Signet DL50/K Assembly instructions

Approved Document No. DAU0000050 Rev 2• Page 1
DL50/K
AUDIO-FREQUENCY
INDUCTION LOOP KIT
INSTALLATION &
SET-UP MANUAL
Please read these instructions carefully before
installing your DL50 induction loop system
About this kit .............................................................................................. 2
What is an induction loop system? .......................................................... 2
Familiarisation with your DL50 induction loop amplifier ...................... 3
Planning the system .................................................................................. 4
Safety precautions ...................................................................................... 6
Connecting the unit ................................................................................... 6
System set-up and testing ......................................................................... 8
Troubleshooting ......................................................................................... 10
Technical specification .............................................................................. 11
© Errors and omissions excepted. The manufacturer of this equipment operates a policy of continuous
improvement & reserves the right to alter product specifications at its discretion & without prior notice.
Approved Document No. DAU0000050 Rev 2•Page 12

Induction loop systems 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 a telephone earpiece. This signal is converted by the
hearing aid into a sound suited to its user’s specific hearing requirements.
An induction loop system uses this same principle but generates a much larger magnetic
field than that created by a telephone earpiece and radiates it around a room via a ‘loop’ of
cable. Any hearing impaired person positioned within the loop can hear the loop signal by
switching their hearing aid to the correct position.
An induction loop system therefore comprises four main elements:-
The audio source – typically a microphone, a television or a radio (or any combination of these).
The induction loop amplifier
The loop – a single turn of wire usually run around the perimeter of the room.
The receiver(s) – any behind-the-ear type hearing aid with a ‘T’ or ‘MT’ switch.
The Disability Discrimination Act has led to an increasing number of induction loop systems
being fitted in cinemas, theatres, churches, post offices, etc, allowing people with hearing
difficulties to participate fully in general conversation, public performances and other
social/work related activities. This kit, specially designed by one of the UK’s leading
manufacturers of induction loop equipment, helps you to bring these same benefits into
the comfort of your own home.
About this kit
What is an induction loop system?
This kit includes everything you need to create a high quality stand-alone loop system for a
living room, bedroom, TV lounge, study or any other room up to 7m x 7m (23ft x 23ft) in size.
Please ensure that the following accessories are included in your kit:-
1 x DL50 audio frequency induction loop amplifier
1 x Plug-top power supply
1 x 33m (108ft) reel of induction loop cable
1 x SCART to phono audio connection lead
1 x Microphone c/w 1.5m (5ft) lead and mounting attachments
1 x Installation manual (i.e. this manual)
1 x Accessory pack containing four stick-on cabinet feet and a small flat-headed screwdriver
Should any of the above items be missing, please contact your vendor.
Approved Document No. DAU0000050 Rev 2•Page 2 Approved Document No. DAU0000050 Rev 2•Page 11
Technical specifications
POWER REQUIREMENTS 12V a.c. 1.5A max (via plug-top power supply)
MAX. COVERAGE AREA 50 square metres (7m x 7m or 23ft x 23ft)
CONTROLS Input signal level control
Tone control (boost +16dB; cut -20dB at 1KHz)
Loop signal control
Microphone priority control
(all controls are screwdriver adjustable to prevent them being
accidentally altered once they have been set up)
INDICATORS Power on (green)
Input signal (red)
Loop strength meter (green to yellow to red)
INPUTS Two 3.5mm mono microphone inputs with phantom power
Two phono (line level) inputs
Alert trigger input - normally open (close to trigger)
OUTPUTS One loop output (via push-and-hold connector) - only use the
loop cable supplied with your DL50/K kit
One headphone output (confirms audio input signal level)
DIMENSIONS 40mm (Height)
85mm (Depth)
185mm (Width)
WEIGHT 550g (amplifier only)

Approved Document No. DAU0000050 Rev 2•Page 10 Approved Document No. DAU0000050 Rev 2•Page 3
Familiarisation with your DL50 induction loop amplifier
Below is an overview of the indicators, controls and connectors on your DL50 induction
loop amplifier. The amplifier has one set of phono inputs (for the direct connection of
televisions, etc), two microphone inputs and an alert input (the alert input is normally used
for special applications only). It also includes four screwdriver-adjustable level controls plus
a number of indicators to assist you in setting up the system. Connections are also provided
for the attachment of the induction loop cable.
