Sound Level Meters

CEL633 Integrating Sound Level Meter


The CEL633A Sound Level Meter is for measuring environmental noise in communities and around the perimeter of industrial sites.

  • Environmental Noise Surveys
  • BS4142 Mixed Residential and Industrial Noise
  • Noise at Work Assessments
  • Data Logging with Time History Noise Profile stores
  • Voice Notes and Audio Recording
  • Automatic Timers
  • Measures Leq, Min, Max, Ln, etc. Simultaneously
  • Range: 20 to 140 dB(A)
  • Data Markers and Back Erase
  • Weatherproof Outdoor Kit available


  • IEC 61672 Class 1 or Class 2
  • IEC60851 and IEC 60804 Type 1 or Type 2
  • ANSI S1.4 and ANSI S1.43 to Type 1 or Type 2

The CEL633A sound level meter is available as either Class 1 or Class 2 - the most common for environmental noise measurement and more accurate being Class 1. This meter also has everything needed for occupational noise measurement in line with the EU regulations, making it ideal for anybody involved in both environmental (outside the factory) and occupational (inside the factory) noise.

If the meter is to be left unattended in poor weather conditions then the Outdoor Kit should be used to offer protection against the elements. The Outdoor Kit also includes a rechargeable battery pack for longer term monitoring.

peli case

Exclusive to Midas

The Class 1 Noise Measurement Kit (CEL633A1-K) is supplied in a tough Peli Case with custom foam to protect the meter, calibrator and accessories.

Average Sound Level and Statistical Parameters

The CEL633A has a very wide span, covering 20 to 140dB in a single range. This is particularly important when monitoring in an environmental with generally low noise levels and occasionally high ones - for example when cars pass. The most useful parameter when measuring environmental and community noise is the Leq, the average sound level. The meter measures the periodic Leq and also includes five Ln values for statistical analysis of the noise.

Data Logging and Insight Software

The CEL633A comes complete with data logging capability with measurements stored in the meter's large internal memory.


When connected to a Windows computer using the free CasellaDrive software, the meter acts like a memory stick (shows as a removable drive) so the measurements can be loaded into a spreadsheet or moved to your hard drive for long term storage. There is no need to buy special software.


sound meter softwareDue to the large amount of data and the potential complexity of the measurements, we would recommend the use of the Insight software. It simplifies the process of downloading the measurements and stores them in a database, managed by person, place or process criteria. To get the Insight software for the CEL633A include item ISC020 with your order.

Our Recommendation

Most environmental noise surveys demand the use of a Class 1 Sound Level Meter that can make repeating measurements, such as the 5 minute LAeq and L90 (background noise), as required by BS4142 and related regulations. We recommend the standard CEL633A1 Class 1 Sound Level Meter for most situations. If tonal noise is present or a frequency analysis is required by the regulations then we recommend the CEL633C1 Environmental Sound Level Meter with 1/3 Octave Bands.

Most applications demand the use of a Calibrator to check the function of the meter, so we recommend the CEL120/1 Calibrator.

Finally, we also recommend the Insight software to ease download and processing. If unsure, Insight can be easily added at a later date.


The CEL633A is a Sound Level Meter that includes the usual environmental noise measurement parameters such as statistical Ln and Leq. It also has a detailed Time History store, audio recording and automatic measurement timers.

  • Environmental noise measurements
  • Noise Ordinance and Community noise assessments
  • Noise in mixed residential and industrial areas - BS4142
  • Occupational noise measurements
  • Noise source identification

Due to the nature of environmental noise surveys (both the acoustic nature and the political nature) we recommend the use of a Class 1 sound level meter.

The version of the CEL630 series of meters includes all the Environmental noise parameters along with a detailed time history store and automatic timers, making it ideal for both short term and longer term assessments.

As most occupational noise regulations accept Class 2 as being adequate, all versions of the CEL633 are suitable for that application too. If you need to measure both environmental and occupational noise then this meter will do both.

