www.redbackaudio.com.au
Redback® Proudly Made In Australia
6
Redback® A 4270/80
Four Zone Paging PA Amplifier
5.0 AUDIO CONNECTIONS
The amplifier has three balanced XLR audio inputs, three dual RCA line inputs which are internally
mixed to create mono signals and a front mounted Music Input for portable devices. This input when
connected, over-rides the rear channel 3 audio sources and is adjusted via the volume 3 level control.
A VOX function is also included which when enabled will allow input 1 to mute inputs 2 and 3, or
input 2 to mute input 3. The VOX circuitry is selected by internal switches as shown in figure 5. The
VOX1 switch when set to ON will allow input 1 to mute inputs 2 & 3. The VOX2 switch when set to ON
will allow input 2 to mute input 3. The VOX sensitivity is adjusted by the trimpots located on the front
of the amplifier.
Fig 3 shows a typical install where the A 4270 has a balanced microphone connected to input 1 and
a Line level source connected to input 2. If the VOX1 switch is set to “ON”, the microphone will VOX
mute the CD player connected to input 2.
Fig 3
6.0 POWER SUPPLY
The amplifier operates on 230V AC or primarily for battery backup operation a 24V DC supply. Ensure power is switched
OFF at the front panel before connecting either mains power to the IEC socket or 24V DC to the screw terminal input. As
high currents may be drawn when operating from a 24V DC supply confirm the capacity of the DC power supply used.
7.0 PHANTOM POWER
All three microphone inputs have DIP switch selectable phantom power. When enabled 15V DC will be connected to the
Hot and Cold pins of the corresponding XLR. To access the DIP switches, first disconnect power from the unit and then
remove the lid. The location of the DIP switches is shown in figure 4.
The Phantom power DIP switch settings are:
DIP 1 enables the phantom power to the XLR connector on input 1.
DIP 2 enables the phantom power to the XLR connector on input 2.
DIP 3 enables the phantom power to the XLR connector on input 3.
DIP 4 is not used.
8.0 VOX MUTING
Vox muting is provided on inputs one and two, which, when activated, automatically mutes the other inputs.
The VOX1 switch when set to ON will allow input 1 to mute inputs 2 & 3. The VOX2 switch when set to ON will allow
input 2 to mute input 3.
The VOX sensitivity is adjusted by the trimpots located on the front of the amplifier (see figure 1).
Speakers fitted with
100V line transformers.
CD
REDBACK
240V AC @ 50Hz
RISK OF ELECTRIC SHOCK
OPEN BY QUALIFIED
PERSONNEL ONLY
!
CAUTION
Tape Out
Line 1
Mic 3
Mic 2
Mic 1
1
2
3
1 • Shield
2 • Hot
3 • Cold
MIc XLR
wiring
Configuration
Line 2
Line 3
L
R
L
R
L
R
Output
125W
Fuse
5 Amp
7.5 Amp
250W
AC Fuse (M 205)
DC Fuse
Output
125W
10 Amp
20 Amp
250W
Resettable
DC Fuse
L
R
Optional
Plugin
- +
+ _
24V
DC IN
Made in Australia by
Altronic Distributors Pty Ltd
www.redbackaudio.com.au
CH1
CO
M
CAN
EV
100V OUT
(MAIN)
- +
+ _
AL
CH2
OUT4
(100V)
OUT3
(100V)
OUT2
(100V)
OUT1
(100V)
Evac
Volume
V/Over
Volume
Chime
Volume
DIP
Switches
To Paging
Console 1
To Paging
Console 2
(16GB
Maximum)
Micro SD Card
Output
Triggers
Levels
+ _
+ _
+ _
+ _
1 2
3
4
2
1
3
2
1
3
2
1
3
1
2
3
1 • Earth/Shield
2 • Signal Hot
3 • Signal Cold
MIc XLR
wiring
Configuration
