GRAS RA4800 User manual

LI0275 – 2 November 2020
Instruction Manual
GRAS RA4800 Adapter for Sensitivity Verication
of Flush and Surface Microphones

Instruction Manual RA4800 | 2
Revision History
Revision Date Description
1 2 November 2020 First edition
Copyright Notice
© 2020 GRAS Sound & Vibration
http://www.grasacoustics.com
Any technical documentation that is made available by GRAS is the copyrighted work of GRAS
and is owned by GRAS.
The content in this document is subject to change without notice. GRAS Sound & Vibration is not
liable or responsible for any errors or inaccuracies that may appear in this document.
Trademarks
Any product names mentioned in this document may be trademarks or registered trademarks of
their respective companies and are hereby acknowledged.

Instruction Manual RA4800 | 3
Contents
Introduction ......................................................................................................................4
Description ........................................................................................................................4
Procedure .......................................................................................................................... 5
Correction values ............................................................................................................. 5
Warranty, Service and Repair......................................................................................... 6

Instruction Manual RA4800 | 4
Introduction

using the RA4800, there is no need for dismounting the microphone from the structure on which

of the measurement setup.
It will normally be used with a sound calibrator such as the GRAS 42AG Multifunction Sound
Calibrator.
Description
The adapter has three main features.
• 
• It has a soft cushion similar to those found on circum-aural headphones. It creates a closed
cavity over the microphone to be calibrated.
• 
and will be the same from one calibration to the next.
Top view Side view
1” collar
Soft cushionSpacers
Spacers Soft cushion

Fig. 1. The RA4800 adapter/eld verication set for level calibration.

Instruction Manual RA4800 | 5
Procedure

G.R.A.S. 42AG
dB Hz Met
dB Hz Met
G.R.A.S. 42AG
dB Hz Met
dB Hz Met
Fig. 2. In-situ verication using 42AG and RA4800.

it there until the reading on the analyzer is stable.
Refer to the manual for 42AG for further information about how to operate the calibrator.
Correction values
250 Hz 1 kHz Accuracy
40LA - 0.6 dB -2.1 dB ±0.2 dB
40LS - 0.6 dB -2.1 dB ±0.2 dB
48LA -0.8 dB -3.0 dB ±0.2 dB
48LX-1 -0.8 dB -3.0 dB ±0.2 dB
48LX-4 -0.8 dB -3.0 dB ±0.2 dB
48LX-8 -0.8 dB -3.0 dB ±0.2 dB

Instruction Manual RA4800 | 6
Warranty, Service and Repair
Warranty, Service and Repairs
GRAS products are made of components from our proven standard portfolio and are all manu-
factured of high-quality material and branded parts that were chosen and processed to ensure
life-long stability and robustness.
The warranty does not cover products that are damaged due to negligent use, an incorrect power
supply, or an incorrect connection to the equipment.
Further information about warranty and our repair service can be found at
grasacoustics.com/repair-center
WEEE directive:
2002/96/EC
CE marking directive:
93/68/EEC
Manufactured to conform with:
RoHS directive:
2002/95/EC
GRAS Sound & Vibration continually strives to improve the quality of our products for our
