Ampetronic ILD500 User manual

1. It is important to read these instructions, and to follow them.
2. Keep this instruction manual in an accessible place.
3. Clean only with a dry cloth. Cleaning fluids may effect the equipment.
4. Do not block any ventilation openings. Install in accordance with the
manufacturer’s instructions.
5. Do not install near any heat sources such as radiators, heating vents, or other
apparatus that produces heat.
6. WARNING - THIS APPARATUS MUST BE EARTHED / GROUNDED.
7. Only power cords with the correct power connector may be used to maintain
safety. Cables incorporating the UK 13A fused plug, Schuko with earthing
contacts and UL approved “grounding type” are acceptable. These must be
plugged into power outlets which provide a protective earth.
8. Refer all servicing to qualified personnel. Servicing is required when the
apparatus has been damaged in any way, such as a power supply cord or
plug is damaged, liquid has been spilled or objects have fallen into the
apparatus, the apparatus has been exposed to any rain or moisture, does not
operate normally or has been dropped.
9. WARNING - To reduce risk of fire or electric shock, do not expose this
apparatus to rain or moisture. The apparatus shall not be exposed to dripping
or splashing and no objects filled with liquids, such as vases, shall be placed
on the apparatus.
TO PREVENT ELECTRIC SHOCK DO NOT
REMOVE THE COVER. THERE ARE NO
USER SERVICEABLE PARTS INSIDE.
REFER SERVICING TO QUALIFIED
PERSONNEL.
.
ILD500 HANDBOOK
Box Contents
1 x ILD500
1 x Loop connector
1 x Installation & Commissioning
Handbook
2 x 1U Rack mounting ears
1 x Power Cable
Handbook Contents
!
!Introduction
!Quick Start
!Overview
!Installation
!Troubleshooting
!Accessories
!Technical Specification
!Warranty
!Declaration of Conformity
Safety
The Lightning bolt triangle is used to alert the user
to the risk of electric shock.
SAFETY
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
This symbol is used to alert the user to important
operating or maintenance instructions.

For those who have a good appreciation of loop systems, the following is a
very quick guide to setting up the amplifier:
All you need is a power source, a signal source and a loop. See “Designing
Induction Loops” handbook or contact Ampetronic for advice.
Installation
1. Turn all controls fully anti-clockwise.
2. Connect loop cable of appropriate length / gauge.
3. Connect signal input(s).
4. Connect power. See points 6 and 7 in SAFETY Section.
5. If rackmounted remove all rubber feet from units. DO NOT re-fit the feet
fixing screws as this may cause damage and invalidate the warranty.
Operation
6. Switch ON - Check green POWER LED flashes during self test and
illuminates continuously when checks are completed.
7. Apply input signal, and increase the input control until two green
COMPRESSION LEDs begin to light on the peaks of the signal.
8. Adjust the LOOP CURRENT control until the CURRENT LEDs illuminate
to achieve the desired peak current.
9. Repeat step 6 for the other input if used.
10.Listen to the magnetic field produced inside the loop area using a
receiving device (e.g Ampetronic ILR3), or examine the performance in
more detail with a field strength meter.
11.Adjust METAL LOSS CORRECTION to achieve a flat frequency
response.
OVERVIEW
QUICK START
MIC and LINE: Screwdriver adjustable controls which set the
level of signal fed into the compressor from Mic and Line inputs.
COMPRESSION: Shows the amount of gain reduction in
decibels that is applied to the input signal(s).
LOOP CURRENT: Screwdriver adjustable control which sets the
level of output current delivered into the loop.
CURRENT: Indicates the peak current delivered into the loop.
LOOP MONITOR: 3.5mm jack socket for use with stereo
headphones to listen directly to the signal in the loop.
OVERLOAD, OVERHEAT, LOOP ERROR: Warning LEDs, see
Troubleshooting section for explanation and advice.
POWER: LED to indicate AC power is applied to the unit.
I / O: Power switch.
Rack ear fixing screws - A PH2 screwdriver is required.
AC POWER: Standard 3-pole IEC320 connector containing
primary fuse for the unit.
LOOP OUTPUT: 2-pole high current connection to the loop cable.
METAL LOSS CORRECTION: Screwdriver adjustable control
which compensates for the frequency dependent effects of metal.
SLAVE I/O: Post compressor signal for use with ancillaries.
±15V 150mA DC OUTPUT: 3-pin power Mini DIN
LINE INPUT: 6.4mm Jack socket for balanced line level signals.
MIC INPUT: XLR socket for use with balanced microphones.
GAIN BOOST: Increases gain of MIC input by 15dB.
PHANTOM: Applies +15V phantom power to MIC input.
DC
INTRODUCTION
The ILD500 Induction Loop Driver has been designed as a high quality
amplifier for use with conference rooms, stadia, theatres, sports halls,
confidential rooms, lecture halls and cinemas. Depending on a number of
factors regarding the installation of the loop and set-up of the amplifier, the
2
ILD500 can provide compliance with IEC60118-4 for areas > 700m .
Ease of installation and use have been major factors in the design,
combined with optimised performance, and freedom from R.F.I
generation.
The ILD500 has two inputs which allow connection to a standard line
level signal and a balanced microphone.
For more complex installations, you may need additional ancillary
equipment such as microphone pre-amplifier(s), adaptor(s) for use
with 100V Line, or signal processing units. See Accessories, or
contact Ampetronic for advice.
 

