venting is not
blocked.
TEDS
The G.R.A.S. flush-mount microphones have TEDS according to IEEE 1451.4, 27 v 1.0. The
TEDS (Transducer Electronic Data Sheet) is a memory in the microphone. At delivery, the factory
has stored the G.R.A.S. type number, serial number and the sensitivity value as measured during
factory calibration.
If your measurement platform supports intelligent transducers according to IEEE 1451.4 (TEDS),
this information will automatically be retrieved. G.R.A.S. updates the stored sensitivity value as
normal procedure in the calibration service.

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Applications for Flush-mount Measurement Microphones
The G.R.A.S. line of flush-mount measurement microphones combines the high precision and
reliability of G.R.A.S. measurement microphones with the need for fitting sensors into very
confined spaces and narrow structures. With a height of less than 10 mm (0.4 inch) and thin coax
connection, these acoustic sensors can be integrated into literally any design without sacrificing
aerodynamic properties.
Fig. 1. A G.R.A.S. 1/4” flush-mount microphone
mounted with mounting adapter.
General Handling Rules for Flush-mount Microphones
Save the Protection Grid
If you use the flush-mount microphone without grid (normal flush-mount application) then store
the grid. Mount the protection grid whenever the flush-mount microphone is removed from its
operating position.
Physical Deformation
Do not let any object touch the diaphragm. Avoid also touching it with your fingers.
Cleaning
If you must clean the diaphragm, use clean and dry air. This is available in cans from e.g. camera
shops.

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Delivered items and Accessories
Delivered Items
The microphone sets are delivered with an integrated thin (1.1 mm) coaxial cable terminated with
a Microdot male connector. Standard cable length is 1.5 m (4.92 feet).
All the microphones listed below can be ordered with customized cable length, e.g. 47AX-CL,
where CL is the cable length in centimeters. For instance, if you wish to order with 25 m cable,
you write 47BX-CL2500.
47AX 1/2” Flush-mount Microphone
Item Part Number
1/2” Flush mount Microphone with 1.5m integrated coax cable 47AX
Microdot female - BNC male adapter AE0046
47AD 1/2” Flush-mount Microphone
Item Part Number
1/2” Flush mount Microphone with 1.5m integrated coax cable 47AD
Microdot female - BNC male adapter AE0046
47BX 1/4” Flush-mount Microphone
Item Part Number
1/4” Flush mount Microphone with 1.5m integrated coax cable 47BX
Microdot female - BNC male adapter AE0046
47DX 1/8” Flush-mount Microphone
Item Part Number
1/8” Flush mount Microphone with 1.5m integrated coax cable 47DX
Microdot female - BNC male adapter AE0046

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Optional Accessories – Mounting
Mounting Adapters
Item Part Number
Mounting Adapter for 1/2” Flush-mount Microphone Set RA0501
Mounting Adapter for 1/4” Flush-mount Microphone Set RA0502
Mounting Adapter for 1/8” Flush-mount Microphone Set RA0503
Removal Tool for 1/2” and 1/4” Flush-mount Microphone Sets RA0302
Optional Accessories – Calibration
Adapters for Sensitivity Calibration
Item Part Number
G.R.A.S Kit for Sensitivity Calibration of Flush-mount Microphones OP0023
This kit contains:
Pistonphone Calibration Adapter for 1/2” Flush-mount Mic. Set RA0221
Pistonphone Calibration Adapter for 1/4” Flush-mount Mic. Set RA0228
Pistonphone Calibration Adapter for 1/8” Flush-mount Mic. Set RA0278
The adapters can be ordered separately or as part of the OP0023 kit.
Accessories for Frequency Calibration
Item Part Number
Calibration Stand AL0021
G.R.A.S Kit for Frequency Calibration of Flush-mount Microphones OP0024
This kit contains:
Electrostatic Actuator for Flush-mount Microphone Sets RA0285
Actuator Calibration Adapter for 1/4” Flush-mount Microphone Sets RA0242
Actuator Calibration Adapter for 1/8” Flush-mount Microphone Sets RA0279
Actuator Calibration Holder for Flush-mount Microphone Sets RA0289
For the 1/2” Flush-mount Microphone Set, no adapter is needed. The adapters can only be ordered as part of the
OP0024 kit. The AL0021 Calibration Stand must be ordered separately.

