JL Audio HD750/1 Owners Manual

OWNER’S MANUAL

Monoblock Full-Range 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 call the JL Audio Technical Support Department

at [phone] during business hours.

PROTECT YOUR HEARING!

Input Sensitivity

Control
(pg. 10)

Output Polarity

Selection

(pg. 11)

Infrasonic Filter

Selector

(pg. 11)

Input Voltage

Selection

(pg. 9)

Speaker Outputs

(pgs. 13-14)

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 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 w arra nty.

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.

(pg. 10)

Filter Slope

Selection

(pg. 11)

Power Status

Indicator

(pgs. 14-15)

Filter Mode

Selection

Filter Frequency

Selector

(pg. 11)

2 | JL Audio - HD750/1 Owner’s Manual

Chassis Ground

Connector

(pgs. 6-7)

+12 V Power

Connector

(pgs. 6-7)

+12 VDC Ground Remote

+12 VDC Ground Remote

Remote Turn-On

Connector

(pgs. 6-7)

Left & Right
Input Jacks

L

Inputs

R

(pg. 9)

Left & Right Preamp

Output Jacks

(pg. 12)

Remote Level
Control Knob

L

Preouts

R

Jack for

(pg. 13)

Remote

Level

Control

Cooling Efficiency Considerations:

Your JL Audio amplifier employs an
advanced type of heat management, called
RealSink ™. This feature takes advantage of
convection and radiation effects to remove
heat from the amplifier circuitry. For optimum
cooling performance, the vertical heat sinks
located at the sides of the amplifier 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.

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.

Input Sensitivity

Control
(pg. 10)

Input Voltage

Selection

(pg. 9)

Output Polarity

Selection

(pg. 11)

Infrasonic Filter

Selector

(pg. 11)

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.

Speaker Outputs

(pgs. 13-14)

3

PRODUCT DESCRIPTION

The JL Audio HD750/1 is a very powerful
and compact monoblock (single channel),
full-range amplif ier utilizing patented Single
Cycle Control™ Class D technology. This
groundbreaking technology delivers reference­grade sonic performance while requiring
far less current from the vehicle’s electrical
system than a conventional amplif ier.

Unlike most monoblock amplifiers, the
HD750/1 is a full-range design, so it can be
used as a subwoofer amplifier or as a very
powerful full-range or satellite amplifier,
using a second 750/1 to form a stereo pair.

JL Audio’s exclusive R.I.P.S. power supply
design optimizes the output the amplifier for any
impedance between 1.5 and 4 ohms, allowing
you to get full use of the HD750/1’s performance
capabilities with a wide range of speaker systems.

The tightly regulated power supply design also
means that the HD750/1’s clean power output
capability remains stable over a wide range of
vehicle voltages, resulting in enhanced f idelity.

A flexible input and crossover section permits
operation with a wide variety of source units
and system configurations. The HD750/1’s
preamp output can send pass-through signals
from the inputs to feed additional amplifier(s).

4 | JL Audio - HD750/1 Owner’s Manual

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).
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 re-connection during
installation. This step is not optional!

2) Run 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. 4 AWG is recommended for wire
runs greater than 72 inches (180 cm) in
length. Use of 8 AWG power wire is acceptable
for shorter runs, such as from a power
distribution block to the amplifier or from a
trunk-mounted battery. Use a 2 AWG or 1/0
AWG main power wire with a fused power
distribution block when additional amplifiers
are being installed with the HD750/1 and
powered from the same main power wire.

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 connected to the amplifier.

4) Run signal cables (RCA cables) and remote

turn-on wire from the source unit or interface
processor to the amplifier mounting location.

5) Run speaker wire from the speaker systems to

the amplifier mounting location.

6) Find a good, solid, bare metal grounding

point close to the amplifier and connect the
negative power wire to it using appropriate
hardware. Use minimum 8 AWG power wire,
no longer than 36 inches (90 cm) or 4 AWG
wire up to 60 inches (150 cm) long from the
amplifier to the ground connection point. In
some vehicles, it may be necessary to upgrade
the battery’s ground wire as well. (See pages 6,
7 for important notice).

7) Securely mount the amplifier using
appropriate hardware. (See page 8 for detailed
mounting instructions).

8) Connect the remote turn-on wire and the
positive and negative power wires to the
amplifier’s power connector plug. Then insert
the power connector plug into the amplifier’s
power connector receptacle, pushing firmly.

9) Connect the RCA input cables
to the amplifier.

10) Connect the speaker wires to the speaker
connector plug and insert the plug firmly into
the speaker connector receptacle.

11) Carefully review the amplifier’s control

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

12) Install power wire fuse (60A for a

single HD750/1) and reconnect the negative
battery post terminal.

13) 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.

14) Make necessary adjustments to the input

sensitivity controls to obtain the right
overall output and the desired balance
in the system. See Appendix C (pages 18, 19)
for the recommended input sensitivity
setting method.

15) Enjoy the fruits of your labor with your

favorite music.

5

POWER AND TURNON CONNECTIONS

Remote

Level

Control

Inputs

L

R

L

R

Preouts

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.

+12 VDC Ground Remote

+12 VDC Ground Remote

+12V Battery Connection

You will need to connect a power wire to
the vehicle’s positive battery terminal, using
an appropriate power ring or specialized
battery terminal connector, such as the JL
Audio XB-BTU or XD-BTS. This connection
must be tight and corrosion-free to ensure
proper connectivity. This wire MUST be fused
appropriately for safety. Any power wires run
through metal 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.