     
       


OVER
LOAD
OVER
HEATPOWER
CURRENT
2.8 3.6 4.5 5.7 7.1 9.0
A peakLOOP
MONITOR
MICLINELOOP
CURRENT
COMPRESSION
6 12 18 24 30 36
dB
INDUCTION
LOOP DRIVER
ILD 500
LOOP
ERROR
1
2
3















AC POWER
LOOP OUTPUT
INDUCTION LOOP DRIVER ILD500
Designed and Engineered in the UK
INPUT 230V
45 - 65Hz
Power: 85W
Fuse: T 630mA L
SLAVE I/O
±15V 150mA
DC OUTPUT
LINE INPUT
MIC
METAL LOSS
CORRECTION
0
0.5
1.0
1.5
2.0
2.5
3.0
dB / Octave
Gain boost
Phantom
Serial Nº
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
SINGLE – TURN
LOOP ONLY
Loop resistance
Min:0.3W Max:2.0W
For details consult
instructions or
www.ampetronic.com


For those who have a good appreciation of loop systems, the following is a very quick guide to setting up the amplifier: All you need is a power source, a signal source and a loop. See “Designing Induction Loops” handbook or contact Ampetronic for advice.
Installation 1. Turn all controls fully anti-clockwise.
2. Connect loop cable of appropriate length / gauge.
3. Connect signal input(s).
4. Connect power. See points 6 and 7 in SAFETY Section.
5. If rackmounted remove all rubber feet from units. DO NOT re-fit the feet
fixing screws as this may cause damage and invalidate the warranty.
Operation 6. Switch ON - Check green POWER LED flashes during self test and
illuminates continuously when checks are completed.
7. Apply input signal, and increase the input control until two green
COMPRESSION LEDs begin to light on the peaks of the signal.
8. Adjust the LOOP CURRENT control until the CURRENT LEDs illuminate
to achieve the desired peak current.
9. Repeat step 6 for the other input if used.
10.Listen to the magnetic field produced inside the loop area using a
receiving device (e.g Ampetronic ILR3), or examine the performance in
more detail with a field strength meter.
11.Adjust METAL LOSS CORRECTION to achieve a flat frequency
response.
OVERVIEW
QUICK START
MIC and LINE: Screwdriver adjustable controls which set the
level of signal fed into the compressor from Mic and Line inputs.
COMPRESSION: Shows the amount of gain reduction in
decibels that is applied to the input signal(s).
LOOP CURRENT: Screwdriver adjustable control which sets the
level of output current delivered into the loop.
CURRENT: Indicates the peak current delivered into the loop.
LOOP MONITOR: 3.5mm jack socket for use with stereo
headphones to listen directly to the signal in the loop.
OVERLOAD, OVERHEAT, LOOP ERROR: Warning LEDs, see
Troubleshooting section for explanation and advice.
POWER: LED to indicate AC power is applied to the unit.
I / O: Power switch.
Rack ear fixing screws - A PH2 screwdriver is required.
AC POWER: Standard 3-pole IEC320 connector containing
primary fuse for the unit.
LOOP OUTPUT: 2-pole high current connection to the loop cable.
METAL LOSS CORRECTION: Screwdriver adjustable control
which compensates for the frequency dependent effects of metal.
SLAVE I/O: Post compressor signal for use with ancillaries.
±15V 150mA DC OUTPUT: 3-pin power Mini DIN
LINE INPUT: 6.4mm Jack socket for balanced line level signals.
MIC INPUT: XLR socket for use with balanced microphones.
GAIN BOOST: Increases gain of MIC input by 15dB.
PHANTOM: Applies +15V phantom power to MIC input.
DC
INTRODUCTION
The ILD500 Induction Loop Driver has been designed as a high quality amplifier for use with conference rooms, stadia, theatres, sports halls, confidential rooms, lecture halls and cinemas. Depending on a number of factors regarding the installation of the loop and set-up of the amplifier, the
2
ILD500 can provide compliance with IEC60118-4 for areas > 700m .
Ease of installation and use have been major factors in the design,
combined with optimised performance, and freedom from R.F.I
generation.
The ILD500 has two inputs which allow connection to a standard line
level signal and a balanced microphone.
For more complex installations, you may need additional ancillary
equipment such as microphone pre-amplifier(s), adaptor(s) for use
with 100V Line, or signal processing units. See Accessories, or
contact Ampetronic for advice.



















OVER
LOAD
OVER
HEATPOWER
CURRENT
2.8 3.6 4.5 5.7 7.1 9.0
A peakLOOP
MONITOR
MICLINE LOOP
CURRENT
COMPRESSION
6 12 18 24 30 36
dB
INDUCTION
LOOP DRIVER
ILD 500
LOOP
ERROR
1
2
3








 
 



AC POWER
LOOP OUTPUT
INDUCTION LOOP DRIVER ILD500
Designed and Engineered in the UK
INPUT 230V
45 - 65Hz
Power: 85W
Fuse: T 630mA L
SLAVE I/O
±15V 150mA
DC OUTPUT
LINE INPUT
MIC
METAL LOSS
CORRECTION
0
0.5
1.0
1.5
2.0
2.5
3.0
dB / Octave
Gain boost
Phantom
Serial Nº
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
SINGLE – TURN
LOOP ONLY
Loop resistance
Min:0.3W Max:2.0W
For details consult
instructions or
www.ampetronic.com

