Redback A 4427 User manual

Redback® A 4427 8 Channel Public Address Mixer
User manual revision number: 1.0 29/10/2018
Operating Manual
A 4427 8 CHANNEL MIXER WITH MESSAGE PLAYER
IMPORTANT NOTE:
Please read these instructions carefully from front to back prior to installation.
They include important setup instructions.
Failure to follow these instructions may prevent the unit from working as designed.
Redback® Proudly Made In Australia
Distributed by Altronic Distributors Pty. Ltd.
Phone: [phone] Fax: [phone] Internet: www.altronics.com.au
8 CHANNEL PA MIXER

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Redback® A 4427 8 Channel Public Address Mixer
REDBACK is a registered trademark of Altronic Distributors Pty Ltd
Since 1976 Redback ampliers have been manufactured in Perth, Western Australia by Altronics. With close to 40 years
experience in the commercial audio industry, we offer consultants, installers and end users reliable products of high build
quality with local product support. We believe there is signicant added value for customers when purchasing an
Australian made Redback amplier or PA product
Australian Made Status
All Redback house products made by Altronics will now be sporting the ofcial Australian Made logo. Since starting manu-
facturing of commercial audio equipment in the mid 70’s we have always taken pride in producing a quality local product.
The new adoption of the Australian Made logo will help us get the word out to local and export markets that our
products carry the ofcial compliance seal of the Australian Made campaign. We have always pushed our ‘local is better’
line in all of our marketing efforts, it’s always an added boost when you are backed up by a widely recognised and
respected icon.
Industry leading 10 year warranty.
There’s a reason we have the industry leading DECADE warranty. It’s because of a long tried and tested history of
bulletproof reliability. We’ve heard PA contractors tell us they still see the original Redford amplier still in service in schools
- that’s over 39 years of operation - and still going strong!
Published by Altronic Distributors
© 2018 Altronic Distributors

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Redback® A 4427 8 Channel Public Address Mixer
1.0 INTRODUCTION
This unique Redback PA mixer features six input channels which are user selectable for either balanced mic or line as well
as two dedicated line level RCA inputs and a 3.5mm audio jack for portable devices. In addition it incorporates a MP3
based message player for playback of Alert, Evacuation or Chime tones.
The unit has six levels of priority with adjustable sensitivities, and a 24V DC output (limited to 120mA current draw) which
becomes live when any triggers are activated or VOX/PTT circuitry becomes active.
2.0 FEATURES
• Eight input channels
• Micro SD card message player for audio announcements
• Individual level, bass and treble control on all inputs
• Six levels of VOX priority
• Adjustable VOX sensitivity
• 3.5mm music input
• Adjustable input sensitivity on line inputs
• 24V DC battery back up terminals
• In built Alert/Evac/Chime functionality
• 24V DC output
• MP3 active indicator
• LED VU meter
• 10 Year Warranty
• Australian Designed and Manufactured
3.0 WHAT’S IN THE BOX
A 4427 Mixer 8 Channel with MP3 Message player
24V 1A DC Plugpack
Instruction Booklet

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Redback® A 4427 8 Channel Public Address Mixer
4.0 FRONT PANEL GUIDE
Fig 1 shows the layout of the A 4427 front panel.
Fig 1
1 Inputs 1-8 volume controls
Use these controls to adjust the output volume, bass and treble of inputs 1-8.
2 Master Volume
Use this control to adjust the master volume.
3 Signal Presence Indicator
This LED indicates when a signal is present at any of the inputs.
4 MP3 Active Indicator
This LED indicates when an MP3 is playing.
5 On/Fault Indicator
This led indicates when the unit has power if the LED is blue. If the LED is red a fault has occured with the unit.
6 Standby Switch
When the unit is in standby mode this switch will illuminate. Press this button to switch the unit ON. Once the
unit is ON the On indicator will illuminate. Press this switch again to put the unit back in standby mode.
7 LED VU Meter
This LED bargraph provides a visual indication of the output signal.
8 Music input
This input will override input 8 when connected. Use this for connection of portable music players.
9 VOX Sensitivities
These trimpots set the VOX sensitivities of input 1-6.
1
7
Power/
Master Volume
Vox 1
Music
Input
Volume 1
Signal
Present
Fault
On
Standby
Bass Treble Sens. Vox 2
Volume 2
Bass Treble Sens. Vox 3
Volume 3
Bass Treble Sens. Vox 4
Volume 4
Bass Treble Sens. Vox 5
Volume 5
Bass Treble Sens. Vox 6
Volume 6
Bass Treble Sens.
Volume 7
Bass Treble Bass Treble
Volume 8
MP3
Active
-12dB -9dB -6dB -3dB 0dB
-15dB
2 3 4 5 6
89
8 Channel Mixer
A 4427
0
2
46
8
10 0
2
46
8
10 0
2
46
8
10 0
2
46
8
10 0
2
46
8
10 0
2
46
8
10 0
2
46
8
10 0
2
46
8
10 0
2
46
8
10

