Toa A-3506D User manual

OPERATING INSTRUCTIONS
MIXER AMPLIFIER
Thank you for purchasing TOA’s Mixer amplier.
Please carefully follow the instructions in this manual to ensure long, trouble-free use of your equipment.
A-3506D, A-3512D, A-3524D, A-3548D
The gure represents the A-3548D.

2
TABLE OF CONTENTS
1. SAFETY PRECAUTIONS ............................................................................. 3
2. GENERAL DESCRIPTION .......................................................................... 5
3. FEATURES ............................................................................................................ 5
4. HANDLING PRECAUTIONS ...................................................................... 5
5. INSTALLATION PRECAUTIONS ............................................................. 6
6. NOMENCLATURE AND FUNCTIONS ................................................. 7
Front ............................................................................................................................. 7
Rear ............................................................................................................................. 8
7. CONNECTIONS ................................................................................................ 11
7.1. Speaker Connection ........................................................................................... 11
7.2. Input Terminal Connections and Settings ......................................................... 12
7.3. Connecting to the Power Remote Control Output Terminal ............................... 13
7.4. Connecting to the Emergency Control Output Terminal .................................... 14
7.5. Connecting to the Zone Control IN/OUT Terminal ............................................. 14
7.6. Connecting to the Control Input Terminal ........................................................... 15
7.7. Connecting the External Equipment between the Line Output and
the Power Amplifier ............................................................................................. 15
7.8. Removable Terminal Plug Connection ............................................................... 16
8. SETTINGS ........................................................................................................... 17
8.1. Zone Selection Button Setting ............................................................................ 17
8.2. Line Output Interlock Switch Setting .................................................................. 17
8.3. Audio Detection Function Setting ....................................................................... 17
8.4. Broadcast Mode Setting for Input 1 ................................................................... 18
9. VOLUME ADJUSTMENT ........................................................................... 18
10. SPEAKER ZONE SELECTION ............................................................ 18
11. INSTALLING TO AN EQUIPMENT RACK .................................... 19
12. CONTROL SETTINGS ............................................................................. 19
13. PRIORITY BROADCAST FUNCTION .............................................. 20
13.1. Priority Broadcast ............................................................................................ 20
13.2. Emergency Broadcast ...................................................................................... 21
13.3. Normal Broadcast ............................................................................................ 21
13.4. Relationship between Priority Broadcast by Control Input/
Emergency Broadcast and Power On/Off ....................................................... 21
13.5. Factory-preset Operation ................................................................................. 22
13.6. Operation When the Priority Broadcast Function Is Activated
by Audio Detection ........................................................................................... 23
14. BLOCK DIAGRAM ....................................................................................... 25
15. SPECIFICATIONS ........................................................................................ 26
Accessories .............................................................................................................. 27
Optional products ...................................................................................................... 27

3
When Installing the Unit
• Do not expose the unit to rain or an environment
where it may be splashed by water or other liquids,
as doing so may result in re or electric shock.
• Use the unit only with the voltage specied on
the unit. Using a voltage higher than that which is
specied may result in re or electric shock.
• Do not cut, kink, otherwise damage nor modify
the power supply cord. In addition, avoid using the
power cord in close proximity to heaters, and never
place heavy objects -- including the unit itself -- on
the power cord, as doing so may result in re or
electric shock.
• Be sure to ground to the safety ground (earth)
terminal to avoid electric shock. Never ground to a
gas pipe as a catastrophic disaster may result.
• Avoid installing or mounting the unit in unstable
locations, such as on a rickety table or a slanted
surface. Doing so may result in the unit falling down,
causing personal injury and/or property damage.
• Since the unit is designed for indoor use, do not
install it outdoors. If installed outdoors, the aging of
parts causes the unit to fall off, resulting in personal
injury. Also, when it gets wet with rain, there is a
danger of electric shock.
• The terminals marked with the symbol are
hazardous live.
The external wiring to these terminals requires
installation by an instructed person.
When the Unit is in Use
• Should the following irregularity be found during
use, immediately switch off the power, disconnect
the power supply plug from the AC outlet and
contact your nearest TOA dealer. Make no further
attempt to operate the unit in this condition as this
may cause re or electric shock.
· If you detect smoke or a strange smell coming
from the unit.
· If water or any metallic object gets into the unit
· If the unit falls, or the unit case breaks
· If the power supply cord is damaged (exposure of
the core, disconnection, etc.)
· If it is malfunctioning (no tone sounds.)
• To prevent a fire or electric shock, never open nor
remove the unit case as there are high voltage
components inside the unit. Refer all servicing to
your nearest TOA dealer.
• Do not place cups, bowls, or other containers of
liquid or metallic objects on top of the unit. If they
accidentally spill into the unit, this may cause a re
or electric shock.
• Do not insert nor drop metallic objects or ammable
materials in the ventilation slots of the unit’s cover,
as this may result in re or electric shock.
• Do not touch a power supply plug during thunder
and lightning, as this may result in electric shock.
Indicates a potentially hazardous situation which,
if mishandled, could result in moderate or minor
personal injury, and/or property damage.
CAUTION
When Installing the Unit
• Never plug in nor remove the power supply plug with
wet hands, as doing so may cause electric shock.
• When unplugging the power supply cord, be sure to
grasp the power supply plug; never pull on the cord
itself. Operating the unit with a damaged power
supply cord may cause a re or electric shock.
Indicates a potentially hazardous situation which,
if mishandled, could result in death or serious
personal injury.
WARNING
1. SAFETY PRECAUTIONS
• Before installation or use, be sure to carefully read all the instructions in this section for correct and safe
operation.
• Be sure to follow all the precautionary instructions in this section, which contain important warnings and/or
cautions regarding safety.
• After reading, keep this manual handy for future reference.
Safety Symbol and Message Conventions
Safety symbols and messages described below are used in this manual to prevent bodily injury and property
damage which could result from mishandling. Before operating your product, read this manual rst and
understand the safety symbols and messages so you are thoroughly aware of the potential safety hazards.