Fuse Location

INSTALLATION
Location:
The unit may be free standing or 19” rack mountable using the pair of rack
ears supplied. The screws which fix the rack ears to the unit are located at
the front of each side panel, as shown ( ) in the Overview. A PH2
screwdriver will be required to remove and replace the 2 pairs of screws
when fixing the rack ears in place. Remove four rubber feet.
The location must provide satisfactory ventilation for the equipment.
An internal fan provides forced ventilation using the air vents at the
left side (intake) and rear panel (exhaust) of the unit. Both of these vents
must be unobstructed for satisfactory cooling. If the unit is installed in an
enclosed environment, sufficient air flow into the enclosure must be
provided through vents, fans or other means, such that the units exhaust
air is not recycled to the inlet - causing it to OVERHEAT.
Slave
I/O
Output
Metal
Loss
Correction
Compression LEDs
Current LEDs
Overheat
LED
Microphone
Input
Microphone
Gain
Line
Gain
+15V
Loop
Current
Line
Input Loop
Output
Loop
Monitor
Gain
Boost
Compressor
Phantom
Power
Switch
Overload
LED
Loop
Error
LED
Block Diagram
Connections
Connection of
male XLR for microphone
input
balanced
+ (Signal hot)
- (Signal cold)
12
3
Screen
TIP
SOURCE
TO ILD500
LINE INPUT
SLEEVE
RING
Connection of 3-pole Plug
with balanced signals.
Use Twin-screened cable.
+ (Signal hot)
- (Signal cold)
LINE
INPUT
MIC
INPUT
SLAVE
I/O
LOOP
CONNECTOR
+ (Signal)
TIP
SOURCE
TO ILD500
SLEEVE
RING
LINE INPUT
Connection of 3-pole plug.
Use Twin-screened cable.
Must be 3m or less.
Unbalanced
Balanced
TIP
RECORDING DEVICE
TO ILD500
SLAVE I/O
SLEEVE
RING
Connection of 3-pole Plug
to use Slave I/O socket
for recording output.
+ (Signal)
+15V
Power
Supply
Power
LED
Earth
Link
230V
or
120V
AC Power
-15V
0V
Power
Switch
15V
150mA
DC
Output
Socket
0V
+15V -15V
Use cable supplied.
Must be 3m or less.
8.0 0m m
20 .00 m m
use either NL4 connections 1or 2, or both as required
1+
2+
LOOP +
1-
2-
LOOP -
Internal unit connections

INSTALLATION
Location:
The unit may be free standing or 19” rack mountable using the pair of rack
ears supplied. The screws which fix the rack ears to the unit are located at
the front of each side panel, as shown ( ) in the Overview. A PH2
screwdriver will be required to remove and replace the 2 pairs of screws
when fixing the rack ears in place. Remove four rubber feet.
The location must provide satisfactory ventilation for the equipment.
An internal fan provides forced ventilation using the air vents at the
left side (intake) and rear panel (exhaust) of the unit. Both of these vents
must be unobstructed for satisfactory cooling. If the unit is installed in an
enclosed environment, sufficient air flow into the enclosure must be
provided through vents, fans or other means, such that the units exhaust
air is not recycled to the inlet - causing it to OVERHEAT.
Slave
I/O
Output
Metal
Loss
Correction
Compression LEDs
Current LEDs
Overheat
LED
Microphone
Input
Microphone
Gain
Line
Gain
+15V
Loop
Current
Line
Input Loop
Output
Loop
Monitor
Gain
Boost
Compressor
Phantom
Power
Switch
Overload
LED
Loop
Error
LED
Block Diagram
Connections
Connection of
male XLR for microphone
input
balanced
+ (Signal hot)
- (Signal cold)
12
3
Screen
TIP
SOURCE
TO ILD500
LINE INPUT
SLEEVE
RING
Connection of 3-pole Plug
with balanced signals.
Use Twin-screened cable.
+ (Signal hot)
- (Signal cold)
LINE
INPUT
MIC
INPUT
SLAVE
I/O
LOOP
CONNECTOR
+ (Signal)
TIP
SOURCE
TO ILD500
SLEEVE
RING
LINE INPUT
Connection of 3-pole plug.
Use Twin-screened cable.
Must be 3m or less.
Unbalanced
Balanced
TIP
RECORDING DEVICE
TO ILD500
SLAVE I/O
SLEEVE
RING
Connection of 3-pole Plug
to use Slave I/O socket
for recording output.
+ (Signal)
+15V
Power
Supply
Power
LED
Earth
Link
230V
or
120V
AC Power
-15V
0V
Power
Switch
15V
150mA
DC
Output
Socket
0V
+15V -15V
Use cable supplied.
Must be 3m or less.
8.0 0m m
20 .00 m m
use either NL4 connections 1or 2, or both as required
1+
2+
LOOP +
1-
2-
LOOP -
Internal unit connections

