User Manual
www.redbackaudio.com.auRedback® Proudly Made In Australia6
Redback® A 4275C/85C 125/250W Mixer Amplier
1.5 REAR PANEL CONNECTIONS
Fig 1.5 shows the layout of the rear panel.
Fig 1.5
1 Switched 24V 1A output, PTT (Push to talk) muting, Remote Volume and Power fail Contacts
Switched 24V 1A output
When set to “On” via the output DIP switch (see DIP switch settings section 2.3 ) 24V DC appears at the “24V DC
Switched Out” terminals on the rear panel, whilst the PTT terminals are shorted together, or whenever any
priority/Vox is activated. The switched 24V output could be used to control external devices like remote volume
controls with bypass relays for emergency paging.
PTT Muting Contacts
These contacts are shorted together to activate. The The PTT (Push to talk) is normally done with the switch of a
push to talk microphone.
Remote Volume
Overall volume can be adjusted by a remotely located volume control. This requires a two wire gure 8 type cable
and a 1kohmΩ potentiometer connected as shown in section 2.6. Maximum distance 100m.
Power Fail Contacts
These contacts close when the power to the amplier is removed. This could be used to activate a buzzer or
remote warning light to indicate power failure to the amplier.The A 4275C/85B range of mixer ampliers have
provison to plug in an optional Alert/Evacuation module (A 4573). The controls are listed below (see section 2.5
for more details).
2 Voice Over Volume
Use this trimpot adjustment to change the output level of the playback message.
3 Chime Volume
Use this trimpot adjustment to change the output level of the chime volume.
4 Alert and Evacuation Volume
Use this trimpot adjustment to change the output level of the alert and evacuation tone.
5 Alert, Evacuation, chime and cancel contacts
Use these contacts to trigger the chime tones, the alert tone, the evacuation tone and to cancel any
of the tones once triggered. All tones & cancel function are operated by a closing contact to ground.
This could be triggered via building re indicator board, break glass alarm etc.
6 Preamp Out (Balanced Line Output)
A 3 pin 600ohm 1V balanced XLR output is provided for passing the audio signal on to other slave ampliers
or to record the output of the amplier. This output can be set up to be effected (post master volume) by the
master volume control or unaffected (pre master volume). Factory default setting disables the preout. (Refer to
section 2.3 DIP switch settings).
DIP 2
SW Item On Off
1
2
Input 4 Level 1V 100mV
3
Not USed
4 Input 3 Level 1V 100mV
Input 3 Priority On Off
*
DIP 1
SW Item On Off
1
2
Input 2 Level 1V 100mV
3
Input 2 Priority On Off
4 Input 1 Level 1V 100mV
Input 1 Priority On Off
*
*
4 -16Ω70V
230V AC @ 50Hz
100V
OUTPUTS
L
R
24V DC IN
Balanced Mic
+
_
PTT
(short to
activate)
Power Fail
(Contacts
close on
power fail)
SendReturn
Tape Out
Preamp Out
Link To Charge
Backup battery
Input 1Input 3 Input 2Input 4Input 5Input 6
ALERT - EVAC MODULE
Output Levels
Voice Chime Alert
Over & Evac
EV
COMCANCH
AL
Triggers
L
R
+
–
Rem. Vol
Connect
to 1KΩ Pot
+
–
+
–
+
–
Line
24V DC
Switched
Output
DIP 5
Interface
DIP 4
DIP 1
DIP 2DIP 3
Balanced Mic
Line
Balanced Mic
Line
Balanced Mic
Line
Balanced Mic
Line
Balanced Mic
Line
Balanced Line
L
R
L
R
L
R
L
R
L
R
2
6
7
3 4 5
161718
1
15
14
13 12
10 911
8
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!
CAUTION
Made in Australia
by Altronic
Distributors
Pty Ltd
DIP 3
SW Item On Off
1
2
Input 6 Level 1V 100mV
3
Not USed
4 Input 5 Level 1V 100mV
Not USed
SW
Item On
Off
1
2
3
4
Not Used
Not Used
Not Used
Not Used
DIP 4
SW
Item On Off
Switched 24VDC Out On Off
Phantom Power Input 6 On Off
On Off
1
2
3
4
Phantom Power Input 5
On Off
5
Phantom Power Input 4
On Off
6
Phantom Power Input 3
On Off
7
Phantom Power Input 2
On Off
8
Phantom Power Input 1
Preamp Out
†
Post
Pre
†
Sets the Preamplifier output to
Pre or Post Master.
DIP 5
Priority or VOX muting is only
functional on inputs 1-3. When
VOX is enabled on input 1 it will
override all other inputs includ-
ing the Alert/Evac Module. VOX
enabled on input 2 will override
inputs 3-6. VOX enabled on input
3 will override inputs 4-6.
If the Alert/Evac module is fitted
it will override inputs 2-6.
*
Model
125W
5AAC Fuse
250W
7.5A
AC Fuse Ratings
RESETTABLE
DC FUSE
DIP 5
DIP 4
DIP 1
DIP 2DIP 3
IMPORTANT NOTE
Ensure power is switched OFF when
adjusting DIP switches. New
settings will be effective when
power is switched back on.
2 1
3
2 1
3
2 1
3
2 1
3
2 1
3
2 1
3
1 2
3
1 2 3 4 5 6 7 8
1 2 3 4
1 2 3 4
1 2 3 4
1 2 3 4
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