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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
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.
2.
3.
4.
RCA Input Jacks
Gain Control
Bass Boost Control
Freq (Hz) Selection Control
5.
6.
7.
8.
Crossover Frequency Multiplier Switch
X-Over Mode Switch
Input Select Switch
Speaker Level Inputs
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APX280M Power System Amplifier
• 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
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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APX280M Power System Amplifier
INSTALLATION
This section suggests Mounting and Wiring Precautions for installing the Clarion
APX280M amplifier. If you do not posses the necessary tools and installation experience, do not attempt to install this amplifier. Instead, contact your local Clarion dealer to perform the installation.
MOUNTING PRECAUTIONS
Prior to mounting the amplifier, make sure it is safe to mount the amplifier in that
location. Failure to do so can result in serious damage to the boat. In addition, stainless steel hardware should be used to mount the amplifier and additional accessories. When possible, use a nut and bolt with a lock washer to secure the amplifier.
Extra care and attention is necessary in marine installations due to the uncertainty of
water conditions.
Additional precautions and suggestions:
1. For the most efficient cooling, mount the amplifier so cool air runs along the
length of the heat sink, rather than across them. To increase air movement and
circulation, a cooling fan can be installed.
2. Mount the amplifier on a rigid surface; avoid mounting to subwoofer enclosures or
areas prone to vibration.
3. Prior to drilling and holes, make sure the proposed mounting holes will not cut
into the fuel tank, fuel lines, electrical wiring, or through the boat.
4. Do not mount the amplifier where it is susceptible to water.
WIRING PRECAUTIONS
Read all of the wiring precautions prior to making any connections. If you are
unsure and/or don't have the necessary installation hardware, contact your local
Clarion dealer to perform the installation.
1. Before you begin the installation, make sure the source unit Power switch is in the
OFF position.
2. Disconnect the negative (-) lead of the battery (or batteries) before making any
power connections.
3. When making connections, be sure that each connection is clean and secure.
Insulate final connections with electrical tape or shrink tubing. Failure to do so
may damage your equipment.
4. A good ground is critical for the performance of the amplifier. A ground wire
should be run directly from the battery to the amplifier. Use black insulated 10gauge or larger wire for the amplifier's ground (-) power lead.
5. Add an additional fuse holder and fuse at the positive (+) terminal of the battery.
The fuse rating should equal the total current consumption at full output of the
amplifier(s). Use red insulated 10-gauge or larger wire for the amplifier's
positive (+) power lead. Do not install the fuse until the complete installation has
been performed.
6. When replacing the amplifier's fuse, always use one having the same amperage
rating. Substituting a higher rated fuse or a slow-blow type can result in serious
damage to the amplifier.
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Operation/Installation Manual
7. When creating passage holes for power cables, RCA's cords, and speaker wires,
use grommets to eliminate any sharp edges created during drilling. This will
protect the wire from being nicked and causing a short circuit.
8. Extra cable can cause signal loss and act as an "antenna" for noise. Use only
high-quality RCA cords that are no longer than necessary.
9. In multiple amplifier systems, it is recommended to use a relay on the remote
turn-on lead of the radio.
WIRING AND APPLICATIONS
The Clarion APX280M 2-channel marine audio amplifier can be used in a variety of
system applications. Here are some examples to help plan your own installation.
Bridged - Mono Subwoofer System
Set X-Over Mode to LP and adjust
FREQ to speaker specifications.
Subwoofer 4 Ohms
Figure 4
In this application the amplifier is bridged for mono operation to drive a subwoofer.
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APX280M Power System Amplifier
2-Channel Full-Range, Satellite, or Subwoofer Stereo System
(Set INPUT SELECT Switch to STEREO)
Set X-Over Mode as
shown.
Set X-Over Mode as shown;
adjust FREQ to speaker
specifications.
Set X-Over Mode as shown;
adjust FREQ to speaker
specifications.
Figure 5
In this application, the amplifier is used in stereo and drives two full-range (or
satellite or subwoofer) speakers. NOTE: A passive crossover must be used
with satellite speakers.
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Operation/Installation Manual
Mixed-Mode Satellite and Subwoofer System
(Set INPUT SELECT Switch to STEREO)
FREQ (Hz)
80
100
125
150
200
L (mH)
8.0
6.4
5.1
4.2
3.2
C (µF)
497
398
318
265
199
Subwoofer 4 Ohms
NOTE: Chart values based on
4 Ohm speakers.
Figure 6
The amplifier can be configured for a mixed-mode operation. The table provides
component values to create a 6dB per octave crossover at specified frequencies.
Use components that have a + 5% tolerance and capacitors rated at 100V.
NOTE: Choose the same frequency for both LP and HP crossovers. Do not overlap frequencies, as this may damage the amplifier.