4.Connect AC power to the ILD500. See points 6 and 7 in Safety section.
5. Switch ON. The POWER LED will flash for a few seconds while an internal
self test is performed and the loop resistance is tested. If both tests are
successful, the POWER LED will illuminate continuously and the unit will be in
an operational mode. If the POWER LED continues to flash, or the ‘Loop Error’
LED illuminates, consult the Troubleshooting section.
6. Select one input and apply a suitable, audio signal (ideally a CD player with
music or continuous speech applied to the LINE INPUT, with no connection to
the MIC input). Turn the associated input control clockwise until two
COMPRESSION LEDs are illuminated on the peaks of the signal.
7. Turn the LOOP CURRENT control clockwise until the target current is
achieved – as indicated by the CURRENT LEDs. Note that consecutive LEDs
illuminate at 2dB intervals. Headphones can be used with the LOOP MONITOR
socket to listen directly to the loop current. If high frequency oscillation of low
frequency hum is experienced, consult the Troubleshooting section.
8. The loop system should now be providing a magnetic field inside the area of
the loop – use the ILR3 or field strength meter (FSM) to examine its
performance with respect to:
a) Magnetic field strength. This will vary across the coverage area, due to
layout, metal loss and LOOP CURRENT.
b) Frequency response. Metal losses tend to increase with frequency, and
may require the adjustment of the METAL LOSS CORRECTION.
As a result of this analysis, adjust the LOOP CURRENT and set the METAL
LOSS CORRECTION (on the rear of the unit) to achieve best sound quality.
This should result in an adequate magnetic field strength and level frequency
response in order to satisfy IEC 60118-4. Note: Do not adjust the METAL
LOSS CORRECTION whilst listening via the LOOP MONITOR socket.
Once the LOOP CURRENT and METAL LOSS CORRECTION have been
adjusted to the correct level they should not need re-adjusting.
9. If not already done so, steps can now be taken to integrate the ILD500 into a
PA / mixer arrangement following standard audio techniques. If any unusual
effects are experienced refer to the troubleshooting section.
Note: Ideally, each input signal level should be set up to achieve 6dB (one
LED) of COMPRESSION with the quietest level of input that is likely to be
used. This will maximise the dynamic range of the system and ensure
satisfactory performance.
10.Repeat above procedure for other signal input if used. When adjusting each
input, make sure that the signal(s) are removed from the other inputs. This
ensures that all signals are set to equivalent loudness and drive the
compressor properly.
Tools & Equipment:
Small hand tools including a wire stripper and a small flat bladed screwdriver.
An ILR3 loop receiver or a magnetic field strength meter is vital to check that
the loop system is providing the desired level of performance.
A pair of stereo headphones with a 3.5mm jack plug connection is also useful
to monitor the loop signal.
System Requirements:
The induction loop cable itself should be already installed according to the
“Designing Induction loops” handbook, or as per specific design instructions
provided by Ampetronic. As a result, a target peak current should be known,
based on achieving acceptable field strength across the area to be covered.
Connection and Set-up:
It is advised that the loop system is initially set up using a local audio source
such as CD player, which is not connected into any other system. This avoids
the complication of ground loops and feedback etc, whilst the unit is set up.
The following procedure describes the installation of a stand alone ILD500,
and does not incorporate connection of other ancillary units such as
microphone pre-amps or signal processing units.
1. Turn all controls fully anti-clockwise.
2. Connect the loop cable into the Loop connector supplied. Where using a
perimeter loop (floor/ceiling level), the feed cable should be tightly twisted
and less than 20m in length. Total resistance of loop and feed must be
between 0.3W and 2.0W (at DC). The “Designing Induction Loops” handbook
contains more details on loop and feed cables. The correct design and
positioning of the actual loop is vital for satisfactory system performance. If in
doubt consult Ampetronic for advice.
3. Connect the signal input(s) appropriately:
a) Suitable dynamic or condenser microphone with balanced cable feed.
Select phantom power as required, depending on the type of microphone
you are using. Connect to MIC input using a 3-pole XLR plug wired as
per Connections drawing.
b) Line level input from other audio equipment such as PA system,
mixing desk or CD player to the LINE INPUT.
You may use either or both inputs.
Do not run the input and output cables close together.
The SLAVE I/O must NEVER be used as a separate input. It must only be
used with Ampetronic signal processing equipment, or for obtaining a signal
for recording. See Connections section for details.

4.Connect AC power to the ILD500. See points 6 and 7 in Safety section.
5. Switch ON. The POWER LED will flash for a few seconds while an internal
self test is performed and the loop resistance is tested. If both tests are
successful, the POWER LED will illuminate continuously and the unit will be in
an operational mode. If the POWER LED continues to flash, or the ‘Loop Error’
LED illuminates, consult the Troubleshooting section.
6. Select one input and apply a suitable, audio signal (ideally a CD player with
music or continuous speech applied to the LINE INPUT, with no connection to
the MIC input). Turn the associated input control clockwise until two
COMPRESSION LEDs are illuminated on the peaks of the signal.
7. Turn the LOOP CURRENT control clockwise until the target current is
achieved – as indicated by the CURRENT LEDs. Note that consecutive LEDs
illuminate at 2dB intervals. Headphones can be used with the LOOP MONITOR
socket to listen directly to the loop current. If high frequency oscillation of low
frequency hum is experienced, consult the Troubleshooting section.
8. The loop system should now be providing a magnetic field inside the area of
the loop – use the ILR3 or field strength meter (FSM) to examine its
performance with respect to:
a) Magnetic field strength. This will vary across the coverage area, due to
layout, metal loss and LOOP CURRENT.
b) Frequency response. Metal losses tend to increase with frequency, and
may require the adjustment of the METAL LOSS CORRECTION.
As a result of this analysis, adjust the LOOP CURRENT and set the METAL
LOSS CORRECTION (on the rear of the unit) to achieve best sound quality.
This should result in an adequate magnetic field strength and level frequency
response in order to satisfy IEC 60118-4. Note: Do not adjust the METAL
LOSS CORRECTION whilst listening via the LOOP MONITOR socket.
Once the LOOP CURRENT and METAL LOSS CORRECTION have been
adjusted to the correct level they should not need re-adjusting.
9. If not already done so, steps can now be taken to integrate the ILD500 into a
PA / mixer arrangement following standard audio techniques. If any unusual
effects are experienced refer to the troubleshooting section.
Note: Ideally, each input signal level should be set up to achieve 6dB (one
LED) of COMPRESSION with the quietest level of input that is likely to be
used. This will maximise the dynamic range of the system and ensure
satisfactory performance.
10.Repeat above procedure for other signal input if used. When adjusting each
input, make sure that the signal(s) are removed from the other inputs. This
ensures that all signals are set to equivalent loudness and drive the
compressor properly.
Tools & Equipment:
Small hand tools including a wire stripper and a small flat bladed screwdriver.
An ILR3 loop receiver or a magnetic field strength meter is vital to check that
the loop system is providing the desired level of performance.
A pair of stereo headphones with a 3.5mm jack plug connection is also useful
to monitor the loop signal.
System Requirements:
The induction loop cable itself should be already installed according to the
“Designing Induction loops” handbook, or as per specific design instructions
provided by Ampetronic. As a result, a target peak current should be known,
based on achieving acceptable field strength across the area to be covered.
Connection and Set-up:
It is advised that the loop system is initially set up using a local audio source
such as CD player, which is not connected into any other system. This avoids
the complication of ground loops and feedback etc, whilst the unit is set up.
The following procedure describes the installation of a stand alone ILD500,
and does not incorporate connection of other ancillary units such as
microphone pre-amps or signal processing units.
1. Turn all controls fully anti-clockwise.
2. Connect the loop cable into the Loop connector supplied. Where using a
perimeter loop (floor/ceiling level), the feed cable should be tightly twisted
and less than 20m in length. Total resistance of loop and feed must be
between 0.3W and 2.0W (at DC). The “Designing Induction Loops” handbook
contains more details on loop and feed cables. The correct design and
positioning of the actual loop is vital for satisfactory system performance. If in
doubt consult Ampetronic for advice.
3. Connect the signal input(s) appropriately:
a) Suitable dynamic or condenser microphone with balanced cable feed.
Select phantom power as required, depending on the type of microphone
you are using. Connect to MIC input using a 3-pole XLR plug wired as
per Connections drawing.
b) Line level input from other audio equipment such as PA system,
mixing desk or CD player to the LINE INPUT.
You may use either or both inputs.
Do not run the input and output cables close together.
The SLAVE I/O must NEVER be used as a separate input. It must only be
used with Ampetronic signal processing equipment, or for obtaining a signal
for recording. See Connections section for details.

