Cirrus Research CR308 User manual

Instrument
Handbook
CR308/310 Sound
Level Meters

CR:308 & CR:310 sound level meters - instrument handbook
2CR:308 & CR:310 sound level meters - instrument handbook 3
CR:308 & CR:310 sound level meters - instrument handbook CR:308 & CR:310 sound level meters - instrument handbook
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The contents of this manual, including any illustrations, technical informaiton and
descriptions, were correct at the time of printing. Cirrus Research plc reserves the right
to make any changes necessary, without notice, in line with the policy of continuing
product development and improvement.
No part of this publication may be duplicated, reprinted, stored in a data processing
system or transmitted by electronic, mechanical, photographic or other means, or
recorded, translated, edited, abridged or expanded without the prior written consent
of Cirrus Research plc.
No liability is accepted for any inaccuracies or omissions in this manual, although due
care has been taken to ensure that it is complete and as accurate as possible.
Accessories supplied by Cirrus Research plc have been designed for use with the
instrumentation manufactured by Cirrus Research plc. No responsibility is accepted for
damage caused by the use of any other parts or accessories.
In order to take account of a policy of continual development, Cirrus Research plc
reserves the right to change any of the information contained in this publication
without prior notice.
Produced by Cirrus Research plc, Acoustic House, Bridlington Road, Hunmanby, North
Yorkshire, YO14 0PH, United Kingdom.
Version 1.1
cr308-310/rev2/1018/en
© Copyright Cirrus Research plc 2018
Contents
1. Overview
2. First time use
3. Instrument features
4. Display interface
5. Keypad interface
6. Instrument operation
6.1 Selecting the frequency and time weighting
6.2 Maximum, minimum and LCpk values
6.3 Setting the level alarm (CR:308)
6.4 Performing and printing a measurement (CR:310)
7. Calibrating the meter
8. Specification and technical information
9. Reference information for periodic testing
10. Options and accessories
11. Serial connection
12. Appendix A - CE Declaration of Conformity
13. Appendix B - Warranty information
14. Cirrus Research oces
4
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CR:308 & CR:310 sound level meters - instrument handbook
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1. Overview
Welcome to your new CR:308/310 series sound level meter. You’ve taken a great step
towards protecting people’s hearing and this entry level meter will make it quick and
easy for you to take simple noise measurements, providing you with the basic data you
need.
The CR:308 is a general purpose digital sound level meter, designed to IEC 61672
to Class 2. The instrument has ‘F’ (fast) and ‘S’ (slow) time response and ‘A’ and ‘C’
frequency weightings. Additional features include max and min hold for the duration of
the measurement, LCpk, and limit alarm, which you can set to indicate if the threshold
you have set has been exceeded.
With the exception of the alarm indication, the CR:310 includes the features of the
CR:308, with the addition of increased measurement capability, including integrating
averaging, and the ability to print results directly from the meter.
2. First time use
Before using your meter for the first time, please check the contents of your instrument’s
case, which should include the following:
• Sound level meter and Class 2 microphone
• Windshield
• 2 x AA batteries
Before starting a measurement, remove the black microphone protective cap (if fitted)
and where necessary, place the windshield carefully over the end of the microphone
capsule.
Microphone
Backlit display
Control keypad
Connectors
Model number

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Tripod mount
Serial number label
Battery compartment
AC/DC out Serial connector for printer*
*Printer functionality only available on the CR:310 model.
USB power input

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4. Display interface
CR:308 & CR:310 main display
Measurement indicator
Overload indicator
Measurement
Alarm indicator
(CR:308 only)
Battery level
Measurement type
Under-range indicator
Calibration display (press the CAL button) - see page 14
Calibrator level
Correction to
be applied
Current
measured level
CR:308 alarm set display (press ) - see page 12
Threshold level set
Alarm level
enabled/disabled
CR:310 measurement display - see page 13
Overall measurement value
Under-range/
overload
indicator
Measurement
duration