Detailed connection diagrams, system planning and system set-up information can be
found later in this manual.
LOOP
OUTPUT
CONNECTOR
MICROPHONE
PRIORITY
CONTROL
12V a.c. 1.5A
PLUG-TOP
POWER SUPPLY
CONNECTION
ALERT
INPUT
CONNECTOR
PHONO
INPUT
CONNECTORS
MIC. 1
INPUT
CONNECTOR
MIC. 2
INPUT
CONNECTOR
DL50 amplifier : front view
DL50 amplifier : rear view
TONE
CONTROL
HEADPHONE
SOCKET
INPUT SIGNAL
LEVEL CONTROL
INPUT
SIGNAL
INDICATOR
LOOP
STRENGTH
METER
POWER ON
INDICATOR
LOOP
SIGNAL
CONTROL
(in icates the
power being
riven into
the loop)
If no sound is being picked up by the hearing aid or induction loop test receiver, first check
that the amplifier’s power indicator is lit.
Troubleshooting
If the power indicator IS lit:-
Check that the amplifier’s input signal
indicator is lit.
If the input signal indicator IS NOT lit, make
sure all microphone and audio connection
leads are correctly plugged in.
Adjust the amplifier’s input signal and
microphone priority controls until its input
signal indicator flickers.
If there is still no sound being picked up by
the hearing aid or induction loop test
receiver, check that the loop cable is not
broken or misconnected.
Tip: The loop strength meter WILL NOT
illuminate if there is a break in the loop
cable or if it is misconnected.
If the power indicator IS NOT lit:-
Check that the plug-top power supply is
correctly plugged into the mains supply
and the amplifier.
If the power indicator is still not lit, the
power supply or the amplifier could be
faulty. Return the amplifier and PSU to
your vendor for repair.

Approved Document No. DAU0000050 Rev 2•Page 4
Microphones
One microphone is
supplied with the DL50
and this is sufficient for
most applications. It is
normally positioned where
it will best pick up general
conversation and/or the
sound of telephones or
doorbells ringing.
Loop cable
The loop cable (supplied) should be run around the perimeter
of the room. It should be located at least 1.2 metres away
from the nearest hearing aid and is therefore best tucked under
the edge of the carpet or fixed to skirting boards or the ceiling.
Should you encounter a doorway, window or passageway,
run the cable up and over (using cable clips) or below the
obstruction but try to keep such deviations to a minimum.
Ensure that the cable is adequately protected from being
crushed in walkways and by furniture.
Audio input
Most televisions, DVD
players, etc, can be
connected to the DL50
using the SCART-to-Phono
lead supplied.
Amplifier location
The amplifier should be sited
as close as possible to the equipment
to which it is connected. Due
consideration should be given to
ensure any microphones you wish
to use have long enough leads to
reach the required sound source.
Planning the system
Careful planning of the induction loop system prior to installation is essential. Please refer
to the diagram below and the hints and tips section on the adjacent page to help avoid
poor performance and the need to re-position the amplifier or loop cable at a later stage.
A typical DL50 domestic loop system
Detailed connection
diagrams and system set-up
information can be found
later on in this manual.
Approved Document No. DAU0000050 Rev 2•Page 9
When testing the installation, you may
hear a slight ‘humming’ noise in the
background, especially if using an
induction loop test receiver. This IS NOT a
fault with the induction loop system but a
common occurrence caused by mains
wiring. This hum will normally NOT be
heard by hearing aid users as most modern
hearing aids are equipped with built-in
filters which cancel this noise out.