LOOP ERROR LED illuminated:
Indicates that the loop cable connected to the unit is outside specification.
Check that the loop cable is connected, terminated correctly and inserted into
the LOOP OUTPUT socket. Ensure the DC resistance is acceptable.
Low magnetic field strength:
Due to insufficient LOOP CURRENT or excessive metal loss.
May require a special loop design to achieve acceptable performance, contact
Ampetronic for advice.
Instability or high frequency noise
1) It is possible for the loop cable to become grounded under fault conditions,
resulting in instability which may sound like high frequency noise, buzz or
whistling. The results of this type of fault are unpredictable and may appear as
any combination of the front panel indication errors.
This fault is easy to determine: simply unplug the loop cable from the amplifier
and test with a resistance meter between either of the loop wires and a good
earth point such as a metal radiator. There should be an infinitely high reading
i.e. no connection at all. Any reading indicates a failure of the loop cable
insulation and you will need to either repair or replace the loop cable.
2) Instability can be caused by using poor quality signal cables, long
unbalanced (2-wire) signal runs to the inputs, or by running input cables in
close proximity with the loop wire over any appreciable distance. Loop
amplifiers are capable of delivering high currents at audio frequencies. If the
loop cable is run close to sensitive signal cables it may be possible to induce a
signal back into the input of the amplifier causing feedback. Cable runs and
loop wires should be kept well apart from each other. To avoid interference a
proximity of 300mm should only be run for a few meters. Always used
balanced (3-wire) circuits where possible.
3) Instability can cause the amplifier to run hot and may result in the
OVERHEAT LED illuminating. Always used balanced (3-wire) circuits where
possible.
If the loop is high resistance >5Ω - check all connections and re-tighten, there
may be something loose.
If the loop is low resistance <0.5Ω - check for short circuits in the loop connector.
²
If the loop is just very low resistance, fold a defined length (see below) of 0.5mm
cable in half and twist it together neatly – using a hand drill can be helpful. Coil this
loosely on the forearm and bind it so that it does not come un-coiled. Then connect
the two ends in series with the low resistance loop to ensure that the unit will
always turn on, but the system performance is un-affected. 5m of 0.5mm² wire will
add approximately 0.15 W to loop resistance. Use an appropriate length to ensure
the loop resistance exceeds 0.3W. Note: High or low resistance loops can be
encountered in a venue with a pre-installed loop, which was designed for use with
an old loop driver which might be being replaced. Before using this loop ensure
that the existing loop will allow the system to perform to an acceptable level by
checking it's layout details in the 'Designing Induction loops' handbook.
POWER LED not illuminated:
Check that the power (O / I) switch is toggled to the ON (I) position.
A 20mm fuse is incorporated in the AC POWER socket. It is necessary to
remove the power cord before extracting the fuse holder. Test the continuity of
the fuse using a multimeter. A spare fuse is provided in the fuse holder.
Any replacement fuse must be of the same fuse rating and type as
printed on the rear panel of the unit.
POWER LED flashing continuously:
Amplifier has failed self test and is in safe mode. No signal will be fed into the
loop. Switch the unit OFF, remove all connections except the loop and power
connections, turn all front panel controls to minimum and switch back ON. If
the problem persists, contact Ampetronic for advice.
COMPRESSION LEDs not illuminating:
Check input connections.
Ensure that the appropriate front panel control (Mic / Line) is turned up.
Check that there is sufficient signal level for the required input.
CURRENT LEDs not illuminating:
Check that the COMPRESSION LEDs are illuminating.
Check that the LOOP CURRENT control is turned up sufficiently.
Check that the LOOP ERROR, or OVERHEAT LEDs are not illuminated.
Ensure the POWER LED is illuminated and not flashing.
Remove any connection to the SLAVE I/O socket.
Check that the loop cable is connected, terminated correctly and inserted into
the LOOP OUTPUT socket.
Check the loop cable is not open circuit, short circuit, or connected to earth
(see Instability or high frequency noise section of Troubleshooting).
Note: You can listen to the actual loop signal by using a pair of headphones
plugged into the loop monitor socket.
OVERLOAD LED illuminated:
Indicates that too much current is being delivered into the loop.
Check that the COMPRESSION LEDs are illuminating.
Remove any connection to the SLAVE I/O socket.
Turn the LOOP CURRENT control down to avoid running too much current
into the loop.
Check the loop cable is not open circuit, short circuit, or connected to earth
(see Instability or high frequency noise section of Troubleshooting).
OVERHEAT LED illuminated:
Indicates that the internal heatsink is too hot. Loop current is not delivered.
Ensure that the unit is installed in a location with sufficient ventilation.Check
the loop cable is not open circuit, short circuit, or connected to earth (see
Instability or high frequency noise section of Troubleshooting).
TROUBLESHOOTING