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5. Keypad interface
CR:308 keypad
Calibration display (press the CAL button) - see page 14
CR:310 keypad
As per the CR:308 (above) with the following dierences.
Set alarm
Power on/o
Softkey: Exit
Select measurement
view
A or C weighting toggle
Reset max/min
Fast/Slow toggle
Perform calibration
Softkey: CAL/OK
Measurement start/stop
Perform calibration
Softkey: CAL/Print
6. Instrument operation
Fit new batteries by sliding the battery cover open and inserting two AA batteries in the
correct orientation.
Switch on and allow the instrument to settle for 60 seconds before calibrating.
Before starting a measurement, calibrate the instrument as per the guidance in Chapter
7 of this handbook.
6.1 Selecting the frequency and time weighting
Select the measurement frequency and time weighting required:
To toggle between A and C weighting, press
To toggle between fast and slow weighting, press
The measurement type is displayed in the main window:
LAF - A frequency weighting and fast time weighting
LCF - C frequency weighting and fast time weighting
LAS - A frequency weighting and slow time weighting
LCS - C frequency weighting and slow time weighting
To toggle the measurement values, press . This will toggle through the following
measurement values if the meter is set to LAF:
LAF > LAFMax > LAFMin > LCpk > LAF
Integrating averaging measurements Lxeq1s and Lxeq8h are available for measurements
on the CR:310 instrument.
6.2 Maximum, minimum and LCpk values
Maximum, minimum and LCpk values are shown for the duration of time since the
meter was switched on, or since the reset button was last pressed.
These values can be reset by pressing

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6.3 Setting the level alarm (CR:308)
The level alarm function can be used to trigger an alert if the noise level exceeds a
predetermined value, which is set by you.
To set the alarm level, press to enter the alarm set up display.
Set the desired level using the arrow buttons and enable the alarm using the arrow
buttons to select the tick (a cross denotes that the level alarm is disabled). When set,
press (OK).
NB: the alarm level must be set to less than 129dB.
With the alarm level enabled, the main display will show if the level has been exceeded
by showing an Asterix (*) next to the sound level reading. The triggered threshold limit
can be reset by pressing .
NB: this will also reset the maximum, minimum ad LCpk measurement.
6.4 Performing and printing a measurement (CR:310)
Press to start or stop a measurement. Whilst a measurement is running, the latest
values will be displayed on the screen, with the measurement duration shown at the
bottom. Alternative measurement parameters can be viewed by pressing the up/down
arrow buttons.
Overload and under-range are denoted by the ^ and indicators in the top right corner
of the screen.
After stopping a measurement, the overall measurement values are displayed. Press the
up/down arrows to scroll through the overall measurement values.
If a printer is attached, the results can be printed by pressing (Print).
The measurement view can be canclled by pressing (Exit).
^

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7 Calibrating the meter
Before making a measurement, it is important that you calibrate your instrument with
an acoustic calibrator, such as the Cirrus Research CR:514 1kHz 94dB calibrator.
To start the process of calibration, ensure the microphone is fitted correctly and place
the acoustic calibrator over the microphone.
Press to enter the calibration menu.
Use the arrow keys to set the CAL LEVEL to the acoustic calibration level (94.0dB for
the CR:514 calibrator).
Use the arrow keys to set the CORRECT value to 0.2dB, which will make the adjustment
for the gap between the calibrator and the microphone (pressure field of the acoustic
calibrator and the free field of the instrument and microphone) (for HY205 microphone).
This will result in the meter reading 93.8dB when a 94dB calibrator is used.
Switch on the acoustic calibrator and press to automatically calibrate the meter.
Press to exit from the calibration display and to return back to the main display.
8 Specification and technical information
Standards: IEC 61672-1:2013 Class 2
Measurement range: 30dB (A)~130dB (A)
40dB (C)~130dB (C)
Frequency weighting: A and C
Time weighting: Fast (F) and Slow (S)
Display functions: Normal, Maximum, Minimum,
C peak
Measurement functions: LAF, LAS, LCF, LCS, LCpk
Noise floor < 25dB (A) and 35dB (C)
Display flags: Alarm Limit, Overload,
Under-range
Auto calibration range: ±4.5dB
Reference point: 94dB (1kHz), 92.9dB (8kHz)
Settling time: 60s
Display: Backlit 128×64 LCD
Resolution: 0.1dB
Electrical inputs: 5V power in via mini USB
Power: 2 x AA/LR6 1.5V batteries
or 5V DC via Mini USB input
Battery life: 24 hours with alkaline batteries
Microphone: ½” pre-polarised electret
condenser type HY:205
Operating temperature: 0°C to +40°C
Operating humidity: 25%~90%
Atmospheric pressure: 65kPa~108kPa

