owner’s manual
4-Channel Class-D 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 (954) 443-1100 during business hours.
ProteCt Your Hearing!
installation aPPliCations
Cooling efficiency Considerations:
Your JL Audio amplifier employs an
safety Considerations:
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.
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 of a second amplifier,
including an identical one.
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.
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.
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.
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.).
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.
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:
Power Status
Indicator
(pg. 16)
Filter Slope
Selection
(pg. 11)
Input Sensitivity
Control
Input Mode
Selection
(pg. 9)
Preouts From
Selection
(pg. 13)
Input Sensitivity
Control
(pg. 10)
Filter Slope
Selection
(pg. 11)
(pg. 10)
Remote Level
Filter Mode
Selection
(pg. 11)
Filter Mode
Selection
(pg. 11)
Filter Frequency
Selector
(pg. 11)
Input Voltage
Selection
(pg. 10)
Control
Selection
(pg. 13)
Input Voltage
Selection
(pg. 10)
Filter Frequency
Selector
(pg. 11)
Chassis Ground
Connector
Front Left & Right
Channel Input Jacks
(pg. 9)
Left & Right Preamp
Front
Speaker Outputs
(pgs. 14-15)
Rear
Speaker Outputs
(pgs. 14-15)
Output Jacks
(pg. 13)
(pgs. 6-7)
Jack for
Remote Level
Control Knob
(pg. 13)
+12 V Power
Remote Turn-On
Connector
Rear Left & Right
Channel Input Jacks
(pg. 9)
Connector
(pgs. 6-7)
(pgs. 6-7)
L
+12 VDC Ground Remote
L
Front
Inputs
R
Rear
Preouts
R
Remote
Level
Control
2 | JL Audio - HD600/4 Owner’s Manual
3
ProduCt desCriPtion
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.
The JL Audio HD600/4 is a very powerful
and compact four-channel, full-range amplifier
utilizing patented Single Cycle Control™
Class D technology for all channels. This
groundbreaking technology delivers reference-
grade sonic performance while requiring
far less current from the vehicle’s electrical
system than a conventional amplifier.
JL Audio’s exclusive R.I.P.S. power supply
design optimizes the output of each channel pair
for any impedance between 1.5 and 4 ohms per
channel (3-8 ohms bridged) allowing you to get
full use of the HD600/4’s performance capabilities
with a wide range of speaker systems.
The tightly regulated power supply design also
means that the HD600/4’s clean power output
capability remains stable over a wide range of
vehicle voltages, resulting in enhanced fidelity.
The HD600/4 flexible, studio-grade signal
processing allows it to be deployed in a wide
range of system applications:
5) As a very powerful (300W x 2) two-channel
satellite amplifier in a bi-amplified system,
delivering high-passed signals to a stereo
speaker system. Preamp outputs permit
connection of a separate amplifier to drive the
subwoofer system.
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
6) As a powerful (300W x 2) two-channel
subwoofer amplifier in a bi-amplified system,
delivering low-passed signals to a dual
subwoofer system. Preamp outputs permit
connection of a separate amplifier to drive the
satellite speakers.
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 power
distribution block when additional amplifiers
are being installed with the HD600/4 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.
to the amplifier.
10) Connect the speaker wires to the speaker
connector plugs and insert the plugs firmly
into the speaker connector receptacles.
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 (50A for a
single HD600/4) 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.
The HD600/4’s flexible input and crossover
sections permit operation with a wide variety of
source units and system configurations. It can be
operated with a single pair of stereo inputs or with
separate inputs for its front and rear channels.
The HD600/4’s preamp output can send pass-
through signals from the Front Inputs only or it
can sum all four input channels to feed a non-
fading signal to a separate subwoofer amplifier.
1) As a four-channel (150W x 4) full-range
amplifier, delivering full-range signals to two
separate stereo speaker systems (front and rear,
for example).
As we said, it’s very flexible.
