Jbl LC-A304, LCA 502, LC-A504, LC-A752 User Manual
Amplifiers
Thank you for purchasing a
JBL Loud + Clear amplifier. In
order that we may better serve you
should you require warranty service on your new amplifier, please
retain your original purchase
receipt and return the enclosed
warranty registration card.
Important: Installation of automotive stereo components can
require extensive experience in
performing a variety of mechanical and electrical procedures.
Although these instructions
explain, in a general sense, how
to install Loud + Clear amplifiers,
they may not show the exact
installation methods for your
particular vehicle. If you feel
you lack the tools or necessary
experience, ask your authorized
JBL car-audio dealer about professional installation options.
Installation Warnings and Tips
• Always wear protective
eyewear when using tools.
• Turn off all audio systems and
other electrical devices before
you start.
• Disconnect the negative (–) lead
from your vehicle’s battery.
• Check clearances on both sides
of a planned mounting surface
before drilling any holes or
installing any screws. Remember
that the screws can extend behind
the surface.
• At the installation sites, locate
and make a note of all fuel lines,
hydraulic brake lines, vacuum
lines and electrical wiring. Use
extreme caution when cutting or
drilling in and around these areas.
• Before drilling or cutting holes,
use a utility knife to remove
unwanted fabric or vinyl to keep
material from snagging in a
drill bit.
• When routing cables, keep inputsignal cables away from power
cables and speaker wires.
• When making connections,
ensure that they are secure and
properly insulated.
• If the amplifier’s fuse must be
replaced, use only the same type
and rating as that of the original.
Do not substitute another kind.
Warning: Playing loud music in
an automobile can permanently
damage your hearing as well as
hinder your ability to hear traffic.
We recommend listening at low
levels while in your car. JBL
accepts no liability for hearing
loss, bodily injury or property
damage resulting from use or
misuse of this product.
Choosing a Location and Mounting the Amplifier
Amplifiers need air to stay cool. Suitable locations are under seats
(provided the amplifier doesn’t interfere with the seat-adjustment
mechanism), in the trunk or in any location that provides enough air
for the amp to cool itself. Do not mount the amplifier with the heat-sink
fins facing downward; this makes convection cooling of the amplifier
impossible.
Mount the amplifier so that it is not damaged by the feet of back-seat
passengers or shifting cargo in the trunk. Mount the amplifier so that it
remains dry – never mount an amplifier outside the car or in the engine
compartment.
Using the amplifier as a template, mark the location of the mounting holes
on the mounting surface, drill pilot holes and attach the amplifier to the
mounting surface with screws. Make sure the amplifier is mounted securely.
Wiring the Power Connections
Refer to Figures 1–4 for connector locations. Use at least 10-gauge wire
for power and ground connections.
For power, remote and ground connections strip off one end of each
jacket to reveal bare wire for insertion into the barrier-strip connectors.
Connect a wire from the GND connector on the amplifier to the nearest
bare-metal chassis component; scrape away the paint to ensure good
conductivity. Next, connect a wire between the BATT terminal on the
amplifier and the POS (
wire through a factory-installed grommet in the firewall, or install a
grommet if a factory grommet is not available. You must install, within
18" of the battery connection, a fuse holder and fuse with the same
rating as the fuse in the amplifier’s chassis. This will prevent a short
circuit from causing damage to the amplifier or the car. Connect a wire
between the REM terminal of the amplifier and the “remote out” or
power-antenna lead on the vehicle’s radio.
+) terminal of the vehicle’s battery. Pass the
If you are bridging the amplifier, connect the speaker wires to the terminals marked “bridged,” observing proper polarity. The total impedance
of the speaker system connected to the amplifier must be at least four
ohms in bridged mode.
If you are running the amp in Tri-Mode (stereo and mono simultaneously),
connect the satellite speakers to the speaker connector as you would a
pair of stereo speakers. Connect the subwoofer to the terminals marked
“bridged.” Refer to the chart below to determine the capacitor and
inductor values you’ll need to route bass signals to the woofer, and the
midrange and high frequencies to the satellite speakers. These passive
crossover components will also ensure that the impedance of the speaker
system doesn’t drop below two ohms.
FREQUENCY INDUCTOR CAPACITOR
Crossover 6dB/oct. LP 6dB/oct. HP
(4 ohm) (4 ohm)
75Hz 8.0mH 530µF
100Hz 6.4mH 400µF
125Hz 5.0mH 318µF
150Hz 4.2mH 265µF
175Hz 3.6mH 227µF
200Hz 3.2mH 198µF
Wiring the Speaker-Output Connections
Connect the speakers, observing proper polarity, to the speaker-output
barrier strip. The total impedance of the speaker system connected to the
amplifier when the amplifier is driven in stereo must be at least two ohms.
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