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MLD9 MultiLoop Driver

The MLD9 MultiLoop driver is now obsolete – please see C10-2 MultiLoop hearing loop driver

The MLD9 is the new global benchmark for professional audio induction loop systems. The elegant, sturdy units feature the most compact design on the market, requiring only a single 19” rack mount.

The MLD9 provides one of the highest outputs available in any dual channel loop driver and is capable of driving a wide variety of multiple loop configurations from multiple simple loops to phase shifted array systems for the most challenging requirements.

With an Ampetronic MultiLoop™ Low Loss design, the MLD9 will drive an area up to 3,300m2, or can be used to drive two perimeter looped areas of up to 1,300meach.

The MLD9 also features Class G technology which halves power consumption and heat dissipation. Designed to provide optimum efficiency and ample current for Standard compliant field strength, coupled with unmatched voltage headroom to ensure crystal clear sound reproduction without clipping or distortion at practical loads. MLD units are built to our
exacting standards and are backed by our 5 year warranty.

MultiLoop™ Applications

The flexibility of Ampetronic MLD units allows each output channel to drive separate loops, or two drive two overlaid loop patterns, with or without the selectable phase shift between the two channels.

Two separate simple area loops (or perimeter loops) can be driven at the same phase or with 90° phase shift. This can be used to cover large areas with no metal losses, or multiple different areas in the same facility.

Two loop layouts can be driven configured as multiple loop segments with or without phase shift. Simple array, low loss array or low spill array designs can create different performance to optimise field strength
over any area, and minimise loop ‘spill’ for adjacent systems or for confidentiality.

Contact Ampetronic for free advice on all loop applications, design tools and support are available to check the expected performance for your application. Most commonly used design types are low loss and low spill:

MultiLoop Low Loss Systems are used to:

  • Compensate for high losses due to metal structures
  • Drive large areas where perimeter loops cause too much variation

MultiLoop Low Spill Systems are used to:

  • Perform the same tasks as Low Loss systems, but also minimise ‘spill’
    – confines signal to within 1.5m of looped area, suitable for adjacent rooms e.g. cinemas, classrooms, or confidential applications.

Maximum area coverage for MLD9 MultiLoop™ systems (m2)

Loop DesignNo Metal Loss*Moderate Metal Loss**High Metal Loss***
Low Loss3,300925425
Low Spill1,225700325
Perimeter Loop @ 1:1 Aspect Ratio2 x 800max 5m loop widthn/a
Perimeter Loop @ 3:1 Aspect Ratio2 x 1,300max 5m loop widthn/a

Typical scenarios are based on *a building with no structural metal, **a building with reinforced concrete (re-bar) construction.

Applications include

  • Conference facilities
  • Stadia & Sports Halls
  • Cinemas & Theatres
  • Courts & Confidentiality
  • Classrooms & Lecture Halls
  • Airports & Railway Stations

Product Code:

The MLD9 MultiLoop driver is now obsolete – please see C10-2 MultiLoop hearing loop driver


  • Features
  • Specifications
  • Standards
  • Downloads
    • Drives 2 output channels at 9.2ARMS each, featuring accurate and stable 90° phase shift
    • Up to 3,300m2 MultiLoop area coverage
    • Space saving 1U rack mount unit, the most space efficient loop driver available
    • Front inlet & rear exhaust fan cooling for true rack mount integration
    • High efficiency Class-G amplifier with low heat dissipation
    • Rack mount or free standing installation
    • Can be used with or without phase shift to drive independent loops
    • Optimised to reproduce speech frequencies with unmatched intelligibility
    • Supreme musical reproduction
    • Automatic Gain Control
    • Metal loss correction
    • Active loop error monitoring & dual loop fault detection at start-up
    • Versatile input selection
      • 2 x XLR balanced mic / line switchable inputs
    • Low lifetime cost
      • Based on proven technology to ensure excellent reliability
      • 5 year warranty
    • Tested to, and compliant with: IEC 62489-1 induction loop amplifier performance standard
    • Free technical support