2) As a powerful (150W x 4) four-channel satellite
amplifier in a bi-amplified system, delivering
high-passed signals to front and rear speaker
systems. Preamp outputs permit connection of a
separate amplifier to drive the subwoofer system.
15) Enjoy the fruits of your labor with your
favorite music.
3) As a 600W full-system amplifier in
bi-amplified mode with one channel pair
driving subwoofers in low-pass mode (150W
x 2 or 300W x 1) and the other channel pair
driving main speakers in high-pass mode
(150W x 2).
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 page 7
for important notice).
4) As a very powerful (300W x 2) full-range
amplifier, delivering full-range signals to a
stereo speaker system.
4 | JL Audio - HD600/4 Owner’s Manual
5
Power and turn-on ConneCtions
ground Connection
The HD600/4’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 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.
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.
We do not recommend the use of “copper-
clad 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 MetaWire™. Tinned
copper wire (silver color) is acceptable as the
tin-plating is only a very minor component of
the wire.
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.
+12 VDC Ground Remote
Front
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 HD600/4 is being run from that
power wire, we recommend a 50A 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 of an
ANL (large-blade) fuse and holder. Please consult
with your JL Audio dealer to make sure that the
wire, fuse holder and fuse rating you have selected
are appropriate for your system’s needs.
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. Each amplifier can
then be fused independently at the outputs of
the power distribution block. Use JL Audio part
XC-FOA-2PAK and appropriate MaxiFuse™ type
fuses with JL Audio distribution blocks.
Please consult with your JL Audio
+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. This connection must be tight and
corrosion-free to ensure proper connectivity. This
wire MUST be fused appropriately for safety. Any
positive 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.
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.
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.
turn-on wire
The HD600/4 uses a conventional +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 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.
Power wire requirements
The HD600/4’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 HD600/4 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 distribution
block mounted as close to the amplifiers as
possible and should connect to the HD600/4 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.).
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.
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!
6 | JL Audio - HD600/4 Owner’s Manual
7
amPliFier mounting oPtions
The HD600/4 has two mounting options to
ease in installation.
Control Panel seCuritY CoVer
amPliFier inPuts
CHannel Control seCtions
The HD600/4 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 HD600/4 has two separate input sections,
one for the “Front” left and right channels and
another for the “Rear” left and right channels.
Each section consists of a pair 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.
Flanking the “General Setup” section
on the Control Panel of the amplifer are
two sets of identical controls: one for the
“Rear Channel Controls” (on the left side)
and one for the “Front Channel Controls”
of the amplifier (on the right side).
In each of these sections you will find an
“Input Voltage” range switch and a rotary
control labeled “Input Sens.” (Input Sensitivity).
These controls are designed to match the input
sensitivity of the HD600/4 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!
standard mounting
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 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.
mote
L
Front
Inputs
Rear
P
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.
R
“inPut mode” switCH
The Control Panel houses an “Input
Mode” switch located under the “General Setup”
heading. This switch allows operation of all four
amplifier channels with only one pair of input
signals or with independent front and rear input
signal pairs.
Note: The Channel Control sections also house
“Filter Mode”, “Filter Slope” and “Filter Freq.”
controls. These are crossover filter controls
and will be discussed in the next section of this
manual. This section will explain the Input
Controls only.
lateral mounting Feet
Lateral Mounting Feet are also included with
your HD600/4 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.
To use separate inputs for the “Front” and
“Rear” amplifier sections, (in order to permit
front-to-rear fading, for example), select “4 Ch.”
on the “Input Mode” switch. In this mode, you
must connect separate pairs of input cables to the
“Front” and “Rear” amplifier inputs.
To operate all four channels of the HD600/4
with a single pair of stereo inputs, select the
“2 Ch.” position on the “Input Mode”
switch and connect a single pair of input
cables to the “Front” input jacks only. In
this mode, the amplifier will route the
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.
signals connected to the “Front” inputs to
the Front and Rear amplifier channels.