Short Term Environmental and Community Noise Surveys

The CEL633 sound level meter measures the noise parameters that are needed by most regulations:

  • Periodic A-weighted Leq (the average sound level)
  • Ln Percentiles (the statistical values such as L10 and L90)

Noise Source Identification

Unattended noise measurement is convenient but causes problems when the time comes to identify the source of the noise. Was it a car, a strong gust of wind blowing the leaves or somebody shouting. The CEL633 can record the audio so that you can listen to the interesting bits, enabling you to make a positive identification of the noise source.

Please visit the Voice Notes and Audio Recording page for more details.

Long Term Environmental Noise Surveys

The addition of a detailed time history store allows for post processing and graphing the noise levels down to a resolution of 1 second, and the automatic timers make it easy to run repeating measurements (for example repeating 5 minute measurements in addition to the 1 second Time History).

The sound level meter can by mounted on a standard camera tripod, but if it is to be left unattended in poor weather conditions you will also need the weather protection offered by the Outdoor Kit.

Occupational Noise

The CEL633 is also suitable for the measurement of noise in the workplace:

  • Leq (average sound level) for LEP,d calculations
  • Peak for loud banging noise
  • "A" and "C" weighting for hearing protector evaluation

Environmental Noise

The CEL633A is an Environmental sound level meter, suitable for applications that demand an accurate meter of the correct grade along with detailed measurement storage with Time History and automatic measurement timers.

This meter can be used without a computer, reading the measurements from the screen, but really benefits from having the Insight software to download the detailed time history measurements.

  • Designed for environmental noise measurements
  • Meets the required standards (Type 1 or Type 2)
  • All parameters needed: LAeq, LAmax, Ln, etc.
  • Storing and download to computer
  • Detailed time history store
  • Colour coded display for ease of use

As this meter measures all parameters at the same time there is no need to select what you need beforehand. Just make the measurement and everything is there.

1. Calibration Check

Most regulations state that the meter's calibration should be checked before making measurements, and that you should keep records of these calibration checks.

Fit the Calibrator over the microphone as shown on the right and switch it on. The meter automatically detects the presence and correct fitting of the Calibrator and then starts the calibration process, which only takes a few seconds.

Calibration details are stored in the meter so that you can either make note or download them to a computer.

calibrating the meter
Calibration Check

Manual Measurements

To start a measurement, simply press the Run/Stop key, shown on the right.

This starts the measurement and storing process for all parameters, the most important being LAeq, Lmax and Ln (L10, L90, etc). It also stores the time history of the noise, which provides a graph of the sound level over time.

When you are happy that you have measured for long enough simply press the Stop key.

start noise measurement
Starting a Measurement
Not Running

Colour Coded Display

The current state of the sound level meter can be seen at a glance.

When not running the meter shows the current sound level and the border is red.

When running the meter shows the measurement parameters such as Leq and the border is green.


Automatic, Repeating Measurements

timed noise measurements
Setting the Timers

For many environmental noise surveys, you need periodic (usually 5 minute, 15 minute or 1 hour) measurements showing values such as the Leq and the L90.

To make this type of measurement, set the meter to make repeating measurements of the required duration. The meter will now run for the specified period. It will then stop, store the results and start again automatically. Advanced timers even allow different measurement times for different days.

It is better to mount the meter on a tripod for this type of measurement. A tripod mount is included on the back of the meter. It can be fitted to a standard camera tripod, or we can provide you with a suitable one.


Measurement Stores

The CEL633A comes complete with a number of noise measurement stores:

  • Time History - usually set to a fast rate, such as 1 second, to provide a detailed graph of the sound level over time
  • Periodic Measurements - usually set to 5 minutes, 15 minutes or 1 hour depending on applications. Can also be fixed periods. These are the most important environmental noise measurements, including parameters such as LAeq, LAmax and LA90.
  • Audio Recordings - recordings of the actual sound so you listen and make a positive identification of the noise source.

All these measurement stores are included with the CEL633A sound level meter, even if you choose not to buy the additional software. There is more information below about the different download options.

The more advanced Insight software can be downloaded free of charge for 30 days in case you are not sure whether you need the extra reporting features that it offers.