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APX280M Power System Amplifier
SETTING THE GAIN
After completing the installation, follow these steps to set the Gain Control and
then perform the Final System Checks.
1. Turn the Gain Control all the way counter-clockwise.
2. Turn the vessel's Ignition Switch to the ON position. Then turn the ON/OFF
Switch on the source units to the ON position. Set all Tone or Equalization
Controls to "flat" positions and turn Loudness off.
3. Play a CD or Tape and set the Volume Control at 75% of full level.
NOTE: If the system uses an equalizer, set its frequency controls to "flat"
positions.
4. Slowly increase the Gain Control. Stop when you hear a slight distortion of
audio.
SETTING THE CROSSOVER
The Clarion APX280M features a fully adjustable crossover. To set the
crossover, follow these steps.
1. Using the X-Over Mode Switch, select the desired mode - LP for Low Pass,
HP for High Pass and OFF for Full Range.
2. Using the Freq (Hz) Control, select the desired frequency. If the desired
frequency exceeds the range of the Freq (Hz) Control, press the Crossover
Frequency Multiplier Switch to increase the value by a multiplier of 10.
• For example, 55Hz x 10 = 550Hz or 550Hz x 10 = 5.5kHz.
SETTING THE BASS BOOST
1. Initially set the Bass Boost control to its full left position (i.e. 0dB).
2. Listen to a variety of music styles (e.g. Rock, Rap, etc.) and slowly increase
the Bass Boost control until a noticeable increase in low bass response is
perceived.
3. Slowly adjust the Bass Boost control (up or down) to realize the best bass
response.
CAUTION: If you hear a "pop" (due to speaker over-excursion), lower the
Bass Boost to prevent speaker damage. If the system sounds muddy and
distorted (due to amplifier clipping), lower Bass Boost to avoid shutdown from
overheating.
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Operation/Installation Manual
FINAL SYSTEM CHECK
1. Start the engine and turn on the source unit. After a two-second delay,
slowly increase the Volume Control and listen to the audio. If you hear any
noise, static, distortion or no sound at all, check the connections, and also refer
to Troubleshooting. Depending on your system design, the levels may become
quite loud even at low Volume Control settings. Until you get an "audio feel"
of the system's power, use care when adjusting controls.
2. Turn the Balance Controls to their extreme positions and listen to the results.
Audio imaging should match control settings (audio from the left speaker when
balance is left).
3. Increase the volume and verify that the amplifier reproduces audio (at full
frequencies) without distortion. If you hear distortion, check the connections
and verify that the Gain Control is set correctly. Another possibility is
damaged speakers or under-powered speakers. Once again refer to
Troubleshooting for additional help.
TROUBLESHOOTING
Problem
No Audio.
Solution
Low or no remote turn-on voltage. Check remote connections at amplifier and
source unit.
Blown amplifier fuse. Replace with new fast-blow fuse (same rating).
Power wires not connected. Check battery and ground wiring at amplifier;
also check battery connections.
Speaker leads shorted. Check speaker continuity to ground, it should not show
a common ground.
Speakers not connected or are blown. Check speaker connections at amplifier,
measure coil impedance.
Problem
Audio cycles on and off.
Solution
Thermal protection circuits are shutting amplifier off. Check location for
adequate ventilation; consult an authorized Clarion Audio Dealer.
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APX280M Power System Amplifier
Problem
Distorted audio.
Solution
Gain is not set properly, or damaged speaker cones. Review Setting Gain;
inspect each speaker cone for signs of damage (i.e. frozen cone, burning smell,
etc.)
Problem
Audio lacks punch.
Solution
Speakers wired incorrectly, which causes cancellation of bass frequencies.
Check polarity of wires from amplifier to each speaker as defined by the
system design.
Problem
Amplifier fuse keeps blowing.
Solution
Incorrect wiring or short circuit. Review Installation and check all wiring
connections.
Problem
Whining or ticking noise in the audio with engine on.
Solution
Amplifier is picking up alternator noise or radiated noise. Turn down input
gain; move audio cables away from power wires. Check power and ground
connections on amplifier; install an in-line noise filter on source unit's power
wire; check alternator and/or voltage regulator; test for weak battery or add
water to battery.
PRODUCT SPECS
Frequency Response
Signal Noise Ratio
THD
Input Sensitivity Low Level
Input Sensitivity Speaker Level
Max. Power Output
Cont. Power Output
2-Ohm Stereo Output
Bridged Power
Dimensions
Current Consumption at output
@ max power
10
20Hz ~ 20kHz
>100db
.05% all channels driven
250mV ~ 2.5 V
500mV ~ 5V
320W (160Wx 2)
160W (80w x 2) @ .08% THD
125W x 2 @ .05% THD
300W x 1 @ .05% THD
2-1/8"H x 8-1/4"W x 9" L
28A @ 382 Watts
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Operation/Installation Manual
CLARION LIMITED WARRANTY
For USA and Canada only
If purchased from an authorized Clarion dealer, this product is warranted against all defects in materials
and workmanship for a period of one (1) year from the date of original purchase. Clarion ProAudio products, except for speakers, are covered by a two (2) year limited warranty when purchased from and
installed by an authorized Clarion dealer.