    Equipment supplied as standard

    • Handbook and installation instructions
    • 197 x 252mm loop system present sign (deaf logo)
    • Region specific mains cable
    • Loop connector for each output
    • Rack mount brackets
    • Status Connector
    • DC Connector

    MLD9 optional accessories

    Ampetronic can supply a range of accessories to meet the specific needs of your installation:

    Installation Accessories

    • 18mm x 0.25mm copper tape
    • PVC extrusion to protect copper tape
    • Installation / warning tape to fix cable or tape to a floor

    Input adaptors

    By using the appropriate input adaptor or preamplifier the MLD9 will accept multiple additional inputs or audio inputs from other sources:

    Input TypeAdaptor
    100V line input
    Low impedance speaker line
    Line Level
    ATT-UX transformer isolated attenuators
    Unbalanced microphonesMAT1 adaptor

    Power220W 230V AC nominal, 45-65Hz [120V option available]
    Power switch & LED indicator (Hearing Loop logo) on front panel
    Input 1 & 2
    Programmable Microphone / Line
    Microphone specification; 200 – 600Ω, sensitivity -55dBu.
    Selectable 12V phantom power on microphone only
    Line sensitivity; -30dBu
    Scredriver adjustable front panel recessed gain control
    Link In6.35mm jack socket for linking more than one amplifier.
    Inserting plug disables other inputs


    Loop Output Drive Voltage31.8VRMS (45Vpk) at maximum output current per channel
    Loop Output9.2ARMS (13Apk) up to 60 seconds continuous 1kHz sine wave
    peak >13A per channel
    Drive CurrentCont. pink noise 4.6ARMS short term peaks >19A per channel
    Front panel recessed controls
    Drive current indicated on two 6-LED displays in 3dB increments
    Link Out6.35mm jack socket for linking more than one amplifier.
    Loop ConnectorsNeutrik NL4 Speakons (supplied) for each output
    Loop MonitorProvides access to monitor actual loop current via a 3.5mm
    stereo headphone connector on front panel
    Channel A on left, channel B on right
    StatusA pair of isolated relay contacts to indicate system status;
    fault = open circuit: system O.K. = short circuit
    DC OutputResettable, fuse protected 12V 0.1A.


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




    Frequency Response80Hz to 6.5kHz
    DistortionTHD+N <0.2% 1kHz sine at full current
    Automatic Gain ControlThe AGC is optimised for speech. Dynamic range >36dB
    Metal Loss CorrectionCorrects system frequency response due to metal structures in a building.
    Gain constant at 1kHz, adjustable gain slope from 0 to 3dB per octave.
    This does not compensate for signal loss from metal structures which can be significant.
    Phase ShiftUser selectable at 0° or 90° between outputs


    Fault MonitoringFault indicators on the front panel;
    Clipping – delivering over the rated voltage (per channel)
    Temp – unit is too hot (temporarily mutes output signal)
    Loop error – short circuit / open circuit error (per channel)
    Status ContactA pair of relay contacts are provided for remote fault monitoring
    CoolingTwin variable speed fan cooled. Front inlet, rear exhaust.


    SizeFull width 1U 19″ rack mount
    Width 430mm Depth 330mm Height 44mm
    Mounting OptionsFreestanding
    1U 19″ rack mount (brackets included)
    EnvironmentIP20 rated; 20 to 90% relative humidity; 0 to 35ºC


  • This product is designed to form part of a system that can meet all of the requirements of the international loop performance standard IEC60118-4, and the relevant parts of BS7594. To fully meet requirements of these standards, correct design, installation, commissioning and maintenance are required.

    All specification data has been compiled in accordance with IEC62489-1, the international standard for audio frequency induction loop equipment. Specification data should only be compared with data compliant to this standard.

    This product is CE market to all relevant safety and EMC standards, and is NRTL(ETL) approved for sale in North America.

    For detailed information on approvals, standards compliance and how to interpret the technical parameters on Ampetronic datasheets, please visit the support section of our website or contact support@ampetronic.com.

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