800 Series

Audio-Frequency Induction Loop Systems

Audio-frequency induction loop systems (AFILS) allow hearing impaired people to hear more clearly. Most hearing aids have a ‘T’ or ‘MT’ switch which allows them to pick up the electromagnetic field generated by an induction loop system. The hearing aid converts this signal into a sound suited to its user’s specific hearing requirements. Any person with a hearing aid positioned within or near the loop (see example schematics below) can hear the loop signal by switching their hearing aid to the correct position, allowing them to participate more effectively in general conversation, ordering goods or services, listening to public performances, etc.








This page aims to give you a broad overview of our PDA Range of audio-frequency induction loop equipment. More detailed information can be found in our 32-page “Guide To Audio-Frequency Induction Loop Systems” which can be downloaded via the link at the bottom of this page.


C-TEC’s PDA range of induction loop equipment is one of the most comprehensive in the UK. It comprises a huge range of amplifiers, microphones, connector plates and test equipment covering virtually every conceivable AFILS application.


Designed to meet or exceed the requirements of BS7594 and EN60118-4 when correctly installed, all amplifiers in the PDA range offer excellent intelligibility, true current mode amplification, phantom power (for electret microphones) and full compatibility with our ‘outreach plate’ audio input extension system (except the PL1, VL1 and DL50). Many are also available in kit format for ease of specification, purchase and installation.

A brief overview of C-TEC’s induction loop amplifiers can be found below. Individual PDA RANGE datasheets and instruction manuals are located in our downloads section.


1.2m.sq. PL1 portable induction loop system

Ideal for restricted person to person contact in areas such as banks, post offices, small meeting rooms, reception desks, open plan offices and ticket booths

Portable, lightweight design means the system can be moved easily from location to location

Automatic shut-off facility (user selectable for 10, 30 or 60 minutes) helps preserve battery life

Can be used as normal whilst charging.


1.2m.sq. ML1/K double gang fixed counter loop system

Ideal for banks, post offices, small meeting rooms, reception desks, ticket booths and any other application requiring restricted or small area coverage

Requires no specialist audio experience or connectors – can be fitted by any competent electrician

Space-saving double-gang wall-mounting amplifier fits standard UK 25mm back boxes (requires fixed mains wiring).


1.2m.sq. PDA102C free-standing counter induction loop system

Ideal for banks, post offices, small meeting rooms, reception desks, ticket booths and any other application requiring restricted
or small area coverage

Includes a 3.5mm microphone input (for use with the AMT microphone supplied) and a line/outreach socket

Designed to be free-standing or wall-mounted
using the keyholes provided


1.2m.sq. VL1/B1 12V vehicle induction loop system

Ideal for cars, taxis, buses and other private/commercial vehicles

Kit includes a compact mini-induction loop amplifier with keyholes for dashboard mounting, a cigarette lighter power adaptor, an AMT microphone, a pre-formed loop and an ‘AFILS fittted’ sticker

Amplifier operates at 12V d.c. (24V vehicle kit also available, order code VL1/B2)

Metal compensation control helps combat the frequency response problems caused by metal ‘absorbing’ the magnetic field


50m.sq. PDA102L/R/S small room induction loop systems

Three variants available

PDA102L, ideal for use in small meeting rooms, council chambers, doctor surgeries, etc.

PDA102R, ideal for small room applications where equipment needs be mounted above suspended ceilings, etc.

PDA102S, ideal for use in nursing home TV lounges.


50m.sq. DL50/K domestic induction loop system

Free-standing – ideal for bedrooms, living rooms, TV lounges, studies and other domestic applications

Simple to adjust, tamper-resistant drive, level, tone and mic. priority controls

Alert tone input for doorbells, fire alarms, security
systems, etc.


200m.sq. AK Range induction loop amplifiers and kits

Available in a wide range of kit formats – suitable for use in meeting rooms, waiting rooms, TVlounges, health and fitness suites, churches, etc

PDA200E amplifier includes straightforward internal screw connectors

Wall-mounting metal enclosure for permanent installation

Internal drive, level and tone controls


200m.sq. to 900m.sq. PDA Pro-range induction loop amplifiers

Ideal for theatres, cinemas, churches, conference halls and other applications where top quality sound is a must

Each unit includes two XLR 3-pin input sockets (one balanced mic. and one switchable balanced mic./line) and one outreach connector.

Adjustable level controls provided for all inputs – can be used individually or together as a three-input mixer

Metal compensation control helps offset the frequency response problems associated with excessive metal in a building

Advanced audio signal processing with automatic gain control


The Outreach Plate audio input extension system comprises a range of wall, ceiling and desk mountable single gang audio input plates specifically designed to increase the audio input capability of an induction loop system. Covering the most common variants of audio connector, they work by mixing the signals from various audio input sources into one balanced line level input which can be fed into the line input of a compatible amplifier.

Mountable on 25mm single gang back boxes, each plate features a built-in mixer, pre-amp, input level control and balanced output.

Typically, up to 10 Outreach plates (any mix) can be daisy-chained to one balanced line level input with cable lengths of up to 100m easily achievable using standard two-pair audio cable with no recognisable degradation of audio signal quality.

Each outreach plate requires four wires, two balanced line (A+, A–), one ground (0V) and one power connection (12-32 V DC regulated). To facilitate their straightforward connection, most PDA Range amplifiers are fitted with an Outreach connection socket as standard.


There is nothing electrically special about induction loop cable. Almost any stranded or solid single core cable with tough insulation can be used, provided it is not liable to break (to minimise the chance of it shorting to earth and damaging the amplifier’s output) and is of the appropriate gauge and DC resistance (0.5 to 1 Ohm). If purchasing a PDA Range induction loop kit, always use the loop cable supplied with the kit. If purchasing an amplifier that does not include loop cable, refer to the loop cable selection chart in our “Guide To Audio-Frequency Induction Loop Systems” which can be downloaded via the link at the bottom of this page.


Electret microphones have the highest tolerance of magnetic feedback and are therefore recommended for induction loop systems. Dynamic microphones should not be used as they contain moving coil magnets which can be affected by the magnetic field generated by the loop. Phantom power is provided on all PDArange amplifiers, so electret microphones with internal batteries are not necessary.

The PDA Range includes a wide selection of electret microphones, please refer to our “Guide To Audio-Frequency Induction Loop Systems” which can be downloaded via the link at the bottom of this page.


Fosmeter Pro

FPROK1 Induction Loop Test Kit

We recommend all induction loop systems are tested using our new FPROK1 induction loop test kit which includes everything you need to ensure compliance with EN 60118-4 (the updated European Standard for Magnetic field strength in audio-frequency induction loops for hearing aid purposes) including a magnetic field strength meter and calibrated signal generator.

For further information on our FPROK1 test kit click here