8 | JL Audio - HD600/4 Owner’s Manual
9
“input Voltage” switch
“input sens.” Control
CrossoVer Controls
A wide range of signal input voltages can
be accommodated by each of the HD600/4’s
differential-balanced inputs (200mV – 8V RMS).
This wide range is split up into two sub-ranges,
accessible via the “Input Voltage” switches located
in each input section of the amplifier. Be aware
that each input section’s “Input Voltage” switch
will have to be configured, regardless of how many
input cables are actually feeding the amplifier.
The “Low” position on each “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, 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 each “Input Voltage”
switch selects an input sensitivity range between
800mV and 8V. 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 a pair of RCA plugs for each input pair
or use the JL Audio ECS Speaker Wire to RCA
adaptor (XB-CLRAIC2-SW).
Located next to the “Input Voltage” switch
in each input section is a rotary 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 a given input voltage). Rotating the
control counter-clockwise will result in lower
sensitivity (quieter for a given input voltage). To
properly set each pair of amplifier channels for
maximum clean output, please refer to Appendix
C (pages 18, 19) in this manual.
After using this procedure, you can then adjust
the relative level of each channel pair by adjusting
the input sensitivity downward on either or both
channel pairs, if they require 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.
Be aware that both “Input Sens.” adjustments
will have to be made, regardless of how many
input cables are feeding the amplifier. These
controls will allow you to set the appropriate
relative levels for the “Front” channels relative
to the “Rear” channels and any other amplifier
channels in the system.
Crossovers are groups of electronic filters
designed to control the frequency ranges
that each speaker in a system will be tasked
with reproducing. Proper crossover setup is
critical to sound quality and reliability.
The HD600/4 has two individual filters,
one for the “Front” channels and the
other for the “Rear” channels. Each can be
configured as a high-pass filter (attenuates low
frequencies) or as a low-pass filter (attenuates
high frequencies). Additionally, the user can
select from a shallow (12dB/octave) filter slope
or a more aggressive (24dB/octave) slope.
Each Channel Control section contains
identical crossover filter controls.
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 a rate of 12 dB per octave
(Butterworth alignment).
“ 24dB”: Configures the filter to attenuate
frequencies above or below the selected
filter frequency at a rate of 24 dB per octave
(Linkwitz-Riley alignment).
Depending on the speaker system and the
vehicle, different filter slopes may be required to
produce a smooth transition between the sound
of different speakers in the system.
In high-pass mode, the sharper “24dB” setting
will do a better 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 a subwoofer system.
The shallower “12dB” octave setting
allows for more output overlap between
the speakers being crossed over. In many
cases, this will result in a smoother “blend”
or transition between speaker systems.
Experiment to find the slope or combination
of slopes which best matches the acoustic
requirements of your system.
1) “Filter Mode” Control: this switch allows you
to configure the filter for that Channel Pair
into one of two filter types.
“Off”: Defeats the filter completely, allowing
the full range of frequencies present at the
inputs to feed that pair of channels. This
is useful for systems utilizing outboard
crossovers or requiring full-range reproduction
from that pair of channels.
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.
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.
“HP” (High-Pass): Configures the
CH 1&2 filter to attenuate frequencies
below the selected filter frequency.
Useful for connection of component
speakers in a bi-amplified system.
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 cutoff frequency
with a higher level of precision, consult the charts
in Appendix B (page 18) of this manual.
“LP” (Low-Pass): Attenuates frequencies
above the selected filter frequency.
Useful for connection of subwoofer(s)
in a bi-amplified system.
10 | JL Audio - HD600/4 Owner’s Manual
11
bi-amPliFied sYstems
bi-amplified system with one
PreamP outPuts
Bi-amplified systems are defined as systems
in which separate amplifier channels drive low-
frequency (LF) and high-frequency (HF) speakers
and are separately filtered to send appropriate
frequency ranges to each speaker system.
