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Cirrus Optimus Yellow

Basic Workplace Sound Level Meter

Cirrus Optimus Yellow SLM
Cirrus Optimus Yellow Kit
DSC_0078-1 - Copy_edited


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.

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

Data Download

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.

Full Specification

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.

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