Clarion APX400 Stereo Amplifier User Manual

The Clarion APX400.4M is a full-featured four-channel amplifier. It comes
with the following features:
• Full frequency response with low distortion and exceptional signal to noise
• Advanced circuit design features bridgeable and mixed mode operation for
use in a variety of 4, 3 or 2 channel systems
• Independent front and rear, low-pass/high-pass electronic crossovers each
with a 12dB per octave slope and full adjustment range (from 55Hz to 550Hz
Front and 55Hz to 5.5kHz Rear) to aid in audio system design
• Variable bass boost circuit to reinforce low frequency signals that may be
lost due to subwoofer box design
• Adjustable input level controls with ground loop isolation accepting a wide
range of input signals
• Remote turn-on with “soft start” muting to prevent turn-on “thump”
• Pulse-Width Modulated (PWM) MOSFET power supply with low AM RFI
and protection circuits for overheating and speaker shorts
• 2 ohm load capacity to drive a variety of speaker systems
• Gold-plated input/output connectors and an external automotive type fuse
• Aluminum heat sink for efficient heat dissipation
• Low profile, compact size for space limited installations
To start enjoying your new Clarion four-channel amplifier, please read the
instructions listed in this manual. Keep all instructions for future reference.
Please fill out and send in the enclosed warranty card to protect your purchase
and aid in warranty service. Also, save your original sales receipt as proof of
Description • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1
Input Connections and Audio Controls • • • • • • • • • • • • • • • • • • • • 1
Connections for Power and Speakers • • • • • • • • • • • • • • • • • • • • • 3
Applications • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 4
Installation • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 9
Mounting Precautions • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 9
Wiring Precautions • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 9
Setting the Gain • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 11
Setting the Crossover • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 11
Setting the Bass Boost • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 11
Final System Checks • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •12
Troubleshooting • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •12
Product Specs • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •13
Notes • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •13
The Clarion APX400.4M 4-channel marine amplifier is an excellent choice for
creating a variety of multi-channel sound systems. It features built-in system
design flexibility that allows you to create a 2, 3 or 4 channel amplifier with a
flip of a switch. You can also configure the front or rear amplifier sections for
a mixed mode operation to drive a set of satellite speakers and/or subwoofer.
The built-in 12dB per octave electronic crossover lets you custom tailor the
sound of the front and rear channels, using two independent filters with
adjustable crossover frequencies for high-pass or low-pass filtering.
The amplifier also uses an unregulated MOSFET power supply for superior
control of output wattage. A toroid-coil transformer yields maximum power
transfer with minimum heat loss. Careful circuit design keeps AM RFI at low
levels, so you won’t hear unwanted noise when the level is cranked up.
Protection circuits safeguard the amplifier against overheating, speaker shorts,
or improper load conditions that may occur.
All connections and controls are on the end panels and are easy to understand.
We use gold-plated RCA and barrier connectors to ensure the best electrical
connection for your system. Included are external automotive type fuses that
are easy to replace.
The front panel of the APX400.4M contains connections for RCA Inputs and
Audio Control as shown below.
The Input Connections are gold-plated RCA Jacks and are labeled as FRONT
Figure 1-
1. Front RCA Input Jacks
2. Rear RCA Input Jacks
3. Front Gain Control
4. Rear Gain Control
5. Bass Boost Control
6. Rear Channel Input Selector
7. Front Input Mode Switch
8. Rear Input Mode Switch
9. Speaker Level Inputs
10. Front Frequency Control
11. Front X-Over Mode Switch
12. Rear Frequency Control
13. Multiplier Switch
14. Rear X-Over Mode Switch
provide a wide adjustment range to accommodate output levels from any brand
of source unit.
• Gain Controls - Seperate Front and Rear Gain Controls allow 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 lowfrequency 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 undesired, set Bass Boost to 0dB.
