JL Audio HD750/1 User manual

OWNER'S MANUAL
H:J750/1
Monoblock Full-Range Amplifier
Thank you for purchasing a ]L 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.

©o
PROTECT YOUR HEARING!
We value you as along-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 aspeaker 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 arecord
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
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 ofasecond 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.
Power Status FilterSlope
Indicator Selection
Ipgs.14·1S) (pg.1')
jFilter Mode jFilter Frequency
Selection Selector
_____ (pg 10) -- -- (pg. 11) -
/r====tlc========= ;;;;;;~~~1 80 1"0
I~~:; "I I~,~~:d.' 60.~OO
Mode Slope Filter Freq. (Hz)
Status
JL AUDIO. HD?
Chassis Ground Leh &Right
Connector Input Jacks
(pgs.6-7) (pg.9) Jack for
+ 12 VPower jRemote Turn-On jLeh &Right Preamp Remote Level
~~,r--- Connector_ _ Connector _ Output Jacks _Control Knob __
r=.-----===tl===::...:.:(
P9
S.6-7) (pgs.6-7) Ipg 12) (pg 13)
I .~,~- '~~(;;;;;;;;l;;;;;;;;;;;;@ @ ~.. \
@ II[ POWER CONNECTOR II Inpu.. P,eou" Remote
@ ~ [~J r' R@ @ R C~~~~~,
2I JL Audio -HD750/1 Owner's Manual

SafetyConsiderations:
Your amplifier needs to be installed in adry,
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 ofacollision or asudden 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 agas tank, brake line, wiring harness or
othervital 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 carefuJIy 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.
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 avolume of air as possible.
Enclosing the amplifier in asmall, 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 afan. In normal
applications, fan-cooling
is not necessary.
If mounting the amplifier under aseat,
make sure there is at least 1inch (2.5 em) of
space above the amplifier's outer shell to permit
proper cooling.
InputSensitivity OutputPolarity
Control Selection
(pg. 10) (pg. 11) Infrasonic Filter
~
InputVoltage jSelector
Selection (pg 1l) ---------...,rT-~
- -- (pg.9) -- ---
1 l~~~~~~
{II)
ILJ ILJ
[U
lowlHigh
01 180deg Off I30Hz
Input Input Output Infrasonic
Sens. Voltage Polarity Filter
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)/1 Monoblock Amplifier
jI SPEAKER OUT I ~ @
~amp@
Speaker Outputs
(pgs. 13-14)
=====@======j==~=====1IH==~~\
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3

PRODUCT DESCRIPTION
The JL Audio HD750/1 is avery powerful
and compact monoblock (single channel),
full-range amplifier utilizing patented Single
Cycle Control
~ Class Dtechnology. This
groundbreaking technology delivers reference-
grade sonic performance while requiring
far less current from the vehicle's electrical
system
than aconventional amplifier.
Unlike most monoblock amplifiers, the
HD750/1 is afull-range design, so it can be
used as asubwoofer amplifier or
as avery
powerful full-range
or satellite amplifier,
using asecond 750/1 to form astereo pair.
JL Audio's exclusive R.I.P.S. power supply
design optimizes the output the amplifier for any
impedance between
1.5 and 4ohms, allowing
you to get full use
of the HD750/l's performance
capabilities with awide range
of speaker systems.
The tightly regulated power supply design also
means that the HD750/l's clean power output
capability remains stable over awide range
of
vehicle voltages, resulting in enhanced fidelity.
Aflexible input and crossover section permits
operation with awide variety
of source units
and system configurations. The HD750/l's
preamp output can send pass-through signals
from
the inputs to feed additional amplifier(s).
4I JL Audio -HD750/1 Owner's Manual