Check that the loop strength meter
is not permanently lit red. The meter is
designed to light progressively from
1 to 3 (green to yellow to red) in line
with the loop signal strength. If it is
continually lit red, the signal will be
distorted and the amplifier may overheat.
If necessary, re-adjust the loop signal
control accordingly and re-test the sound
quality following steps 4 and 5.
8
Important note
Adjust the tone control to suit the user.
Turning the control clockwise usually
improves speech intelligibility and makes
the sound more ‘natural’. Turning it anti-
clockwise makes the sound ‘warmer’.
Large turns in either direction may lead to
you having to adjust the loop signal control
accordingly (see step 4).
TIP: If the user is not present, plugging a set
of headphones into the amplifer’s socket
will indicate the effect of any adjustments.
6
If two microphones are used, more
emphasis can be given to one over the
other by turning the amplifier’s
microphone priority control clockwise or
anti-clockwise to suit. When the control is
in the centre position (its default setting),
equal emphasis is given to both
microphones.
7

Approved Document No. DAU0000050 Rev 2•Page 5
Maximum area coverage
The maximum coverage provided by the loop system is 50m2(i.e. a room up to 7 x 7 metres
in size). Longer rooms can be covered provided width x length measurements do not exceed
50 metres.
Trial loops
Always run a trial loop and test to evaluate performance by listening to the signal with
either a hearing aid or a dedicated loop test receiver, such as SigNET’s RxTI (loop testing
equipment can be ordered using the ancillary order form attached). Refer to our dedicated
‘system set-up and testing’ section on pages 8 and 9 for further details.
Audio sources without output sockets
Some older televisions and other audiovisual appliances may not have a suitable output
socket for direct connection to the loop amplifier. NEVER attempt to make your own
connections by opening the appliance as high voltages WILL be present. Instead, place a
microphone next to the audio source in question.
Ventilation
The amplifier can become quite warm during normal operation so the airflow around it
must not be restricted. Ensure that the four rubber feet supplied in the accessory pack are
attached to the bottom of the unit as shown on page 7.
The ‘isolation’ issue
When a hearing aid user switches his or her hearing aid to the ‘T’ position, its on-board
microphone is switched off and the only noise that can be heard is the loop signal. If an
induction loop amplifier is connected to just one sound source, such as a television, some
hearing aid users (but not all) have said the lack of background noise makes them feel
isolated. This issue can be overcome by positioning a microphone where it will convey
background noise and pick up general conversation. (A maximum of two microphones can
be connected to the DL50, one is supplied as standard, if you require another you can order
one using the ancillary order form attached).
Overspill and ‘cross-talk’
The signal generated by the loop will radiate outside as well as inside the loop. If there are
any other loop systems in close proximity, overspill such as this may lead to ‘cross-talk’
(signals from different loops merging into one). Although not usually a problem in
domestic applications, special designs of loop can be implemented to help reduce the
overspill field. In the unlikely event of you encountering such problems, contact your
vendor for assistance.
Hints & tips
Approved Document No. DAU0000050 Rev 2•Page 8
With all system connections in place (see
pages 6 & 7), apply power to the amplifier
and check its green ‘power on’ indicator is lit.
System set-up and testing
Always run a trial loop to ensure correct operation. Only when you are happy with the
sound quality should you permanently fix the loop using tape, cable clips or a staple gun.
Turn on the system’s audio input source
(usually a television and/or a microphone)
and ensure it is producing an audio signal.
Note, SCART outputs have a fixed level signal
and altering the TV’s volume control will not
affect this.
1
2
3Using the flat-headed screwdriver
supplied, turn the amplifier’s input signal
level control clockwise until its input signal
indicator begins to flicker. This flickering
is associated with peaks in the audio
signal - if permanently lit, the signal will be
distorted. Re-adjust the control accordingly.
Set the loop field
strength by turning the
loop signal control in small
increments. After each slight
adjustment, check the audio
signal using a hearing aid or
induction loop test receiver
whilst standing in the centre
of the loop/room. Repeat
until an acceptable signal
level is received.