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Mounting and Removal
General Information
The procedure for mounting 1/2”, 1/4” and 1/8” flush-mount microphone sets is the same. The
only difference is the dimensions of the mounting holes.
The microphones are typically mounted without the microphone grid. Store the microphone grid
for future use. It is needed during transport and during sensitivity calibration with a pistonphone.
It is important that the microphone is not mounted in a way that requires major force to remove it
for service or calibration.
We recommend the use of our mounting adapters. These are made of plastic and ensure that the
microphone is electrically insulated from the test structure and easy to install and remove. The
microphone grid must be removed.
Item Part Number
Mounting Adapter for 1/2” Flush-mount Microphone Set RA0501
Mounting Adapter for 1/4” Flush-mount Microphone Set RA0502
Mounting Adapter for 1/8” Flush-mount Microphone Set RA0503
The adapters give a snug fit and thereby excellent acoustic performance as no open space is cre-
ated between the microphone cartridge and the mounting surface. An O-ring between the adapter
and the microphone housing provides acoustical sealing.
Caution. Never use the thread for the microphone grid for mounting purpose!
Avoid sharp bends of the coaxial cable.
Mounting without Adapters
Below you will find the measures needed for the various mounting alternatives, including the
measures you need to make your own mounting solution. If you have special installation require-
ments, you are welcome to contact G.R.A.S. to find a customized solution.
Mounting with Adapters
The adapter must be glued to the test object. When applying glue, only apply to the surface
shown on the drawings. Be careful not to drop any glue on the microphone diaphragm.
On the drawings, the hole dimensions 32 mm for 1/2”, 32 mm for 1/4” and 28 mm for 1/8” are
suggested as practical limits as you need some working space when attaching the microphone set
to the adapter using an O-ring.
With the adapter mounted in the test object, the microphone is attached to the adapter with an
O-ring that is part of the Adapter Kit. You can twist the O-ring once to increase the force on the
flush-mount microphone set.

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Measures, 1/2” Flush-mount
Ø11.9
Ø18
Ø12.7
2
3.8 8
1.7
5
Ø13.2
9.2
Ø18
Ø15 ± 0.1
Ø25
Minimum Ø32
3 ± 0.1
Glue only this surface
of the adapter
O-ring for attaching the
microphone set
to the adapter
Adapter
Dimensions for mounting without adapter
Dimensions for mounting with adapter
Fig. 2. Dimensions for mounting without and with the RA0501 Mounting Adapter. All measures in mm.

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Measures, 1/4” Flush-mount
Ø18 Ø18
Ø25
Minimum Ø32
3 ± 0.1
Ø8.5 ± 0.1
3.9
8.1
Ø6.35
Ø5.9
1.7
2
Ø7
4.9
9.1
Glue only this surface
of the adapter
O-ring for attaching
the microphone set
to the adapter
Adapter
Dimensions for mounting with adapter
Dimensions for mounting without adapter
Fig. 3. Dimensions for mounting without and with the RA0502 Mounting Adapter. All measures in mm.

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Measures, 1/8” Flush-mount
Minimum Ø28
Ø20
Ø5.5 ± 0.1
2 ± 0.1
Ø12
9.4
3.4
Ø3.49
Ø12
8.9
2.9
Ø3.18
Ø2.77
4
1.05
Glue only this surface
of the adapter
O-ring for attaching
the microphont
to the adapter
Adapter
Dimensions for mounting with adapter
Dimensions for mounting without adapter
Fig. 4. Dimensions for mounting without and with the RA0503 Mounting Adapter. All measures in mm.

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Removal of 1/2 inch and 1/4 inch Flush-mount Microphones
Once mounted, a flush-mount microphone can be difficult to remove. The G.R.A.S. RA0302
Removal Tool for 1/2 inch and 1/4 inch flush-mount microphones makes it possible to remove
the microphone without damage to structure, microphone housing or cable. The removal tool
holds the microphone housing with 8 claws, tightened and loosened by turning a knob, see Fig. 5.
Knob Claws
Space for cable
Fig. 5. The RA0302 Removal Tool for 1/2-inch and 1/4-inch flush-mount microphones.
1. If the surface microphone is secured with an O-ring, start by removing it.
2. Loosen the claws by turning the knob counterclockwise.
3. Slide the removal tool over the surface microphone and tighten its claws firmly by turning the
knob clockwise.
Caution: To avoid damage to the cable, be sure to locate it in the space between the claws, as
shown in Fig. 5, and Fig. 6, steps 2 and 3.
4. Pull out the microphone.
5. Loosen the claws by turning the knob counterclockwise. Remove the microphone.
The removal tool should not be used for mounting.
1 2 3 4 5
Fig. 6. Removal of a 1/2 inch flush-mount microphone. The procedure for a 1/4 inch microphone is the same.