CasellaDrive Free Software

caselladrive sound level software

When the CEL633A is connected to a computer it works like a memory stick, so there are no complicated driver installations. However, the files are coded and compressed so you won't be able to read them directly.

The CasellaDrive software decodes the files and makes them available to copy into Excel or any similar spreadsheet program.

Most files are simple Comma Separated Text (CSV) files that can be read into many different programs. Audio recordings are in the standard WAV format, to be listened to using standard media playing applications.

More information on the CasellaDrive page.

Insight Software

insight noise management software

The Insight software is an option that can be purchased with the meter or at a later date. A trial version can also be downloaded - this is a full featured version of the software but time limited to 30-days, after which time you need to buy a licence to continue using it.

This software downloads the measurements from the sound level meter, storing them on your computer. You can carry out analysis of the sound levels and produce a number of reports.

For more information please visit the Insight page.


The CEL633A Environmental Sound Level Meter is available on its own or with a selection of accessories. The standard CEL633A1 meter satisfies the needs of most environmental noise surveys and occupational noise assessments.

  • Class 1 or Class 2? - Regulations will usually state which you need
  • Accessories? - Calibrator is often essential, carrying case is useful.
  • Insight Software? - Makes download and analysis more convenient


Sound Level Calibrator

sound level calibrator

The most important of the accessories is the Calibrator. Most regulations state that you should use one to check the function of the meter before making any measurements.

Class 1 or Class 2 Sound Level Meter?

A Class 1 sound level meter is a little more accurate than a Class 2 model. Many environmental noise regulations, and the authorities controlling them, demand the use of a Class 1 sound level meter for this type of application. Check with your regulations first. If you have any doubts then a Class 1 meter is the safer option, as you are not left explaining why you used the less accurate model. If in doubt, contact us on for advice.

Insight Software

The CEL633A is a data logging meter that does not require any additional software - when plugged into a computer it acts like a memory card. You can manually copy the data to your computer or load it into a spreadsheet program using a small conversion application. However, the Insight software makes this process more convenient, links the measurements to person, place or process, and presents the results graphically.

We recommend the Insight software with the CEL633 if you are going to take advantage of the Time History store as processing the large amounts of data in a spreadsheet can be rather time consuming.

High Level Microphone - 165dB

For some applications with extremely high noise levels, such as weapons testing, firing ranges and controlled explosions, the standard upper limit of 140dB may not be adequate. In this case we have a 1/4" High Range microphone that extends the measurement limit to 165dB.

Please see the High Range Microphone page for more information.

Order Codes

Sound Level Meter CEL633A1 - Class 1 Integrating Sound Level Meter £2155.00
  CEL633A2 - Class 2 Integrating Sound Level Meter £1640.00
Calibrator The Calibrator is available as Class 1 or Class 2, usually to match the class of the meter:  
  CEL120/1 Class 1 Sound Level Calibrator £515.00
  CEL120/2 Class 2 Sound Level Calibrator £252.00
Software ISC020 Insight Software £295.00
Accessories CEL6840 Carrying Case for CEL633 Sound Level Meter, Calibrator and accessories £74.00
  PELI-SLM Peli Case for CEL Sound Level Meter, Calibrator and accessories. £175.00
  PC18 AC Power Adapter for the CEL633 Sound Level Meter £32.00


The CEL633A1 and CEL633A2 data logging Integrating Sound Level Meters are available as either Class 1 or Class 2 as defined by the international sound level meter standards.


Sound Level Meter Standards

  • IEC 61672 Class 1 or Class 2
  • IEC 60651 and IEC 60804 Type 1 or Type 2
  • ANSI S1.4 and ANSI S1.43 Type 1 or Type 2


Using a meter that meets these standards is essential for repeatable results and especially for any measurements that will be used for legal purposes.

