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Redback Phase 5 Public Address PA Amplifier 250W 4 Input

SKU : A4387

RRP: $995.00
Our Price: $752.10
Less: $242.90


  • Description
  • Reviews

This 250 Watt 4 channel mixer amplifier is specifically designed for applications requiring up to three microphone inputs, without compromising output power and overall performance. The amplifier features three inputs which can be configured for either microphone or line level operation. The amplifier conservatively delivers 250W RMS power. Frequency response 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 amplifier operates 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 configured internally to 70V line or low impedance (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 amplifier also utilises a half power mode which enables the amplifier 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 amplifiers.

Remote volume available when A 4373 Digital volume control module fitted internally and external A 2280B wall plate or 1KΩ potentiometer connected. Alert and Evacuation tones (conforming to AS1607.4) along with chime tones and voice over message option available when optional A 4573 fitted.


  • 3 Balanced microphone inputs / 3 Aux inputs / 1 Music input
  • Robust design incorporating latest Mosfet technology
  • Very Low noise and distortion
  • 100V standard with optional 70V and 4-16Ω outputs
  • 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 Alert/Evac module with voice over message for emergency tones (A 4573)
  • Optional remote volume (With A 4373 Digital volume control module fitted and external A 2280B wall plate)
  • Rack Mountable (suits 19 inch racks) with optional A 4376 rack ears


  • Power Outputs
  • Power: 250 watts RMS
  • Distortion: < 0.5%, @ 1kHz
  • Output line: 100V
  • Frequency Response
  • Mic inputs : 50Hz - 12kHz, -3dB
  • Line inputs: 50Hz - 15kHz, -3dB
  • Mic Sensitivity
  • Mic inputs: 3mV
  • Line inputs: 1V
  • Music input: 500mV
  • Signal to Noise Ratio
  • Mic inputs: > 75dB below rated output
  • Line Output: 600Ω balanced, 0dB , 3 Pin XLR
  • Output Connectors
  • Speakers: Screw terminals
  • Input Connectors
  • Inputs: 3 pin XLR balanced or 2 x RCA
  • 24V DC power: Screw terminals
  • 240V AC power: IEC power connector
  • Muting: PTT via microphone switch contacts, VOX muting (inputs 1-2)
  • Controls
  • Mic/Line/Music inputs: Volume
  • Power: On/off switch
  • Indicators: Power, signal present, output peak limiting, overtemp ,Overload Protect, Half Power, 24V DC
  • Power Supply: 240V AC or 24V DC
  • Fuse Protection: 125W - 5A AC ,10A DC, 250W - 7.5A AC ,20A DC
  • Dimensions: 483W x 300D x 88H

*Specifications are subject to change without notice.

100% developed, designed & assembled in Australia.
Since 1976 Redback PA products have been manufactured in Perth, Western Australia by Altronics. With over 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. Read more about our Australian Made products

Backed by an industry leading 10 Year Manufacturer Warranty.
Our Redback products have a long tried and tested history of bulletproof reliability. Altronics offers a 10 Year Warranty on all Australian Made Redback products. Our local in-house service department has all the know how to answer technical queries and provide timely service. Read more about our industry leading warranty.

  • Model: A4387
  • Brand: Redback

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