4
5When you are satisfied with the signal
in the centre of the loop, move around the
room to ensure coverage is consistent
throughout. Pay particular attention to areas
where the hearing aid user is likely to sit.
Next, if possible with the hearing aid user
in position, set the amplifier’s tone and
microphone controls to suit their personal
preference following steps 6 and 7.

Approved Document No. DAU0000050 Rev 1 •Page 6 Approved Document No. DAU0000050 Rev 1 •Page 7
Safety precautions
Connecting the phono inputs
Connection to most televisions, DVD
players, etc, can be made using the
SCART-to-Phono lead supplied:-
Connecting the microphone input(s)
One microphone is supplied with the DL50.
This should be connected to the rear of the
amplifier as shown below:-
Ensure that the amplifier IS NOT located in areas with poor ventilation, high ambient
temperatures or high humidity. It SHOULD NOT be exposed to direct sunlight, high dust
levels or be placed next to vibrating or heat-generating equipment.
The 230Vd.c. to 12V a.c. plug-top power supply (supplied) is designed for use with the
DL50 amplifier ONLY. DO NOT use any other plug-top power supply with the DL50 and
DO NOT plug the lead into any other electrical appliances as this may cause irreparable
damage. Replacement PSUs, if required, can be ordered using the ancillary order form
attached.
DO NOT dismantle or attempt to modify the amplifier or its plug-top power supply. No
user-serviceable fuses or parts are included. For repair, consult your vendor.
Ensure the plug-top power supply’s lead, the loop cable and all relevant audio/microphone
lead(s) are fixed securely into position before operation. Do not leave any trailing leads.
For added protection, during thunderstorms or when the amplifier is to be left
unattended for prolonged periods of time, unplug the plug-top power supply from the
wall outlet.
Connecting the unit
Please refer to the safety precautions below before attempting to
make any connections or operating your DL50 loop amplifier.
An optional Phono-to-Phono
lead is available for use with
certain types of satellite and
cable TV boxes - refer to the
ancillary order form attached.
Connecting the plug-top power supply
The plug-top power supply should be
connected to a 230V d.c. wall socket and
the 12V a.c input on the rear of the amplifier:-
Connecting the loop cable
Both ends of the loop cable should be
connected to the amplifier’s loop cable
push-and-hold terminals as shown below.
Attaching the cabinet feet
The four self-adhesive rubber feet provided
in the DL50’s accessory pack should be stuck
to the underside of the amplifier as shown.
Connecting the alert input
The alert input is designed for use by specialist installers, i.e. qualified electricians, only.
When triggered (by a normally open volt-free switch across its connectors) it causes a pulsed
alert tone in the loop. This can be used to warn the user that a doorbell has rung or a fire
alarm has sounded. DO NOT attempt to use this input unless you are qualified to do so.
In domestic applications, alerting the user to a ringing doorbell, etc, can be achieved much
more easily by placing a microphone in a strategic position in the room.
Connect the loop cable by pushing one of
its prepared ends into the left terminal
and the other into the right terminal.
The push-and-hold connectors will
automatically grip the ends. Any excess
cable should be neatly tied up and placed
where it cannot be tripped over. If you
need to remove the cable at any time, you
must first insert a terminal screwdriver
into the rectangular hole
directly below the
cable insertion hole
(see right). This will
open the insertion hole
and allow the cable to
be removed.
If required, an
additional microphone
can be connected to
the amplifier’s second
microphone
socket -
refer to the ancillary
order form attached.
12V
Note: it does not
matter which phono
plug goes into which
socket
Only use the plug-top power supply supplied
with your DL50 kit. Note that there are no
user-servicable parts on this power supply
and in the event of failure you must
purchase a replacement lead. Refer to the
ancillary order form attached for details.
✕
33m length of loop cable
(Note that the adhesive can
take some time to set and
therefore the amplifier should
be handled with care until it is
located in its final position).
12V
Only use the
loop cable
supplied with
your DL50/K
kit