Measurement range 20 to 140 dB (single range), 143 dB Peak Measured Parameters  
Display 320 x 240 pixel color TFT Frequency weightings A, C and Z (simultaneous)
Output to PC USB Mini B Time weightings Fast, Slow and Impulse
    Amplitude weightings Q3, Q4 and Q5
Batteries 3 x AA Alkaline Thresholds 70 to 90 dB (applies to Lavg)
  (15 hours with backlight off)    
External Power 9 to 14V DC at 150mA Sound Level LXY, LXYMax, LXYMin, LC-LA
  (2.1mm connector) Integrated LXeq, Lavg, LAE
    Peak LXPeak
Dimensions 72 x 229 x 31mm, 295g Takt Max LTM3, LTM5, LXIeq
  2.8" x 9.0" x 1.2". 10.4oz Statistical 5 x Ln values
Memory 2GB Time History Level 1 Periods of 1 minute to 1 hour
  >1 year when logging set to 1 second Time History Level 2 Periods of 1 second to 30 mins
Timers Duration 1s to 24h    
  On/Off Timers: 6 sets with selectable times    
  and repeat function.    
Audio Recording 8kHz sampling, 60 hours recording Where X is frequency weighting A, C or Z
  24kHz sampling, 10 hours recording and Y is time weighting Fast, Slow or Impulse

Prices and Ordering

The Class 1 sound level meter is available alone or as part of a Kit, which includes Meter, Calibrator and Peli Carrying Case.

Order Code
Price (GBP)
Type 1 / Class 1 Advanced Integrating Sound Level Meter
In stock
Kit with CEL633A1 Sound Level Meter, Calibrator, Windshield, Peli Case
In stock
Insight Software for CEL620, CEL630 and dBadge
In stock


The Class 1 sound level meter is available alone or as part of a Kit, which includes Meter, Calibrator and Peli Carrying Case.

Order Code
Price (GBP)
Type 1 / Class 1 Advanced Integrating Sound Level Meter
In stock
Kit with CEL633A1 Sound Level Meter, Calibrator, Windshield, Peli Case
In stock
Insight Software for CEL620, CEL630 and dBadge
In stock


Individual items and spares for the CEL633 series meters.

Order Code
Price (GBP)
Class 2 Acoustic Calibrator
In stock
Class 1 Acoustic Calibrator
In stock
Case for CEL240 and 600 Series Sound Meter and Calibrator
In stock
Peli Case and Foam for CEL Sound Meter and Accessories
In stock
Windshield for CEL240 and 600 Series Sound Level Meters
In stock
Power Supply Unit for CEL dBadge and SLM
In stock
Microphone Extension Cable 5m
1 week
Microphone Extension Cable 10m
1 week
Microphone Extension Cable 30m
1 week
Power Supply for USB Powered Meters
In stock
Car Accessory Socket Power Supply for USB Powered Meters
In stock
High range microphone (165dB) for CEL630 series
3 weeks
High range microphone adapter
3 weeks


The CEL633C1 (top of the range version) is available for hire as a hand-held meter or as part of an Outdoor Kit.

CEL633C1-K Noise Kit Hire
First week: £262.00 then £34.00 for any additional days. Price includes delivery and collection.

WPK-633C1 Outdoor Noise Measurement Kit
First week: £325.00 then £42.00 for any additional days. Price includes delivery and collection.

Delivery Charges within the UK

These delivery charges are for Sound Level Meters and Noise Measurement Kits within mainland UK.

Meters and Kits £12.00  
Small Spares £6.00  

Value Added Tax - VAT

VAT is charged at 20% on all our products shipped to a UK address or invoiced to a UK address.

Contact Midas

Midas Safety Services are happy to discuss your Sound and Noise Level Testing requirements and arrange a no-obligation meeting if that would be helpful.

Please contact us on 0117 318 2163/0776 232 3367 or email

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CEL633 noise at work sound level meter

CEL633 Sound Level Meter

Product List:


General purpose sound level meter which is very easy to use.

CEL620B Octave Band sound level meter

A practical meter perfect for a detailed noise at work survey and subsequent hearing protection assessment.


Class 2 Sound Level Meter.


Data Logging Integrating Sound Level Meter.

Dosebadge Kits

The doseBadge is a unique solution for Personal Noise measurements.


Noise Dosemeter and Handled Meter Combinations.


Environmental Sound Level Meter


CEL633C Environmental Sound Level Meter with 1/3 Octaves