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Redback® A 4427 8 Channel Public Address Mixer
5.0 REAR PANEL CONNECTIONS
Fig 2 shows the layout of the A 4427 rear panel.
Fig 2
1 RCA Inputs
The line inputs are dual RCA connectors which are internally mixed to produce a mono input signal. The input
sensitivity of these inputs can be adjusted to 100mV or 1V via the DIP switches DIP1 - DIP7 (refer to DIP switch
settings).
2 Microphone Inputs
There are six microphone inputs which all incorporate a 5 way euro connector. Phantom power is available on
each Mic input and is selected via DIP switches on DIP1 - DIP6 (For more details see DIP switch settings).
A PTT connection is also available for PTT muting and a 24V DC (limited to 120mA current draw) output is
provided for each microphone for activation of external indicators. (The PTT and 24V DC OUT connections are
wired using the ground as a common connection).
3 Dip Switches DIP1 - DIP6
These are used to select various options such as phantom power on mic inputs, VOX options and input
sensitivities. Refer to DIP Switch Settings section.
4 Dip Switches DIP7
These are used to select the input sensitivities of the Line inputs 7 & 8. Refer to DIP Switch Settings section.
5 Tape Out
Dual RCA’s provide a line level output for recording purposes or to pass the output on to another amplier.
6 Preamp Out (Balanced Line Output)
A three pin 600 ohm 1V balanced XLR output is provided for passing the audio signal on to a slave amplier
or to record the output of the amplier.
7 Alert, Evacuation, Chime and Voice Over Message Volumes
Use these trimpots to adjust the output levels of the alert and evacuation tone and the chime and voice over
message.
8 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.
9 DIP 8
These switches provide various play modes (see DIP switch settings for more details).
10 Micro SD Card
This is used to store the MP3 audio les for the Alert, Evacuation and Chime tones and the Voice Over message.
The Micro SD card needs to be pushed in to insert and to remove.
11 RJ45 Interface
This is for future expansion of product.
12 24V DC Out
This is a 24V DC output which is activated when any of the Alert, Evacuation or Chime triggers are operated. It
also becomes active when any of the VOX circuits are enabled or any of the PTT muting is activated.
13 24V DC Input (Backup)
Connects to a 24V DC backup supply with at least 1 amp current capacity. (Please observe the polarity)
14 24V DC input
Connects to a 24V DC Plugpack with 2.1mm Jack.
Output
DIP 8
Chime Voice Alert
Over /Evac
Alert Evac
Ch 1
Com Can
Tape Out
Mic 1
+
-
24V DC In
DIP 1 DIP 2 DIP 3 DIP 4 DIP 5
L
R
L
R
24VDC
Backup
16GB
Maximum
Micro
SD Card
Line 1
Line 2
L
R
Mic 2
Mic 1
DIP 6 DIP 7
Ch 2
24VDC
Output
(120mA
Limited)
Interface
ALERT/EVAC/CHIME
MODULE
Output
Triggers
Levels
Mic 1
L
R
Line 3
Line 4
L
R
Mic 4
Mic 3
Mic 1
L
R
Line 5
L
R
Mic 6
Mic 5
Line 6Line 7Line 8
L
R
L
R
PTT
OUT
PTT
OUT
PTT
OUT
+_
+_
4 2
1
3
56
79
10
111213
14 8
1 2 3 4 5 6 7 8
1 2 3 4
1 2 3 4
1 2 3 41 2 3 4
1 2 3 41 2 3 4
1 2 3 4
1 2
3