ALL PURCHASES OF CLARION PRODUCTS FROM NON-AUTHORIZED CLARION DEALERS ARE
SUBJECT TO FURTHER WARRANTY RESTRICTIONS AS DESCRIBED BELOW.
The conditions of this limited warranty and the extent of responsibility of Clarion Corporation of America
("Clarion") under this limited warranty are as follows :
1. PROOF OF DATE OF PURCHASE WILL BE REQUIRED FOR WARRANTY SERVICE OF THIS
PRODUCT. IN THE CASE OF THE TWO (2) YEAR LIMITED WARRANTY FOR CLARION PROAUDIO
PRODUCT, PROOF OF INSTALLATION BY AN AUTHORIZED CLARION DEALER IS REQUIRED.
INFORMATION ABOUT CLARION AUTHORIZED WARRANTY SERVICE CENTERS MAY BE
OBTAINED BY CONTACTING OR WRITING CLARION AT THE ADDRESS LISTED BELOW.
2. This limited warranty will become void if service performed by anyone other than an approved Clarion
Warranty Service Center results in damage to the product.
3. This limited warranty does not apply to any product which has been subject to misuse, neglect or
accident, or which has had the serial number altered, defaced or removed, or which has been
connected, installed, adjusted or repaired, other than in accordance with the instructions furnished by
Clarion.
4. his limited warranty does not cover car static or other electrical interferences, tape head or laser pick-up
cleaning or adjustments, or labor costs for the removal or reinstallation of the unit for repair.
5. The sole responsibility of Clarion under this limited warranty shall be limited to the repair of the product
or replacement of the product, at the sole discretion of Clarion.
6. Product must be shipped in its original carton or equivalent carton, fully insured, with shipping charges
prepaid. Clarion will not assume any responsibility for any loss or damage incurred in shipping.
7. CLARION PRODUCTS, INCLUDING PROAUDIO PRODUCTS, PURCHASED FROM A SOURCE
OTHER THAN AN AUTHORIZED CLARION DEALER, INCLUDING ANY AND ALL PURCHASES VIA
THE INTERNET FROM A NON INTERNET AUTHORIZED CLARION DEALER, SHALL NOT BE
COVERED BY ANY CLARION LIMITED WARRANTY TO THE EXTENT ALLOWED BY APPLICABLE
LAW. IN THE EVENT AND TO THE EXTENT APPLICABLE LAW PROHIBITS ELIMINATION OF
WARRANTIES UNDER THESE CIRCUMSTANCES, THE APPLICABLE LIMITED WARRANTY PERIOD
SHALL BE DEEMED TO BE FIFTEEN (15) DAYS FROM THE DATE OF ORIGINAL PURCHASE.
8. ALL IMPLIED WARRANTIES EXCEPT TO THE EXTENT PROHIBITED BY APPLICABLE LAW SHALL
HAVE NO GREATER DURATION THAN THE WARRANTY PERIOD SET FORTH ABOVE. UNDER NO
CIRCUMSTANCES SHALL CLARION BE LIABLE FOR ANY LOSS OR DAMAGE, DIRECT OR
CONSEQUENTIAL, ARISING OUT OF THE USE OR INABILITY TO USE THE PRODUCT. BECAUSE
SOME STATES DO NOT ALLOW LIMITATIONS ON HOW LONG AN IMPLIED WARRANTY LASTS OR
EXCLUSIONS OR LIMITATIONS OF INCIDENTAL OR CONSEQUENTIAL DAMAGES, THE ABOVE
LIMITATIONS OR EXCLUSIONS MAY NOT APPLY TO YOU
9. THIS LIMITED WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS, AND YOU MAY ALSO HAVE
OTHER RIGHTS WHICH VARY FROM STATE TO STATE.
10. The laws of the State of California shall govern and control this limited warranty, its interpretation and
enforcement.
11. Should you have any difficulties with the performance of this product during the warranty period, please
call or visit our web site for a listing of Authorized Warranty Service Centers in your area. You may also
contact the Clarion Customer Service at the address listed below for any service help you may need
with Clarion products.
In USA:
Clarion Corporation of America
Attn:Customer Service Manager
661 W. Redondo Beach Blvd
Gardena, CA.90247-4201
1-800-GO-CLARION
(310)327-9100
www.clarion.com
In Canada:
Clarion Canada Inc.
Warranty Service Center
2239 Winston Park Drive
Oakville,Ontario L6H 5R1
(905)829-4600
www.clarioncanada.com
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