LOOP ERROR LED illuminated:
Indicates that the loop cable connected to the unit is outside specification.
Check that the loop cable is connected, terminated correctly and inserted into
the LOOP OUTPUT socket. Ensure the DC resistance is acceptable.
Low magnetic field strength:
Due to insufficient LOOP CURRENT or excessive metal loss.
May require a special loop design to achieve acceptable performance, contact
Ampetronic for advice.
Instability or high frequency noise
1) It is possible for the loop cable to become grounded under fault conditions,
resulting in instability which may sound like high frequency noise, buzz or
whistling. The results of this type of fault are unpredictable and may appear as
any combination of the front panel indication errors.
This fault is easy to determine: simply unplug the loop cable from the amplifier
and test with a resistance meter between either of the loop wires and a good
earth point such as a metal radiator. There should be an infinitely high reading
i.e. no connection at all. Any reading indicates a failure of the loop cable
insulation and you will need to either repair or replace the loop cable.
2) Instability can be caused by using poor quality signal cables, long
unbalanced (2-wire) signal runs to the inputs, or by running input cables in
close proximity with the loop wire over any appreciable distance. Loop
amplifiers are capable of delivering high currents at audio frequencies. If the
loop cable is run close to sensitive signal cables it may be possible to induce a
signal back into the input of the amplifier causing feedback. Cable runs and
loop wires should be kept well apart from each other. To avoid interference a
proximity of 300mm should only be run for a few meters. Always used
balanced (3-wire) circuits where possible.
3) Instability can cause the amplifier to run hot and may result in the
OVERHEAT LED illuminating. Always used balanced (3-wire) circuits where
possible.
If the loop is high resistance >5Ω - check all connections and re-tighten, there
may be something loose.
If the loop is low resistance <0.5Ω - check for short circuits in the loop connector.
²
If the loop is just very low resistance, fold a defined length (see below) of 0.5mm
cable in half and twist it together neatly – using a hand drill can be helpful. Coil this
loosely on the forearm and bind it so that it does not come un-coiled. Then connect
the two ends in series with the low resistance loop to ensure that the unit will
always turn on, but the system performance is un-affected. 5m of 0.5mm² wire will
add approximately 0.15 W to loop resistance. Use an appropriate length to ensure
the loop resistance exceeds 0.3W. Note: High or low resistance loops can be
encountered in a venue with a pre-installed loop, which was designed for use with
an old loop driver which might be being replaced. Before using this loop ensure
that the existing loop will allow the system to perform to an acceptable level by
checking it's layout details in the 'Designing Induction loops' handbook.
POWER LED not illuminated:
Check that the power (O / I) switch is toggled to the ON (I) position.
A 20mm fuse is incorporated in the AC POWER socket. It is necessary to
remove the power cord before extracting the fuse holder. Test the continuity of
the fuse using a multimeter. A spare fuse is provided in the fuse holder.
Any replacement fuse must be of the same fuse rating and type as
printed on the rear panel of the unit.
POWER LED flashing continuously:
Amplifier has failed self test and is in safe mode. No signal will be fed into the
loop. Switch the unit OFF, remove all connections except the loop and power
connections, turn all front panel controls to minimum and switch back ON. If
the problem persists, contact Ampetronic for advice.
COMPRESSION LEDs not illuminating:
Check input connections.
Ensure that the appropriate front panel control (Mic / Line) is turned up.
Check that there is sufficient signal level for the required input.
CURRENT LEDs not illuminating:
Check that the COMPRESSION LEDs are illuminating.
Check that the LOOP CURRENT control is turned up sufficiently.
Check that the LOOP ERROR, or OVERHEAT LEDs are not illuminated.
Ensure the POWER LED is illuminated and not flashing.
Remove any connection to the SLAVE I/O socket.
Check that the loop cable is connected, terminated correctly and inserted into
the LOOP OUTPUT socket.
Check the loop cable is not open circuit, short circuit, or connected to earth
(see Instability or high frequency noise section of Troubleshooting).
Note: You can listen to the actual loop signal by using a pair of headphones
plugged into the loop monitor socket.
OVERLOAD LED illuminated:
Indicates that too much current is being delivered into the loop.
Check that the COMPRESSION LEDs are illuminating.
Remove any connection to the SLAVE I/O socket.
Turn the LOOP CURRENT control down to avoid running too much current
into the loop.
Check the loop cable is not open circuit, short circuit, or connected to earth
(see Instability or high frequency noise section of Troubleshooting).
OVERHEAT LED illuminated:
Indicates that the internal heatsink is too hot. Loop current is not delivered.
Ensure that the unit is installed in a location with sufficient ventilation.Check
the loop cable is not open circuit, short circuit, or connected to earth (see
Instability or high frequency noise section of Troubleshooting).
TROUBLESHOOTING