The most common application of
bi-amplification in mobile audio is to drive a
subwoofer system from one or more amplifiers or
channels and component speakers from separate
amplifiers or channels.
Hd600/4 in four-channel mode and
a separate subwoofer amplifier
This configuration requires that the
separate subwoofer amplifier has a built-in
low-pass filter. In this configuration, the
“Front” channels of the HD600/4 will drive
front component speakers (stereo 150W x 2)
with high-pass filtering. The “Rear” channels
will drive rear component speakers in stereo
(150W x 2) with high-pass filtering.
The HD600/4 incorporates a pass-through
preamp output section, so that additional
amplifiers can easily be connected to the same
signal(s) feeding the HD600/4. These preamp
output signals are accessible via a stereo pair
of RCA-type jacks, labeled “Preouts”, on the
Connection Panel.
3) “F+R” (Front + Rear): This mode delivers a
sum of the signals being fed to the “Front
Inputs” and the “Rear Inputs” of the
amplifier. When the HD600/4 is being used
to drive front and rear speaker systems, this
preamp output mode will deliver a summed
front/rear signal to the subwoofer amplifier,
while permitting fading of the front and rear
speaker systems from the source unit.
L
The HD600/4 can be configured to drive a
bi-amplified system by itself or with a separate
subwoofer amplifier.
The separate subwoofer amplifier will drive the
subwoofer system with low-pass filtering (select a
filter frequency of 80-90 Hz to start). The inputs
of the subwoofer amplifier can be fed from the
HD600/4’s preamp output or from a dedicated
subwoofer output on the source unit.
remote leVel Control (oPtional)
With the addition of the optional Remote Level
Control (HD-RLC), you can control the volume
of one or both channel pairs of the HD600/4
from the front of the vehicle. This is useful for
subwoofer level control or even as a master
volume control for the system.
The HD-RLC connects to the jack labeled
“Remote Level Control” on the Connection
Panel of the amplifier using a standard telephone
cable (supplied with the HD-RLC).
Preouts
Remot
Level
Contro
R
bi-amplified system with one Hd600/4
In this configuration, the “Rear” channels
of the HD600/4 will drive subwoofers
(stereo 150W x 2 or bridged 300W x 1) with
low-pass filtering. The “Front” channels
will drive component speakers in stereo
(150W x 2) with high-pass filtering.
Crossover Setup for Bi-Amplified System with one
HD600/4 and a separate subwoofer amplifier:
Once the input and preamp output sections
have been configured appropriately, go to the
“Front Channel Controls” Section. Select “HP”
(high-pass) on the “Filter Mode” switch and
“12dB” or “24dB” on the “Filter Slope” switch
and an appropriate “Filter Freq.” (80-90 Hz is a
good starting point).
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 HD600/4 (if the 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 of signals feeding the HD600/4’s inputs.
The pass-through Preamp Outputs can be
configured two different ways using the switch
labeled “Preouts From” in the “General Setup”
section of the Control Panel.
If desired, multiple HD amplifiers can be
controlled from a single HD-RLC controller
using a simple phone line “splitter” and multiple
phone cables.
Crossover Setup for Bi-Amplified System
with one HD600/4:
Once the input sections have been configured
appropriately, go to the “Rear Channel Controls”
Section. Select “LP” (low-pass) on the “Filter
Mode” switch and “12dB” or “24dB” on the
“Filter Slope” switch and an appropriate “Filter
Freq.” (80-90 Hz is a good starting point).
Next, turn your attention to the “Front
Channel Controls” Section. and select “HP”
(high-pass) on the “Filter Mode” switch and
“12dB” or “24dB” on the “Filter Slope”
switch and an appropriate “Filter Freq.”
(again, 80-90 Hz is a good starting point).
After proper adjustment of the Front and
Rear channel “Input Range” and “Input
Sens.” controls using the method shown
in Appendix C (pages 18, 19), you can
Next, turn your attention to the “Rear
Channel Controls” Section and select “HP”
(high-pass) on the “Filter Mode” switch and
“12dB” or “24dB” on the “Filter Slope” switch
and an appropriate “Filter Freq.” (again, 80-90 Hz
is a good starting point).