TYPICAL INSTALLATION SEQUENCE
The following represents the sequence for
atypical 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 from the battery location
to the amplifier mounting location, taking
care to route it in such away 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
em) 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 apower
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
em) 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 agood, solid, bale 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 em) or 4 AWG
wire up to 60 inches (150 em) long from the
amplifier to the ground connection point. In
some vehicles, it may be (.. ?ssary to upgrade
the battery's ground wire as well. (See pages 6,
7for important notice).
7) Securely mount the amplifier using
appropriate hardware. (See page 8for 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 alow 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
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
I !POWER CONNECTORJ I
lrxxlJ
+12V Battery Connection
You will need to connect apower wire to
the vehicle's positive battery terminal, using an
appropriate power ring or specialized battery
terminal connector, such
as the ]L Audio
XB-BTU. 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 ahigh quality
insulating grommet to prevent damage to the
insulation
of the wire. Failure to do so may result
in adangerous short circuit.
Power Wire Requirements
The HD750/l'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
em). 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 asingle
main power
wire, use 2
AWG or 1/0 AWG pure copper wire
as amain power wire. This 2
AWG or 1/0 AWG
power wire should terminate into adistribution
block mounted
as close to the amplifiers as
possible and should connect to the HD7501I with
4
AWG or 8 AWG pure copper power wire.
Please note that lower
AWG numbers mean
bigger wire and vice-versa (l/O AWG
is the largest,
2
AWG is smaller, then 4 AWG, then 8 AWG, etc.).
6I JL Audio -HD750/1 Owner's Manual
DIMPORTANTI
We do not recommend the use of "copper-
clad
aluminum wire" or "CCA" wire because
this wire is significantlyless conductive than
pure copper wire. Only use pure copper power
wire, such as
IL Audio's MetaWire'". Tinned
copper wire (silver color) is acceptable as the
tin-plating is only avery minor component of
the wire.
Fuse Requirements
The installation ofafuse on each power wire,
within
18 wire inches (45 cm) ofthe positive
battery terminal
is vital to protect the wire and
the vehicle from fire in the event
of acollision or
short-circuit. The fuse value at each power wire
should be high enough for all ofthe equipment
being
run from that power wire. Ifonly the
HD750/1
is being run from that power wire, we
recommend a60A fuse be used. AGU (big glass
fuse).
AFS (small blade fuse) or MaxiFuse~ (big
plastic-body fuse) types are recommended.
If
other amplifiers are also being powered from the
wire
and exceed 80 amps in total fuse rating, we
recommend the use ofan ANL (large-blade) fuse
and holder. Please consult with your
]L Audio
dealer to make sure that the wire, fuse holder and
fuse rating you have selected are appropriate
for
your system's needs.
No fuse
is required or recommended directly
before the amplifier power connection.
If one is
desired, use a60A AGU, AFS or MaxiFuse'" type
in an appropriate fuse block.
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 asolid piece ofsheet metal
in the vehicle. The surface
of the sheet metal
should be sanded at the contact point to create
aclean, metal-to-metal connection between
the chassis and the termination
of the ground
wire with abrass
or copper power ring. For
optimal grounding,
we recommend the
use
of a IL Audio ECS master ground lug
(XB-MGLU). Alternatively, asheet metal
screw or bolt can be used with astar washer.

DIMPORTANTI
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 preventvoltage
drops, these wires should be
upgraded to 4
AWG
pure copperwire when installing amplifier
systems
with main fuse ratings above 60A.
Turn-On Wire
The HD750!l uses aconventional +12V remote
turn-on wire, 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 offwhen +12V is switched off. If
asource unit does not have adedicated remote
turn-on output, the amplifier's turn-on lead can
be connected to
+12V via aswitch that derives
power from an ignition-switched circuit.
The HD750/l'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
(l2mm)
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 1inch
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.
DIMPORTANTI
Never make power connections with a"live"
wire. Always disconnect
the negative battery
post before making any connections or
adjustments to a12V powerconnection!
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
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 liS-inch
hex wrench. Next, using appropriate mounting
screws (not included), secure the amplifier
by its
four Lateral Mounting Feet.
DIMPORTANTI
Checkbefore drilling any holes in your vehicle
to
make sure that you will not be drilling
through agas tank, brake line, wiring harness
or other vital vehicle system.
8I JL Audio -HD750/1 Owner's Manual
CONTROL PANEL SECURITY COVER
The HD750/1 features aControl Panel Security
Cover.
When installed, the cover ensures that
your amplifier settings are not accidentally
changed while creating aclean 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 asingle 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 security cover once all
adjustments have been made, insert the tongue on
the cover's left edge into the groove where the left-
side 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.