High-pass/Low-pass Filter Controls
• Freq (Hz) Controls - The front crossover frequency is fully adjustable
between 55Hz and 550Hz. The rear crossover frequency is fully adjustable
between 55Hz and 5500Hz (via the Rear 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 either of the X-Over
Mode Switches is set to OFF, varying the Freq (Hz) Control will produce no
• Rear X-Over Frequency Multiplier Switch - When engaged, this switch
increases the crossover frequency of the rear channels by a factor of 10.
Example: If the Freq (Hz) dial is set for 240Hz, pushing in the multiplier
Switch changes the setting to 2400Hz.
• X-Over Mode Switches - These switches are equipped with 12dB per octave
electronic filters for precise frequency attenuation with minimal phase
distortion. The steep crossover slopes keep midrange tones out of the
subwoofer and thereby eliminating an unnatural “nasal” tone quality in the
audio system. Each filter is activated by sliding the X-Over Mode Switch to
either LP or HP.
• Input Mode Switches - These switches allow you to set the input mode for
front and rear channels. 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 the APX400.4M as a
bridged 2 channel amplifier. L + R (sum mono) allows a stereo input to be
summed into a mono output.
• Rear Channel Input Select - This switch allows you to use a 2 channel input
to drive all 4 channels of this amplifier.
• 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 RCAoutputs 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
The rear panel of the APX400.4M contains power and speaker connections as
shown below.
Figure 2-
1. Left Front Speaker Output
2. Right Front Speaker Output
3. Remote Turn-on Input
4. Ground Input
5. Battery + 12V Input
6. 40 Amp Fuse
7. Left Rear Speaker Output
8. Right Rear Speaker Output
The Clarion APX400.4M 4-channel marine amplifier can be used in a variety
of system applications. We’ve enclosed some example systems to help plan
your own installation.
4-Channel Full-Range Stereo System
Figure 3 - In this application, the APX400.4M is used as a 4-channel amplifier
to drive four full-range speakers in stereo.
4-Channel Stereo System
2-Channels High-Pass, 2-Channels Low-Pass
Figure 4 - In this 4-channel system, the APX400.4M drives a pair of stereo
satellites for the front and a pair of stereo subwoofers for the rear. Note the
filter settings.
2-Channel Stereo System with Low-Pass
Bridged Mono Channel
Figure 5 - The APX400.4M can also be used to drive a pair of stereo satellites
for the front and a single mono subwoofer for the rear. Note the filter settings.
2-Channel High Power Systems (Satellite or Subwoofer)
Figure 6 - The APX400.4M can be set up as a 2-channel high-power amplifier
to drive a pair of satellites (or subwoofers).
Mixed-Mode System On Rear; Full-Range
Speakers On Front
FREQ (hz)
L (mH)
C (uF)
NOTE: Chart values based on 4 ohm speakers.
Figure 7 - The amplifier can be configured for a mixed-mode operation on
either channels 1/2 or 3/4 amplifier sections. 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.
This section lists Mounting and Wiring Precautions for installing the Clarion
APX400.4M. Combined with the experience of a professional installer, these
safeguards provide enough detail to successfully complete an installation. If
you do not have the necessary skills, do not install the amplifier yourself.
Instead, see your authorized Clarion dealer for installation recommendations.
Although the Clarion APX400.4M incorporates heat sinks and protection
circuits, mounting the amplifier in a tight space without any air movement can
still damage internal circuitry over time. Choose a site that provides adequate
ventilation and is isolated from the marine environment. For easy system setup, mount the amplifier so the front panel controls will be accessible after
In addition, observe the following precautions:
1. For the most efficient cooling, mount the amplifier so cool air runs along the
length of the fins rather than across them. Remember, any moving air will
dissipate heat.
2. Mount the amplifier on a rigid surface. Avoid mounting to subwoofer
enclosures or areas prone to vibration.
