JL Audio M4500 Owner's Manual

Thank you for purchasing a JL Audio amplifier for

your marine sound system.

Your amplifier has been designed and manufactured to exacting

standards in order to ensure years of musical enjoyment in your vehicle.

For maximum performance, we highly recommend that you have

your new amplifier installed by an authorized JL Audio dealer. Your

authorized dealer has the training, expertise and installation equipment

to ensure optimum performance from this product. Should you

decide to install the amplifier yourself, please take the time

to read this manual thoroughly so as to familiarize yourself

with its installation requirements and setup procedures.

If you have any questions regarding the instructions in this

manual or any aspect of your amplifier’s operation, please contact your

authorized JL Audio dealer for assistance. If you need further assistance,

please call the JL Audio Technical Support Department

at [phone] during business hours.

OWNER’S MANUAL

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.

Input Voltage

Selection

(pg. 6)

Channels 3 & 4

Preamp Input Jacks

(pg. 6)

Channels 1 & 2

Preamp Input Jacks

(pg. 6)

Left & Right

Preamp Output

Jacks

(pg. 8)

Ch. 3 & 4

Bass Boost

On/Off Switch

(pg. 8)

Pre-Out Signal

Selection Switch

(pg. 8)

Power
Status

Indicator

(pg. 10)

Jack for

Remote Bass

Control Knob

(pg. 8)

Ch. 3 & 4

Input Selection

Switch
(pg. 6)

Ch. 1 & 2 Filter

Frequency

Selector

(pg. 7)

Ch. 1 & 2 Input

Sensitivity

Control

(pg. 6)

Protection Status

Indicator

(pg. 10)

Ch. 1 & 2

Filter Mode

Selection

(pg. 7)

Ch. 3 & 4

Filter Mode

Selection

(pg. 7)

Ch. 3 & 4

Input Sensitivity

Control

(pg. 6)

Ch. 3 & 4

Filter Frequency

Selector

(pg. 7)

Remote Turn-On

Connector

(pg. 5)

Chassis Ground

Connector

(pg. 5)

+12 V Power

Connector

(pg. 4)

Channels 3 & 4

Speaker Outputs

(pg. 8)

Channels 1 & 2

Speaker Outputs

(pg. 8)

2 JL AUDIO M4500

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.

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.

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 or a
sudden jolt to the vessel.

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.

Channels 3 & 4

Speaker Outputs

(pg. 8)

Channels 1 & 2

Speaker Outputs

(pg. 8)

JL AUDIO M4500 3

PRODUCT DESCRIPTION

The JL Audio M4500 is a four-channel,
full-range audio amplifier utilizing patented
Absolute Symmetry™ Class A/B technology
for all channels.

The M4500 can be operated with a wide
variety of source units and system configurations.

TYPICAL INSTALLATION SEQUENCE

The following represents the sequence for a
typical amplifier installation, using an aftermarket
source unit. Additional steps and different
procedures may be required in some applications.
If you have any questions, please contact your
authorized JL Audio dealer for assistance.

1) Disconnect the negative battery post

connection and secure the disconnected cable
to prevent accidental re-connection during
installation. This step is not optional!

2) Run positive and negative power wire

(minimum 8 AWG) from from the battery
location to the amplifier mounting location,
taking care to route it in such a way that it
will not be damaged and will not interfere
with vessel operation. Use 4 AWG or larger
power wire and a power distribution block
if additional amplifiers are being installed
with the M4500.

3) Connect power wire to the positive battery

post. Fuse the wire with an appropriate fuse
block (and connectors) within 18 inches (45
cm) wire length of the positive battery post.
This fuse is essential to protect the vessel.
Do not install the fuse until the power wire
has been connected to the amplifier.

4) Connect negative power wire to the negative

battery post. Use the same size power
wire as the wire connected to the “+12V”
connection (minimum 8 AWG).

5) Run signal cables and remote turn-on wire

from the source unit to the amplifier
mounting location.

6) Run speaker wire from the speaker system

to the amplifier mounting location.

7) Securely mount the amplifier.

8) Connect the positive and negative power

wires to the amplifier. A fuse near the
amplifier is not necessary.

9) Connect the remote turn-on wire to

the amplifier.

10) Connect the input cables to the amplifier.

11) Connect the speaker wires to the amplifier.

12) Carefully review the amplifier’s control

settings to make sure that they are set
according to the needs of the system.

13) Install power wire fuse (50A for a single

M4500) and reconnect the negative
battery post terminal.

14) Turn on the source unit at a low level

to double-check that the amplifier is
configured correctly. Resist the temptation
to crank it up until you have verified the
control settings.

15) Make necessary adjustments to the input

sensitivity controls to obtain the right
overall output and the desired balance in the
system. See Appendix A (page 12)
for the recommended input sensitivity
setting method.

16) Enjoy the fruits of your labor with your

favorite music.

POWER CONNECTIONS

Before installing the amplifier, disconnect the

negative (ground) wire from the vessel's battery.
This will prevent accidental damage to the system,
the vessel and your body during installation.

4 JL AUDIO M4500

The M4500’s “+12 V DC” and “Ground”
connections are designed to accept 4 AWG power
wire. 4 AWG is a minimum power wire size for
this amplifier.

If you are installing the M4500 with other
amplifiers and wish to use a single main power
wire, use 4 AWG or larger main power wire
(depending on the overall current demands of all
the amplifiers in the system). This 4 AWG or
larger power wire should terminate into a
distribution block mounted as close to the
amplifiers as possible and should connect to the
M4500 with 4 AWG power wire.

