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XA88 transport hearing loop driver

The XA88 Large Transport Vehicle Induction Loop Driver has reached End of Manufacture and is superseded by the T14-1 Transport hearing loop driver for rail and the T14-1 Transport hearing loop driver for bus and coach.

Compare the T14-1 to the XA88 here.

There is also a transition guide available here: T14-1 to XA88 Transition Summary

If you have any questions regarding the T14-1 or support for the XA88 please contact us on +44 (0) 1636 610062

The XA88 is a specialist Hearing Loop driver, designed for use bus, rail and other transport vehicles. The unit is designed for the OEM and vehicle engineering customer, to be integrated into public address and passenger communication systems on board the vehicle. It is backed by Ampetronic’s 5-year warranty and experienced specialist technical support.

The unit has two balanced transformer-isolated inputs (for connection to line-level sources or intercom/PA speaker systems), and provides superior sound quality with metal loss frequency response correction. The XA88 meets EMC and environmental standards for use on rail and automotive vehicles. With power supply options to suit many common rail and commercial vehicle power systems, and remote enable and status interfaces for more complex applications, it is the obvious choice for any quality on-board audio system that requires an Audio Induction Loop.

N.B. The XA88 Large Transport Vehicle Induction Loop Driver requires a detailed application review by Ampetronic to ensure compatibility with vehicle design for optimum operation.


  • Metro & Underground Rail Systems
  • National and Regional Railways
  • Trams & Light Rail (LRVs)
  • Buses & Coaches
  • Boats & Ferries

Product Code: XA88 (A DC power supply option, 24V, 72V, 110V ,will need to be selected when ordering)

Typical Loop Installation

In a rail vehicle or bus, the floor, walls, and roof are all usually metal. To keep away from metal sheets near the plane of the loop (and thereby minimise loss of energy), it is most common to place the loop around the upper part of the wall, typically 1.8m to 2m above floor level. This is usually some 300mm below the roof height. The best location will depend on the exact vehicle design.

Metal Loss

Most transport vehicles have metal construction – the bodyshell is usually metal panels with frames and structural supports. Although the interior may use non-metal panels, an induction loop installed inside such a vehicle will experience significant loss of energy and changed frequency response.
The XA88 has sufficient loop drive capacity to overcome the loss of loop signal in most cases. The unit’s metal loss compensation will correct the frequency response up to 4dB/octave slope.

System Testing

Each vehicle design has a different metal construction, and so the metal loss will be different. The only reliable way to determine the metal loss – which determines the loop current – is to measure the performance of a trial loop installation in the same or a very similar design of vehicle.

Ampetronic can provide site survey services to help you conduct a trial installation and effectively measure the proposed system’s performance. We can also provide a package of project services, carrying out commissioning or troubleshooting as required. Measurement instruments are available to help you or your customer to regularly test the installed loop’s performance.

Product code:

  • Features
  • Standards
  • Specifications
  • Accessories
  • Downloads
    • Area coverage (no metal) >300m2
    • Area coverage (metal vehicles) 25m2-100m2 depending on metal structures & loop wire location
    • Low lifetime cost
    • Excellent reliability
    • 5 year warranty
    • Simple integration
    • Power supply options (Common transport supplies: 24VDC, 72VDC, 110VDC, others possible)
    • 2 transformer isolated inputs for direct intercom or PA speaker line connection or 0dBu line input
    • Metal loss correction
    • Variable up to 4dB / octave
    • Unrivalled intelligibility
    • Free remote technical support
  • Rail:

    The XA88 is compliant with rail standard BS EN 50155:2017 and associated standards including BS EN 50121-3-2:2016 (EMC) and EN 61373:2010 (shock and vibration). In addition, the XA88 is compliant with EN 45545-2:2013 (Smoke and Fire behaviour) to HL3.


    The 24V variant of the XA88 is compliant with automotive regulation EN/ECE R10 encompassing the requirements of EN 50498:2010.

    Loop Performance

    The XA88 will enable an Audio Frequency Induction Loop system that meets the requirements of EN 60118-4 to be created, if the system is specified, installed and commissioned in an appropriate manner, including observing Ampetronic instructions.

