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Audio Frequency Induction Loop Systems
CCSS is an experienced installer of induction loops to British Standard Code of Practice for Audio Frequency Induction Loop Systems BS 7594.
A hearing loop is a cable that encloses the audience area which amplifies sounds as an aid for those wearing a hearing aid when switched to the “T” setting.
The big advantage is that this allows the sound to be heard by the hearing aid user without all the background noise that may exist within a room. Receivers can also be used with an induction loop for anyone who does not have a suitable hearing aid.
The installation of an induction loop helps businesses meet its requirements of reasonable adjustments being made to premises under the Disability Discrimination Act.
CCSS recommends the installation of C-Tec’s high quality equipment and further product information can be found here.
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. For further details, click here to download our 32-page Guide to Audio-Frequency Induction Loop Systems.
ABOUT THE PDA RANGE OF AUDIO FREQUENCY INDUCTION LOOP SYSTEMS
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.
AMPLIFIERS
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. More detailed information can be found in our Guide to AFILS or via the individual PDA RANGE datasheets and instruction manuals located in our downloads section).
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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 Can be used as normal whilst charging. |
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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). |
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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 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 |
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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 Metal compensation control helps combat the frequency response problems caused by metal ‘absorbing’ the magnetic field |
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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. |
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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 |
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120m.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 |
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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
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.
INDUCTION LOOP CABLE
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 AFILS.
MICROPHONES
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 AFILSfor further information.
INDUCTION LOOP TEST EQUIPMENT
We recommend all induction loop systems are tested using our ‘FoSmeter H’ loop listening device (order code AHHM/H) and a set of 32 Ohm headphones (order code HEAD1).
For compliance with BS7594 (the code of practice for audio-frequency induction loop systems), we recommend you also check the system using a pink noise generator as the system’s audio source.
It is recommended that the minimum magnetic field strength of an AFILS system over a covered area should be 400mARMS per metre. The most efficient way of ensuring this requirement is met is to measure the magnetic field strength of a steady output from the AFILS amplifier. Unlike music or speech (both of which provide a variable sound output from which it is virtually impossible to obtain an accurate RMS reading), a sine wave has a steady level and frequency. When fed into an AFILS system, a sine wave therefore gives a constant magnetic field strength, which can be easily and accurately measured using a magnetic field strength meter.
The following PDA RANGE test equipment is available:-
• FoSmeter H Combined magnetic field strength meter & loop listener (part no. AHHM/H)
• FoSmeter+ Combined sine wave generator & magnetic field strength meter (part no. AMSW)
• FoSmeter Magnetic field strength meter (part no. AHHM)
• SWGN sine wave generator (part no. SWGN)
• AL1 3.5mm jack (for SWGN) to 3.5mm jack lead
• AL2 3.5mm jack (for SWGN) to double phono lead
• AL3 3.5mm jack (for SWGN) to bare ended lead
• HEAD1 Headphones for use with FoSmeter H
More detailed information on our AFILS testing equipment can be found in our Guide to AFILS.
