G.R.A.S. 47AX Manuel utilisateur
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
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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LI0063 – Revision 29 May 2015
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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LI0063 – Revision 29 May 2015
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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LI0063 – Revision 29 May 2015
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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LI0063 – Revision 29 May 2015
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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LI0063 – Revision 29 May 2015
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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LI0063 – Revision 29 May 2015
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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LI0063 – Revision 29 May 2015
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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LI0063 – Revision 29 May 2015
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.
Ce manuel convient aux modèles suivants
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