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Cirrus Research · Optimus+ · Handheld sound level meter

Optimus+ Industrial Sound Level Meter

Current

Handheld Class 1 or Class 2 sound level meter for occupational noise surveys, measuring all frequency and time weightings at once in a single 20 to 140 dB range. Models run from basic level and time history (CR:151B/152B) through integrating Leq, peak and noise dose (CR:161B/162B) to real-time 1:1 octave bands (CR:161C/162C). All record VoiceTag audio notes and download to NoiseTools.

Specifications verified on .

Type
Handheld sound level meter
Class
Class 1
Channels
1
Octave bands
1/1
Connectivity
USB type B, Bluetooth Low Energy, AC/DC output (ZL:174 cable)
Weight
300 g
Battery life
12 h
Compare with other instrumentsAll handheld sound level meters

Specifications

As published by Cirrus Research. Fields the manufacturer does not publish are omitted rather than estimated.

Standards and class — Optimus+ Industrial Sound Level Meter
SpecificationValue
IEC 61672-1 classClass 1
StandardsIEC 61672-1:2013 class 1 or class 2, IEC 61672-1:2002 class 1 or class 2 group X, IEC 60651:2001 type 1 or type 2, IEC 60804:2000 type 1 or type 2, IEC 61252:1993, ANSI S1.4-1983 (R2006), ANSI S1.43-1997 (R2007), ANSI S1.25:1991, IEC 61260:1996 and ANSI S1.11-2004 (octave band models), DIN 45657:2005-03
Pattern approvalsPTB (DIN EN 61672), optional, LNE (IEC 61672), optional, Leq and octave band models
Measurement — Optimus+ Industrial Sound Level Meter
SpecificationValue
Channels1
Measurement range20 to 140 dB, single RMS range
Frequency range31.5 Hz to 16 kHz (1:1 octave bands, C models)
Frequency weightingsA, C, Z
Time weightingsF, S, I
Simultaneous weightingsYes
ParametersLXY (X = A, C, Z; Y = F, S, I), LXYmax, LXYmin, LXeq, LCpeak, LZpeak, LApeak, LCeq-LAeq, LXE, LAIeq, LAVG, Dose and estimated dose, NR/NC (C models)
DosimetryYes
Exchange rates3 dB, 4 dB, 5 dB
Analysis — Optimus+ Industrial Sound Level Meter
SpecificationValue
Octave bands1/1
Audio recordingYes
Logging and data — Optimus+ Industrial Sound Level Meter
SpecificationValue
Shortest logging interval10 ms
Memory8 GB standard; 32 GB factory option
Hardware — Optimus+ Industrial Sound Level Meter
SpecificationValue
Microphoneclass 1: MK:224 or MK:229 1/2" pre-polarised; class 2: MK:216 pre-polarised
Detachable preamplifierYes
Displayhigh-resolution colour display with ambient light sensor and illuminated keypad
Battery4 x AA alkaline or lithium
Battery life12 h
External power5 to 15 V DC via ZL:171 cable
Weight300 g
Dimensions (mm)283 x 65 x 30
Operating temperature (°C)-10 to 50
Connectivity and software — Optimus+ Industrial Sound Level Meter
SpecificationValue
ConnectivityUSB type B, Bluetooth Low Energy, AC/DC output (ZL:174 cable)
Remote controlMyCirrus mobile apps (iOS, Android) via Bluetooth
SoftwareNoiseTools, MyCirrus app

Variants

Variants of the Optimus+ Industrial Sound Level Meter as the manufacturer names them
VariantDifference
CR:151B / CR:152BClass 1 / class 2; sound level, maximum level and time history only
CR:161B / CR:162BClass 1 / class 2; adds integrating (Leq) and peak parameters, noise dose and estimated dose
CR:161C / CR:162CClass 1 / class 2; adds real-time 1:1 octave bands and NR/NC values and curves

Where this data comes from

Manufacturer documents used for this record
KindDocumentAccessed
Product pageOptimus+ Industrial Sound Level Meter
DatasheetOptimus+ Industrial datasheet (English, 2026)
ManualOptimus user manual (English)

Verified on . Only the manufacturer’s own published material is used; distributor pages are not sources.

Spec out of date? Tell us (reference cirrus-optimus-plus-industrial).

Verified owner reviews

Reviews from people who own and use this instrument, each checked against a serial number by a person.

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Known issues and firmware notes

Hardware and firmware problems reported by owners, with the firmware version concerned and any manufacturer response.

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Feature requests

Functions owners would like to see in a firmware update or a successor model.

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