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Redback® A 4427 8 Channel Public Address Mixer
6.0 CONNECTIONS
Fig 3
4 -16Ω70V
230V AC @ 50Hz
100V
A 4370
MODEL AC FUSE
5A
A 4380 7.5A
INPUT
24V DC
+
–
RISK OF ELECTRIC SHOCK
OPEN BY QUALIFIED
PERSONNEL ONLY !
CAUTION
OUTPUTS
+
–
+
–
+
–
+_
VOLUME
1
2
3
1 • Shield 2 • Hot 3 • Cold
LINE IN
0
2
46
8
10
21
3
LINE OUT
RESETTABLE
FUSE
Made in Australia by
Altronic Distributors Pty Ltd
www.altronics.com.au
24V DC
OUT
(1A Max)
2 1
3
2 1
3
REDBACK® A 4370 AMPLIFIER
REDBACK® A 4427 MIXER
Output
DIP 8
Chime Voice Alert Over /Evac
Alert
Evac
Ch 1
Com
Can
Tape Out
Mic 1
+
-
24V DC In
DIP 1
DIP 2
DIP 3
DIP 4
DIP 5
L R
L R
24VDC
Backup
16GB
Maximum
Micro
SD Card
Line 1
Line 2
L R
Mic 2
Mic 1
DIP 6
DIP 7
Ch 2
24VDC
Output
(120mA
Limited)
Interface
ALERT/EVAC/CHIME
MODULE
Output
Triggers
Levels
Mic 1
L R
Line 3
Line 4
L R
Mic 4
Mic 3
Mic 1
L R
Line 5
L R
Mic 6
Mic 5
Line 6Line 7Line 8
L R
L R
PTT
OUT
PTT
OUT
PTT
OUT
+_
+_
TUNER
REDBACK
Evacuation tones can be triggered by closing contacts such as switches, from Fire Indicator Boards
or the like.
Evacuation Trigger Alert Trigger Chime1 Trigger Cancel Trigger Chime2 Trigger
CD
REDBACK
Telephone Paging
System
1 2 3 4 5 6 7 8
1 2 3 4
1 2 3 4
1 2 3 41 2 3 4
1 2 3 41 2 3 4
1 2 3 4
1 2
3
Note: All DIP switches are ON when in the up position.

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Redback® A 4427 8 Channel Public Address Mixer
Figure 3 demonstrates a basic install with ve input sources. The VOX priorities are set for 3 levels of priority, so that the
microphone on input 1 has the highest priority. The input 1 DIP1 switch settings are set for a 100mV sensitivity balanced
microphone input with the priority/VOX enabled which makes this input priority level 1. (Refer to section 7.0 for more
details about DIP switch settings).
Input 2 is connected to a telephone paging system with a line level output. The Input 2 DIP2 switch settings are set for a
line level input with 1V input sensitivity and the VOX is enabled which makes this input priority level 2.
Input 3 is shown with a microphone connected. The Input 3 DIP3 switch settings are set for a 100mV sensitivity balanced
microphone input and with the VOX enabled which makes this input priority level 3.
Inputs 4 and 5 are set as line level inputs with a sensitivity of 1V and the VOX priority disabled.
The output of the mixer is fed into a power amplier which drives the speakers.
All DIP switch settings are shown below. NOTE: The switches are ON when in the up position.
1 2 3 4
DIP 1
Input 1 Settings
SW1 set to OFF - Phantom power disabled
SW2 set to ON to enable the VOX/priority
SW3 set to OFF
SW4 set to OFF to set Input to Microphone Input
1 2 3 4
DIP 2
Input 2 Settings
SW1 set to OFF - Phantom power disabled
SW2 set to ON to enable the VOX/priority
SW3 set to ON - Line Input Sensitivity set to 1V
SW4 set to ON to set Input to line Input
1 2 3 4
DIP 3
Input 3 Settings
SW1 set to OFF - Phantom power disabled
SW2 set to ON to enable the VOX/priority
SW3 set to OFF
SW4 set to OFF to set Input to Microphone Input
1 2 3 4
DIP 4
Input 4 Settings
SW1 set to OFF - Phantom power disabled
SW2 set to OFF to disable the VOX/priority
SW3 set to ON - Line Input Sensitivity set to 1V
SW4 set to ON to set Input to line Input
1 2 3 4
DIP 5
Input 5 Settings
SW1 set to OFF - Phantom power disabled
SW2 set to OFF to disable the VOX/priority
SW3 set to ON - Line Input Sensitivity set to 1V
SW4 set to ON to set Input to line Input
ON
ON
ON
ON
ON