4
Warning: Operation of this equipment in a residential environment could cause radio interference.
• When moving the unit, be sure to remove its power
supply cord from the wall outlet. Moving the unit
with the power cord connected to the outlet may
cause damage to the power cord, resulting in re or
electric shock. When removing the power cord, be
sure to hold its plug to pull.
• Do not block the ventilation slots in the unit’s cover.
Doing so may cause heat to build up inside the
unit and result in re. Also, periodically clean the
ventilation slots of dust.
• Avoid installing the unit in humid or dusty locations,
in locations exposed to the direct sunlight, near the
heaters, or in locations generating sooty smoke
or steam as doing otherwise may result in re or
electric shock.
• To avoid electric shocks, be sure to switch off the
unit’s power when connecting speakers.
• Be sure to follow the instructions below when rack-
mounting the unit. Failure to do so may cause a re
or personal injury.
· Install the equipment rack on a stable, hard oor.
Fix it with anchor bolts or take other arrangements
to prevent it from falling down.
· When connecting the unit’s power cord to an AC
outlet, use the AC outlet with current capacity
allowable to the unit.
· Rack-mounting screws are not supplied with the
optional MB-25B Rack mounting bracket. Prepare
them that are appropriate for the equipment rack.
When the Unit is in Use
• Do not place heavy objects on the unit as this may
cause it to fall or break which may result in personal
injury and/or property damage. In addition, the
object itself may fall off and cause injury and/or
damage.
• Make sure that the volume control is set to minimum
position before power is switched on. Loud noise
produced at high volume when power is switched
on can impair hearing.
• Do not operate the unit for an extended period of
time with the sound distorting. Doing so may cause
the connected speakers to heat, resulting in a re.
• Contact your TOA dealer as to the cleaning. If dust is
allowed to accumulate in the unit over a long period
of time, a re or damage to the unit may result.
• If dust accumulates on the power supply plug or
in the wall AC outlet, a re may result. Clean it
periodically. In addition, insert the plug in the wall
outlet securely.
• Switch off the power, and unplug the power supply
plug from the AC outlet for safety purposes when
cleaning or leaving the unit unused for 10 days or
more. Doing otherwise may cause a re or electric
shock.
• The socket-outlet shall be installed near the equipment and the plug (disconnecting device) shall be
easily accessible.
• The apparatus shall be connected to a mains socket outlet with a protective earthing connection.