After proper adjustment of the HD600/4’s and
the subwoofer amplifier’s “Input Range” and
“Input Sens.”, you can fine tune filter frequencies
and slopes and attenuate either pair of channels
to achieve proper balance. For proper adjustment
of the “Input Sens.” controls of the HD600/4 use
the method shown in Appendix C (pages 18, 19).
For precise filter frequency information for the
HD600/4 refer to Appendix B (pages 18). Refer to
the subwoofer amplifier owner’s manual for its
proper adjustment levels.
L
Preouts
Remote
Level
Control
R
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 a level attenuator.
Depending on the application, you may want
the HD-RLC to only affect one channel pair or
both channel pairs. A switch labeled “Remote
Level Control” in the “General Setup” Section
of the Control Panel allows you to determine
whether the HD-RLC affects the level of all
channels “All Ch.” or only the rear channels
“Rear Ch.”
1) “Front”: The preamp output delivers the same
signal that is connected to the HD600/4’s
“Front Inputs”. This mode is useful for
feeding a subwoofer amplifier when the
HD600/4 is being used to drive front and rear
speaker systems. In this mode, the preamp
output level will track with the signal level
of the front input signals, allowing the user
to fade the rear channels in and out, without
affecting the subwoofer level.
fine tune filter frequencies and slopes and
attenuate either pair of channels to achieve
proper balance. For precise filter frequency
information refer to Appendix B (page 18).
12 | JL Audio - HD600/4 Owner’s Manual
13
The RBC-1 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-1 to an HD amplifer, the control will
not work. You must use the HD-RLC controller.
If you connect a load higher than 4Ω nominal
per channel in stereo mode (or 8Ω in bridged
mode), power will drop by half with every
doubling of impedance above 4Ω stereo / 8Ω
mono. If you connect a load lower than 1.5Ω
nominal per channel in stereo mode (or 3Ω in
bridged mode, 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 16 for details.
To bridge a pair of channels, use the “Left +”
and “Right –” speaker connectors only
(the “Left –” and “Right +” remain unused).
Then connect a mono signal to both left and
right RCA inputs for that channel pair. This
requires an RCA “Y-Adaptor” (sold separately),
because a bridged pair of channels requires that
both amplifier channels of the bridged pair
receive input. Connection of only one RCA input
will result in reduced power output, increased
distortion and can cause the amplifier to overheat.
When bridged, each channel pair will
For example, if you are using the HD600/4 in a
stand-alone bi-amplified mode, you may want the
HD-RLC to only affect the level of the subwoofer
channels. Setting the “Remote Level Control”
switch to the “Rear Ch.” position accomplishes
this (provided the subwoofer system is connected
to the rear channels).
In other cases, you may want control of all
four channels at the same time, so you would
set the “Remote Level Control” switch to the
“All Ch.” position.
sPeaker outPuts
The HD600/4 employs JL Audio’s exclusive
Regulated, Intelligent Power Supply (R.I.P.S.)
design. The operation of the R.I.P.S. system is
independent for each pair of channels. This
sophisticated power supply allows the amplifier to
produce its optimum power (150 watts x 4) over a
wide range of speaker impedances.
deliver optimum power into a 3-8Ω load.
Operating bridged channel pairs into a load
lower than 3Ω is not recommended.
Speaker loads below 1.5Ω nominal per channel
in stereo or 3Ω nominal in bridged mode 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 plugs from the
amplifier chassis (pull back firmly) and back out
the set screws on each 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 of the screw.
bridging Considerations
Bridging is the practice of combining the
output of two amplifier channels to drive a single
load. When bridged, each channel produces
signals of equal magnitude, but opposite polarity.
