ADS 3120 Plus User manual

Installation &
Operation Guide
ADS 3120 Plus
120W ac/dc
Mixer Amplifier
PLEASE NOTE: THIS MANUAL AND THE NOTES CONTAINED HEREIN ARE COPYRIGHT AND
MAY NOT BE REPRODUCED EITHER WHOLLY OR IN PART, IN ANY WAY WHATSOEVER,
WITHOUT WRITTEN CONSENT OF ADSworldwide.
Audio Design Services Ltd, St David’s House, Adcroft St, Higher Hillgate, Stockport, Cheshire SK1 3HW, UK.
TEL: [phone] FAX: [phone]. WEB: www.ads-worldwide.net
© 2008

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Product Compliance to EC directives for Standard Products
All standard products conform to the relevant directives, regulations and standards
for electronic and associated apparatus. The equipment is CE marked both on the
apparatus and the packaging.
Our products meet the appropriate British and International standards. A product
‘Declaration of Conformity’ Statement is available for each of the product ranges
(available on request). This covers both the EMC and Low Voltage Directives.
UNPACKING
While all ADSworldwide equipment is carefully packed to prevent damage in
transit, we recommend that the equipment is unpacked and inspected immediately
on receipt. If damage has occurred please advise your carrier and your supplier
who will arrange appropriate action.
If it is necessary to re-pack the equipment for onward shipping or returning to
ADSworldwide for service PLEASE ENSURE THAT THE ORIGINAL PACKING
OR EQUIVALENT IS USED.

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IMPORTANT
The lightning flash with arrowhead symbol, within an equilateral triangle, is
intended to alert the user to the presence of un-insulated dangerous voltage within
the product's enclosure that may be of sufficient magnitude to constitute a risk of
electric shock to persons.
The exclamation mark within an equilateral triangle is intended to alert the user to
the presence of important operating and maintenance instructions in the literature
accompanying the appliance.
TO PREVENT THE RISK OF ELECTRIC SHOCK, DO NOT REMOVE COVER
(OR BACK). NO USER SERVICABLE PARTS INSIDE. REFER SERVICING TO
QUALIFIED PERSONNEL.

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TABLE OF CONTENTS
INTRODUCTION .................................................................................................... 5
Features.............................................................................................................................. 5
Safety Information............................................................................................................... 5
OPERATION........................................................................................................... 7
General Installation............................................................................................................. 7
Front Panel ......................................................................................................................... 7
Rear Panel .......................................................................................................................... 8
Priority Connections ........................................................................................................... 8
MIC 1 and MIC 2 ..........................................................................................................................8
Input Connections............................................................................................................... 9
MIC 1 and MIC 2 ..........................................................................................................................9
MIC 3 and AUX 1 .........................................................................................................................9
MIC 4, MIC 5, AUX 2 and AUX 3 .................................................................................................9
Phantom Power ................................................................................................................ 10
Loudspeaker Output ......................................................................................................... 10
Loudspeaker Loading.................................................................................................................10
Booster Output.................................................................................................................. 11
Variable Output ..........................................................................................................................11
Fixed Output...............................................................................................................................11
dc Power ........................................................................................................................... 11
Facility Terminals.............................................................................................................. 11
dc Output....................................................................................................................................11
Restoration .................................................................................................................................11
Accessories ...................................................................................................................... 12
Some Possible Interfaces................................................................................................. 12
TROUBLESHOOTING.......................................................................................... 13
SPECIFICATIONS ................................................................................................ 14
NOTES ................................................................................................................. 15
WARRANTY CONDITIONS .................................................................................. 16

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Audio Design Services Ltd., St David’s House, Adcroft Street, Higher Hillgate, STOCKPORT SK1 3HW.
INTRODUCTION
Features
The ADS 3120 Plus is a 120 watt rms, two-zone, mixer amplifier suitable for powering
medium to large sound systems where music may be required in one area and quiet in the
rest of the building. Messages can be relayed to both areas using the priority switching
system.
Features include
220-240Vac at 50Hz or 24Vdc power operation
two balanced microphone inputs (MIC 1 and MIC 2) with priority paging & chime
three more balanced inputs switchable between microphone and line level
two outputs - one for speech and music, one for speech only
(this facility is only available on MIC 1 and MIC 2)
each input has phantom power facility
volume controls for all inputs, located on the front panel
separate bass, treble and master volume controls, located on the front panel
supplied with 19-inch rack mount ears.
Additional features on the new version (Plus) of the ADS 3120 include
XLR and ¼ inch 3-pole jack combination sockets for MIC 1, MIC 2 and MIC 3
5-pin DIN sockets for MIC 1 and MIC 2
(to accept microphones fitted with a 5-pin DIN plug – e.g. the ADS Signet 1A)
volume restoration
trim control on MIC 1 and MIC 2.
Safety Information
WARNING – THIS APPLIANCE MUST BE EARTHED
IMPORTANT
The wires in the mains lead are coloured in accordance with the following code
Green and yellow Earth (E); Blue: Neutral (N); Brown: Live (L).
As the colours of the wires in the mains lead of the apparatus may not correspond with the
coloured markings identifying the terminals in your plug proceed as follows
the wire coloured green and yellow must be connected to the terminal
marked by the letter E (or the safety earth symbol), or coloured green and
yellow
the wire coloured blue must be connected to the terminal marked with the
letter N or coloured black
the wire coloured brown must be connected to the terminal marked with the
letter L or coloured red.