AMPLIFIER INPUTS
The HD75011 has asingle input section
consisting of apair of RCA-type input jacks on
the Connection Panel of the amplifier and a
pair of input controls on the Control Panel of
the amplifier: an "Input Voltage" switch and an
"Input Sens." rotary control.
@(i
Inputs
,@ (i
iNPUT CONTROLS
On the amplifier's control panel you will find
an "Input Voltage" range switch and arotary
control labeled "Input Sens." (Input Sensitivity).
These controls are designed to match the input
sensitivity of the HD750/1 to the specific signal
source that is feeding it and must be adjusted,
with care, follOWing the procedures outlined in
this manual. Failure to make correct adjustments
can result in weak output, excessive distortion
and/or undesirable noise in the audio output of
the amplifier!
Monoblock Amplifier
"Input Voltage" Switch
Awide range of signal input voltages can be
accommodated by the HD750/l's differential-
balanced inputs (200mV - SV RMS). This wide
range is split up into two sub-ranges, accessible via
the "Input Voltage" switch. The "Low" position
on the "Input Voltage" switch selects an input
sensitivity range between 200mV and 2Y. This
means that the "Input Sens." rotary control will
operate within that voltage window. If you are
using an aftermarket source unit, with preamp-
level outputs, this is most likely the position that
you will use (regardless of what voltage output
capability is claimed by the source unit).
The "High" position on the "Input Voltage"
switch selects an input sensitivity range between
SOOmV and Sy' This is for use with speaker-level
outputs from source units and small amplifiers
found in many OEM (factory-installed) systems.
To use speaker-level sources, splice the speaker
output wires of the source unit or small amplifier
onto apair of RCA plugs for each input pair
or use the JL Audio ECS Speaker Wire to RCA
adaptor (XB-CLRAIC2-SW).
The HD750/1 features stereo inputs, even
though it is a mono amplifier. This has been
done to permit the amplifier to sum stereo
input signals to mono, which is particularly
useful for driving subwoofers. Even if you
have adedicated mono subwoofer signal
available or are feeding aleft channel only or
aright channel only into the amplifier, you
must feed both inputs of the HD750/1.
Connection of only one RCA input will result
in reduced power output, increased distortion
and can cause the amplifier to overheat. To
connect a mono signal to both inputs, use
an RCA "Y-Adaptor" (sold separately).
lut
ns.
I-
~
Low IHigh 0118
Input Qu'
Voltage
Pol.
9