Note: Smaller AWG numbers mean bigger wire
and vice-versa (1/0 AWG is the largest, 2 AWG is
smaller, then 4 AWG, then 8 AWG, etc.).

To connect the power wires to the amplifier,
first back out the set screw on the top of the
terminal block, using the supplied 2.5 mm hex
wrench. Strip 1/2 inch (12 mm) of insulation from
the end of each wire and insert the bare wire into
the terminal block, seating it firmly so that no
bare wire is exposed. While holding the wire in
place, tighten the set screw firmly, taking care not
to strip the head of the screw and making sure
that the wire (not the insulation) is firmly gripped
by the set screw.

The ground connection should be made using
the same gauge wire as the power connection.

Any wires run through barriers must be
protected with a high quality rubber grommet
to prevent damage to the insulation of the wire.
Failure to do so may result in a dangerous short
circuit.

Many vessels employ small (10 AWG - 6 AWG)
wire to connect the alternator’s positive
connection to the battery. To prevent voltage
drops, this wire should be upgraded to 4 AWG
when installing amplifier systems with main
fuse ratings above 60A.

It is common for the alternator to be grounded
through its chassis. If the alternator is not
grounded through its chassis and instead employs
a small (10 AWG - 6 AWG) wire to connect to
ground, this wire should also be upgraded to 4
AWG when installing amplifier systems with main
fuse ratings above 60A.

FUSE REQUIREMENTS

It is absolutely vital that the main power
wire(s) to the amplifier(s) in the system be
fused within 18 inches (45 cm) of the positive
battery post connection. The fuse value at each
power wire should be high enough for all of the
equipment being run from that power wire. If
only the A4300 is being run from that power wire,
we recommend a 50A fuse be used. AFS (mini
blade fuse), AGU (big glass fuse) or MaxiFuse™
(big plastic-body fuse) types are recommended.

No fuse is required or recommended directly
before the amplifier power connection. If one is
desired, we recommend the use of a 50A fuse.

TURNON LEAD

The M4500 uses a conventional +12V remote
turn-on lead, typically controlled by the source
unit’s remote turn-on output. The amplifier will
turn on when +12V is present at its “Remote”
input and turn off when +12V is switched off. If
a source unit does not have a dedicated remote
turn-on output, the amplifier’s turn-on lead can
be connected to +12V via a switch that derives
power from an ignition-switched circuit.

The M4500’s “Remote” turn-on connector is
designed to accept 18 AWG – 12 AWG wire. To
connect the remote turn-on wire to the amplifier,
first back out the set screw on the top of the
terminal block, using the supplied 2.5mm hex
wrench. Strip 1/2 inch (12mm) of wire and insert
the bare wire into the terminal block, seating it
firmly so that no bare wire is exposed. While
holding the wire in the terminal, tighten the set
screw firmly, taking care not to strip the head of
the screw and making sure that the wire (not the
insulation) is firmly gripped by the set screw.

JL AUDIO M4500 5

INPUT SECTION

The M4500’s input section allows you to send
signals to the amplifier section through the use of
either two or four differential-balanced inputs.

Input connections are via traditional

RCA-type jacks.

If you wish to send four discrete channels into
the M4500, simply use all four inputs (channels
1 & 2 and channels 3 & 4) and set the “CH 3&4
Input From” switch to “Discrete”.

If you wish to feed all four channels by using
only two channels of input, set the “CH 3&4
Input From” switch to “1&2” and use only the
inputs to channels 1 & 2.

Input Voltage Range:

A wide range of signal input voltages can be
accommodated by the M4500’s input sections
(200mV – 8V). This wide range is split up into
two sub-ranges, accessible via a switch located to

the left of the Input Connectors. Be aware that the

position of this switch will dictate the sensitivity
range for all four input channels.

The “Low” position on the “Input Voltage”
switch selects an input sensitivity range between
200mV and 2V. This means that the “Input
Sens.” rotary control will operate within that
voltage window. If you are using a source unit
with conventional preamp-level outputs, this is
most likely the position that you will use.

The “High” position on the “Input Voltage”
switch selects an input sensitivity range between
800mV and 8V. This is useful for certain high­output preamp level signals as well as speaker­level outputs from source units not equipped with
preamp-level outputs.

To use speaker-level sources, splice the speaker

output wires of the source unit onto a pair of RCA

plugs for each input channel pair. No line output
converter is needed in most cases.

The output of the amplifier will decrease for
a given input voltage when the “Input Range”
switch is placed in the “High” position.
Conversely, the output will be higher with the
switch in the “Low” position. While this may
sound counter-intuitive, it is consistent with the
descriptions in this section.

INPUT SENSITIVITY CONTROLS

Once the appropriate “Input Voltage” range
has been selected, the controls labeled “Input
Sens.” located in each “Channel Controls”
section can be used to match the source unit’s
output voltage to the input stage of each pair of
amplifier channels for maximum clean output.
Rotating the control clockwise will result in
higher sensitivity (louder for a given input
voltage). Rotating the control counter-clockwise
will result in lower sensitivity (quieter for a given
input voltage.)

To properly set the amplifier for maximum
clean output, please refer to Appendix A (page

14) in this manual. After using this procedure,
you can then adjust any or all “Input Sens.”
levels downward if this is required to achieve the
desired system balance.

6 JL AUDIO M4500