The combined output of the two channels
provides twice the output voltage available from a
single channel. The HD600/4 has been designed
for bridging of its channel pairs without the need
for input inversion adaptors.
Unlike conventional amplifiers that require
a specific impedance to produce optimum
power, the R.I.P.S.-equipped HD600/4 gives
you the freedom to use a variety of speaker
configurations that achieve final nominal
impedances between 1.5 – 4Ω per channel in
stereo (without sacrificing power output or sound
quality). When bridged, each channel pair will
optimize output at 300 watts between 3 – 8Ω.
The operation of the R.I.P.S. circuitry is
entirely automatic and adjusts itself every time the
amplifier is turned on. There are no user controls
to configure. The system operates through
multiple stages of impedance optimization,
choosing the stage most appropriate to the actual
impedance of the speakers you connect to it.
14 | JL Audio - HD600/4 Owner’s Manual
15
“status” led / ProteCtion CirCuitrY
There is a single multi-color LED on the
control panel of the amplifier to indicate the
amplifier’s operating status. This LED’s behavior
is as follows:
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 of the circuitry
in the JL Audio amplifiers requires specifically
trained service personnel. Do not attempt
to service the amplifier yourself or through
unauthorized repair facilities. This will not only
void the warranty, but may result in the creation
of more problems within the amplifier.
aPPendix a:
4) Alternating Red and Green: lights to indicate
that the amplifier is experiencing a fault
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 a low supply voltage
condition. If battery voltage drops below 8.5
volts at any point, the amplifier (except for the
“Status” LED) will shut itself off to protect itself
and the vehicle’s charging system. If the voltage
drops below 6 volts, the “Status” LED will also
turn off.
Hd600/4 specifications
Amplifier Topology: Class D, switching type with
patented Single-Cycle Control™ technology.
Power Supply: Pulse width modulation-regulated
switching power supply
1) Flashing Green: amplifier is powering up,
audio output is muted.
Recommended Fuse Value / Type: 50A (AFS, AGU or
MaxiFuse™)
Rated Power (Stereo):
2) Constant Green: amplifier is on and
functioning normally, audio output is active.
150W RMS x 4 @ 1.5-4Ω (11V - 14.5V)
Rated Power (Bridged):
300W RMS x 2 @ 3-8Ω (11V - 14.5V)
THD at Rated Power: <0.03% @ 4Ω per channel
(Average at 1 kHz)
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 amplifier. The red
light will turn green and the amplifier will
return to full-power operating mode when its
temperature returns to a safe level.
The amplifier will turn back on automatically
when voltage climbs back above 9 volts. This
shut-down and turn-on behavior may happen
in a rapid cycle when bass-heavy program
material causes a weak charging system to
momentarily dip too low. If this is happening
in your system, have your charging system
inspected to make sure it is working properly.
Signal to Noise Ratio (20 kHz Bandwidth):
Referred to Rated Power: 110 dBA
Referred to 1 Watt: 88.2 dBA
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.
Frequency Response: 6 Hz - 30 kHz (+0, -1dB)
Damping Factor:
300 @ 4Ω per ch. / 50 Hz
Jl audio technical support:
(954) 443-1100
9:00 AM – 5:30 PM (Eastern Time Zone)
Monday - Friday
150 @ 2Ω per ch. / 50 Hz
3) Constant Amber (yellow): lights to indicate
that the impedance of the speaker load
connected to the amplifier is lower than
the optimum load impedance range for the
amplifier. When this light is on, a protection
circuit engages and reduces the power output
of the “Front” or the “Rear” channels,
depending on which channel is experiencing
the problem. The amber indicator will also
light when a short-circuit is detected in the
speaker wiring (this can be a short between the
positive and negative speaker wires or between
either speaker wire and the vehicle chassis).
This can be used to diagnose a short-circuit by
only connecting one of the amplifier sections
at a time (“Front” or “Rear” channels). The
amber LED will light when you connect the
section that is experiencing the problem and
turn the volume up.