Interference
1) Background magnetic field signals or interference may be present in any
location and may not be anything to do with the loop system. Monitor this
with a loop receiver (such as an ILR3). If the interference is still present with
the loop system switched off, then you need to locate and eliminate the
source of interference before switching the loop system back on.
2) Magnetic fields can be induced into any low impedance electrical path or
loop. Multiple ground earth systems may experience the pick up of the loop
signal, and cause difficulties with other systems that are not designed to
reject such interference. Check entire sound system for evidence of loop
signal, and trace source of pick-up.
3) Under certain circumstances, the loop signal may appear as jagged lines
or hum bars on a CCTV picture. This could be due to running CCTV (low
impedance unbalanced 2-wire circuit) cables in close proximity to the loop
cable. Separate the cables to reduce the effect.
4) Remote (and apparently unconnected) PA systems can sometimes pick
up loop signals. This is usually because the loop cable becomes damaged
(see point 1 of Instability) or induces signals into the remote system through
long unbalanced cables. Always run long audio signal cables as 3-wire
balanced circuits and keep away from loop cables.
5) See also point 1 of Instability.
Failed AC power fuse in rear of unit
Unplug the loop and AC power supply from amplifier, and replace the failed
fuse with the spare fuse in AC power input fuse tray. Reconnect the AC
power supply and switch on. If the fuse fails again, return the unit to
Ampetronic for evaluation - it may well be covered under warranty, which
will be invalidated by removing the cover. If the fuse does not fail a 'loop
error' may be indicated, but shows that the unit is working correctly.
Re-connect the loop and switch the power off then on again to reset loop
error. If the fuse fails when the loop is re-connected to the unit, then the
loop could be shorted to electrical mains (and building) earth. This can
happen even if no audio signal is present, as the short to earth is likely to
cause an instability / oscillation / feedback condition to develop. A loop
cable short to earth most commonly occurs where flat copper tape is
installed on a metal-clad raised access flooring system. If the insulation on
the flat copper tape is abraded (for example by a piece of metal swarf
trapped below the copper tape), the conductor could short to the earthed
tiles. When installing on raised access floors, it is advisable to insulate
beneath the flat copper tape installation using Ampetronic PWT or similar
tape. The loop short to earth may only be completed when a person steps
on the tape in the affected location, which can create significant difficulties
when diagnosing the cause of fuse failure. Contact Ampetronic for further
advice if a unit is suffering recurring but untraceable failure of the rear panel
fuse.
AC Power Supply: Output:
3-pole IEC320 connector. NL4 speakon (1+ & 2+ connected
85W nominal for either version. internally as are 1- & 2- to allow ‘star-
45-65Hz quad’ method of cable connection).
Current: >9A peak (6.4A ) into 1W
RMS
230V Version Voltage: >20V peak (14.1V )
RMS
Nominal: 230V AC Loop Resistance: 0.3W to 2.0W
Fuse: T 630mA L resistive or 2.2W max impedance
Range: 207-253V AC reactive at 1.6kHz.
Quiescent: 100mA THD+N <0.2% @ 1kHz @ 9.0Apk
Typical: 400mA (O/P 3A pink noise)
RMS
Frequency Response:
120V Version Measured at low level with no metal
Nominal: 120V AC loss correction.
Fuse: T 1.25A L 80Hz to 6.5kHz -3.0dB
Range: 108-132V AC 100Hz to 5.5kHz ± 1.5dB
Quiescent: 200mA
Typical: 800mA (O/P 3A pink noise)
RMS Metal Loss Correction:
0dB (flat) to 3dB/Octave boost.
Microphone Input: Gain at 1kHz remains constant.
XLR socket.
Input Impedance: 200-600W Loop Monitor:
Sensitivity: -70dBu (245uV ) for full
RMS 3.5mm 3-pole (stereo) jack socket
output. 0.675Vpk at 9.0Apk output
Overload: >-5dBu (436mV )
RMS
±15V 150mA DC Output:
Line Input: 3 pin power Mini DIN socket.
6.4mm 3-pole Jack socket. Regulated DC output for powering
Input Impedance: 1MWAmpetronic pre-amps & accessories.
Sensitivity: -30dBu (24mV ) for full
RMS
Environmental:
output.
Ventilation: See Installation section
Overload: >+20dBu (7.75V )
RMS for details.
0 0
Ambient temperature: -10 C to +40 C
Slave I/O:
Relative Humidity: < 90%
6.4mm 3-pole Jack socket.
Input Impedance: 100kW
Source impedance: 220W
Output level: 0dBu (0.775V )
RMS
Compression (AGC):
>36dB dynamic range
Controlled by adjusting input level.
Standards:
Loop Design: Meets relevant CE, EMC and
Depends on application, see safety standards.
Designing induction loops handbook
or consult Ampetronic. Please contact Ampetronic if you need
further assistance.
IP rating: IP20
Physical: Weight: 3.75kg
Width: 430mm
Depth: 220mm
Height: 44mm
19” rack width, 1U high.
TECHNICAL SPECIFICATIONS

