User Manual

www.redbackaudio.com.au Redback® Proudly Made In Australia 3
Redback® A 4270/80 Four Zone Paging PA Amplier
1.0 OVERVIEW
The Redback® A 4270 125 Watt and A 4280 250 Watt 4 Zone paging ampliers are specically designed for multi zone
applications. Based on the popular Redback® A 4377 and A 4387 amplier series, these ampliers have three inputs
which can be congured for either microphone or line level. The addition of zone paging is made possible by connecting
Redback® A 4488 paging consoles to the amplier. The ampliers have a main 100V speaker output plus as additional
four separate 100V output speaker loads, each of which has provision for background music which can be overriddden by
the A 4488 paging microphones.
The Redback® A 4270 conservatively delivers 125W RMS power, while the A 4280 delivers 250W RMS. Frequency re-
sponse extends from 50Hz to 15kHz ±3dB at a total harmonic distortion (THD) of less than 0.5% @ 1kHz.
Vox muting is provided on inputs one and two, which, when activated, automatically mutes the other inputs. Bass and
treble controls and phantom powering capability enable unparalleled exibility for a wide scope of applications such as
factories, workshops, mine sites, sports clubs and ofce buildings.
The ampliers operate from 240V AC mains or 24V DC permitting battery backup operation during mains power failure.
The output comes standard suitable for a 100V line load, but this can be congured internally to 70V line or low imped-
ance (4 - 16Ω) loads.
Thermal overload, overcurrent and overload protection circuitry and fuses on both AC and DC provide excellent fault
condition protection and robust performance. The amplier also utilises a half power mode which enables the amplier to
continue to run at a reduced output level if it is being over driven.
Tape output sockets are provided for recording purposes or feeding into additional power ampliers.
Remote volume available when A 4373 Digital volume control module tted internally and external A 2280B wall plate or
1KΩ potentiometer connected.
MP3 based Alert and Evacuation tones along with chime tones and voice over message are built standard functions of the
ampliers.
2.0 FEATURES
• 3 Balanced microphone inputs / 3 Aux inputs / 1 Music input
• Robust design incorporating latest Mosfet technology
• Very Low noise and distortion
• 100V Main Output standard with optional 70V and 4-16Ω outputs
• 100V Outputs 1- 4
• Zone paging (via optional Redback® A 4488 paging consoles)
• Background music (BGM) selectable to Outputs 1-4
• MP3 based Alert/Evac tones with MP3 voice over message for emergency tones
• 240V AC or 24V DC operation
• VOX muting on inputs 1 and 2 (Switch selectable internally)
• Adjustable VOX level sensitivities
• Bass and Treble controls
• Tape Output
• Phantom power on microphone inputs (DIP switch selectable internally)
• Multi stage thermally cued fan cooling
• Output Peak Limited
• Thermal Overload protected
• Signal Presence Indicator
• Half power mode when overdriven
• Fault Indicators
• 24V DC Power Status Indicator
• Optional remote volume (With A 4373 Digital volume control module tted and external A 2280B wall plate)
• Rack Mountable (suits 19 inch racks) with optional A 4376 rack ears