CROSSOVER CONTROLS
Crossovers are groups of electronic filters
designed to control the frequency ranges
that each speaker in asystem will be tasked
with reproducing. Proper crossover setup
is
critical to sound quality and reliability.
The HD750/1 has one filter, which
can be
configured as ahigh-pass filter (attenuates low
frequencies) or as alow-pass filter (attenuates
high frequencies). Additionally, the user can
select from ashallow (l2dB/octave) filter slope
or amore aggressive (24dB/octave) slope.
.JL AUDIO. HC75
DIMPORTANTI
The output of the amplifier decreases for a
given
input voltage when the "Input Range"
switch is placed in
the "High" position. The
output increases with the switch in the "Low"
position.
While this may sound counter-
intuitive, it is
correct as described.
"Input Sens." Control
Located to the left of the "Input Voltage"
switch
is arotary control labeled "Input Sens.".
Once the appropriate
"Input Voltage" range has
been selected, this control 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 agiven
input voltage). Rotating the control counter-
clockwise will result in lower sensitivity (quieter
for agiven input voltage).
To properly set the
amplifier for maximum clean output, please refer
to Appendix C(pages
18, 19) in this manual.
Off I HP I LP
Filter
Mode
12dB I24dB
Filter
Slope
,".:0
Filter Freq. (Hz)
HC750/1 Monoblocl
eq.(Hz)
Input
Sens.
Lov
II
Vc
1) "Filter Mode" Control: this switch allows you
to defeat or configure the filter into one oftwo
filter types:
"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.
After using this procedure, you can then adjust
the relative level by adjusting the input sensitivity
downward, ifit requires attenuation to achieve
the desired system balance.
Do not increase the
"Input Sens." setting for
any amplifier in the system beyond the
maximum
level established during the procedure outlined in
Appendix C(pages
18, 19). Doing so will result in
audible distortion and possible speaker damage.
10 I JL Audio -HD750/1 Owner's Manual
"HP" (High-Pass): Configures the filter
to attenuate frequencies below the selected
filter frequency. Useful for connection
of
component speakers in abi-amplified system.
"LP" (Low-Pass): Attenuates frequencies
above the selected filter frequency.
Useful for connection ofsubwoofer(s)
in abi-amplified system.

2) "Filter Slope" Control: This switch allows you
to select from two filter slopes:
"12dB": Configures the filter to attenuate
frequencies above
or below the selected
filter frequency at arate
of 12 dB per octave
(Butterworth alignment).
"24dB": Configures the filter to attenuate
frequencies above
or below the selected
filter frequency at arate
of 24 dB per octave
(Linkwitz-Rileyalignment).
Depending on the speaker system and the
vehicle, different filter slopes may be required
to
produce asmooth transition between the sound
of different speakers in the system.
In high-pass mode, the sharper "24dB" setting
will do abetter job
of protecting small speakers
with limited power handling. In low-pass
mode, the "24dB" setting can also help by more
aggressively removing lower midrange output
from asubwoofer system.
The shallower "12dB" octave setting
allows for more output overlap between
the speakers being crossed over. In many
cases, this will result in asmoother "blend"
or transition between speaker systems.
Experiment to find the slope or combination
of slopes which best matches the acoustic
requirements
of your system.
3) "Filter Freq. (Hz)" Control:
This control selects the frequency at which the
filter begins to attenuate the signal
and refers
specifically to the frequency at which output
has been attenuated
by -3dB.
The filter frequency markings surrounding this
rotary control are for reference purposes and are
generally accurate to within
1/3 octave or better. If
you would like to select the filter cutofffrequency
with ahigher
level of precision, consult the charts
in Appendix B(page
18) of this manual.
INFRASONIC FILTER
The "Infrasonic Filter" is a 24 dB/octave high-
pass filter, with afixed cutofffrequency
of 30 Hz.
This filter
is designed to conserve amplifier power
and protect subwoofer systems, without audibly
degrading the sub-bass output.
0
I-
80deg. OffI30Hz
utput
Infrasonic
,Iarity Filter
With ported enclosures, the use of the
"Infrasonic Filter" is highly recommended to
protect the speaker(s) from excessive excursion
below box tuning.
With sealed enclosures, the use
of the filter
is less necessary, but can still help protect the
speaker system from excessive excursion.
The "Infrasonic Filter"
can be completely
defeated by selecting the "Off" position
on its
switch. This bypasses all signal from flowing
through the circuit.
11