Power Wire Requirements

The HD750/1’s “+12 VDC” and “Ground”
connections are designed to accept 4 AWG power
wire. 4 AWG pure copper wire is recommended
for any power wire run longer than 72 inches (180
cm). For runs shorter than 72 inches, 8 AWG pure
copper power wire is acceptable.

If you are installing the HD750/1 with other
amplifiers and wish to use a single main power
wire, use 2 AWG or 1/0 AWG pure copper
wire as a main power wire. This 2 AWG or
1/0 AWG power wire should terminate into a
fused distribution block mounted as close to the
amplifiers as possible and should connect to the
HD750/1 with 4 AWG or 8 AWG pure copper
power wire.

Please note that lower 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.).

6 | JL Audio - HD750/1 Owner’s Manual

We do not recommend the use of “copper­clad aluminum wire” or “CCA” wire because
this wire is significantly less conductive than
pure copper wire. Only use pure copper power
wire, such as JL Audio’s Premium Power Wire.
Tinned copper wire (silver color) is acceptable
as the tin-plating is only a very minor
component of the wire.

Fuse Requirements

The installation of a fuse on the main power
wire, within 18 wire inches (45 cm) of the positive
battery terminal is vital to protect the wire and
the vehicle from fire in the event of a collision
or short-circuit. The fuse value at each power
wire should be just high enough for all of the
equipment being run from that power wire. Do
not use a fuse with a value that far exceeds the
total fuse rating of the electronics connected to
the wire.

If only the HD750/1 is being run from
that power wire, we recommend a 60A fuse
be used. AGU (big glass fuse). AFS (small
blade fuse) or MaxiFuse™ (big plastic­body fuse) types are recommended.

If other amplifiers are also being powered from
a main power wire and exceed 80 amps in total
fuse rating, we recommend the use of an ANL
(large-blade) fuse and holder at the batter y plus
a fused distribution block near the amplifiers.
Each amplifier must be fused independently at
the outputs of the fused power distribution block.
We recommend appropriately rated Ma xiFuse™
fuses and a JL Audio fused distribution block.

Please consult with your JL Audio
dealer to make sure that the wire, fuse
holder and fuse ratings are appropriate
for your system’s needs. The safety of
your installation depends on appropriate
power connections and fuse protection.

Ground Connection

The chassis ground connection must be
made using 4 AWG or 8 AWG pure 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 with a brass or copper power ring. 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.

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 pure copper wire when installing amplifier
systems with main fuse ratings above 60A.

Turn-On Wire

The HD750/1 uses a conventiona l +12V
remote turn-on wire, 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 amplif ier’s
turn-on lead can be connected to +12V via a
switch that derives power from an ignition-

switched circuit.

The HD750/1’s “Remote” turn-on connector

is designed to accept 18 AWG – 12 AWG wire. 18
AWG is more than adequate for this purpose.
To connect the remote turn-on wire to the
amplifier, first back out the set screw on the
bottom of the Power Connector Plug, using the
supplied 2.5 mm hex wrench. Strip 1/2 inch
(12mm) of wire and insert the bare wire into the
receptacle, seating it firmly so that no bare wire
is exposed. When using smaller wire, it may
be necessary to strip 1 inch of insulation from
the wire and fold the bare wire in half prior to
insertion. While holding the wire in the terminal,
tighten the set screw firmly using the supplied

2.5 mm hex wrench, taking care not to strip the
head of the screw and making sure that the wire
is firmly gripped by the set screw.

Amplifier Power Connector Plug

To connect the power wires and the remote
turn-on wire to the amplifier, unplug the power
connector plug from the amplifier chassis (pull
back firmly) and back out the set screws on
the connector plug, using the supplied 4 mm
hex wrench for the “+12 VDC ” and “Ground”
connections and the supplied 2.5 mm hex wrench
for the “Remote” connection. Strip 3/8 inch (10
mm) of insulation from the end of each wire and
insert the bare wire into the receptacle on power
connector plug, seating it firmly so that no bare
wire is exposed. While holding each wire in place,
tighten each set screw firmly, taking care not to
strip the head of the screw.

Never make power connections with a “live”
wire. Always disconnect the negative battery
post before making any connections or
adjustments to a 12V power connection!

7

AMPLIFIER MOUNTING OPTIONS

The HD750/1 has two mounting options to

ease in installation.

Standard Mounting

The standard method of mounting requires
removal of the four corner caps with the 3/16-inch
hex wrench included with your amplifier. Using
appropriate mounting screws (not included),
secure the amplifier in all four corners and
replace the corner caps.

Lateral Mounting Feet

or other vital vehicle system.

CONTROL PANEL SECURITY COVER

The HD750/1 features a Control Panel Security
Cover. When installed, the cover ensures that
your amplifier settings are not accidentally
changed while creating a clean aesthetic for the
amplifier and your installation. The control panel
security cover is pre-installed at the factory and
must be temporarily removed for access to the
controls described throughout this manual.

The security cover is secured by a single 2.5
mm hex-head screw at the far right of the panel.
Loosen the hex-head screw to release the security
cover (it is not necessary to completely remove the
screw). To re-install the securit y cover once all
adjustments have been made, insert the tongue on
the cover’s left edge into the groove where the left­side heatsink meets the control panel, hinge the
panel closed and secure the screw using the
supplied 2.5 mm hex wrench. Do not overtighten
the screw.

Lateral Mounting Feet are also included with
your HD750/1 to provide an alternative mounting
option. Each mounting foot should be attached
to the bottom of the amplifier by screwing the
provided bolt into the bottom of the amplifier and
up into the corner cap with the supplied 1/8-inch
hex wrench. Next, using appropriate mounting
screws (not included), secure the amplifier by its
four Lateral Mounting Feet.

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

8 | JL Audio - HD750/1 Owner’s Manual