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Storage Temperature: -20°C to +60°C
Dimensions: 215mm×68mm×32 mm
Weight: 220g (including battery)
Electrical Outputs: AC (tip 3.5mm jack) and DC (middle
3.5mm jack)
DC Output: voltage 15mV/dB, range 450mV~1950mV
AC Output: RMS 2V
9 Reference Information for Periodic Testing
Reference level (1kHz) 94dB
Reference level (8kHz) 92.9dB (A)
Linear range 8kHz 30-130dB
Linear range 4kHz 30-130dB
Linear range 1kHz 30-130dB
LCPeak maximum (500Hz, 1kHz, 8kHz) 133dB
Self-generated noise floor A weight = 25dB
C weight = 35dB
Self-generated noise floor with mic fitted A weight = 25dB
C weight = 35dB
Dummy microphone capacitance 18pf
Recommended dummy microphone KP:66
Multifrequency acoustic calibrator correction data (set to pressure and test on A
weighting)
Frequency Correction
125Hz 0.0
1kHz 0.2
8kHz 2.6

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Free field correction for HY205 microphone.
Frequency / kHz Free field
correction / dB
Frequency / kHz Free field
correction / dB
10.1 6.3 1.7
1.25 0.1 82.6
1.6 0.2 10 4.4
20.3 12.5 5.3
2.5 0.5 16 6.5
3.15 0.7 18 7.1
41.0 20 7.8
51.4 --- ---
Case reflection and windshield attenuation data.
Frequency / kHz Case correction Windshield
correction
Uncertainty
63 0 0 0.27
125 0 0 0.27
250 0.13 0.05 0.27
500 0.18 0.08 0.27
1000 0.09 0.1 0.27
2000 -0.16 0.26 0.27
4000 0.01 0.53 0.32
8000 -0.10 0.26 0.30
16000 -0.17 -0.58 0.29
Add the above data to your measurement to correct.
Directionality plots and case reflection plots

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10 Options and accessories
The following table contains information about the model options and accessories
available with this sound level meter.
Cirrus part number Description
CR:308 Basic sound level meter with threshold
CR:310 Basic sound level meter with
measurement
PR:310 Thermal printer (for CR:310 only)
CR:514 Acoustic calibrator
CK:380 Kit case (empty)
CK:381 CR:308 kit including case, meter and
calibration
CK:382 CR:310 kit including case, meter and
calibrator
UA:30X Spare windshield
CP:65 Carrying pouch (sound level meter and
calibrator)
11 Serial connection
DB9, RS232 communication rate at 9600 Baud.
1 bit start, 8 bits data, 1 bit stop, No parity

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12 Appendix A - CE Declaration of Conformity
Manufacturer:
Cirrus Research plc
Acoustic House
Bridlington Road, Hunmanby
North Yorkshire
YO14 0PH
Telephone: [phone]
Equipment manufactured after June 2018.
Equipment description
CR:308 sound level meter
CR:310 sound level meter
Along with their standard accessories.
According to:
EMC Directive 2014/30/EU
Low Voltage Directive 2014/35/EU
Signed June 2018
Martin Williams
Director
13 Appendix B - Warranty Information
1. The period of the initial guarantee starts from the date of purchase, as a new
instrument, from Cirrus Research plc or their formally approved distributors. The
periods are as follows unless otherwise stated by Cirrus Research plc in writing:
Products manufactured by Cirrus Re-
search plc
24 months
Repairs 3 months
Replacement microphone capsules 12 months
Spare parts (excluding replacement
microphone capsules)
3 months
Products manufactured by a third party
(see clauses 12 & 14 below)
Based on the individual manufacturer’s
warranty
2. The initial guarantee covers all faults and accidental damage to the product.
3. Warranty extension
If the product is returned to Cirrus Research plc or one of its Authorised Service &
Calibration Centres for routine verification & calibration after the initial guarantee
period, upon completion of the verification the product will be given an additional free
one (1) year warranty.
This must be done with a 6-week window of the anniversary date of shipment. This is
limited to 3 weeks either side of the anniversary date of the shipment.
It follows that if an instrument is routinely verified by Cirrus Research plc (or an
Authorised Service & Calibration Centre) every year after the initial warranty period, the
warranty is eectively continuous to a maximum of fifteen (15) years from the original
date of purchase.
There will be a charge for the verification (or calibration) of the equipment.
4. Buying back into the warranty
Where the warranty has expired, the customer can buy back into the warranty scheme.
This reactivates the warranty for a further 12 months and provides the same level of
cover as for the initial period above.
This must be purchased at the same time as a calibration or verification.
The maximum period of any warranty, whether it had been extended or not, is 15 years
from the original purchase date.

