Optimus Yellow Sound Level Meters- CR:150 Series

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The Optimus Yellow is the entry-level device of Cirrus’ well-renowned Optimus range. Capable of measuring the maximum noise level during a session, this device provides simple and easy-to-understand data.

The Optimus Yellow is a state-of-the-art sound level meter that has been designed by the engineers at Cirrus to meet the very latest standards in noise measuring and monitoring.

Most suited for applications where only simple noise level data is required, the Optimus Yellow can record the maximum sound level (LMax) in decibels, which refers to the loudest recorded noise level during a period of data capturing. This data will give you a basic understanding of the noise levels where you are measuring, and will allow you to identify any particular noise hotspots.

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 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 displa