JL Audio A6450 User Manual

A6450

six-channel system amplifier

OWNER’S MANUAL

Thank you for purchasing a JL Audio amplifier for

your automotive 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 and extended warranty

coverage, 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.

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 vehicle.
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 vehicle 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
vehicles with 12 volt, negative-ground electrical
systems. Use of this product in vehicles 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 certif ied 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.

Chassis Ground

+12 V Power

Connector

(pg. 4)

Connector

(pg. 5)

Remote Turn-On

Connector

(pg. 5)

Channels 1 & 2

Speaker Outputs

(pg. 8)

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 amplif ier
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.

Channels 3 & 4

Speaker Outputs

(pg. 8)

Channels 5 & 6

Speaker Outputs

(pg. 8)

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 vehicle’s safety
equipment (air bags, seat belt systems, ABS brake
systems, etc.). You should also take the time to
securely mount the amplifier using the supplied
screws so that it does not come loose in the event
of a collision or a sudden jolt to the vehicle.

Stupid Mistakes to Avoid

• Check before drilling any holes in your vehicle

to make sure that you will not be drilling
through a gas tank, brake line, wiring harness or
other vital vehicle system.

• Do not run system wiring outside or underneath

the vehicle. This is an extremely dangerous
practice which can result in severe damage to
your vehicle and person.

Input Voltage

Selection

(pg. 6)

Channels 3 & 4

Preamp Input Jacks

Channels 1 & 2

Preamp Input Jacks

(pg. 6)

(pg. 6)

Channels 5 & 6

Preamp Input Jacks

Indicator

(pg. 6)

Power
Status

(pg. 9)

Protection Status

Indicator

(pg. 9)

Jack for

Remote Bass

Control Knob

(pg. 8)

Ch. 1 & 2 Input

Sensitivity

Control

(pg. 6)

Bass Boost

On/Off Switch

(pg. 8)

Ch. 1 & 2

Filter Mode

Selection

(pg. 7)

Input Mode

Switch
(pg. 6)

Ch. 1 & 2 Filter

Frequency

Selector

(pg. 8)

Ch. 3 & 4

Input Sensitivity

Control

(pg. 6)

Ch. 5 & 6

Input Sensitivity

Control

(pg. 6)

Ch. 3 & 4

Filter Mode

Selection

(pg. 7)

Ch. 5 & 6

Filter Mode

Selection

(pg. 7)

Ch. 3 & 4

Filter Frequency

Selector

(pg. 8)

Ch. 5 & 6

Filter Frequency

Selector

(pg. 8)

2 JL AUDIO A6450

• Protect all system wires from sharp metal

edges and wear by carefully routing them,
tying them down and using grommets and
loom where appropriate.

• Do not mount the amplifier in the engine

compartment, under the vehicle, on the roof
or in any other area that will expose the
amplifier circuitry to the elements.

JL AUDIO A6450 3

PRODUCT DESCRIPTION

The JL Audio A6450 is a six-channel,
full-range audio amplifier utilizing patented
Absolute Symmetry™ Class A/B technology
for all channels.

The A6450 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 or OEM Interface
processor (like the CleanSweep CL441dsp).
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 power wire (minimum 8 AWG) 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 vehicle operation. Use 4 AWG
or larger power wire and a power distribution
block if additional amplifiers are being
installed with the A6450.

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 vehicle.
Do not install the fuse until the power wire
has been securely connected to the amplifier.

4) Run signal cables and remote turn-on wire

from the source unit to the final amplifier
mounting location.

5) Run speaker cables from the speaker systems

to the amplifier mounting location.

6) Find a good, solid metal grounding point

close to the amplifier and connect the
negative power wire to it using appropriate
hardware (use of the JL Audio ECS master
ground lug, XA-MGL-1 is recommended).
Use the same size power wire as the wire
connected to the “+1 2VD C” connection
(minimum 8 AWG), no longer than 36 inches

(90 cm) from the amplifier to the ground
connection point. In some vehicles, it may be
necessary to upgrade the battery ground wire.
(See page 5 for important notice).

7) Securely mount the amplifier using the

supplied screws.

8) Connect the positive and negative power

wires to the amplifier. A fuse near the
amplif ier 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 cables 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 the power wire fuse (60A for a

single A6450) 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 14)
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 vehicle’s battery.
This will prevent accidental damage to the system,
the vehicle and your body during installation.

The A6450’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 A6450 with other
amplifiers and wish to use a single main power
wire, use 2 AWG or 1/0 AWG main power wire
(depending on the overall current demands of all
the amplifiers in the system). This 2 AWG or
1/0 AWG power wire should terminate into
a distribution block mounted as close to the
amplif iers as possible and should connect to the
A6450 with 4 AWG power wire.

Note: Smaller AWG numbers mean bigger
wire and vice-versa (1/0 AWG is the largest, 2
AWG is sma l l e r, t hen 4 AWG , t h e n 8 AWG , e t c .).

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 f irmly, taking care not
to strip the head of the screw.

