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MinusNine Digital Hard Squelch

MinusNine miniature, inductively-coupled wireless earphone with Hard Squelch



The MinusNine is a miniature, inductively-coupled wireless earphone utilising an advanced digital microelectronics platform running custom software. It produces outstanding speech quality, reduced interference levels, precise output level control and is anatomically profiled to fit deep into the ear canal making it discreet, secure and usable in the left or right ear. Special functions include hard-squelch, which fully mutes the earphone when no audio signal is present, automatic gain control and low battery alarm. The MinusNine is robust and designed to operate in hostile environments and incorporates a hygienic user-replaceable cerumen (earwax) filter system. Design emphasis has been placed on its ability to suppress interference; typically generated by data systems in vehicles, TDMA noise from TETRA/P25 terminals and Cellphones as well as mains-borne noise from electric motors, neon signs and power lines. A full range of compatible neckloops, shoulder loops and brooch inductive transmitters is available to operate with the MinusNine wireless earphone.


  • Frequency Range: 300-3000Hz

    DSP Type: Digital Hybrid, DSP and EEPROM with custom Firmware & Software

    Distortion: <10% @ 1kHz

    Receiver: Magnetic moving armature

    Max Output Sound Pressure Level (2cc coupler) @1kHz:96dB ±2dB or preset to customer requirement

    Quiescent Noise Control (no audio input): Soft Squelch. Hard Squelch option

    Quiescent Noise (Soft Squelch): 35dB (With hard squelch option quiescent is silent)

    End of Battery Life: Audible Beep

    Battery: 1.4 VDC A10 Zinc Air or Equivalent

    Minimum Operating Voltage: 1.1 VDC

    Typical Battery Life (A10 Zinc Air):>50 hours

    Sensitivity (Standard): 75dB@1kHZ ±3dB/10mA/M

    Size: Nominal max, Length:15mm x Width:8mm

    Weight (including battery): 1.75 grams inc. battery

    Operating Temperature Range: -10°C to +40°C

    Cerumen Filter Type: Replaceable Mesh Filter

    Colour Options: Beige, Mid Brown, Dark Brown

    Custom Fit Option: Available at additional charge. Ear impressions required

    CE Conformity: 89/336/EWG-Electromagnetic Compatibility

    ROHS & WEEE: ROHS: Compliant. WEEE: Compliant




Contact Us

Sensorcom Ltd.

London, BR3 4LZ, 

United Kingdom

Tel: +44 (0) 208 639 4440

Fax: +44 (0) 208 639 4442

E-Mail: info@sensorcom.com 


The MEL Group

Laurence Walter House

Addison Road, Chilton Ind. Est,

Sudbury, Suffolk

CO10 2YW, UK


BSI registered

Holds Certificate No: FM 561435 and operates a Quality Management System which complies with the requirements of ISO 9001:2008 for the following scope:

The design, manufacture, repair and supply of audio communication devices, assisted listening devices and a range of associated products and accessories.


The “end of life disposal” of electrical products  in an environmentally friendly way, is the responsibility of the Purchaser.