Interference
1) Background magnetic field signals or interference may be present in any
location and may not be anything to do with the loop system. Monitor this
with a loop receiver (such as an ILR3). If the interference is still present with
the loop system switched off, then you need to locate and eliminate the
source of interference before switching the loop system back on.
2) Magnetic fields can be induced into any low impedance electrical path or
loop. Multiple ground earth systems may experience the pick up of the loop
signal, and cause difficulties with other systems that are not designed to
reject such interference. Check entire sound system for evidence of loop
signal, and trace source of pick-up.
3) Under certain circumstances, the loop signal may appear as jagged lines
or hum bars on a CCTV picture. This could be due to running CCTV (low
impedance unbalanced 2-wire circuit) cables in close proximity to the loop
cable. Separate the cables to reduce the effect.
4) Remote (and apparently unconnected) PA systems can sometimes pick
up loop signals. This is usually because the loop cable becomes damaged
(see point 1 of Instability) or induces signals into the remote system through
long unbalanced cables. Always run long audio signal cables as 3-wire
balanced circuits and keep away from loop cables.
5) See also point 1 of Instability.
Failed AC power fuse in rear of unit
Unplug the loop and AC power supply from amplifier, and replace the failed
fuse with the spare fuse in AC power input fuse tray. Reconnect the AC
power supply and switch on. If the fuse fails again, return the unit to
Ampetronic for evaluation - it may well be covered under warranty, which
will be invalidated by removing the cover. If the fuse does not fail a 'loop
error' may be indicated, but shows that the unit is working correctly.
Re-connect the loop and switch the power off then on again to reset loop
error. If the fuse fails when the loop is re-connected to the unit, then the
loop could be shorted to electrical mains (and building) earth. This can
happen even if no audio signal is present, as the short to earth is likely to
cause an instability / oscillation / feedback condition to develop. A loop
cable short to earth most commonly occurs where flat copper tape is
installed on a metal-clad raised access flooring system. If the insulation on
the flat copper tape is abraded (for example by a piece of metal swarf
trapped below the copper tape), the conductor could short to the earthed
tiles. When installing on raised access floors, it is advisable to insulate
beneath the flat copper tape installation using Ampetronic PWT or similar
tape. The loop short to earth may only be completed when a person steps
on the tape in the affected location, which can create significant difficulties
when diagnosing the cause of fuse failure. Contact Ampetronic for further
advice if a unit is suffering recurring but untraceable failure of the rear panel
fuse.
AC Power Supply: Output:
3-pole IEC320 connector. NL4 speakon (1+ & 2+ connected
85W nominal for either version. internally as are 1- & 2- to allow ‘star-
45-65Hz quad’ method of cable connection).
Current: >9A peak (6.4A ) into 1W
RMS
230V Version Voltage: >20V peak (14.1V )
RMS
Nominal: 230V AC Loop Resistance: 0.3W to 2.0W
Fuse: T 630mA L resistive or 2.2W max impedance
Range: 207-253V AC reactive at 1.6kHz.
Quiescent: 100mA THD+N <0.2% @ 1kHz @ 9.0Apk
Typical: 400mA (O/P 3A pink noise)
RMS
Frequency Response:
120V Version Measured at low level with no metal
Nominal: 120V AC loss correction.
Fuse: T 1.25A L 80Hz to 6.5kHz -3.0dB
Range: 108-132V AC 100Hz to 5.5kHz ± 1.5dB
Quiescent: 200mA
Typical: 800mA (O/P 3A pink noise)
RMS Metal Loss Correction:
0dB (flat) to 3dB/Octave boost.
Microphone Input: Gain at 1kHz remains constant.
XLR socket.
Input Impedance: 200-600W Loop Monitor:
Sensitivity: -70dBu (245uV ) for full
RMS 3.5mm 3-pole (stereo) jack socket
output. 0.675Vpk at 9.0Apk output
Overload: >-5dBu (436mV )
RMS
±15V 150mA DC Output:
Line Input: 3 pin power Mini DIN socket.
6.4mm 3-pole Jack socket. Regulated DC output for powering
Input Impedance: 1MWAmpetronic pre-amps & accessories.
Sensitivity: -30dBu (24mV ) for full
RMS
Environmental:
output.
Ventilation: See Installation section
Overload: >+20dBu (7.75V )
RMS for details.
0 0
Ambient temperature: -10 C to +40 C
Slave I/O:
Relative Humidity: < 90%
6.4mm 3-pole Jack socket.
Input Impedance: 100kW
Source impedance: 220W
Output level: 0dBu (0.775V )
RMS
Compression (AGC):
>36dB dynamic range
Controlled by adjusting input level.
Standards:
Loop Design: Meets relevant CE, EMC and
Depends on application, see safety standards.
Designing induction loops handbook
or consult Ampetronic. Please contact Ampetronic if you need
further assistance.
IP rating: IP20
Physical: Weight: 3.75kg
Width: 430mm
Depth: 220mm
Height: 44mm
19” rack width, 1U high.
TECHNICAL SPECIFICATIONS

Details of all products and services provided by Ampetronic can be found
at www.ampetronic.com
Wall mount brackets are available for mounting the amplifier on the wall
with appropriate fixings.
Microphone pre-amplifiers for 1, 2 or 5 microphones, as well as other line
level signals. These can be powered from either the ±15V DC power
socket on the rear of the unit, or a stand alone power supply.
Signal processing units are available for use with low spill array systems.
Input adaptors for a range of applications such as 100V line audio & low Z
speaker systems are available.
This product carries a five year parts and labour warranty from date of
shipment from Ampetronic. To qualify for the five year warranty, the
product must be registered at www.ampetronic.com (products/warranty),
without which the warranty will be valid for two years only.
The five year warranty is dated from the time the equipment leaves
Ampetronic and NOT when it is installed.
Manufacturer: Ampetronic Ltd.
Northern Road,
Newark,
Nottinghamshire.
NG24 2ET
United Kingdom.
Declares that the product:
Description: Induction Loop Driver
Type name: ILD500
Conforms to the following Directive(s) and Norm(s):
Directive 2004/108/EC
EMC: EN55103-1 : 2009 Emission
EN55103-2 : 2009 Immunity
Directive 2006/95/EC
Safety: EN60065 : 2002
Date: January 2011
J.R. Pieters
Managing Director
Ampetronic Ltd.
WARRANTY
DECLARATION OF CONFORMITY
UP15401-5
ACCESSORIES