3. Prior to drilling, make sure proposed mounting holes will not cut into the
fuel tank, fuel lines, brake lines (under chassis), or electrical wiring.
Read all wiring precautions. If you are not sure of the connections, contact
your authorized Clarion dealer.
1. Before installation, make sure the source unit Power switch is in the OFF
2. Disconnect the negative (-) lead of the battery before making any power
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 secure clean ground connection is critical to the performance of your
Clarion amplifier. Use the shortest ground wire possible and securely connect
to the vessel battery to minimize resistance and avoid noise problems.
5. Add an external fuse on the amplifier’s positive (+) power lead and connect
it as close as possible to the vessel’s (+) battery terminal. Use a rating that
equals the total current consumption at full output of all amplifiers in the
system. Adding an external fuse will protect the electrical system from short
circuits that can cause a fire.
6. Refer to the Figure 8 when making electrical connections. Connect the
amplifier’s positive (+) lead via a fuse directly to the positive (+) terminal on
the battery. Do not connect this wire to the vessel’s fuse panel. Use redinsulated 10-gauge (or larger) wire for the amplifier’s positive (+) power lead
and the same-gauge black insulated wire for the ground.
7. When replacing the amplifier ’s fuse, always use one having the same current
rating. Substituting a higher-rated fuse or a slow-blow type can result in
serious damage to the amplifier.
8. Make sure that your vehicle’s electrical system (alternator, battery, etc.) is
capable of handling the additional load. If you are planning a multi-amplifier
system, you may need to add a second battery and possibly upgrade the
alternator with a higher-output rated model. Consult your authorized Clarion
dealer for recommendations.
9. To avoid noise problems, run the amplifier’s positive (+) power lead along
one side of the vessel to the battery. Run the remote turn-on wire and RCA
audio cables down the center, and route the speaker wires along the remaining
side. If wires must cross, run them perpendicular to each other.
10. When creating passage holes for the power wire, use grommets to eliminate
any sharp edges created during drilling. This will protect the wire from being
nicked and causing a short circuit.
11. Extra cable can cause signal loss and act as an “antenna” for noise. Use
only high-quality RCA cables that are no longer than necessary to make a
direct connection with the source unit or equalizer.
Figure 8 - Electrical connections for the APX400.4M
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 vehicle’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”
4. Slowly increase the Gain Control. Stop when you hear a slight distortion of
The Clarion APX400.4M features fully adjustable front and rear crossovers.
To set the crossovers, 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) Selection Control, select the desired frequency. If the
desired frequency exceeds the range of the Freq (Hz) Selection 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.
3. Repeat steps 1 and 2 for both the front and rear crossovers.
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
3. Slowly adjust the Bass Boost control (up or down) to realize the best bass
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
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 output 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.
No Audio.
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.
Audio cycles on and off.
Thermal protection circuits are shutting amplifier off. Check location for
adequate ventilation; consult an authorized Clarion Audio Dealer
Distorted audio.
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,
Audio lacks punch.
Speakers wired incorrectly, which causes cancellation of bass frequencies.
Check polarity of wires from amplifier to each speaker as defined by the
system design.
Amplifier fuse keeps blowing.
Incorrect wiring or short circuit. Review Installation and check all wiring
Whining or ticking noise in the audio with engine on.
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
Frequency Response
Signal Noise Ratio
Input Sensitivity Low Level
Input Sensitivity Speaker Level
Max. Power Output
Cont. Power Output
2-Ohm Stereo Output
Bridged Power
Current Consumption @ Max Power Output
20Hz ~ 20kHz
.05% all channels driven
250mV ~ 2.5V
500mV ~ 5V
380W (190 x 2)
200W (50W x4) @.08% THD
90 x 4 @ .8% THD
190 x 2 @ .8% THD
2 1/8”H x 8 1/4”W x 12” L
46A @ 380 Watts
661 W. Redondo Beach Blvd.
Gardena, CA 90247
Rev.2 (05/00)
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