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If a 13-amp (BS1363) plug or other type of plug is used, a 5-amp fuse must be fitted either
in the plug or at the distribution board.
For mains connection other than in the UK, refer to your local requirements for connection
to the mains supply.
IEC Mains Inlet Socket
Brown Live
Fuse (max 5A)
Fuse Holder
13A Mains Plug Wiring (UK)
Green/Yellow Earth
Blue Neutral

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Audio Design Services Ltd., St David’s House, Adcroft Street, Higher Hillgate, STOCKPORT SK1 3HW.
OPERATION
General Installation
ALWAYS ensure that the equipment is properly earthed (grounded).
Operating without an earth is dangerous and may cause high levels of
audible hum from the speaker outputs.
NEVER remove the top cover of the amplifier or make an internal adjustment
with the ac mains supply connected. All internal servicing should be
performed by a competent and qualified engineer.
DO NOT expose the unit to rain or moisture. If any fluids or foreign objects
should enter the unit, disconnect the power plug immediately.
DO NOT site the equipment in locations exposed to direct sunlight, near
heaters or other heat sources. Avoid locations with high humidity or dust
levels.
DO NOT obstruct the ventilation slots in the amplifier case and allow
adequate ventilation. (Ensure that a 1U ventilation panel is fitted above the
unit if the amplifier is rack-mounted.)
DO NOT run microphone cables near mains, data, telephone or 100V lines.
AVOID jointing the microphone cables if possible. If this is unavoidable, make
sure a good screen connector is used.
ALWAYS use a balanced or floating low impedance microphone on long
microphone runs, terminating in a balanced input.
Front Panel
1 2 3 4 5 6 7 8 9 10 11
1 OVERLOAD LED INDICATOR 7 BASS CONTROL
2 MIC 1 8 TREBLE CONTROL
3 MIC 2 9 MASTER GAIN
4 MIC 3 / AUX 1 10 POWER LED
5 MIC 4 / AUX 2 11 POWER ON/OFF SWITCH
6 MIC 5 / AUX 3

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Rear Panel
12 13 14 15 16 17 18 19 20 21 22 23 24
12 MAINS SOCKET
13 DC IN TERMINALS
14 LOUDSPEAKER TERMINALS
15 BOOSTER OUT (VARIABLE)
16 BOOSTER OUT (FIXED OR VARIABLE)
17 AUX 3
18 MIC 5
19 AUX 2
20 MIC 4
21 AUX 1
22 MIC 3
23 MIC 2
24 MIC 1
25 MIC 1 Priority Connection
26 MIC 2 Priority Connection
27 MIC 1 Trim Control
28 MIC 2 Trim Control
Priority Connections
MIC 1 and MIC 2
Pin Function
1 Signal + Positive signal input from the microphone.
2 Ground Connect to chassis or screen.
3 Signal - Negative signal input from the microphone.
4 Access Close pins 4 and 5. For priority access.
5 Access Close pins 4 and 5. For priority access.
26 25
28 27
180
o
5-pin DIN socket