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Redback® A 4427 8 Channel Public Address Mixer
7.0 DIP Switch settings
The A 4427 has 8 sets of DIP switches.
DIP1 - DIP6 select the inputs 1 - 6 as either Mic or Line, sets the Line Input level sensitivity, enables phantom power and
enables VOX priorities for inputs 1-6 as outlined below.
(* Priority/VOX muting is only available for inputs 1-6. Inputs 7-8 have no priority levels.)
DIP 1
Switch 1 - ON - Enables Phantom power to the Mic on input 1.
Switch 2 - ON - Sets Input 1 priority or VOX to ON.
Switch 3 - Sets Line 1 input sensitivity to either ON - 1V or OFF - 100mV.
Switch 4 - Input 1 Select - OFF - Mic, ON - Line
DIP 2
Switch 1 - ON - Enables Phantom power to the Mic on input 2.
Switch 2 - ON - Sets Input 2 priority or VOX to ON.
Switch 3 - Sets Line 2 input sensitivity to either ON - 1V or OFF - 100mV.
Switch 4 - Input 2 Select - OFF - Mic, ON - Line
DIP 3
Switch 1 - ON - Enables Phantom power to the Mic on input 3.
Switch 2 - ON - Sets Input 3 priority or VOX to ON.
Switch 3 - Sets Line 3 input sensitivity to either ON - 1V or OFF - 100mV.
Switch 4 - Input 3 Select - OFF - Mic, ON - Line
DIP 4
Switch 1 - ON - Enables Phantom power to the Mic on input 4.
Switch 2 - ON - Sets Input 4 priority or VOX to ON.
Switch 3 - Sets Line 4 input sensitivity to either ON - 1V or OFF - 100mV.
Switch 4 - Input 4 Select - OFF - Mic, ON - Line
DIP 5
Switch 1 - ON - Enables Phantom power to the Mic on input 5.
Switch 2 - ON - Sets Input 5 priority or VOX to ON.
Switch 3 - Sets Line 5 input sensitivity to either ON - 1V or OFF - 100mV.
Switch 4 - Input 5 Select - OFF - Mic, ON - Line
DIP 6
Switch 1 - ON - Enables Phantom power to the Mic on input 6.
Switch 2 - ON - Sets Input 6 priority or VOX to ON.
Switch 3 - Sets Line 6 input sensitivity to either ON - 1V or OFF - 100mV.
Switch 4 - Input 6 Select - OFF - Mic, ON - Line
Input 1: When VOX is enabled on input 1 it will override inputs 2 - 8.
Input 2: When VOX is enabled on input 2 it will override inputs 3 - 8.
Input 3: When VOX is enabled on input 3 it will override inputs 4 - 8.
Input 4: When VOX is enabled on input 4 it will override inputs 5 - 8.
Input 5: When VOX is enabled on input 5 it will override inputs 6 - 8.
Input 6: When VOX is enabled on input 6 it will override inputs 7 - 8.
DIP 7 sets the input sensitivity of the Line inputs 7 and 8.
DIP 7
Switch 1 - Sets Line 7 input sensitivity to either ON - 1V or OFF - 100mV.
Switch 2 - Not Used.
Switch 3 - Not Used.
Switch 4 - Sets Line 8 input sensitivity to either ON - 1V or OFF - 100mV.
DIP 8 sets the functionality of the Alert/Evacuation/Chime outputs
DIP 8
Switch 1 - ON - Hold trigger contact closed to play, OFF - Hold trigger contact closed
momentarily to play.
Switch 2 - ON - Activates MIC pre-announcement chime (activated by PTT on mic inputs)
Switch 3 - Not Used
Switch 4 - Not Used
Switches 5-8 - Sets the Alert to Evacuation tone change-over time (refer to gure 4). Fig 4.
5 6 7 8
DIP 8

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Redback® A 4427 8 Channel Public Address Mixer
8.0 ALERT, EVACUATION and CHIME MP3 FILES and ALERT and EVAC VOICE OVER MESSAGES
The supplied MIcro SD card houses all the MP3 audio les used for the output tones. These les are stored in ve separate
folders (see gure 5) and relate to the corresponding output. e.g. the Alert folder houses the MP3 le to be played when
the Alert mode is triggered.
These les can be any length and bit rate, but must be in MP3 format (they cannot be Wav les or AAC les).
(NOTE: only one MP3 le can be in each folder).
There is also a folder labelled “#LIBRARY# which contains a host of sample MP3 les.
The “Voice” folder contains the MP3 audio les played as the Alert and Evacuation messages. There are separate folders
for both the Alert and Evacuation messages as shown in gure 5.
The messages have to be recordered in MP3 format using any readily available PC software or other means, and then
transferred to these folders.
Activating the Voice Over Message:
Voice over messages become active when an MP3 le is present in the relevant folder. If the voice over message is not
required leave the folder empty.
Fig 5
9.0 INSTALLING MP3 FILES
You will rst need to remove power from the A 4427 then remove the Micro SD card from the rear of the unit.
To remove the Micro SD card push the card in and it will eject itself.
In order to access the program, the Micro SD card will need to be connected to a PC. You will need a PC or laptop equipped
with an Micro SD card reader to do this. If a Micro SD slot is not available then the Altronics D 0371A USB Memory Card
Reader or similar would be suitable (not supplied).
Step by step guide to installing an MP3 onto the Micro SD card with a Windows installed PC
Make sure the PC is on and card reader connected and correctly installed. Then insert the SD card into the reader.
Go to “My Computer” or “This PC” and open the SD card which is usually marked “Removable disk”.
In this case it is named “Removable disk (O:) as shown in gure 6.