OUTPUT POLARITY CONTROL
Depending on the distance relationship of
the mid-bass speakers and the subwoofers in a
system, it can be desirable to reverse the polarity
ofthe subwoofer system in order to produce
abetter transition between subwoofer
and
midbass speaker output. This is normally done
by swapping the positive and negative wires
connected to the subwoofer(s).
IHigh
Jut
tage
01180deg.
Output
Polarity
offl3C
Infraso
Filte
PREAMP OUTPUTS
The HD750/1 incorporates apass-through
preamp output section, so that additional
amplifiers can easily be connected to the same
signal(s) feeding the HD750/1. These preamp
output signals are accessible via astereo pair
of RCA-type jacks, labeled "Preouts", on the
Connection Panel.
@,I
Preouts R,
@, i
Amplifier
The "Output Polarity" switch on the HD
750/1 allows you to quickly peform this polarity
inversion without touching any wires. Simply
flip the switch from the
"0" (normal) to the "180
deg." (reversed) position.
Neither switch position
is "correct" for every
system. Experiment to determine which polarity
produces the best overall bass performance
in your system, listening in particular to the
mid-bass smoothness and impact to make your
determination.
If you change crossover slopes
or crossover filter frequencies, you may need to
revisit this control
as these can affect the phase of
the speaker systems in the overlap region.
12 I JL Audio -HD750/1 Owner's Manual
The term "pass-through" refers to the fact that
the Preamp
Output signals are not affected by any
crossover filter or input sensitivity setting selected
on the HD750/1 (ifthe input signal
is full-range,
the Preamp Output will be full-range). These
preamp output signals are buffered to prevent
noise and are always preamp level, regardless
of
the level ofsignals feeding the HD750/l's inputs.

When connected to the amplifier, the HD-RLC
operates as follows.
At full counter-clockwise
rotation, the audio will mute completely.
At full
clockwise rotation the level will be the same
as if
the HD-RLC was not connected at all. In other
words, it operates strictly
as alevel attenuator.
@
@
e0e0
( SPEAOCER OUT J
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®
SPEAKER CONNECTIONS
The HD750/1 employs JL Audio's exclusive
Regulated, Intelligent Power Supply (R.LP.S.)
design. This sophisticated power supply allows
the amplifier to produce its
optimum power (750
watts x 1) over awide range of supply voltage and
speaker impedances.
Unlike conventional amplifiers that require
aspecific impedance to produce optimum
power, the R.LP.S.-equipped HD750/1 gives
you the freedom to use avariety ofspeaker
configurations that achieve final nominal
impedances between
1.5 -4Q (without
sacrificing power output
or sound quality).
The operation
of the R.LP.S. circuitry is
entirely automatic and adjusts itselfevery time the
amplifier
is turned on. There are no user controls
to configure. The system operates through
multiple stages ofimpedance optimization,
choosing the stage most appropriate to the actual
impedance
of the speakers you connect to it.
Remote
Level
Control
Preouts
REMOTE LEVEL CONTROL (OPTIONAL)
With the addition ofthe optional Remote Level
Control (HD-RLC), you can control the volume
of the HD750/1 from the front of the vehicle. This
is particularly useful for subwoofer level control.
The HD-RLC connects to the jack labeled
"RemoteLevel
Control" on the Connection
Panel
of the amplifier using astandard telephone
cable (supplied with the HD-
RLC).
If desired, multiple HD amplifiers can be
controlled from asingle HD-RLC controller
using asimple phone line "splitter"
and multiple
phone cables (not supplied).
DIMPORTANTI
The RBC-I Remote Bass Control used with
JL Audio Slash, Slash v2, e-Series, A-Series and
G-Series amplifiers is NOT compatible with the
HD Series amplifiers. If you attempt to connect
an RBC-l to an HD amplifer, the control will
not work. You must use the HD-RLC controller.
DIMPORTANTI
If you connect a load higher than 40 nominal,
power will drop by half with every doubling of
impedance above 40 stereo. If you connect a
load lower than 1.50 nominal, the amplifier
protection circuitry activates a"safe" mode
which reduces amplifier power to protect the
circuitry from failure (the LED status indicator
on the control panel will light up amber to
indicate that this has happened). See page 14
for details.
13

