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| JL Audio - MHD900/5 Owner’s Manual
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Cooling efficiency Considerations:
The outer shell of your JL Audio amplifier
is designed to remove heat from the amplifier
circuitry. For optimum cooling performance,
this outer shell should be exposed to as large a
volume of air as possible. Enclosing the amplifier
in a small, poorly ventilated chamber can
lead to excessive heat build-up and degraded
performance. If an installation calls for an
enclosure around the amplifier, we recommend
that this enclosure be ventilated with the aid
of a fan. In normal applications, fan-cooling
is not necessary.
Mounting the amplifier upside down is
strongly discouraged.
If mounting the amplifier under a seat,
make sure there is at least 1 inch (2.5 cm) of
space above the amplifier’s outer shell to permit
proper cooling.
ProteCt Your Hearing!
We value you as a long-term customer. For
that reason, we urge you to practice restraint in
the operation of this product so as not to damage
your hearing and that of others in your vessel.
Studies have shown that continuous exposure to
high sound pressure levels can lead to permanent
(irreparable) hearing loss. This and all other
high-power amplifiers are capable of producing
such high sound pressure levels when connected
to a speaker system. Please limit your continuous
exposure to high volume levels.
While driving, operate your audio system in
a manner that still allows you to hear necessary
noises to operate your vessel safely (horns,
sirens, etc.).
serial number
In the event that your amplifier requires
service or is ever stolen, you will need to have
a record of the product’s serial number. Please
take the time to enter that number in the space
provided below. The serial number can be found
on the bottom panel of the amplifier and on the
amplifier packaging.
Serial Number:
installation aPPliCations
This amplifier is designed for operation in
vessels with 12 volt, negative-ground electrical
systems. Use of this product in vessels with
positive ground and/or voltages other than 12V
may result in damage to the product and will void
the warranty.
This product is not certified or approved for
use in aircraft.
Do not attempt to “bridge” the outputs of this
amplifier with the outputs of a second amplifier,
including an identical one.
Planning Your installation
It is important that you take the time to read
this manual and that you plan out your
installation carefully. The following are some
considerations that you must take into account
when planning your installation.
Filter Frequency
Selector
(pg. 11)
Filter Frequency
Selector
(pg. 10)
Input Voltage
Selection
(pg. 9)
Infrasonic Filter
Selector
(pg. 11)
Input Sensitivity
Control
(pg. 10)
Input Mode
Selection
(pg. 9)
Filter Slope
Selection
(pg. 11)
Filter Frequency
Selector
(pg. 11)
Input Sensitivity
Control
(pg. 10)
Filter Slope
Selection
(pg. 11)
Input Sensitivity
Control
(pg. 10)
Power Status
Indicator
(pg. 15)
Filter Slope
Selection
(pg. 11)
Left & Right
Input Jacks:
Subwoofer
(pg. 9)
Left & Right
Input Jacks:
Front Channels
(pg. 9)
Speaker Outputs
(pgs. 13-14)
Jack for
Remote Level
Control Knob
(pg. 13)
Left & Right
Input Jacks:
Rear Channels
(pg. 9)
Chassis Ground
Connector
(pgs. 6-7)
Remote Turn-On
Connector
(pgs. 6-7)
+12 V Power
Connector
(pgs. 6-7)
safety Considerations:
Your amplifier needs to be installed in a dry,
well-ventilated environment and in a manner
which does not interfere with your vessel’s factory
installed electronic devices. You should also take
the time to securely mount the amplifier so that
it does not come loose in the event of a collision/
sudden jolt or as a result of the repeated vibrations
the vessel is prone to during normal operation.
stupid mistakes to avoid:
• Check before drilling any holes in your vessel to
make sure that you will not be drilling through
the hull, a fuel tank, fuel line, wiring harness or
other vital vessel system.
• Do not run system wiring outside or underneath
the vessel. This is an extremely dangerous
practice which can result in severe damage to
your vessel and person.
• Protect all system wires from sharp edges
(metal, fiberglass, etc.) by carefully routing
them, tying them down and using grommets
and loom where appropriate.
• Do not mount the amplifier in the engine
compartment or in any other area that will
expose the amplifier circuitry to the elements.
While this amplifier is specially designed
for marine applications, it is not waterproof
and it should not be mounted where it is likely
to get wet.