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This oer can only be redeemed once during the life of the instrument.
5. The initial guarantee, and any extended warranty is not transferrable and is provided
to the original customer only.
6. Where a product is returned for routine verification or calibration, the customer is
responsible for all transportation, duty and other charges.
7. The user shall be responsible for determining if the product is suitable for the use and
that such use complies with any applicable laws, regulations or standards.
8. The customer must notify Cirrus Research plc in writing of any claimed defect in the
product immediately upon discovering it.
9. Where an instrument is being returned under the guarantee or warranty, it must
be returned to Cirrus Research plc without undue delay at the customer’s risk with
transportation charges prepaid.
10. Where the product is deemed to be faulty due to manufacturing defects,
Cirrus Research plc shall:
a. Repair or replace the defective products
b. Be given reasonable time by the customer to make such repairs or
replacements
c. Return the product to the customer at Cirrus Research plc’s expense
11. Cirrus Research plc reserves the right to decline an instrument under the initial
guarantee or extended warranty where;
a. The product has continued to be used after defect has been discovered
b. There is clear evidence of damage or misuse that is deemed to be more
than minor accidental damage
c. The product has been modified or repaired by persons other than those
authorised by Cirrus Research plc
d. The defect arises from the use of the product in conjunction with
products or materials not reasonably contemplated by Cirrus Research plc
e. No fault is found with the product
12. The initial guarantee or extended warranty does not extend to products or materials
not supplied by or manufactured by Cirrus Research plc. Consumable items, including
dry-cell and alkaline batteries are not covered by the initial guarantee or extended
warranty.
13. Where re-chargeable batteries are used as an integral part of the product design and
the product is shipped with the batteries installed (for example the doseBadge5 Noise
Dosimeter), the standard product guarantee and extended warranty applies provided
that the user has used the correct charging instructions and has followed the charging
regime stated in the product manual.
14. No warranty is oered for used equipment unless a special arrangement is made
and is confirmed in writing by Cirrus Research plc
15. Cirrus Research plc reserves the right to amend or update these terms and conditions
without notice.
This warranty does not in any way reduce or aect the legal rights of the buyer and is
in additional to any statutory rights.

CR:308 & CR:310 sound level meters - instrument handbook
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14 Cirrus Research oces
The addresses given below are the Cirrus Research plc oces. Cirrus Research plc also
have approved distributors and agents in many countries worldwide. For details of your
local representative, please contact Cirrus Research plc using the information below.
Contact details for Cirrus Research authorised distributors and agents are also available
from the website at the address shown below.
Head Oce
Cirrus Research plc
Acoustic House
Bridlington Road
Hunmanby
North Yorkshire
United Kingdom
YO14 0PH
Telephone: [phone]
[phone]
Fax: [phone]
Email: [email protected]
Website: www.cirrusresearch.co.uk
Cirrus Germany
Cirrus Research plc Deutschland
Arabella Center
Lyoner Strasse 44 – 48
D-60528 Frankfurt
Germany
Telephone: [phone]
Fax: [phone]
Email: [email protected]
Website: www.cirrusresearch.de
Cirrus Spain
Av. Diagonal 468, 6°
08006 Barcelona
España
Telephone: [phone]
Email: [e-mail]
Website: www.cirrusresearch.es
Cirrus France Ltd
679 avenue de la République
59800
Lille
France
Telephone: [phone]
Email: [email protected]
Web: www.cirrusresearch.fr
Cirrus Environmental
Unit 2 Bridlington Road Industrial Estate
Hunmanby
North Yorkshire
YO14 0PH
United Kingdom
Telephone: [phone]
Email: sales@cirrus-environmental.
com
Website: www.cirrus-environmental.com

cr308-310/rev2/1018/en
www.cirrusresearch.co.uk
[email protected]