DIMPORTANTI
Speaker loads below 1.50 nominal are not
recommended and may cause the amplifier
output to distort excessively.
Speaker Connector Plugs
To connect the speaker wires to the amplifier,
unplug the speaker connector plug from the
amplifier chassis (pull back firmly) and back out
the set screws on the connector plug, using the
supplied 2.0
mm hex wrench. Strip 3/8 inch (10
mm) of insulation from the end of each wire and
insert the bare wire into the receptacle on the
speaker 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 ofthe screw.
You will notice that there are two sets of"+" and
"-" connections on the plug. This is to facilitate
multiple speaker wiring to the HD750/l's mono
output. The two positive and two negative
connections are connected in parallel inside the
amplifier. Connecting two speakers, each to
one set
of positive and negative terminals, will
result in aparallel speaker connection.
If only
connecting one pair
of speaker wires, it is not
necessary
to use both sets of connections.
DIMPORTANTI
Do not chassis ground any speakers connected
to this or any other JL Audio amplifier. Doing
so will cause the amplifier to go into protection
and mute the output.
14 I JL Audio -HD750/1 Owner's Manual
"STATUS" LED / PROTECTION CIRCUITRY
There is asingle multi-color LED on the
control panel
of the amplifier to indicate the
amplifier's operating status. This LED's behavior
is as follows:
1) Flashing Green: amplifier is powering up,
audio output
is muted.
2) Constant Green: amplifier is on and
functioning normally, audio output
is active.
3) Constant Red: lights to indicate that the
amplifier has exceeded its safe operating
temperature, putting the amplifier into a
self-protection mode, which reduces the
peak power output
of the ampli fier. The red
light will
turn green and the amplifier will
return
to full-power operating mode when its
temperature returns
to asafe level.
3) Constant Amber (yellow): lights to indicate
that the impedance ofthe speaker load
connected to the amplifier
is lower than its
optimum load impedance range. When this
light
is on, aprotection circuit engages and
reduces the power output ofthe amplifier.
The amber indicator will also light when a
short-circuit
is detected in the speaker wiring
(this can be ashort between the positive and
negative speaker wires or between either
speaker wire and the vehicle chassis).

4) Alternating Red and Green: lights to indicate
that the amplifier
is experiencing afault
that may require service
of the amplifier, its
wiring or the vehicle's charging system. Audio
is muted when this fault occurs. The most
likely cause
of this fault is alow supply voltage
condition.
If battery voltage drops below 8.5
volts at any point, the amplifier (except for the
"Status" LED) will shut itselfoffto protect itself
and the vehicle's charging system.
If the voltage
drops below 6volts, the "Status"
LED will also
turn off.
The amplifier will
turn back on automatically
when voltage climbs back above 9volts. This
shut-down
and turn-on behavior may happen
in arapid cycle when bass-heavy program
material causes aweak charging system to
momentarily dip too
low. Ifthis is happening
in your system, have your charging system
inspected to make sure it
is working properly.
If no problem is found with the supply
voltage to the amplifier and you are
still seeing alternating Red and Green'
on the "Status"
LED, it is likely that the
amplifier
is suffering from an internal
fault that requires factory service.
For more information on troubleshooting this
amplifier, refer to Appendix D(pages 20,
21).
SERVICING YOUR JL AUDIO AMPLIFIER
If your amplifier fails or malfunctions, please
return it to your authorized
JL Audio dealer so
that
it may be sent in to JL Audio for service.
There are no user serviceable parts or fuses inside
the amplifier. The unique nature ofthe circuitry
in the
JL Audio amplifiers requires specifically
trained service personnel. Do not attempt
to service the amplifier yourselfor through
unauthorized repair facilities. This will
not only
void the warranty, but may result in the creation
of more problems within the amplifier.
If you have any questions about the installation or
setup
of the amplifier not covered in this manual,
please contact your dealer or technical support.
JL Audio Technical Support:
[phone]
9:00
AM -5:30 PM (Eastern Time Zone)
Monday-Friday
15