5
2. GENERAL DESCRIPTION
TOA’s A-3500D Series is a PA amplier equipped with 4 microphone inputs and 1 auxiliary input, and 2-channel
zone selector.
In addition to each individual input volume control function, it is equipped with the Priority broadcast function.
Also, the PFC circuit is provided inside.
The A-3500D Series mixer amplier is ideal for paging announcement and BGM applications in schools, ofces,
and super markets.
3. FEATURES
• 4 kinds of power amplifier outputs: 60 W (A-3506D), 120 W (A-3512D), 240 W (A-3524D), and 480 W (A-3548D)
• Lightweight owing to the built-in digital power amplifier unit
• Emergency broadcast and priority broadcast activated by way of the control input (contact)
• Voice detection function that allows the priority broadcast to be activated by voice
• Remote conrmation function that allows you to conrm the unit’s status through the web browser using a PC
• Switchable speaker output
A-3506D: 8 to 16 Ω or 100 V line
A-3512D, A-3524D, A-3548D: 4 to 16 Ω or 100 V line
• Zone selection buttons for making broadcasts to 2 zones
• Electronically-balanced microphone inputs (Inputs 1 to 4) and phantom power available of Microphone inputs
1 and 2.
• Fine sound adjustment possible by connecting a signal processor like an equalizer between the line output
and the power amplifier input
• Bass and treble tone control knobs
• Output level meter
• Master volume control knob to simultaneously adjust all input levels
4. HANDLING PRECAUTIONS
Some operations differ depending on this unit’s power ON/OFF state. The table below shows the relationship
between the power ON/OFF state and the corresponding operation.
Power state
Normal broadcast Priority broadcast/Emergency
broadcast
From Speaker
output
From Recording
output
Not energized Unlit Disabled Disabled Disabled
Energized
(Power turned OFF)
Unlit Disabled Disabled Occasionally possible
( Power is temporarily turned ON.)
Energized
(Power turned ON)
Lit Enabled Enabled Enabled

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5. INSTALLATION PRECAUTIONS
• The supplied power supply cord is designed for exclusive use with the unit. Never use it with other equipment.
• Install the unit in a well-ventilated environment so that temperature inside the unit will not rise.
• When installing the unit on the desk, keep the unit over 10 cm away from objects that may obstruct air ow as
shown below.
• When installing the unit in an equipment rack, mount perforated panels. See "INSTALLING TO AN EQUIPMENT
RACK" on p. 19.
Over 10 cm
Over 10 cmOver 10 cm
A-3500D Series

7
1. Power switch
Press this switch to turn on the power. To turn off
the power, press this switch again.
Note
Operation of the power switch is disabled while the
priority broadcast or the emergency broadcast is
in progress.
( See "PRIORITY BROADCAST FUNCTION" on p. 20.)
2. Power indicator (Green)
Lights when the power is switched on and goes off
when it is switched off.
3. LED level meter (Green x 3, Orange x 1, Red x 1)
Displays the output level.
Adjust each volume control knob for an appropriate
output sound so that the red indicator does not light.
Operating the unit while the red indicator remains
lit causes the sound quality to degrade.
4. Zone selection buttons
Select the broadcast zones. Pressing the Zone 1
selection button causes the Zone 1 to be selected,
outputting the signals from the zone 1 speaker
output terminal (21) on the rear panel.
In the same manner, pressing the Zone 2 selection
button causes the Zone 2 to be selected, outputting
the signals from the zone 2 speaker output terminal
(21) on the rear panel.
Note
These buttons are effective only when the output
impedance setting switch (22) is set to 100 V line
(high impedance).
5. Zone indicator (Green)
The indicator of the zone selected by the Zone
selection button (4) lights.
Note
These indicators work only when the output
impedance setting switch (22) is set to 100 V line
(high impedance).
6. Overcurrent protection indicator (Red)
Lights while the overcurrent protection circuit is
operating if overcurrent ows through the speaker
output.
7. Thermal protection indicator (Red)
Lights while the internal protection circuit is
operating.
8. Emergency broadcast indicator (Red)
Lights while the emergency broadcast is in progress.
( See "PRIORITY BROADCAST FUNCTION" on
p. 20.)
9. Priority broadcast indicator (Green)
Lights while the priority broadcast is in progress.
( See "PRIORITY BROADCAST FUNCTION" on
p. 20.)
10. Volume control knobs for Inputs 1 through 5
Adjust the volume values of the Inputs 1 through 5.
Rotate each knob clockwise to increase the
volume value and counterclockwise to decrease it.
(See "VOLUME ADJUSTMENT" on p. 18.)
11. Bass control knob
Rotate the knob clockwise to boost the bass and
counterclockwise to cut it.
Setting the knob at the center makes the frequency
characteristic at.
12. Treble control knob
Rotate the knob clockwise to boost the treble and
counterclockwise to cut it.
Setting the knob at the center makes the frequency
characteristic at.
13. Master volume control knob
Adjusts all the volume levels simultaneously.
Rotate the knob clockwise to increase the whole
volume level and counterclockwise to decrease it.
(See "VOLUME ADJUSTMENT" on p. 18.)
1
2
34 5
1110 12 13
6
7 9
8
6. NOMENCLATURE AND FUNCTIONS
[Front]
The gure represents the A-3548D.

