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CLS1 wall mount perimeter hearing loop driver


The Ampetronic CLS1 is the first in a series of induction loop drivers aimed at the demands of the electrical and audio-visual contractor.

Designed for simple discrete installation, the CLS1 is one of the most cost effective and capable solutions in its class. The amplifier is compact and designed specifically for wall mounting. All connections and controls are secured behind a tamper resistant, hinged, detachable cover. Combined with its small size, the range of mounting and cabling options ensure that installation is convenient and tidy in any environment. Input options are comprehensive, with three independent inputs for balanced microphone, balanced and unbalanced line, low impedance and 100V – line speaker systems.

Backed up by Ampetronic’s standard 5 year warranty and comprehensive support services, the CLS1 is truly fit and forget.

Applications include
  • Community Centres
  • Board rooms
  • Churches
  • Interview rooms
  • Meeting rooms
  • Classrooms

The CLS1 enclosure is designed for simple, permanent installation, with secure lid protecting connections and controls, while leaving operation indicators visible. The case is designed to make access simple, and to ensure the amplifier can be installed in the most constrained spaces.


Designed for vertical panel mounting using 4 screws (6 holes provided). Template for screw placements provided. The CLS1 is compact enough to fit on a 1U rack tray with feet removed.

Enclosure access

Hinged lid, secured by 2 Phillips PH2 screws. Lid can be removed completely if required, for ease of access, or if there is no room to hinge the lid forwards.

Cable routing

Knock-outs (diameter 20mm) are provided for routing cables into the enclosure. 2 on the top edge, 4 on the rear face, 4 on the bottom edge, providing excellent installation flexibility.

Cable connections

All input cable connections are made with screw terminals mounted on one side of the PCB. Mains power connections are made to a chassis mounted screw terminal block. Loop connection is made to a screw terminal pair mounted on the PCB. Cable connections are illustrated on a detailed label on the case interior.


3 LED indicators are visible with the case open or closed:

  • AGC Amber LED lit when input signal is activating the automatic gain control
  • Current Green LED lit when current is running in the loop
  • Power Green LED lit when the unit has power


Five controls are located to be accessed only with the lid open, all screwdriver adjustable.

  • Level controls for inputs 1, 2 and 3
  • Metal loss correction
  • Loop drive current

Product Code:

  • Features
  • Specifications
  • Downloads
    • Quick and simple to install
    • Area coverage to >200m2
    • 3 independent configurable inputs
    • Wall mounted
    • Metal Loss Correction
    • 5 Year warranty
    • Cabling and controls behind tamper resistant cover
    • Free Technical support
  • Perimeter Loops – Area Coverage (maximum)

    The CLS1 is designed for perimeter loop applications.

    Room aspect ratio1:12:13:1
    Maximum area coverage m2 120150200

    For any Induction Loop System, area coverage is dependent on several factors. Please check these assumptions and contact Ampetronic for advice if required:

    • The loop is 1-2m above or below the receiver height
    • There are no metal structures in the plane of the loop
    • There is sufficient voltage to drive the cable length – check table below.

    Maximum Cable Length

    The CLS1 is designed for SINGLE TURN loops for optimum audio quality:

    • Loops with DC resistance from 0.20Ω
    • Impedance up to a maximum of 1.8Ω

    Maximum cable length is dependent on cable type and on the application.

    Cable typeMaximum Cable Length (m)
    Normal UseTransient Speech
    1.0mm2 copper6879
    2.5mm2 copper93118
    4.0mm2 copper97126
    1.8mm2 flat copper tape120136

    CLS1 Specifications


    Input 1Balanced Mic, balanced or unbalanced line
    Input impedance 10kΩ per side
    Min level (MIC / Line -73dBu / -31dBu
    Max level (MIC / Line) -37dBu / +5dBu
    Phantom voltage MIC only +12V
    Input 2Balanced or unbalanced line, expansion port
    Input impedance 1MΩ per channel
    Min level -33dBu
    Max level +3dBu
    Input 3Isolated 100V line or low impedance mono or
    stereo speaker
    Input impedance 100V Line / spkr 120kΩ / 7.8kΩ
    Min level 100V Line / spkr +14dBu / -9dBu
    Max level 100V Line / spkr >+47dBu / >+27dBu
    AC power input supply230V 30W 45-65Hz
    120V option available (ETL Approved)
    Connected via chassis mounted screw terminal block
    Input fuse – 230V

    Input fuse – 120V




    Drive voltage>6.4Vrms – 9.0Vpk
    Drive CurrentContinuous 1kHz sine wave >3.3Arms 5.0Apk
    Short term peaks >5Arms 7Apk
    Minimum Loop Resistance0.2Ω
    Maximum Loop Impedance1.5Ω



    Idle1/6 peak Output Current (Speech)1/3 peak Output Current (Pink noise)Full Power
    Driver ChannelsCurrent (ARMS)Load Resistance (Ohms)AC In (W)BTUAC In (W)BTUAC In (W)BTUAC In (W)BTU



    Frequency response80Hz to 6.3kHz ±3dB
    Automatic Gain Control(AGC) Optmised for speech. Dynamic range >36dB
    Metal loss correction(MLC) 0 to 3dB per octave frequency correction (1kHz remains constant). Control mounted on PCB.


    CoolingNatural convection
    EnvironmentIP20, -10ºC to +40ºC
    DimensionsW, H, D: 200mm, 200mm, 44mm
    MountingWall mounting, secured by 4 screws

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