Clarion APX280M User Manual
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APX280M Power System Amplifier
INTRODUCTION
The Clarion APX280M is a full-featured two-channel amplifier incorporating
the following features:
• Specially coated circuit boards, that resist mold, mildew and moisture damage.
• Pulse-Width Modulated (PWM) MOSFET power supply for maximum
performance with minimal distortion.
• Remote turn-on with "soft start" muting to prevent turn-on "thump".
• Advanced circuitry design featuring bridgeable and mixed mode operation for
use in various system configurations.
• Variable high-pass/low-pass electronic crossover with a 12dB per octave slope
(adjustable range: 55Hz to 5.5kHz).
• Variable bass boost circuit to reinforce low frequency signals that may be lost
due to subwoofer enclosure design.
• Adjustable input level controls with ground loop isolation to minimize noise
and distortion.
• 2-ohm stereo stable, 4-ohm mono stable.
• Gold-plated power, speaker, and RCA connectors.
• Speaker level input.
• Low profile construction with aluminum heat sink for efficient heat dissipation.
ABOUT THE MANUAL AND WARRANTY
This manual describes the basic requirements to install the Clarion APX280M
amplifier. The installation of this amplifier can be quite complex to install, if you
do not posses the necessary knowledge and tools to perform this installation,
please contact your local Clarion dealer.
Keep all instructions and sales receipt for future reference and warranty information. Warranty information can be found on page 11 of this manual.
TABLE OF CONTENTS
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Input Connections and Audio Controls . . . . . . . . . . . . . . . . . . . . . . . . . 1
Connections for Power and Speakers . . . . . . . . . . . . . . . . . . . . . . . . . 3
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Mounting Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Wiring Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Wiring and Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Setting the Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Setting the Crossover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Setting the Bass Boost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Final System Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Product Specs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Clarion Limited Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
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Operation/Installation Manual
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DESCRIPTION
The APX280M uses an unregulated MOSFET power supply for superior sound
and output wattage. In addition, a toroid-coil is used to transfer power with minimal performance loss due to heat. To avoid unwanted noise, a double-sided
conformal printed circuit board with strategically placed components keeps AM
RFI subdued.
All of the connections and controls for the APX280M are conveniently located at
the ends of the amplifier and labeled appropriately. To ensure the best possible
electrical connections, the power, speaker, and RCA inputs are gold-plated. In
the event of component failure or a short circuit, the APX280M incorporates
safe guards and an outboard ATC fuse to prevent damage to the amplifier.
INPUT CONNECTIONS AND AUDIO CONTROLS
The front panel of the APX280M contains both connections for RCA and speaker level inputs, along with the audio controls as shown below.
Figure 1
1. RCA Input Jacks
2. Gain Control
3. Bass Boost Control
4. Freq (Hz) Selection Control
5. Crossover Frequency Multiplier Switch
6. X-Over Mode Switch
7. Input Select Switch
8. Speaker Level Inputs
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APX280M Power System Amplifier
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• Gain Control - This allows you to set the nominal operating level of the
amplifier. The amplifier's range, 250mV to 2.5V for RCA inputs or 500mV to
5V for speaker level inputs, can accommodate input levels from virtually any
brand of source unit.
• Bass Boost Control- The amplifier also features a "high-Q" (i.e. narrow
frequency band) Bass Boost circuit. It acts much like an equalizer, with
adjustable gain (from 0 to +18dB) fixed at 45Hz. Use this feature to tune low
frequency audio response to compensate for a less than ideal subwoofer
enclosure design. The added boost produces rich, full bass tones that are
normally difficult to reproduce in the car audio environment. NOTE: If Bass
Boost is undesirable, set Bass Boost to 0dB.
High-pass/Low-pass Filter Controls
• Frequency (Hz) Selection Control - The crossover frequency is fully
adjustable between 55Hz and 5500Hz (via the Crossover Frequency Multiplier)
for a wide range of crossover points. Use this feature, along with your speaker
manufacturer's recommended crossover frequencies, to quickly design a more
advanced system (see Applications on page 6) NOTE: If the X-Over Mode
Switch is set to OFF, varying the Freq (Hz) Control will produce no effect.
• Crossover Frequency Multiplier Switch - When engaged, this switch
increases the crossover frequency by a factor of 10. Example: If the Freq (Hz)
dial is set for 240 Hz, pushing in the Multiplier Switch changes the setting to
2400 Hz.
• X-Over Mode Switch - This switch is equipped with a 12dB per octave
electronic filter for precise frequency attenuation with minimal phase
distortion. The steep crossover slope keeps midrange tones out of the
subwoofer and thereby eliminates an unnatural "nasal" tone quality in the audio
system. A filter is activated by sliding the X-Over Mode Switch to either LP or
HP.
• Input Mode Switch - This switch allows you to set the input mode. Stereo
input allows full left and right stereo operation. Right (bridged) input allows
single channel input for bridged operation. This is especially useful in high-powered
systems when using one amplifier for each subwoofer/speaker. L + R
(sum mono) allows a stereo input to be summed into a mono output.
• Speaker Level Inputs - These provide connections for a high-level stereo
source. In addition, these connections are provided for installations where the
source unit's RCA outputs are unavailable.
WARNING: When using the speaker (high-level) inputs, the Black wire must
be grounded at the Radio. Failure to do this will result in noise and improper
operation.
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Operation/Installation Manual
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CONNECTIONS FOR POWER AND SPEAKERS
The rear panel of the APX280M contains power and speaker connections as
shown below.
Figure 2
1. Left Speaker Output
2. Right Speaker Output
3. Remote Turn-on Input
4. Ground Input
5. Battery + 12V Input
6. 25 Amp Fuse
Figure 3
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