8
[Rear]
14. AC inlet
Connect the supplied power cord to this receptacle.
15. Zone control input terminals
Short-circuit current: 10 mA or less, open voltage:
35 V DC or less, Removable terminal block
(3.81 mm, 4 pins)
Input the control signals for selecting zones. While
the terminals are closed, the corresponding zone
becomes in selected state, disabling operation of
the Zone selection button (4).
Note
Zone control is effective only when the output
impedance setting switch (22) is set to 100 V line
(high impedance).
16. Zone control output terminals
Open collector output, withstand voltage: 30 V
DC or less, current: 25 mA or less, Removable
terminal block (3.81 mm, 4 pins)
Output terminals for using the remote control of
other equipment. The output signal has polarity
(+/–). The terminal corresponding to the selected
zone is closed.
Note
Zone control is effective only when the output
impedance setting switch (22) is set to 100 V line
(high impedance).
17. Line output jacks 1 and 2
0 dB*, 600 Ω, unbalanced type, RCA pin jack x 2
Can be interlocked with the zone selection state.
Signals are output from the Line output jacks 1
and 2 regardless of the zone selection when the
Line output selection interlock is set to OFF. With
the Line output interlock set to ON, the signals
are output from the Line output jack 1 when the
Zone 1 is selected, and from the Line output jack
2 when the Zone 2 is selected.
Use Switch 2 (Line output interlock switch) of the
DIP switch (33) to make the interlock setting.
18. Recording output jack
0 dB*, 600 Ω, unbalanced type, RCA pin jack
Outputs the audio signals of the SUB output.
(See "BLOCK DIAGRAM" on p. 25.)
Used to record the broadcast contents by
connecting the external recording device to this
jack.
19.Poweramplierinputjack
0 dB*, 600 Ω, unbalanced type, RCA pin jack
Input the output of the signal processor or other
devices connected to the line output jack.
( See "Connecting the External Equipment
between the Line Output and the Power Amplier"
on p. 15.)
Connecting a pin plug to this jack disconnects
the power amplier section from the preamplier
section inside the unit.
14
20 21 22 25 26 27 28 29 32 33
15 16
17
18 19
31
30
23 24
The gure represents the A-3548D.
Be sure to use the supplied power cord.
Using any other power cord may cause
electric shock.
WARNING
* 0 dB = 1 V

9
20. Functional ground terminal
Noise may be generated when external equipment
is connected to the unit. In this case, connect
this terminal to the functional ground terminal of
the external equipment, and the noise may be
reduced.
Note
This ground is not for protective ground.
21. Speaker output terminal
Removable terminal block (5.00 mm, 6 pins)
Outputs the audio signals of the MAIN output or
power amplifier output. (See "BLOCK DIAGRAM"
on p. 25.)
When the Zone 1 is selected, audio signals are
output from the Zone 1 speaker output terminal.
In the same manner, when the Zone 2 is selected,
audio signals are output from the Zone 2 speaker
output terminal.
When set to High impedance, audio signals are
always output from the Direct speaker output
terminal regardless of the Zone selection button
setting.
Zone 1
speaker output terminal
Zone 2
speaker output terminal
Direct
speaker output terminal
C Terminal
*1
The table below shows the specications of each
output.
A-3506D A-3512D A-3524D A-3548D
Rated output 60 W 120 W 240 W 480 W
Low impedance 8 to 16 Ω 4 to 16 Ω
High impedance
(100 V line) 170 Ω 83 Ω 42 Ω 21 Ω
Notes
• Never use the low impedance and high
impedance terminals simultaneously. Doing so
may cause damage to the unit or the peripheral
equipment.
• Never make connection to low impedance
terminal when the Impedance setting switch
(22) is set to 100 V.
Tip
To change impedance between high and low, use
the Impedance setting switch (22).
22. Impedance setting switch
Changes the speaker output impedance either to
low or high.
100 V: High impedance
4 – 16 Ω*1: Low impedance
Notes
• Make sure that the power is switched OFF
before changing this switch setting. Change
cannot be performed when the power is on.
• The impedance remains as it is even if you
change the switch setting when the power is
ON. However, the impedance will change when
you turn the power ON again after turning the
power OFF.
23. Power remote control output terminal
Open collector output, withstand voltage: 30 V
DC or less, current: 25 mA or less, removable
terminal block (3.50 mm, 4 pins)
An output terminal that can be used for remote
control of other equipment. Operates in
synchronization with the unit’s power ON/OFF.
When the unit’s power is on, it is activated.
24. Emergency control output terminal
Open collector output, withstand voltage: 30 V
DC or less, current: 25 mA or less, removable
terminal block (3.50 mm, 4 pins)
An output terminal that can be used for remote
control of other equipment.
It is activated during the emergency broadcast
made from the unit.
25. Input 5 jacks
–20 dB*2, 10 kΩ, unbalanced type, RCA pin jack
x 2
Input jacks dedicated for LINE
26. Input setting switch (Input 4)
Set the input sensitivity level (LINE or MIC) of the
Input 4.
Line: –20 dB*2
Mic: –60 dB*2
27. Input jack (Input 4)
- 60 dB*2 (MIC)/ - 20 dB*2 (LINE), 600 Ω,
electronically-balanced, phone jack
28. Input jack (input 3)
–60 dB*2, 600 Ω, electronically-balanced,
dedicated input for microphone with a phone plug
*1 In case of the A-3506D: 8 – 16 Ω
*2 0 dB = 1 V

