REDBACK™125 & 250W PA Amplifiers
Page 1
Doc. BL1517
www.altronics.com.au
Congratulations on purchasing a REDBACK Phase 4 Public Address Amplifier.
Engineered and manufactured to high standards this unit will provide you with many trouble free
years of use.
FEATURES:
• 4 independent 60W amplifiers
• LED bargraph VU meter
• Input signal presence indicator
• 2U 19” rack mount
• 3 pin XLR input
• Level control rear mounted
• Output terminals for 100V and 4 - 16Ω
• Thermal protection
• 240V AC / 24V DC operation
• Australian made
• 10 Year warranty
Audio Connections
The audio Line Input is via the 3 pin XLR socket on the rear panel. This is a 320mV line
level balanced signal which is normally fed from a mixer panel. Pin out details are shown
in diagram 1.
A balanced, Line Out XLR plug is also available for passing the audio signal on to more
amplifiers if required.
Speaker Connections
Speakers with a total impedance of 4 to 16 ohms, or speakers fitted with a line transformer
may be connected.
Always ensure that the total load of the fitted speakers does not exceed the rated output of the amplifier channel (60 Watts per
channel ONLY). Otherwise damage may result.
Always be especially careful to avoid any short circuits and connections to the wrong terminals.
Power Supply
Ensure power is switched off at the front panel of the amplifier. Connect either mains power to the IEC socket with the supplied lead or 24V DC via the rear terminals.
Operation
Confirm all connections are correct. Turn all volume controls on the rear panel of amplifier down. Switch on the power at the
front panel. Slowly increase the volume on each amplifier channel to about half way. Adjust the volume output to a suitable
audio level.
The fault LED on the front panel indicates the amplifier has shutdown due to excessive heat build-up and/or excessive load on
the speaker outputs, the peak LED indicates when peak limiting is in operation and the Signal LED is provided to indicate when
an input signal is present.
Adequate ventilation is required for the amplifier to work within its rated limit. Ensure the vents are free of obstructions at all
times. We recommend that a 1U Vented panel be placed between amplifiers. This is to aid air flow.
Public Address
4 x 60 Watt Power Amplifier
®
Diagram 1: 3 pin XLR pinouts.
21
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io
A
S
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“Hd
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1 • Shield
2 • Hot
3 • Cold
REDBACK™125 & 250W PA Amplifiers
Page 2
Doc. BL1517
REDBACK®Phase 4, 4 x 60W PA Amplifier
T
ROUBLE SHOOTING
If the REDBACK Phase 4 amplifier fails to deliver the rated performance, check the following:
No Power, No Lights
Make sure amplifier power switch is on. Make sure mains power switch is on at the wall. Check the mains and DC fuse.
Replace with only the correct type and rating.
Distorted Output
Check that the speaker type is correct for the output that you are using (ie. 4-16Ω or 100V line). Check for any short circuits on
the speaker line.
Very Low Output Volume
Make sure that the input is the correct level (check for shorted connectors). Check for any short circuits on the speaker line.
Continually Blows Fuses
Make sure that the speaker line is not shorted. Check speaker types and ratings.
Amplifier Keeps on Cutting In & Out
Make sure that there is adequate ventilation around the amplifier. Check the vent slots on the front are not covered or blocked
and the fan on the rear is functioning correctly. Check also speaker types, ratings and for any short circuits on the speaker line.
SPECIFICATIONS
Typical Specifications per channel
(unless otherwise noted)
Power output .............................................. 60 watts RMS
Distortion: .................................................< 0.5%, @ 1kHz
Frequency response: ..........................50Hz - 15kHz, -3dB
Output line: ................................................100V or 4 - 16Ω
Sensitivity:................................................320mV balanced
Signal to noise ratio:..............................................> 90 dB
OUTPUT CONNECTORS
Speakers: ...................................................Screw terminals
INPUT CONNECTORS
Inputs: ..................................................3 pin XLR balanced
24V DC power:...........................................Screw terminals
240V AC power (common): ..............IEC power connector
CONTROLS
Master: ............................................Volume (on rear panel)
Power (common):...........................................On/off switch
Indicators: .................................................................Power
Fault
VU meter
Signal present
Power supply (common): 240V AC or 24V DC (nominal)
Protection.........7.5A AC fuse and 5A DC fuse per channel
Dimensions: .....................................≈ 483W x 330D x 88H
Weight:......................................................................≈ 16kg
Colour: ........................................................................Black
*Specifications subject to change without notice
A 4064 Rear Panel
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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