The ground connection should be made using
the same gauge wire as the power connection
and should be kept as short as possible, while
accessing a solid piece of sheet metal in the
vehicle. The surface of the sheet meta l should
be sanded at the contact point to create a clean,
metal-to-metal connection between the chassis
and the termination of the ground wire. For
optimal grounding, we recommend the use of a
JL Audio ECS master ground lug (X A-MGL-1).
Alternatively, a sheet metal screw or bolt can be
used with a star washer.

Any wires run through metal barriers (such
as firewalls), 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 vehicles employ small (10 AWG ­6 AWG) wire to ground the battery to the
vehicle chassis and to connect the alternator's
positive connection to the battery. To prevent
voltage drops, these wires should 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 va lue at each
power wire should be high enough for all of the
equipment being run from that power wire. If
only the A6450 is being run from that power wire,
we recommend a 60A 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 60A fuse.

TURNON LEAD

The A6450 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 A6450’s “Remote” turn-on connector is
designed to accept 18 AWG – 12 AWG wire. To
connect the remote turn-on wire to the amplif ier,
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 mak ing sure that the wire (not the
insulation) is firmly gripped by the set screw.

4 JL AUDIO A6450

JL AUDIO A6450 5

INPUT SECTION

The A6450’s input section allows you to send
signal to the amplifier section through the use of
two, four or six differential-balanced inputs.

Input connections are via three pairs of
traditional RCA-type jacks.

If you wish to send six discrete channels into
the A6450, simply use all six inputs and set the
“Input Mode” switch in the “Channel 5 & 6
Controls” section to “Discrete”.

If you wish to feed all six channels by using
only four channels of full-range input, set the
“Input Mode” switch in the “Channel 5 & 6
Controls” section to “Sum” and use only the
inputs to channels 1, 2, 3 & 4.

If you wish to feed all six channels by using
two channels of full-range input and two
channels of low-frequency input (subwoofer
output from the source unit), set the “Input
Mode” switch in the “Channel 5 & 6 Controls”
section to “Discrete”. It will be necessary to split
the full-range signals with y-adaptors and feed
these signals into the inputs to channels 1, 2, 3 &

4. The dedicated subwoofer signal should be sent
to channels 5 & 6.

If you wish to use only two channels of input
to deliver signal to all six amplifier channels,
it will be necessary to split the two signals with
y-adaptors and feed these signals into the inputs
to channels 1, 2, 3 & 4. Set the “Input Mode”
switch in the “Channel 5 & 6 Controls”
section to “Sum” and use only the inputs
to channels 1, 2, 3 & 4.

Input Voltage Range:

A wide range of signal input voltages can
be accommodated by theA6450’s CH 1&2 and
CH 3&4 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.

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 an aftermarket
source unit or an OEM interface processor 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 output from source units and
small amplifiers.

To use speaker-level sources, splice the speaker
output wires of the source unit or small amplif ier
onto a pair of RCA plugs for each input pair.
No line output converter is needed in most cases.

The CH 5&6 input section is designed to
accept only line-level signals and may clip
(distort) if high-level signals are applied to it.

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 above.

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.

Do not increase any “Input Sens.” setting for
any channel(s) of any amplifier in the system
beyond the maximum level established during
the procedure outlined in Appendix A (page

14). Doing so will result in audible distortion
and possible speaker damage.

FILTER CONTROLS

Most speakers are not designed to reproduce
the full range of frequencies audible by the
human ear. For this reason, most speaker
systems are comprised of multiple speakers, each
dedicated to reproducing a specific frequency
range. Filters are used to select which frequency
range is sent to each section of a speaker system.
The division of frequency ranges to different
speakers can be done with passive filters (coils
and/or capacitors between the amplifier outputs

and the speakers), which are acceptable and
commonly used for filtering between mid­range speakers and tweeters. Filtering between
subwoofer systems and satellite speaker systems
is best done with active filters, which cut off
frequency content at the input to the amplifier.
Active filters are more stable than passive filters
and do not introduce extraneous resistance,
which can degrade subwoofer performance.

The active filter built into each channel section
of the A6450 can be used to eliminate potentially
harmful and/or undesired frequencies from
making their way through the amplifier sections
to the speaker(s). This serves to improve tonal
balance and to avoid distortion and possible
speaker failure. Correct use of these filters can
substantially increase the longevity and fidelity of
your audio system.

1) “Filter Mode” Control: The A6450 employs a

12dB per octave filter for each pair of channels
(one filter for channels 1&2, another filter for
channels 3&4 and a third filter for channels
5&6). Each of these filters can be configured
independently into one of two filter types
or defeated completely by way of the three­position “Filter Mode” switches:
“Off”: Defeats the filter completely, allowing
the full range of frequencies present at the
inputs to feed the amplifier. This is useful
for systems utilizing outboard crossovers or
requiring full-range reproduction from one or
more of the A6450’s channel pairs.

6 JL AUDIO A6450

JL AUDIO A6450 7