10
29. Input setting switches (Inputs 1 and 2)
Set the input sensitivity level (LINE or MIC) of the
Inputs 1 and 2 (30, 32). When switched to the
microphone input, set the phantom power to ON
or OFF.
Switch position Input specication at the
time of setting
MIC PHANTOM ON –60 dB*, 600 Ω,
phantom power ON
PHANTOM OFF –60 dB*, 600 Ω,
phantom power OFF
LINE –20 dB*, 600 Ω,
with no phantom power
Tip
Phantom power is a 24 V DC.
30. Input terminals (Inputs 1 and 2)
–20 d B* (LINE)/– 60 dB* (MI C), 60 0 Ω, elec t r o n i c ally-
balanced, removable terminal block (3.81 mm, 3
pins)
Input sensitivity can be switched either to the
Line input sensitivity or the Microphone input
sensitivity.
The input sensitivity can be changed with the
Input setting switch (29).
Note
Audio signals applied to this Input 1 or 2 are not
output if a phone plug is inserted into the Input
jack (32) of Input 1 or 2, respectively.
31. Control input terminals
(Control inputs 1 and 2)
Short-circuit current: 10 mA or less, open voltage:
35 V DC or less, Removable terminal block
(3.81 mm, 2 pins)
Input the control signals for controlling the priority
broadcast.
While the terminals are closed, the corresponding
trigger of the priority broadcast becomes input
state.
32. Input terminals (Inputs 1 and 2)
–20 dB* (LINE)/–60 dB* (MIC), 600 Ω, electronically-
balanced, phone jack)
Input sensitivity can be switched either to the
Line input sensitivity or the Microphone input
sensitivity.
The input sensitivity can be changed with the
Input setting switch (29).
33. DIP switch
• Switch 1 (ZONE switch)
Sets the Zone selection buttons (4).
(See "Zone Selection Button Setting" on p. 17.)
• Switch 2 (Line output interlock switch)
Sets an interlock between the zone selection
and the line output.
( See "Line Output Interlock Switch Setting" on
p. 17.)
• Switch 3
(Input 2 audio detection selection switch)
Sets an audio detection function for Input 2.
( See "Audio Detection Function Setting" on
p. 17.)
• Switch 4
(Input 1 audio detection selection switch)
Sets an audio detection function for Input 1.
( See "Audio Detection Function Setting" on
p. 17.)
• Switch 5
(Input 1 broadcast function selection switch)
Sets the broadcast mode for Input 1.
( See "Broadcast Mode Setting for Input 1" on
p. 18).
• Switch 6
Not used.
Note
The audio detection function works only while the
Power switch (1) is placed in ON state.
* 0 dB = 1 V

11
7. CONNECTIONS
External cable wiring must be only carried out by qualified and trained personnel.
7.1. Speaker Connection
For cable wiring to the removable terminal block, refer to p. 16.
Notes
• Never make connection to both 4 – 16 Ω* (low impedance) and 100 V line
(high impedance) terminals simultaneously.
• Never make connection to 4 – 16 Ω* terminal when the Impedance setting
switch is set to 100 V.
Tips
• Either C terminal can be used for connection.
• Recommended speaker cable is IV or HIV cable with thickness described
below.
Solid copper cable: ø0.32 – 2.0 mm
Stranded copper cable: 0.05 – 3.3 mm (AWG 30 – 12)
[Low impedance connection]
Speaker output terminal
A-3506D/3512D/3524D/3548D
4 to16 Ω*
*
*In case of the A-3506D: 8 – 16 Ω
[High impedance connection]
Combined impedance:
170 Ω (A-3506D)
83 Ω (A-3512D)
42 Ω (A-3524D)
21 Ω (A-3548D)
100 V line
100 V line
100 V line
*
For the audio output at high impedance application setting,
refer to "21. Speaker output terminal" on p. 9.

