Cirrus Optimus+ User manual

Instrument
Handbook
Opmus+ GPS
Sound Level Meters

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Optimus+ Sound Level Meters – User Manual
About this manual
The instructions in this user manual refer to the operation of Cirrus Research plc Optimus sound
level meters with version 5.0 or higher of the firmware.
The instruments described in this manual are the Optimus+ Red (CR:160 series) and Optimus+
Green (CR:170 series) with GPS functionality.
This manual describes the recommended usage of the Optimus+ GPS. Any warnings will be
indicated by the following symbol:
The additional information required for testing in accordance with IEC 61672 is provided as a
supplementary document, Optimus Sound Level Meters Technical Data Part B, which is available
for download at:
www.cirrusresearch.co.uk/library/user-manuals/
It is not possible to change the way that the instrument measures through the software or
firmware. Any legal metrology aspects of the instrument cannot be affected by any changes
made in the instrument.
The Common Specifications section on page 33 defines which standards relate to the different
functions available in the instruments. Additional approvals and certifications may apply to the
instruments and these will be listed in the Appendices.
More detailed explanations of the audio recording templates, tonal noise detection and the
repeat measurement timers are available to download from the Cirrus website at
www.cirrusresearch.co.uk/library/user-manuals/

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Optimus+ Sound Level Meters – User Manual
Copyright
Copyright © Cirrus Research plc 2010-2021
All rights reserved.
You may re-use this document/publication (not including the Cirrus Research plc logo and other
product logos) free of charge in any format for research, private study or internal circulation
within an organisation. You must re-use it accurately and not use it in a misleading context.
You must not modify text, images or illustrations in any way. The material must be acknowledged
as Cirrus Research plc copyright and you must give the title of the source document/publication.
Where any third-party copyright material is identified you will need to obtain permission from
the copyright holders concerned.
Trademarks
Cirrus Research plc, the Cirrus Research plc Logo, doseBadge, DOSEBADGE, Optimus, the
NoiseTools Logo and the Noise-Hub Logo are either registered trademarks or trademarks of
Cirrus Research plc in the United Kingdom and/or other countries. Microsoft and Windows are
registered trademarks of Microsoft, Inc. All other trademarks acknowledged.
Updates
In the interests of continuous product improvement, Cirrus Research plc reserves the right to
make changes to product specifications without notice.
To understand the latest updates that have been implemented into this product and to download
the most current version of this user manual, visit our website at
www.cirrusresearch.co.uk
Revision 4 | July 2021

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Optimus+ Sound Level Meters – User Manual
Contents
1. Introduction ............................................................................................................................................5
2. First use...................................................................................................................................................7
2.1 Inserting the batteries ............................................................................................................................................ 8
2.2 Setting the clock ..................................................................................................................................................... 8
2.3 Calibration .............................................................................................................................................................. 9
3. Making a measurement.........................................................................................................................11
4. Operations in more detail......................................................................................................................12
4.1 NoiseTools ............................................................................................................................................................ 12
4.2 Keypad and controls ............................................................................................................................................. 12
4.3 Connectors ........................................................................................................................................................... 13
4.4 Screen saver ......................................................................................................................................................... 14
4.5 Display .................................................................................................................................................................. 15
4.6 Audio recording .................................................................................................................................................... 17
4.7 Timers................................................................................................................................................................... 18
4.8 Back erase/pause ................................................................................................................................................. 18
4.9 Memory................................................................................................................................................................ 19
4.10 Restore factory settings........................................................................................................................................ 19
4.11 Windshield............................................................................................................................................................ 19
4.12 Bluetooth.............................................................................................................................................................. 20
4.13 GPS ....................................................................................................................................................................... 20
5 Getting to know your instrument - features & capabilities....................................................................25
5.1 Views .................................................................................................................................................................... 25
5.2 High-level noise measurement............................................................................................................................. 28
6Menus ...................................................................................................................................................29
7Additional information..........................................................................................................................32
8Appendices............................................................................................................................................33
8.1 IEC 61672 test data............................................................................................................................................... 33
8.2 Common specifications ........................................................................................................................................ 33
8.3 Views .................................................................................................................................................................... 36
8.4 Stored measurements .......................................................................................................................................... 39
8.5 Electrical outputs.................................................................................................................................................. 42
9 Acoustic calibrator information.............................................................................................................44
9.1 Setting up the calibrator....................................................................................................................................... 44
9.2 Calibrating a sound level meter............................................................................................................................ 44
9.3 Changing the battery ............................................................................................................................................ 45
9.4 Specifications........................................................................................................................................................ 46
9.5 Technical information........................................................................................................................................... 46
10 EU Declaration of Conformity................................................................................................................48
11 Product guarantee and extended warranty...........................................................................................49