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Redback® A 4427 8 Channel Public Address Mixer
Fig 6
Open the Removable Disk and you should get a window that looks like gure 7.
Fig 7
The contents of the SD Card include a Library folder of sample MP3 les and ve folders for the MP3 les associated with
the various triggers.
There should be default MP3 les included in each folder. These will need to be replaced with your own MP3 les.
Open the folder in which you want to install an MP3 (in our case its the Alert folder) and you should see an MP3 le which
is named Alert.MP3 as shown in gure 8.

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Redback® A 4427 8 Channel Public Address Mixer
Fig 8
This MP3 le needs to be deleted and replaced by the MP3 le you want to play when you activate the Alert mode. The
MP3 le name is not important. But it is important that there is only one MP3 le in the Alert folder.
Check the properties of the MP3 le.
NOTE the new MP3 le cannot be “Read only”.
To check this, right click on the MP3 le and scroll down and select
Properties, you will get a window that looks like gure 9.
Make sure the “Read Only” box has no tick in it.
The new MP3 is now installed on the card. Repeat these steps for the
other MP3 folders if you need to.
The card can be removed from the PC following windows safe card
removal procedures. Make sure the A 4427 is OFF and insert the SD card
into the slot in the rear; it will click when fully inserted. The A 4427 is
ready to use.
Fig 9
10.0 TROUBLE SHOOTING
If the REDBACK A 4427 mixer fails to deliver the rated performance, check the following:
No Power, No Lights
The standby switch is used to turn the unit on. Make sure this switch has been pressed.
Make sure mains power switch is on at the wall.
Check the supplied plugpack is connected correctly.
MP3 les not playing
The les must be MP3 format. Not wav, AAC or other.
Check Micro SD card is inserted correctly.
DIP switch changes not effective
Turn the unit OFF before changing DIP switch settings. Settings become effective after power is returned.

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Redback® A 4427 8 Channel Public Address Mixer
11.0 FIRMWARE UPDATE
It is possible to update the rmware for this unit by downloading updated versions from www.altronics.com.au or
redbackaudio.com.au.
To perform an update, follow these steps.
1) Download the Zip le from the website.
2) Remove the Micro SD card from the A 4427 and insert it into your PC.
3) Extract the contents of the Zip le to the root folder of the SD Card.
4) Rename the extracted .BIN le to update.BIN.
5) Remove the SD card from the PC following windows safe card removal procedures.
6) With the power turned OFF, insert the SD card back into the A 4427.
7) Turn the A 4427 ON. The unit will check the SD card and if an update is required the A 4427 will perform the update
automatically.
12.0 SPECIFICATIONS
OUTPUT LEVEL:.........................................0dBm
DISTORTION:............................................0.01%
FREQ. RESPONSE:........................140Hz - 20kHz
SENSITIVITY
Mic inputs: ....................................3mV balanced
Line inputs:..........................................100mV-1V
OUTPUT CONNECTORS
Line out: ................................3 pin XLR balanced
Switched out: ..............................Screw terminals
INPUT CONNECTORS
Inputs: ..............5 pin euro connectors or 2 x RCA
............ 3.5mm stereo jack front panel
24V DC power: ...........................Screw terminals
24V DC Power: ...........................2.1mm DC Jack
Remote triggers: ..........................Screw Terminals
CONTROLS:
Power:..........................................Standby Switch
Bass:...........................................±10dB @ 100Hz
Treble:.........................................±10dB @ 10kHz
Master: ....................................................Volume
Inputs 1-8: ...............................................Volume
INDICATORS:....................Power on, MP3 error,
..................MP3 active, Signal Present, VU Meter
POWER SUPPLY:..................................... 24V DC
DIMENSIONS:≈................... 482W x 175D x 44H
WEIGHT: ≈............................................... 2.1 kg
COLOUR: ..................................................Black
* Specications subject to change without notice
All Australian made Redback products are covered by a 10 year warranty.
Should a product become faulty please contact us to obtain a return authorisation number. Please ensure you have all the
relevant documentation on hand. We do not accept unauthorised returns. Proof of purchase is required so please retain
your invoice.