12
7.2. Input Terminal Connections and Settings
7.2.1. Connections
[Inputs 1 and2]
(When connecting a 2-core shielded cable)
For cable wiring to the removable terminal plug, refer to p. 16.
[Inputs 1 through 4 (When connecting to the phone jack)]
HC E
(When connecting a single core shielded cable)
Inputs 3 and 4
Phone jack
Inputs 1 and 2
Removable terminal block
Inputs 1 and 2
Phone jack
A-3506D/3512D/3524D/3548D

13
7.2.2. Inputs 1, 2, and 4 settings
Each of Inputs 1, 2, and 4 has its own setting switch corresponding to each input. Perform their settings as
shown below as needed.
[Inputs 1 and 2]
Set the sound source level to connect and whether or not to use the phantom power when the microphone input
is selected.
(INPUT 1)(INPUT 2)
A-3506D/3512D/3524D/3548D
Input sound source Switch position Input specication
Line level LINE –20 dB*, 600 Ω
Microphone level, phantom power not required MIC – PHANTOM OFF (Factory-preset) –60 dB*, 600 Ω
Microphone level, phantom power required MIC – PHANTOM ON –60 dB*, 600 Ω
[Input 4]
Select the input sensitivity level for the equipment connected to Input 4.
A-3506D/3512D/3524D/3548D
Input sound source Switch position Input specication
Line level LINE –20 dB*, 600 Ω, electronically balanced
Microphone level MIC (Factory-preset) –60 dB*, 600 Ω, electronically balanced
7.3. Connecting to the Power Remote Control Output Terminal
Use this terminal when remotely controlling other equipment. This terminal is activated when the unit is turned
ON.
For cable wiring to the removable terminal plug, refer to p. 16.
To other equipment’s
remote control input terminal
A-3506D/3512D/3524D/3548D
Output specications: Open collector output, withstand voltage: 30 V DC or less, current: 25 mA or less
* 0 dB = 1 V

14
7.4. Connecting to the Emergency Control Output Terminal
Use this terminal when remotely controlling other equipment. This terminal is activated while the emergency
broadcast is in progress from this unit.
For cable wiring to the removable terminal plug, refer to p. 16.
Output specications: Open collector output, withstand voltage: 30 V DC or less, current: 25 mA or less
7.5. Connecting to the Zone Control IN/OUT Terminal
Zone can be selected by a control signal (make contact).
These terminals also output a control signal (logic low) when the zone is in selected state. They can be used
for remotely controlling other equipment.
Note
Zone control is effective only when the output impedance setting switch is set to 100 V line (high impedance).
For cable wiring to the removable terminal plug, refer to p. 16.
Control input signal specications: Short-circuit current: 10 mA or less, open voltage: 35 V DC or less
Control output signal specications: Open collector output (polarized), withstand voltage: 30 V DC or less,
current: 25 mA or less
To other equipment’s
remote control input terminal
A-3506D/3512D/3524D/3548D
A-3506D/3512D/3524D/3548D
Zone 1 control input
Zone 2 control input
Zone 1 control output
Zone 2 control output

15
7.6. Connecting to the Control Input Terminal
Priority broadcast (see p. 20) can be controlled by inputting the contact signal to these terminals.
For cable wiring to the removable terminal plug, refer to p. 16.
Input signal specications: Short-circuit current: 10 mA or less, open voltage: 35 V DC or less
7.7. Connecting the External Equipment between the Line Output and the Power Amplifier
Appropriate sound can be obtained by connecting a signal processor like an equalizer or limiter between the
unit’s preamplier section (Line output jack) and the power amplier section (Power amplier input jack).
Notes
• When using the signal processor, be sure to turn OFF the unit’s line output interlock switch.
• Inserting a pin plug into the unit’s power amplier input jack disconnects the preamplier section from the
power amplier section inside the unit.
Tip
Either Line output 1 or 2 can be used.
Line output specications: 0 dB*, 600 Ω, unbalanced, RCA pin jack
Power amplier input specications: 0 dB*, 600 Ω, unbalanced, RCA pin jack
* 0 dB = 1 V
Input 1
Input 2
A-3506D/3512D/3524D/3548D
IN
OUT
Signal processor
A-3606D/3612D/3624D/3648D