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Powering & Connection – CCP
General Information
The powering and connection is electrically exactly the same as for G.R.A.S. CCP standard
microphone sets. A constant current input module that can deliver 4 mA and 24 V unloaded CCP
voltage supply is required. 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 reduce the dynamic range.
Connection
The flush-mount microphone sets are provided with an integrated cable that is only 1.1 mm in
diameter. The cable is terminated with a Microdot male connector. A G.R.A.S. AE0046 Microdot
- BNC Adapter is included. The cable length is:
• 1.5 m (4.92 feet), in standard flush-mount microphone sets
• Customized length, when ordered as -CL variant
Connection examples
Connection Adapter Adapter Part number
Flush-mount microphone + BNC-BNC extension cable Microdot to BNC
BNC to BNC
AE0046
AE0074
Flush-mount microphone + Microdot-BNC extension cable Microdot to Microdot AE1038
Flush-mount microphone with customized length
(-CL variant) cable (all the way to input module)
Microdot to BNC AE0046
Extension Cables
BNC – BNC
Item Part Number
3 m BNC - BNC Cable (RG-58, 4.9 mm diam.) AA0035
10 m BNC - BNC Cable (RG-58, 4.9 mm diam.) AA0037
Customized length BNC - BNC Cable (RG-58, 4.9 mm diam.) AA0039-CL

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Microdot – BNC
Item Part Number
3 m Microdot - BNC Cable (RG-174, 2.8 mm diam.) AA0070
10 m Microdot - BNC Cable (RG-174, 2.8 mm diam.) AA0072
Customized length Microdot - BNC Cable (RG-174, 2.8 mm diam.) AA0073-CL
3 m Microdot - BNC Cable, High Temp (Hi-Temp, 2 mm diam.) AA0018
10 m Microdot - BNC Cable, High Temp (Hi-Temp, 2 mm diam.) AA0062
Customized length Microdot - BNC Cable, High Temp (Hi-Temp, 2 mm diam.) AA0061-CL
Cable Adapters
Item Part Number
Microdot to BNC AE0046
BNC male to BNC male Adapter AA0037
Microdot male to Microdot male Adapter AE1038

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Calibration
Periodical Calibration
All measurement microphones need periodical calibration for obtaining reliable results. How often
depends on your requirements and on the environment the microphone sets are exposed to. We
recommend at least one calibration per year. G.R.A.S. offers equipment for calibration as well as
calibration services. There are 2 types of calibration:
• Sensitivity (performed with the microphone grid on)
• Frequency response
How to Perform Sensitivity Calibration
Sensitivity calibration requires that the microphone set is detached, the grid mounted, and placed
in the appropriate calibration adapter. The following items are needed:
• A pistonphone (The G.R.A.S. 42AP is recommended)
• One of the following pistonphone calibration adapters contained in the OP0023 Kit for
Sensitivity Calibration of Flush-mount Microphone Sets:
– 1/2” flush-mount microphone set: RA0221
– 1/4” flush-mount microphone set: RA0228
– 1/8” flush-mount microphone set: RA0278
No correction factor is required with any of these adapters.
For further instructions, see the manual for the G.R.A.S. OP0023 Kit for Sensitivity Calibration of
Flush-mount microphones and the manual for your pistonphone.
How to Perform Frequency Calibration
Frequency calibration requires that the microphone set is detached and that the grid is removed.
The G.R.A.S. OP0024 Kit for Frequency Calibration of Flush-mount Microphone Sets and the
G.R.A.S. 14AA Electrostatic Actuator Amplifier are required.
Frequency calibration is performed as described in the manuals for
• G.R.A.S. OP0024 Kit for Frequency Calibration of Flush- mount Microphone Sets
• G.R.A.S. 14AA Electrostatic Actuator Amplifier
• G.R.A.S. 90CA Microphone Calibration System
The only difference is that other actuator and adapters are used. See page 7 for a list of the
contents of the G.R.A.S. OP0024.

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Specifications
Specifications are given on our website. Visit www.gras.dk
Calibration, Warranty and Repair
Calibration
Before leaving the factory, all G.R.A.S. products are calibrated in a controlled laboratory environ-
ment using traceable calibration equipment. A calibration card is included. In addition, the sensi-
tivity data is stored in the TEDS memory.
We recommend a yearly recalibration at minimum, depending on the use, measurement environ-
ment, and internal quality control programs.
We recommend calibration prior to each use to ensure the accuracy of your measurements.
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 which guarantees a highly
reliable connection, enables us to offer 5 years warranty against defective materials and
workmanship.
Exception: For cables, also integrated, a 6 month warranty applies.
Service and Repairs
All repairs are made at G.R.A.S. International Support Center located in Denmark. Our Support
Center is equipped with the newest test equipment and staffed with dedicated and highly skilled
engineers. Upon request, we make cost estimates based on fixed repair categories. If a product
covered by warranty is sent for service, it is repaired free of charge, unless the damage is the
result of negligent use or other violations of the warranty. All repairs are delivered with a service
report, as well as an updated calibration chart.

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G.R.A.S. Sound & Vibration continually strives to improve the quality of our products for our
customers; therefore, the specifications and accessories are subject to change.
WEEE directive:
2002/96/EC
CE marking directive:
93/68/EEC
Manufactured to conform with:
RoHS directive:
2002/95/EC