Altronics Redback a 4425 User manual

A 4425

Public Address Mixer

Operating Instructions

www.altronics.com.au

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 2073 assumes priority 2.

Optional Modules

Alert and evacuation tones are available with the

installation of the optional A 2073 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.

INSTRUCTIONS FOR USE

Remove the mixer from its packaging and inspect for any

damage. If the unit appears to be damaged then do not

operate as this may damage the unit further.

1. Prior to installation, set input configurations as desired

via the DIP switches on rear of unit. The table below

shows the various settings.

TABLE 1: DIP SWITCH SETTINGS

Inputs 1 - 6 (refer to DIP 1-6)

Switch Item On Off

1Input Type Line Mic

2Line Level 1V 100mV

3Priority On Off

4Phan. Pwr On Off

Inputs 7 - 8 (refer to DIP 7)

Switch Item On Off

1Input 8 1V 100mV

2- - -

3- - -

4Input 7 1V 100mV

REDBACK A 4425 Mixer

Page 2

2. Plug in a low impedance microphone into the micro-

phone input, or a music source (tape or Compact Disc

or similar) into the line input.

3. Connect the mixer to an amplifier using a suitable

cable. See figure 2, Connection Details.

4. Turn all controls fully down and then switch the mixer

and amplifier on.

5. Turn up the level control associated with the input that

you are using to about half way. Talk into the micro-

phone (or play some music) and adjust the Master

level to achieve the required level.

For the best sound performance turn the input level con-

trol to a high setting (say 3/4 ) and use the Master as the

volume control. Use the other input level controls to set

the required mixing ratios. Adjust the bass and treble

controls to get the desired sound. For best performance

when using long lines between microphones/mixer and or

amplifier use balanced lines. These reduce noise or hum

that may be induced into the cables. Note that a balanced

line uses three wires (two signal wires and one screened

earth wire or shield) where an unbalanced cable uses

only one signal wire and a screened earth. See the con-

nection details (figure 2) for wiring up plugs etc.

Do not tamper with the unit. Warning Mains Voltage

is Present Inside. Leave servicing to qualified per-

sonnel.

Input 5 Input 1Input 3

Input 2Input 4Input 6

N816

Input 7/8

Mute Level

24V DC

240V AC

Input 8 Input 7

Tape Out

Voice

Over Chime Alert /

Evac

AlEv Chm1 ComChm2

Output

A 4425 Rear Panel Layout

INSTALLING THE TONE GENERATOR

A 2073:

1. Remove lid from unit

2. Unscrew tone generator plate from rear panel

3. Locate tone generator 10 way header on board (this

is located at the rear of the main board)

4. Connect ribbon cable header to the 10 way header

on the board of mixer.

5. The tone generator is held in by way of 2 screws

(supplied) through the rear panel (via the same holes

that the tone generator plate was attached).

6. Refit lid and secure with screws.

NOTE: Tones are operated by closing contacts and

remain operating whilst contacts are closed. The

A2073 assumes priority 2 when installed

INSTALLING THE COMPRESSOR

A 4426:

1. Remove lid from unit

2. Locate tone generator 10 way header on board (this

is located in the middle of the main board)

4. Connect ribbon cable header to the 10 way header

on the board of mixer.

5. The compressor board is mounted onto 4 plastic

standoffs located on the main printed circuit board.

6. Refit lid and secure with screws.

A 4426 header

A 4426 standoffs A 2073 header

A 2073 & A 4426 Header Locations

DIP 7 DIP 6 DIP 5 DIP 4 DIP 3 DIP 2 DIP 1

REDBACK A 4425 Mixer

Page 3

Signal

Shield

XLR Mic

Input

From Microphone

Input

Unbalanced

Signal

Shield

XLR Mic

Input

From Microphone

Input

Balanced

Output

Unbalanced Signal RCA

Shield For Stereo

Amplifiers

RCA

XLR Line

Output

XLR Line

Output

Shield

XLR Amp

Input

Output

Balanced

FIGURE 2.

CONNECTION DETAILS

Microphone Connections

Connector Type:....XLR 3Pin Female

Pin 1:...........................................Earth

Pin 2:...................Signal Inphase (hot)

Pin 3:.........Signal Out of Phase (cold)

Output Connections

Connector Type: ........XLR 3Pin Male

Pin 1:...........................................Earth

Pin 2:...................Signal Inphase (hot)

Pin 3:.........Signal Out of Phase (cold)

TROUBLE SHOOTING

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Fault/Symptom: No Sound

• Check that there is power on both the mixer and power

amplifier. The mixer has a LED light to indicate if there is

power.

• Check input and master volume controls are turned up.

• Check all lead connections

Fault/Symptom: When Paging the Music is Not Muted

• Set the VOX Muting DIP switch to “ON” for that input.

• Adjust the muting level control (inputs 7-8)

Fault/Symptom: Microphone Does Not Work

• The microphone may need phantom power. If so set the

Phantom Power DIP switch on that input to “ON”.

• Check microphone volume is turned up.

Input 7-8 no muting

• Check muting level adjustment on the rear panel

Line level too low

• Check sensitivity DIP switch settings. Set to correct

configuration ie: 100mV or 1V (see table 1 for DIP switch

details)

SPECIFICATIONS

Inputs:..............................6 microphone - balanced 200-600Ω

2 line - unbalanced 100kΩ

Output: ..................................................600Ωbalanced 0dBm

DISTORTION

Mic inputs:......................................................< 0.3% @ 1KHz

Line inputs: .................................................. < 0.3% @ 1KHz

FREQUENCY RESPONSE

Mic: ......................................................................30Hz-15kHz

Line:......................................................................18Hz-23kHz

S/N ratio: ..............................................All controls min. -98dB

Sensitivity: ..............................Mic 1.25mV, line 100mV or 1V

Phantom power: ..........................................Nominal 12V DC

Output connectors:..................................3 pin XLR balanced

..............................................................Dual RCA sockets

INPUT CONNECTORS

Mic inputs:................................................3 pin XLR balanced

Line inputs: ................................................Dual RCA sockets

CONTROLS

Mic inputs: ..................................................................Volume

Line inputs:..................................................................Volume

Bass:..............................................................±10dB @ 100Hz

Treble:............................................................±10dB @ 10kHz

Master: ........................................................................Volume

Indicators: ........................................................Power on LED

Power supply:..........................................240V AC or 24V DC

Dimensions:......................................482W x 152D x 44H mm

Weight: ............................................................................≈3kg

Colour: ............................................................................Black

All measurements measured in respect to 1kHz reference.

*Specifications subject to change without notice

REDBACK A 4425 Mixer

Page 4

Proudly Assembled in Australia

Distributed by Altronic Distributors Pty. Ltd. Perth. Western Australia.

Phone: 1300 780 999 Fax: 1300 790 999

Internet: www.altronics.com.au

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