16 I JL Audio -HD750/1 Owner's Manual

APPENDIX A:
HD7S011 Specifications
Amplifier Topology: Class D, switching type with
patented Single-Cycle Control'M technology.
Power Supply: Pulse width modulation-regulated
switching power supply
Recommended Fuse Value /Type: 60A (AFS, AGU or
MaxiFuse™)
Rated Power:
750W RMS xl @1.5-40 (11V - 14.5V)
THD at Rated Power: <0.03% @ 40
(Average at 1 kHz)
Signal to Noise Ratio (20 kHz Bandwidth):
Referred to Rated Power 111 dBA
Referred to 1Watt: 82.2 dBA
Frequency Response: 6 Hz - 30 kHz (+0, -1 dB)
Damping Factor:
>500 @ 40 per ch.1 50 Hz
>250 @ 20 perch.1 50 Hz
Crossover Filter:
FilterType: State-variable, 12 dBloctave Butterworth or
24 dB/octave Linkwitz-Riley
Filter Modes: Low-Pass or High-Pass, Defeatable.
Cutoff Freq. Range: Continuously variable, 50 -500 Hz
Input Sections:
No. of Inputs: One Stereo Pair, sums to mono
InputType: Differential-balanced with RCA jack inputs
Input Range: Switchable from 200mV - 2V RMS (Low)
to 800mV - 8V RMS (High)
Preamp Output:
2-Channel, buffered pass-through type
Chassis Dimensions (LxWxH):
10.74 in. x 7.85 in. x 1.93 in. (273 mm x 199.5 mm x49 mm)
Dimensions do not include connectors
Due to ongOing product developl1l~nt. :111 specifications are subject to
change without notice
._ .. --------_ ... _._._-----~----_ .. _------
----_ .. _. __ . __ ._._-_ •....-.. __ .. -----
17

APPENDIXB:
Precise FrequencySelection Chart
"FILTER FREQ"
Detent Panel Actual
Number Marking Freq.
Full counter-clockwise: 58
01... . 53
02... .. "50". .. .53
03 53
04......... . .53
05 .54
06 56
07 58
08 "60". ..60
09 62
10 64
11 66
12 68
13.......... .. 71
14......... . 74
15.. . 76
16 ."80"... .80
17.......... . 83
18........... .. ..87
19.......... . 91
20.. .94
21 . 99
22 104
23 109
24 "120" 115
25. .. 121
26... .. 128
27 .. .137
28... .147
29 160
30.......... .. 174
31 .. 191
32 "200" 211
33......... .. 236
34.......... .. 269
35.. .. 309
36. .369
37................ .. .443
38 "500" 484
39 525
Full-clockwise: 528
18 I JL Audio -HD750/1 Owner's Manual
APPENDIXC:
Input Sensitivity Level Setting
JL Audio amplifiers utilizing the Regulated
Intelligent Power Supply (R.I.P.S.) allow
delivery of their rated power when connected
to any load impedance from 1.5 - 40 per
channel and when connected to acharging
system with any voltage from 11 - 14.5V.
This design is beneficial for many reasons.
One of these reasons is ease of setup.
Because each JL Audio amplifier will
always deliver the same amount of power
within its operational range of impedances
and supply voltages, the maximum,
unclipped output is very predictable.
This makes setting the gain structure via the
input sensitivity controls very simple. Following
the directions below will allow the user to adjust
the input sensitivity of the amplifier(s) simply
and easily in just a few minutes using equipment
which is commonly available in installation bays.
Necessary Equipment
•Digital AC Voltmeter
•CD with asine-wave test tone recorded at
odB reference level in the frequency range
to be amplified for that set of channels
(50 Hz for subwoofer channels, 1 kHz for
amidrange application). The CleanSweep·
Calibration Disc contains the appropriate
test tones and is available for sale at
http://store.jlaudio.com Do not use attenuated
test tones (-10 dB, -20 dB, etc.).
Do not increase any "Input Sens." setting in
the system beyond the maximum level
established during this procedure. Doing so
will result in audible distortion and possible
speaker damage.
It will be necessary to re-adjust the "Input
Sens." for the affected channels if any equalizer
boost is activated after setting the "Input
Sens." with this procedure. This applies to any
EQ boost circuit, source unit tone controls or EQ
circuits. EQ cuts will not require re-adjustment.