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Input Connections
MIC 1 and MIC 2
Microphone inputs 1 and 2 use an XLR / ¼” 3-pole jack combination socket and a 180˚
5-pin DIN socket. Any of these connectors may be used. However if priority is required it
may be easier to use the DIN socket and compatible ADS Signet microphone. (See
Priority Connections 25 and 26 and wiring table on Page 8 for the DIN socket.)
The connections on an XLR plug are numbered 1 to 3 and should be connected as follows
Pin 1: Ground (or Screen). Pin 2: Signal+ (or Hot). PIN 3: Signal- (or Cold)
If the signal source is not balanced then Pin 1 should be connected to Pin 3 along with the
Ground (or Screen).
Each of the microphone inputs 1 and 2 is provided with a trim control on the rear panel
(see diagram on Page 8). This control adjusts the sensitivity of the input to allow for a
wide range of input sources. Adjust this control to reduce noise and provide an acceptable,
undistorted output level.
MIC 3 and AUX 1
This microphone input uses an XLR / ¼” 3-pole jack combination socket (see above) and
is balanced. There are no priority functions available with this input. The input can be
reconfigured as an auxiliary input as follows
disconnect the power supply then remove the amplifier top cover
locate the correct switch on the rear PCB
(Three switches are located on the rear PCB. The switch required is the left
hand one when viewed from the front of the amplifier)
set the switch to the position nearest to the rear panel
replace the amplifier top cover.
The auxiliary input uses a phono connection (see below).
Pin (Signal)
Sleeve (Screen)
MIC 4, MIC 5, AUX 2 and AUX 3
Each microphone input uses a ¼” 3-pole jack connection (see below).
Ring (Signal-)
Tip (Signal+)
Sleeve (Screen)
Each auxiliary input uses a phono connection (see above).
XLR/Jack Combination Socket
XLR Plug
Pin Configuration
Balanced Unbalanced

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All inputs are configured as AUX inputs. To configure them as balanced microphone inputs
proceed as follows
disconnect the power supply then remove the amplifier top cover
locate the correct switch on the rear PCB
(MIC 4 is the centre one and MIC 5 the right hand one when viewed from
the front of the amplifier)
set the switch to the position nearest to the front panel
replace the amplifier top cover.
Phantom Power
Each of inputs has the option of phantom power, providing 18Vdc phantom power on the
XLR socket. This is often used to power external low current devices such as electret
condenser microphones. Phantom power is selected by jumpers located internally on the
input board of the amplifier.
NEVER remove the top cover of the amplifier or make an internal
adjustment with the ac mains supply connected. All internal
adjustment must be performed by a competent, qualified engineer.
Having taken all the necessary electrical safety precautions, remove the top cover of the
amplifier and locate the phantom power jumpers for the five microphone inputs. Select the
appropriate jumper setting (by moving the jumper if necessary) for phantom power to be
off or on, as indicated on the inset diagram below.
Loudspeaker Output
Two loudspeaker outputs are available – Music & Speech and Speech Only.
Music & Speech gives an output at all times.
Speech Only gives an output during a priority condition.
Loudspeaker Loading
To allow sufficient transient overload margin it is suggested that the output load should not
exceed approximately 70% of the rated power output.

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Booster Output
Variable Output
Where a variable output is required this is available through the 5-pin DIN output socket
(see Rear Panel No.16 on Page 8). The output is dependent on all controls.
Pin Function
1 Variable output.
2 Screen.
3 Open collector to ground when a
priority signal is present.
4 Fixed output.
5 Ground.
Variable Output
Two phono sockets are available (see Rear Panel No.15 on Page 8). These are connect-
ed together internally and provide a variable output, output varies with the position of the
mixer and master level controls.
dc Power
The amplifier may be operated from a battery power source. Ensure correct polarity
connection when connecting batteries. The amplifier requires a 24Vdc source.
Facility Terminals
A 24Vdc 0.5A supply is provided on the rear panel in conjunction with Busy and Speak terminals.
dc Output
The two left terminals (see diagram below) provide a 24Vdc protected output, which can
be used to supply external devices (such as relays or line pre-amplifiers) up to 250mA.
Restoration
The two right terminals (see diagram below) can be used to drive LEDs in some
microphones to show that other microphones in the system are currently broadcasting.
Busy is used to indicate that the system has a priority running. Speak is used to indicate
that the chime has run and the user can speak now.
Another use for the busy terminal is volume restoration as used on many volume controls
and for the control of other external devices and relays.
When using external relays, ensure that a ‘back EMF’ diode is fitted to the relay or
damage to the amplifier or other connected equipment may result. (‘Back EMF’ is caused
by the collapsing magnetic field in the relay coil as the relay is switched off and depending
on the relay can produce very high voltages. The diode acts as a short circuit and
eliminates ‘back EMF’. Use 1N4001 diode or equivalent).
180o5-pin DIN socket

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Accessories
1 x Instruction Manual
1 x Mains Supply Lead
1 x 19-inch Rack Mounting Kit
Some Possible Interfaces
100V line out to loudspeakers
Paging
Microphones
Radio Mic
Receiver
Tuner
AUX1
CD Player
AUX3
24V battery
dc IN
Microphones can use any MIC input
(unless the shared AUX is in use)
Modules can use any AUX input
(unless the shared MIC is in use)
Booster Amplifier