16
7.8. Removable Terminal Plug Connection
Step 1. Wiring the supplied removable terminal plug.
1-1. Loosen the terminal screws to insert the wire.
1-2. Tighten the terminal screws.
Ensure that the wire does not break free when
pulled. If the wire does pull free, repeat the
connection procedure from the start.
Step 2. Insert the wired terminal plug into the corresponding
terminal block in the unit’s rear panel.
Step 3. Only when the xing screw is inserted, tighten the
xing screw.
Notes
• Do not reverse Steps 1 and 2 above. Poor contact may
result if force is applied to the unit’s internal circuit board
pins while the terminal screws are being tightened.
• When detaching the terminal plug, pull it straight out. Pulling it
out at an angle may cause the terminal plug or terminal block
to break.
Slotted screwdriver
LoosensTightens
Removable terminal plug
(accessory)
Terminal screw
Fixing screw
1
3
[Recommended type of screwdriver ]
Blade width*1
*1For speaker output terminal: About 3.5 mm
For other terminals: About 2.5 mm
Tips
• Applicable cable size
For speaker output terminal For other terminals
Conductor cross-section area 0.05 − 3.3 mm20.08 − 2.0 mm2
AWG AWG 30 − 12 or equivalent AWG 28 − 14 or equivalent
Solid cable and stranded cable Shielded cable
7 mm*27 mm*2
20 mm
*2 Expose 8 mm or more when using the above
ferrule terminal, and cut off an extra conductor
protruding from the sleeve.
Note
Avoid soldering stranded or shielded
cable, as contact resistance may increase
when the cable is tightened and the
solder is crushed, possibly resulting in an
excessive rise in joint temperatures.
• When connecting 2 cables or a shielded cable to a single terminal, use a ferrule terminal with an insulation
sleeve to crimp the cables because such cable conductors could become loose.
(1) Recommended ferrule terminals for signal cables
(made by Phoenix Contact)
Model Number a l1l2
AI 0,34-8 TQ
AI 0,5-8 WH
2
Unit: mm
2.5
12.5
14
8
8
b
0.8
1.1
(2) Recommended ferrule terminals for speaker cables
(made by Phoenix Contact)
Model Number a1l1l2
AI 1,5-8 BK
AI-TWIN 2x1,5-8 BK 6.6
a2
3.6
14
162.3
8
8
a
3.4
Unit: mm
b
1.8
Crimping tool: CRIMPFOX 10S (made by Phoenix Contact)
Insulation sleeve
Contact section
Insulation sleeve
Contact section
a
l2
a1
a2
l1
l2
l1
bb
• Cable sheath to trim

17
8. SETTINGS
8.1. Zone Selection Button Setting
Set whether or not to use the front-mounted Zone selection buttons with Switch 1 of the DIP switch.
Tip
Even when the Zone selection button is set to OFF, you can perform zone selection using the rear-mounted
Zone control input terminal (see p. 14).
OFF: You can use the front-mounted Zone selection buttons. (Factory-preset)
ON: You cannot use the front-mounted Zone selection buttons.
8.2. Line Output Interlock Switch Setting
Set the interlock between zone selection and line output with Switch 2 of the DIP switch.
Switch 2
A-3506D/3512D/3524D/3548D
OFF: Signals are output from the Line output jacks 1 and 2 regardless of zone selection. (Factory-preset)
ON: Signals are output from the Line output jack 1 when the Zone 1 is selected and from the Line output jack
2 when the Zone 2 is selected.
8.3. Audio Detection Function Setting
Set whether or not to use the Audio detection function (see p. 20) for Input 1 with the Switch 4 of DIP switch,
and Input 2 with Switch 3 of the DIP switch.
OFF: You cannot use the Audio detection function.(Factory-preset)
ON: You can use the Audio detection function.
Switch 1
A-3506D/3512D/3524D/3548D
Switches 3, 4
A-3506D/3512D/3524D/3548D