The Nine-Step Procedure
1) Disconnect the Speaker Connector Plug.
2) Turn off all processing on the source unit
(bass/treble, loudness, EQ, etc.). Set fader
control to center position and subwoofer
level control to 3/4 of maximum (if
used to drive the HD750/l). Disconnect
the HD-RLC Remote Level Control
temporarily (ifone is being used).
3) Switch the "Input Voltage" to "Low" and turn
the "Input Sens." control all the way down.
4) Set the source unit volume to 3/4 of full
volume. If the amplifier is being driven by a
source unit's dedicated subwoofer output, also
adjust the source unit's subwoofer level control
to 3/4 of maximum output. This will allow for
reasonable gain overlap with moderate clipping
at full volume.
S) Using the chart below, determine the
target voltage for input sensitivity
adjustment according to the nominal
impedance of the speaker system
connected to each set of outputs.
Nom.
HD 750/1
Impedance (MONO)
80
"
54.8 V
60 54.8V
40
"'i
54.8 V
-CO"
30
47AV
20 38.7 V
1.50 33.5 V
6) Verify that you have disconnected the Speaker
Connector Plug before proceeding. Playa
track with an appropriate sine wave (within
the frequency range to be amplified by each
set of channels) at 3/4 source unit volume.
7) Connect the AC voltmeter to the Speaker
Output contacts of the amplifier.
8) Increase the "Input Sens." control until the
target voltage is delivered. If excessive voltage
is read with the control at minimum (full
counterclockwise), switch the "Input Voltage"
switch to "High" and re-adjust.
9) Once you have adjusted the amplifier to its
maximum unclipped output level, reconnect
the speaker(s). The "Input Sens." controls can
now be adjusted downward if the HD750/1
requires attenuation to achieve the desired
system balance.
19

APPENDIX D: TROUBLESHOOTING
"How do Iproperly set the input sensitivity on my amplifier"
Please refer to Appendix C(pages 18, 19) to set the input sensitivity
for maximum, low-distortion output.
"My amplifier doesn't turn on"
Check the fuse(s), not just visually, but with acontinuitymeter. It
is possible for afuse to have poor internal connections that
cannot be found by visual inspection. It is best to take the
fuse out of the holder for testing. If no problem is found with
the fuse, inspect the fuse-holder.
Check the integrity of the connections made to each of the
"+12VDC", "Ground", and "Remote" terminals. Ensure
that no wire insulation is pinched by the terminal set screw
and that each connection is tight.
Check to make sure there is + 12V at the "Remote" connection of the
amplifier. In some cases, the turn-on lead from the source unit
is insufficient to turn on multiple devices and the use of arelay
is required. To test for this problem, jump the "+12VDC" wire
to the "Remote" terminal to see ifthe amplifier turns on.
"I get adistorted Iattenuated sound coming out of the speaker(s)"
Check the speaker wires for apossible short, either between the
positive and negative leads or between aspeaker lead and
the vehicle's chassis ground. If ashort is present, you will
experience distorted and/or attenuated output. The "Status"
LED will turn amber (yellow) in this situation. It may be
helpful to disconnect the speaker wires from the amplifier
and use adifferent set of wires connected to atest speaker.
Check the nominal load impedance to verify that the amplifier is
driving aload equal to or greater than 1.5 ohms.
Check the input signal and input signal cables to make sure signal
is present at the "Amplifier Inputs" and the cables are not
pinched or loose. It may be helpful to try adifferent set of
cables and/or adifferent signal source to be sure.
"My amplifier's output fluctuates when Itap on it or hit abump"
Check the connections to the amplifier. Make sure that the
insulation for all wires has been stripped back far enough to
allow agood contact area inside the connector plugs.
Check the input connectors to ensure that they all are making good
contact with the input jacks on the amplifier.
--_._---------------- ----
20 I JL Audio -HD750/1 Owner's Manual