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Optimus+ Sound Level Meters – User Manual
1. Introduction
Welcome to your Optimus+ GPS sound level meter. This next-generation instrument from Cirrus
Research plc is powerful yet simple to use and is capable of a wide range of noise measurement
functions.
Microphone capsule
Microphone
preamplifier
Preamplifier locking ring
Ambient light sensor
Display
Soft keys
Control keys

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Optimus+ Sound Level Meters – User Manual
Battery cover screw
Battery cover
Tripod mount
Power button

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Optimus+ Sound Level Meters – User Manual
2. First use
Your sound level meter has been shipped in reusable packaging that should be retained for safe
shipment when returning the instrument for calibration or servicing.
All Optimus+ GPS sound level meters come with the following standard accessories:
• MV:200 microphone preamplifier
• Microphone capsule (attached to the preamplifier)
• Wrist strap
• 4 x AA batteries
• User manual
• Windshield
You may have other accessories, depending on your package.
When connecting the preamplifier, please take great care to only turn the locking ring at the
base.
Twisting the preamplifier body is likely to cause serious damage. The microphone capsule is also
delicate, and care needs to be taken when handling it.
Damage caused by misuse is not covered by the warranty for the instrument.

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Optimus+ Sound Level Meters – User Manual
2.1 Inserting the batteries
Your sound level meter is powered by 4 x AA alkaline batteries (also called MN1500 or LR6).
We recommend that you use alkaline batteries to give the best performance.
Remove the battery cover by loosening the captive locking screw (as shown in the diagram
below).
Please look carefully at the diagram inside the battery compartment that shows the correct
polarity. After inserting the batteries in the correct orientation, replace the cover and tighten the
locking screw.
The instrument is switched on by pressing and releasing the on/off button on the left-hand side
of the case. After the bootup screen has been displayed, your sound level meter will show the
last view you used.
2.2 Setting the clock
Your instrument stores the date and time with all measurements to help when analysing results
and ensuring the accuracy of the data. It is important to check that the instrument’s clock is
correctly set before starting a measurement session. It is visible on the top-right corner of the
screen.
To set the clock, press the ‘menu’ button after the instrument has been turned on. Select the
‘Set Clock’ menu and follow the instructions on-screen.

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Optimus+ Sound Level Meters – User Manual
Please note that the clock might need to be set again if the instrument is stored without batteries
for a prolonged period.
2.3 Calibration
All noise measuring instruments should be calibrated before each use because the microphone
is susceptible to minor damage, even from small knocks.
The calibration process applies corrections (if needed) to your instrument’s readings, to ensure
that your measurements are as accurate as possible.
Calibration should also be carried out at the end of a measurement session to make sure that
nothing has happened to the instrument during the session.
To calibrate your sound level meter, carefully push the microphone into the cavity at the end of
the calibrator. Ensure the microphone is fully inserted into the cavity and is past the ‘O’ ring
seals.
Ensure that the small bleed hole next to the microphone cavity on the calibrator is not blocked,
as this could cause damage to the microphone.
Take care not to use a twisting motion when pushing the microphone into the calibrator, as this
is likely to cause damage to the preamplifier.
Press the ‘on’ button on the end of the calibrator. Press the calibrate button on your sound level
meter.

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Optimus+ Sound Level Meters – User Manual
The instrument will measure the sound level from the acoustic calibrator to determine if it is
within the required tolerance and levels. The calibration level must be stable to within ±0.075
dB for 5 consecutive seconds, for calibration to be successful.
When calibration is complete, your instrument will display the level along with the correction or
adjustment made.
Your sound level meter is pre-set with the correction values needed for Cirrus Research
microphone capsules, so no manual adjustment is required. The calibration level you should
expect is 93.7 dB.
Refer to page 44 for detailed operating information for the CR:514 and CR:515 acoustic
calibrators.