The Ideal Solution for Simple Noise Measurements Optimus Yellow Sound Level Meters

The Optimus yellow instruments are a range of state-of-the-art sound level meters that have been designed to meet the very latest standards for noise measurement instruments.

It has been purposed-designed for applications where only basic noise data is required, such as Sound Level (SPL) or Maximum Sound Level (Lmax). These applications include fire alarm testing, machinery servicing and noise ordinance enforcement.

See what the Optimus Yellow can do for you. Use the form to contact our Noise Experts today.

Why Choose Optimus Yellow?

Optimus® is a Registered Trademark of Cirrus Research plc

Noise Measurement Made Easy

We want to make your job easier, so we designed to Optimus Yellow to offer the highest level of performance without the complicated setup.

  • Every parameter is measured simultaneously, so you can't choose the wrong function or miss any data
  • All it takes is 3 button pushes to get the Optimus Yellow to start measuring. Switch On. Calibrate. Start. It's that simple
  • With it's large OLED display, you can easily view your measurements

Downloading Your Data is Simple

If you need the data logging version of the Optimus Yellow, we'll include our NoiseTools noise analysis software so you can keep a record of your measurements. View the full specifications on the product table below.

You can upgrade this instrument to an Optimus Red or Optimus Green at any time, future-proofing your investment. Contact our Noise Experts today to find out more.

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What our customers say..

It is a first class instrument and should be the prime tool of all environmental and occupational health officers...

Dr Philip Dickinson, Professor, Massey University, New Zealand

Related Products

Which Optimus Yellow is right for you?

There are 4 versions of the Optimus Yellow Sound Level Meters, 2 with Class 2 performance and 2 with Class 1 performance.

The table below shows the different versions and options available with each instrument.

You can also use our interactive Optimus Product Selector to find the best instrument for you.

Instrument Class 1 Class 2 Sound Level Data Logging VoiceTag Software Support Measurement Kit
CR:152A Yes Yes CK:152A
CR:151A Yes Yes CK:151A
CR:152B Yes Yes Yes Yes Yes CK:152B
CR:151B Yes Yes Yes Yes Yes CK:151B

More Information

Find out more

If you have any questions or if you would like any more information, please contact us and we will be pleased to help.

From the UK, contact us on 0845 230 2434.

From outside the UK, please contact us on +44 1723 891655.

You can also contact us via our contact form.



Applicable Standards

IEC 61672-1:2013 Class 1 or Class 2

IEC 61672-1:2002 Class 1 or Class 2 Group X

IEC 60651:2001 Type 1 I or Type 2 I

ANSI S1.4 -1983 (R2006), ANSI S1.43 - 1997 (R2007)

ANSI S1.25:1991


Class 1 MK:224 pre-polarized, Class 2 MK:216 pre-polarized

Microphone Preamplifier

MV:200 Removable Preamplifier (All versions)

Total Measurement Range:

20dB to 140dB RMS Single Range

Noise Floor: <18dB(A) Class 1, <21dB(A) Class 2

Frequency Weightings

RMS & Peak : A, C, & Z Measured Simultaneously

Time Weightings

Fast, Slow & Impulse Measured Simultaneously


High resolution OLED display. Ambient light sensor & illuminated keypad


4GB (B Version), 32GB factory fit option


Measurement verification data stored in secure memory

Time History Data Rates (Global settings)

10ms, 62.5ms, 125ms, 250ms, 1/2 sec, 1 sec, 2 sec (User selectable)

VoiceTag Audio Recording (B Version)

Up to 30 seconds of audio notes with each measurement

Measurement control

Pause & Back Erase with user selectable duration


Size: 283mm x 65mm x 30mm

Weight: 300gms/10oz


4 x AA Alkaline

Battery life

Typically 12 hours with Alkaline AA

Typically 20 hours with Lithium AA Non-Rechargeable

Battery life is dependent upon the battery type, quality & screen brightness


USB Type B to PC

AC & DC Output via ZL:174 (2 x Phono, 1m)

Multi-pin IO for external power via ZL:171 cable (2.1mm socket)

External Power: 5v-15v via MultiIO socket via ZL:171 cable (2.1mm socket)

Tripod Mount

1/4" Whitworth socket


Material: High Impact ABS-PC with soft touch back & keypad


Temperature: Operating -10°C to +50°C, Storage -20°C to +60°C

Humidity: Up to 95% RH Non Condensing

Electromagnetic performance

IEC 61672-1:2002 & IEC 61672-2:2003

Except where modified by EN 61000-6-1:2007 & EN 61000-6-1:2007

Language options

English, French, German, Spanish. Other language options may be available

Software Support

NoiseTools Download, Configuration & Analysis software supplied as standard. Compatible with Microsoft Windows XP, Vista, 7 & 8 (32bit & 64bit)

Measurement Functions

CR:152A & CR:151A

Displayed Functions


Measurement Run Time

CR:152B & CR:151B

Displayed Functions


Measurement Run Time

Stored Functions

LXYMax & Time History of LXYMax

Time & Date of Measurement Start

where x=A ,C ,Z; y= F, S, I

Other functions may calculated by the NoiseTools software and displayed on download.