JL Audio JD400/4 Owner's Manual

OWNER’S MANUAL

400W 4-Channel Class D Amplifier

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, 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 contact the JL Audio Technical Support Department

at [e-mail]/support.

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.).

Chassis Ground

Connector

(pg. 5)

+12 VDC Power

Connector

(pg. 4-5)

Remote Turn-On

Connector

(pg. 6)

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:

CH 1 & CH 2

Speaker Outputs

(pg. 10)

CH 3 & CH 4

Speaker Outputs

(pg. 10)

CH 3 & CH 4

Input Jacks

CH 1 & CH 2

(pg. 7)

Input Jacks

(pg. 7)

INPUT SECTION PREOUTS

CH. 1& 2 CH. 1&2 (only)CH. 3&4

Left & Right

Output Jacks

(pg. 9)

Filter Mode

(pg. 8-9)

Filter

Frequency

Control

(pg. 8-9)

Clipping

Input Sensitivty

Control

(pg. 8)

Input Mode

(pg. 7)

Filter Mode

(pg. 8-9)

Turn-On

Mode
(pg. 6)

Frequency

Control

(pg. 8-9)

Filter

Input

Voltage

(pg. 7)

Clipping

Input Sensitivty

Control

(pg. 8)

2 JL Audio

INSTALLATION APPLICATIONS

IMPORTANT!

!

This amplifier is designed for operation in
vehicles with 12V, 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
th e 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.

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 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 appropriate
hardware 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.

• 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.

WHAT IS INCLUDED

(1) JD400/4 amplifier
(1) 2.5 mm hex wrench
(1) 3 mm hex wrench
(1) Owner's manual

PRODUCT DESCRIPTION

The JD400/4 is a four-channel, full-range
audio amplifier utilizing JL Audio's NexD™ high­speed switching technology to deliver outstanding
fidelity and efficiency. The JD400/4 can be
operated with a wide variety of source units and
system configurations.

For detailed specifications, please refer to
Appendix B (page 15).

JD40 0/4 3

TYPICAL INSTALLATION SEQUENCE

The following represents the sequence
for a typical amplifier installation, using an
aftermarket source unit or OEM Interface
processor (like the JL Audio FiX™ 82 or FiX™ 86).
Additiona l 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 reconnection during
installation. This step is not optional.

2) Run copper power wire 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. See next page for
appropriate wire size.

3) Connect the power wire to the positive battery

post. Fuse the wire with an appropriate fuse
block (and connectors) within 18 inches (45
cm) of wire length from 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 (if

available) from the source unit or processor 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, XB-MGLU is recommended). Use
4 AWG copper wire, 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
appropriate hardware.

8) Connect the positive and negative power

wires to the amplifier. A fuse near the
amplifier is not necessary if this is the only

device being run from the fused main power
wire. If the fused main power wire is shared
with other amplifiers or devices, fuse each
amplifier/device within 12 inches (30 cm) of
wire length, via a fused distribution block or
multiple individual fuse blocks/on-board fuses.

9) Connect the remote turn-on wire to the
amplifier or configure the “Turn-On Mode”
switch for automatic turn-on.

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 (40A for a
single JD400/4) 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
Vol ta ge” and “Input Sens.” controls to obtain

the correct overall output and the desired
system balance. 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.

4 JL Audio

The JD400/4’s “+12 V DC” and “Ground”

!

!

connections are designed to accept 4 AWG power
wire. 4 AWG copper wire is a minimum power

wire size for this amplifier.

If you are installing this amplifier with
other amplifiers, use a main power wire that
is appropriately sized for the overall current
demands of all the amplifiers in the system. This
single copper power wire should terminate into
a fused distribution block, mounted as close to
the amplifiers as possible (within 12 inches /
30 cm of wire length). The fused output of the
distribution block will connect to the amplifier
with 4 AWG copper power wire. JL Audio ECS
fused distribution blocks are recommended
(XD-FDBU–2 and XD-FDBU–4).
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 3 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.

The ground connection should be made using
4 AWG copper wire and should be kept as short
as possible, while accessing a solid piece of sheet
metal in the vehicle. The surface of the sheet
metal 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 (XB-MGLU). Alternatively, a sheet metal
screw or bolt can be used with a star washer.

Any wires run through meta l barriers (such as
firewalls), must be protected with a high quality
insulating grommet to prevent damage to the
insulation of the wire. Failure to do so may result
in a dangerous short circuit.

IMPORTANT!

Only use oxygen-free copper (OFC) wire or
tinned copper wire for your amplifier’s
Power/Ground connections. Copper-clad
aluminum (CCA) wire is not recommended.

IMPORTANT!

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. If the JD400/4 is the only device
connected to this main wire, use a 40A fuse

(MAX I™ big plastic-body fuse is recommended).

No other fuse is required in this situation.

When running multiple devices from one
main power wire, the main fuse value and rating
of the main power wire must be high enough
for all of the equipment being run from it. Use a
fused distribution block to split the main power
wire feed to each device, with appropriate fusing
and power wire for each device.

JD40 0/4 5

TURNON OPTIONS

The JD400/4 can be switched on and off

using one of three methods, determined by the
position of the amplifier’s “Turn-On Mode”
switch. Please read these options and decide
which is best suited for your specific system.

1) +12V Remote turn-on lead

2) DC Offset-Sensing turn-on circuit

3) Signa l-Sensing turn-on circuit

+12V Remote Turn-On: This is the preferred

method for turning the amplifier on/off. The
amplifier will turn on when +12V is present
at its “Remote” input and turn off when +12V
is switched off. This +12V remote turn-on
signal is typically controlled by a source unit
or OEM interface processor’s remote turn­on wire. The amplif ier’s “Remote” turn-on
connector will 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

2.5 mm 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 is firmly gripped by the set screw.

If a source unit does not have a dedicated
remote turn-on output, consider one of the
following alternative turn-on options:

These methods are useful when a conventional
+12V remote turn-on signal is not available in a
system. These allow you to operate the amplifier
without having to locate a remote turn-on lead at
the source unit, which can be very useful when
interfacing the amplifier with OEM (factory)
audio systems that do not use conventional +12V
turn-on leads.

Depending on the characteristics of the audio
signal, one of the following methods may work
better than the other. We recommend trying DC
Offset-Sensing first as it does not require a long
delay to turn the system off after the signal is
shut off.

DC Offset-Sensing: The amplifier will turn on
and off by detecting the presence of a very small
DC signal (offset) that is typical in the audio
output of most OEM (factory) source units and
amplifiers. The amplifier will turn on and off in
reaction to the presence or absence of this DC
offset. The sensitivity of this circuit is designed
for high-level (speaker level) signals, not for low­level (preamp level) signals. The circuit senses

the input signal from the CH. 1 (L) channel
input only.

Signal-Sensing: The amplifier will turn on

and off by detecting the presence of a full-range
audio signal. After approximately 30 seconds,
the amplifier will shut off. The sensitivity of this
circuit is designed for high-level (speaker level)
signals, not for low-level (preamp level) signals.
The circuit is tuned to react to signals at mid­range frequencies. This prevents false switching
from signals created by moving loudspeakers
that are in parallel with the amplifier’s input
signal. The circuit senses the input signal from

the CH. 1 (L) channel input only.

6 JL Audio