www.redbackaudio.com.au Redback® Proudly Made In Australia 1
Redback® S 4457 Evac Relay Override
User manual revision number: 1.0 03/07/2023
Overview
The S 4457 has two independant sets of inputs which are fed to normally open (N/O) and normally closed (N/C) terminals
via internal relays. A closing contact or a 24V DC input can be used to trigger a change of state of both sets of output
terminals.
The relay contacts are rated at 8 amps and an LED illuminates when the relays are activated.
Although this product has a multitude of uses, it has been designed primarily for PA speaker line installations with two PA
systems active in a building.
It is particularly useful for applications where a dedicated Evac speaker system is running alongside a dedicated back-
ground music system in the same building. The Evac override relay box can be used to disconnect the background music
system when the Evac system is active. An example is shown in gure 3.
It can also be useful for applications where two different PA systems are in use in an install with only one output speaker
line. An example is shown in gure 4.
Triggering the Unit
Figure 1 demonstrates a typical example of how to use the relay box with the (voltage free) trigger input. A simple switch
or closing contact from the likes of a re board could be used as the trigger. In this screnario a 24V DC supply is required
at the 24V DC In terminals to power the unit.
Figure 2 demonstrates a typical example of how to use the relay box with the 24V DC trigger input. The 24V DC trigger is
connected to the Evac 24V DC switched output from an A 4565B Evacuation Controller. When the Evac mode is activated
on the A 4565B, 24V DC will be applied at the trigger terminals and activate the internal relays. In this screnario a 24V DC
supply is NOT required to power the unit, as power is derived from the 24V DC trigger input.
Fig 1. Voltage Free trigger activation Fig 2. 24V DC trigger activation
Redback® S 4457
24V DC PLUGPACK
(MINIMUM 0.5A)
SWITCH OR CLOSING CONTACT
FROM FIRE BOARD ETC
24V
DC In
Active
OUT 2 N/C
Trigger
(Voltage Free)
24V
DC In
24V DC
Trigger
OUT 2 N/O
INPUT 2
OUT 1 N/C
OUT 1 N/O
INPUT 1
Redback® S 4457
24V
DC In
Active
OUT 2 N/C
Trigger
(Voltage Free)
24V
DC In
24V DC
Trigger
OUT 2 N/O
INPUT 2
OUT 1 N/C
OUT 1 N/O
INPUT 1
24V DC
IN
1 2 3 4 5 6 7 8
+_
Chime
Vol
Fire
DIP Switches
Alert
24V Out
Fire
24V Out
Evac
24V Out
To Paging
Console
IMPORTANT NOTE
Ensure power is switched off when
adjusting DIP switches. New
settings will be effective when
power is switched back on.
24V DC
IN
(16GB Maximum) V/Over
Vol
Micro SD Card
1 2 3 4 5 6 7 8
To Wall Plates
+-
Bell
24V Out
Common
24V Out
All switched outputs limited to 120mA maximum current draw
Contacts
Evac
Alert
Bell
Cancel
34
(Maximum 500mA per output)
Fire
Vol
Bell
Vol
Evac
Vol
PA Mic
Vol
N/C
N/O
N/C
N/O
N/C
N/O
N/C
N/O
N/C
N/O
12
Redback® A 4565B
www.redbackaudio.com.au
Redback® Proudly Made In Australia2
Redback® S 4457 Evac Relay Override
Typical Applications
The illustration shown in gure 3 provides an example where a dedicated Evac speaker system is running alongside a ded-
icated background music system in the same building. The S 4457 Evac override relay box can be used to disconnect the
background music system when the Evac system is active.
In this example the output of the Evac amplier is connected to Input 1, and the BGM amplier output is connected to In-
put 2. The Evac speaker line is connected to the normally open terminals of Out 1 and the BGM speaker line is connected
to the normally closed terminals of Out 2. In normal use the audio from the BGM amplier is active, but once the S 4457
is activated the Evac audio becomes active and the BGM audio is disconnected.
Fig 3. Evac audio system running alongside a BGM audio system
The illustration shown in gure 4 provides an example where two different PA systems are in use in an install with only one
output speaker line. In this instance the outputs of the S 4457 are actually used as inputs and the inputs used as outputs.
Fig 4. Two PA systems using one output speaker line.
Redback® S 4457
24V
DC In
Active
OUT 2 N/C
Trigger
(Voltage Free)
24V
DC In
24V DC
Trigger
OUT 2 N/O
INPUT 2
OUT 1 N/C
OUT 1 N/O
INPUT 1
240V AC @ 50Hz
Fuse 800mA
Line Mic
L
R
OUTPUT
+
–
2 1
3
BGM Amplier
240V AC @ 50Hz
Fuse 800mA
Line Mic
L
R
OUTPUT
+
–
2 1
3
Evac Amplier
Redback® S 4457
24V
DC In
Active
IN 2 N/C
Trigger
(Voltage Free)
24V
DC In
24V DC
Trigger
IN 2 N/O
OUTPUT 2
IN 1 N/C
IN 1 N/O
OUTPUT 1
240V AC @ 50Hz
Fuse 800mA
Line Mic
L
R
OUTPUT
+
–
2 1
3
Amplier 2
240V AC @ 50Hz
Fuse 800mA
Line Mic
L
R
OUTPUT
+
–
2 1
3
Amplier 1
/
