Redback A 4425A Operating Instructions

Mixer Overview
Description
This Redback ® 8 channel mixer has been designed to meet the
requirements of professional public address installations. Its many
features makes it ideally suited for use in shopping centres,
gymnasiums, places of worship, office complexes, board rooms,
council chambers, court rooms etc.
Inputs and Outputs
Inputs 1-6 can be configured for balanced microphone or line use as
desired. XLR and dual RCA sockets are provided for each of these
inputs. Inputs 7 & 8 are dedicated line inputs provided with dual RCA
sockets and variable muting/ducking level. Outputs are 600Ω/0dBm
XLR balanced or dual RCA sockets for record/tape out.
Input Configuration
Inputs 1-6 include an individual 4 way dip switch enabling selection of
mic or line input operation, adjustable line input sensitivity (100mV or
1V), mic or line operation of priority/VOX muting (see below for
priority details) and phantom power on/off.
A DIP switch is provided for inputs 7 & 8 enabling the adjustment of
the input sensitivity (100mV or 1V).
Front Panel Controls
The front panel includes individual volume controls and tamper proof,
screw driver adjust, treble and bass controls for each input channel.
A LED VU meter and a headphone socket are provided.
Priority and Muting
The mixer incorporates three levels of priority. Inputs 1,2 and 3 will
operate the priority/VOX muting regardless of the input configuration
ie: both microphone and line inputs will operate the priority/VOX
circuit if this function is selected ON for that input. This is
particularly useful when an input is set for line use, as it enables
telephone paging, radio microphone, emergency tones, jukebox or
similar to mute background music on other inputs.
Three level priority operates as shown:
Input 1 Priority 1 – mutes inputs 2 - 8,
Input 2 Priority 2 – mutes inputs 3 – 8,
Input 3 Priority 3 – mutes inputs 4 – 8,
Inputs 4-8 are mixed. If the priority function for inputs 1-3 is turned
off, then inputs assume no priority and its output will be mixed with
inputs 4-8 ie. if all priority functions are switched OFF then all inputs
will be mixed.
When fitted the optional A 4573 assumes priority 2.
® A 4425A
Public Address Mixer
Operating Instructions
Adjusting VOX muting sensitivity
The adjustment pots are located internally. See page 2 for diagram.
1. Switch off the unit and remove the 240V mains lead and 24V in
from the rear.
2. Remove the 6 x M3 screws from the lid and remove the lid.
3. The adjustment pots are located on the main (middle) PCB and
are marked EVAC, MIC1, MIC2, MIC3. Adjust the appropriate pot
clockwise to increase sensitivity and anti-clockwise to decrease
sensitivity.
4. Replace lid and screws and reapply power.
Optional Modules
Alert and evacuation tones are available with the installation of the
optional A 4573 tone generator.
An optional compressor/compander module (A 4426) can be fitted
internally to inputs 7 and 8. This is desirable when using CD/DVD
players as a BGM source. It maintains a consistent output level during
CD/DVD playback to eliminate constant adjustment of volume levels
from quiet tracks to louder tracks on the disc.
Switch
1
2
3
4
Switch
1
2
3
4
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TABLE 1: DIP SWITCH SETTINGS
Inputs 1 - 6 (refer to DIP 1-6)
Item On
Input Type Line
Line Level 1V
Priority On
Phan. Pwr On
Inputs 7 - 8 (refer to DIP 7)
Item On
Input 8 1V
- -
- -
Input 7 1V
Off
Mic
100mV
Off
Off
Off
100mV
-
-
100mV