  • XA88 Specifications


    Power SupplyOptions for 24V, 72V or 110V DC (other voltages possible) – see details above
    Indication: LED on front panel
    Connector: MIL-C-5015 (2 pins of CON3)
    Safety GroundM6 chassis stud (nut & star washer supplied)
    Signal InputsQuantity: 2 (3 to special order – ask for details)
    Typical Source: Intercom / PA line – see details on left for levels
    Format: Balanced, transformer isolated 1500V
    Level selection: In connector, by alternate pin choice
    Adjustment: Front Panel control, per channel
    Connector: MIL-C-5015 (10 pins, CON1)
    Enable InputsQuantity: one per input
    Format: Opto-isolated 1500V from internal circuits (enables have common external reference)
    Level: 5-24V DC enables relevant input.
    Input load: 3.4mA@5V, 16mA@24VDC
    Connector: MIL-C-5015 (4 pins of CON2)
    Indication: LED per channel on front panel


    Loop OutputIncludes configurable output transformer. Values shown at 1.67:1 ratio
    Voltage: 7.1Vrms (11Vpk) at max. drive current
    Current (max): > 11Arms (15.5Apk) with 1kHz sine
    Current (short term): 21Apk absolute max
    Current Adjustment: Front panel control
    Current Indication: LED on front panel
    Connector: MIL-C-5015 (2 pins of CON3)
    Loop ImpedanceUp to 0.49Ω reactive at 1.6kHz, with transformer ratio 1.67:1
    Monitor/StatusIsolated contact, closed when power present & no fault
    Isolation: 1000V AC 50/60Hz
    Contact rating: 1.25A 24V DC or 0.4A 125V AC
    Connector: MIL-C-5015 (2 pins of CON2)
    ProtectionThermal: Heatsink 90 to 125°C: output reduces by up to 3dB
    Heatsink >125°C: output muted. Amp Fault LED Illuminated *
    Output DC Offset: Isolates output if >±0.7 Amp
    – Fault LED Illuminated *
    Output clipping: If continuous, Loop Fault LED illuminated *
    Status relay: Contact opens when any item marked * is detected or power fails


    Freq. Response100Hz to 5kHz ±1.5dB relative to 1kHz at -12dB re: max output, measured as loop current with no metal loss correction.
    CompressionResponse optimised for speech
    Dynamic range: >30dB input, ±1dB output over input range
    Control: By adjusting input level/gain
    Indication: LED on front panel
    Attack / Decay: 7ms / >1s
    Metal Loss Correction0dB to 4dB / octave boost
    Adjusted on front panel control


    DimensionsWidth 251mm, depth 320mm, height 89mm excluding connectors
    ConstructionAluminium, powder coated. IP43 when mounted correctly, IP65 option available. <95% relative humidity, -40°C to +70°C (EN50155 TX)
    Installed unit should be mounted where the heat of normal operation can be dissipated by airflow through the rear heatsink.

    Power Options

    TheXA88 is supplied in 3 DC voltage versions:


    Nominal voltage24V DC
    Voltage range14.4 – 33.6V DC
    CouplingDirect – no power converter
    Overcurrent ProtectionInternal replaceable fuse, T 4A L
    Power Consumption61W (2.54 A) continuous audio
    6W (0.25 A) quiescent
    150W (6.25 A) short-term peak (at full 1kHz sine output)


    Nominal voltage72V DC
    Voltage range43 – 108V DC
    CouplingIsolated – uses power converter
    Overcurrent ProtectionCurrent foldback in power converter & non-replaceable 7A fuse in converter
    Power Consumption70W (0.64 A) continuous audio
    10W (0.14 A) quiescent
    150W (2.08 A) short-term peak (at full 1kHz sine output)


    Nominal voltage110V DC
    Voltage range65 – 150V DC
    CouplingIsolated – uses power converter
    Overcurrent ProtectionCurrent foldback in power converter & non-replaceable 5A fuse in converter
    Power Consumption70W (0.64 A) continuous audio
    10W (0.09 A) quiescent
    150W (1.36 A) short-term peak (at full 1kHz sine output)


    Input Details

    Input 1

    Low level

    High Level

    Input Impedance3.6kΩ120kΩ
    Sensitivity16dBu (130mV rms)+15dBu (4.2V rms)
    Overload:> +19dBu (7.3V rms)> +49dBu (236V rms)


    Input 2

    Low level

    High Level

    Input Impedance3.6kΩ36kΩ
    Sensitivity-16dBu (130mV rms)+ 4dBu (1.3V rms)
    Overload:> +19dBu (7.3V rms)> +39dBu (73V rms)
    Input 3Optional – not normally fitted. Details to customer requirement


    The XA88 uses MIL-C-5015 connectors for proven reliability.

    CON 1Signal Inputs10-pin 18-1 insert
    CON 2Enable & Status6-pin 14S-6 insert
    CON 3Power in & Loop out4-pin 14S-2 insert

    Chassis connectors on the unit are pins in a male shell.

  • Accessories

    Mounting Bracket or Tray

    A mounting can be supplied for the XA88 in your project, subject to agreement of a suitable design. Previous projects have used a rack tray or an asymmetric bracket arrangement to match the available mounting space. Please contact Ampetronic to discuss the options.


    Mating MIL-C-5015 style connectors can be supplied as an optional part. Please contact Ampetronic for further details. If you require accessories not shown here, please contact Ampetronic to discuss your requirements.

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