18
8.4. Broadcast Mode Setting for Input 1
Set the broadcast mode for Input 1 with the Switch 5 of DIP switch.
OFF: Sets the broadcast mode for Input 1 to Priority broadcast (see p. 20).
ON: Sets the broadcast mode for Input 1 to Emergency broadcast (see p. 21). (Factory-preset)
9. VOLUME ADJUSTMENT
Switch 5
A-3506D/3512D/3524D/3548D
Volume control knobs Bass control knob
Treble control knob Master volume control knob
The unit's volume level can be adjusted in 2 steps using individual input volume control knobs and the Master
volume control knob. Therefore, when the Master volume control knob is set to the minimum position, no sound
is output even if each input volume control knob is set to the maximum. Be sure to adjust the entire volume level
with the Master volume control knob in advance.
When the emergency broadcast mode is set, the broadcast can be made at the maximum volume regardless
of the setting position of the Master volume control knob.* Also, the sound characteristic is made at regardless
of the setting positions of the Treble control knob and the Bass control knob.
* Volume control knobs for each input remain effective.
10. SPEAKER ZONE SELECTION
Pressing the unit’s front-mounted Zone 1 selection switch or inputting the control signal to the Zone 1 control
input terminal allows the Zone 1 indicator to light and the broadcast to be output from the speakers connected
to the rear-amounted Zone 1 speaker output terminal. Concurrently, the control signal is output from the Zone
1 control output terminal.
Operation in the case of Zone 2 is the same as above.
Note
Speaker zone control is effective only when the impedance setting switch (p. 9) is set to 100 V line (high
impedance).
When set to High impedance, audio signals are always output from the Direct speaker output terminal regardless
of the Zone selection button setting.

19
11. INSTALLING TO AN EQUIPMENT RACK
When installing the unit to an equipment rack, remove the four plastic feet
screwed on the unit’s base as shown below.
When installing the unit to an equipment rack, use the optional MB-25B Rack mounting bracket.
12. CONTROL SETTINGS
Output levels are adjustable with individual volume controls. For music play
or announcements, adjust the corresponding volume control so that the red
indicator doesn’t light. Note that the sound quality is downgraded when the
red indicator remains lit.
To prevent the accidental change of the settings of input volume and tone
(Bass and Treble) controls, remove their knobs after setting them to the
desired position and attach the supplied volume control covers instead.
Control knob
Volume control cover
(accessory)
A-3506D/3512D/3524D/3548D
Note
To improve ventilation, ensure that a perforated panel (panel with air openings) of 1-unit size or
greater is mounted over and under each unit, as well as on the top and at the bottom of the rack.
MB-25B
Machine screw M4 x 16
(supplied with the MB-25B)
A-3506D/3512D/3524D/3548D
PF-013B Perforated panel
(option)
A-3506D/3512D/3524D/3548D
Rack-mounting screws are not supplied with the optional MB-25B Rack
mounting bracket. Prepare them that are appropriate for the equipment
rack.
CAUTION
Plastic foot
A-3506D/3512D/3524D/3548D

20
13. PRIORITY BROADCAST FUNCTION
13.1. Priority Broadcast
Priority broadcast function refers to a function that mutes the specic audio signal by means of the control
signal or audio signal as a trigger when it is input.
The priority broadcast to be made from this unit can be activated by way of the following 4 signals as triggers.
• Control inputs 1 and 2 (contacts)
• Input 1 audio detection and Input 2 audio detection (Audio inputs)
The front-mounted Priority broadcast indicator remains lit during priority broadcast.
The table below shows the settings related to the unit's priorities.
Priority
level Trigger Broadcast type Audio input State
Input 1
Priority Broadcast
High Control input 1 Priority/Emergency
( Factory default:
Emergency,
see p. 18.)
Broadcast enabled
from Input 1 only
Mutes other inputs
except Input 1
Always "USED"
Input 1
audio detection
Priority NOT USED/USED
( Factory default:
NOT USED,
see p. 17)
Input 2
Priority broadcast
Middle Control input 2 Priority Broadcast enabled
from Input 2 only
Mutes other inputs
except Input 2
Always "USED"
Input 2
audio detection
Priority NOT USED/USED
( Factory default:
NOT USED,
see p. 17)
Normal broadcast Low None Normal Broadcast enabled
from all inputs.
Any inputs remain
not muted.
Always "USED"
Note
You cannot make the audio detection (Input 1) valid when the Control input 1 is set to “Emergency.”
The table below shows the differences between the control input and the audio detection.
Signal that works
as a trigger Settable broadcast Power activation at power-off
Control input Control input 1 Emergency broadcast*1
Priority broadcast
Possible
Control input 2 Priority broadcast
Audio detection*2Audio input 1 Priority broadcast Impossible
Audio input 2 Priority broadcast
*1 Valid only when the broadcast mode of Input 1 is set to “Emergency broadcast.” (See p. 18.)
*2 Valid only when the audio detection is set to "USED". (See p. 17.)