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Audio Design Services Ltd., St David’s House, Adcroft Street, Higher Hillgate, STOCKPORT SK1 3HW.
TROUBLESHOOTING
Symptom Possible Cause Remedy
ac power
LED does
not light
No ac power
Amplifier is off
ac fuse blown
Ensure that the supply cable is correctly connected
to the mains outlet and the supply is turned on.
Switch on amplifier by pressing the on/off switch.
Remove ac power cord from mains supply and
amplifier. Remove and check fuse. Only replace
fuse with the same type and rating – DO NOT USE
A HIGHER RATED FUSE. If the fuse has failed
and a replacement also fails, contact your supplier.
Sound
output is
very low
Incorrect level
settings
Check the trim controls on the rear of the amplifier,
the input level controls and the master output level
control.
Sound
output is
low and
distorted.
Amplifier
gets very
hot.
Impedance
mismatch or a
short on the
loudspeaker line
Oscillation
Check the loudspeaker circuit impedance (the
minimum is shown in the specification). Check for
any short to ground.
Make sure that the loudspeaker circuits are kept
away from sensitive microphone circuits. If these
cross, make sure they do so at right angles.
Excessive
hum or
noise
Poor signal
ground
Earth loop is
present
Check all signal sources to ensure that the ground
(screen) connections to the amplifier are good.
If other equipment with a ground connection is
being used an earth loop may form causing hum.
Disconnect the screen connection at the amplifier.
DO NOT DISCONNECT THE SAFETY EARTH
FROM ANY EQUIPMENT.

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Audio Design Services Ltd., St David’s House, Adcroft Street, Higher Hillgate, STOCKPORT SK1 3HW.
SPECIFICATIONS
Amplifier
Output Power 120W rms into 8Ωat 1 kHz
Constant Voltage Output 100V
Distortion at Rated Power <2% THD
Frequency Response 50Hz to 18kHz, -3dB
Tone Control Range Bass: ±10db at 100Hz
Treble: ±10db at 10kHz
Microphone Input
Sensitivity (MIC 1 & 2) 1mV to 100mV at 600Ω
Sensitivity (MIC 3–5) 1mV at 600Ω
S/N ratio (MIC 1–5) >60dB
Phantom Power 18Vdc
Auxiliary Input
Sensitivity (AUX 1–3) 775mV at 100kΩ, 0dB
S/N ratio (AUX 1–3) >70dB
Booster Output
Output Level 1V at 600Ω
Chime (Bing-Bong)
Note 2
Mute Level <40dB
Operating Conditions
Mains Power 220 – 240Vac at 50Hz
dc Power 24V
ac Power Consumption 320W at rated power
dc Power Consumption 8A at rated power
Size and Weight
Dimensions 88(H) x 428(W) x 268(D) mm
Weight 10.2kg

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NOTES
Reference Note

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Audio Design Services Ltd., St David’s House, Adcroft Street, Higher Hillgate, STOCKPORT SK1 3HW.
WARRANTY CONDITIONS
Audio Design Services Limited warrants that this product is free from defects in material and
workmanship for the period of one year from the date of purchase. If this product is defective,
Audio Design Services Limited agrees to repair or replace it, free of charge, subject to the following:
The defect becomes apparent during unpacking or normal use
The product has not been subjected to misuse, abuse, neglect, accident, incorrect
wiring, improper installation or improper use
The product is intact and has not been tampered with, opened, altered, or repaired
by unauthorized personnel
The product is delivered through the dealer or by the purchaser to Audio Design
Services Ltd with all transportation charges prepaid, within one (1) year of date of
sale
Audio Design Services Ltd personnel examine and judge that the product is
defective. If it is judged to be defective, Audio Design Services Ltd will, at their
discretion, repair or replace the product with new or reconditioned parts or a
product of the same or similar design
Battery warranty is limited to ninety (90) days.
When returning this product, please contact Audio Design Services Ltd to obtain a returns number
which should be marked on any packages to be returned. Please include your name, address,
telephone number, a description of the problem and your sales receipt.
This warranty is in lieu of all other warranties expressed or implied and no one is authorised to
assume any liability on behalf of Audio Design Services Ltd or impose any obligation on it in
connection with the sale of any product other than as outlined above.
Audio Design Services Ltd
T/A ADSworldwide
St David’s House
Adcroft Street
Higher Hillgate
STOCKPORT
SK1 3HW
UK
Telephone: [phone]
Fax: [phone]
Email: [e-mail]
Web: www.ads-worldwide.net