Crossover Filters:
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.
Filter Sets: Two (Front Channel and Rear Channel)
Filter Type: State-variable, 12 dB/octave 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:
For more information on troubleshooting this
amplifier, refer to Appendix D (pages 20, 21).
No. of Inputs: Two Stereo Pairs (Front and Rear)
Input Type: Differential-balanced with RCA jack inputs
Input Range: Switchable from 200mV - 2V RMS (Low)
to 800mV - 8V RMS (High)
There is only one condition that will shut down
an undamaged HD600/4 completely…
If battery voltage drops below 10 volts, the
entire amplifier will shut itself off to protect
itself and the vehicle’s charging system. The
“Status” LED will turn off when this occurs. The
amplifier will turn back on when voltage climbs
back above 11 volts. This may happen in a rapid
cycle when bass-heavy program material causes
a weak charging system to dip below 10 volts
momentarily. If this is happening in your system,
have your charging system inspected to make
sure it is working properly. For information on
troubleshooting this amplifier, refer to Appendix
D (pages 20, 21).
Preamp output:
2-Channel, buffered pass-through type, switch-selectable
to pass signal from “Front” inputs only, or from all four
inputs (summed).
Chassis dimensions (lxwxH):
10.74 in. x 7.85 in. x 1.93 in. (273 mm x 199.5 mm x 49 mm)
Dimensions do not include connectors.
Due to ongoing product development, all specifications are subject to
change without notice.
16 | JL Audio - HD600/4 Owner’s Manual
17
aPPendix b:
aPPendix C:
the nine-step Procedure
Precise Frequency selection Chart
input sensitivity level setting
(follow this procedure for each pair of channels)
1) Disconnect the Speaker Connector Plugs.
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 HD600/4). Disconnect
the HD-RLC Remote Level Control
temporarily (if one is being used).
3) Switch the “Input Voltage” to “Low” and
turn the “Input Sens.” control on both sets of
channels all the way down.
4) Set the source unit volume to 3/4 of full
volume. If either set of channels 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.
7) Connect the AC voltmeter to the “Front
Speaker Outputs” or “Rear Speaker Outputs”
connectors of the amplifier. If the channel pair
is operating in stereo, it is only necessary to
measure one channel in the pair. If bridged,
make sure you test the voltage at the correct
connectors (L+ and R–).
8) Increase the “Input Sens.” control until
the target voltage is delivered for that set
of channels. If excessive voltage is read
on either set of channels with the control
at minimum (full counterclockwise),
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 - 4Ω per
channel and when connected to a charging
system with any voltage from 11 - 14.5V.
This design is beneficial for many reasons.
One of these reasons is ease of setup.
“Filter Freq”
detent
number
Panel
marking
actual
Freq.
Full counter-clockwise: 53
01 . . . . . . . . . . . “50” . . . . . . . . . . . .53
02 . . . . . . . . . . . . . . . . . . . . . . . . . . . .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 . . . . . . . “12 o’clock”. . . . . . . 115
25 . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
26 . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
27 . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
28 . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
29 . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
30 . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
31 . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
32 . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
33 . . . . . . . . . . “250” . . . . . . . . . . 236
34 . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
35 . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
36 . . . . . . . . . . . . . . . . . . . . . . . . . . . 369
37 . . . . . . . . . . . . . . . . . . . . . . . . . . . 443
38 . . . . . . . . . . “500” . . . . . . . . . . 484
39 . . . . . . . . . . . . . . . . . . . . . . . . . . . 525
Full-clockwise: 528
Because each JL Audio amplifier will
always deliver the same amount of power
within its operational range of impedances
and supply voltages, the maximum,
switch the appropriate “Input Voltage”
switch to “High” and re-adjust.
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.
9) Once you have adjusted each set of channels to
its maximum unclipped output level, reconnect
the speaker(s). The “Input Sens.” controls can
now be adjusted downward if either or both
sets of channels requires attenuation to achieve
the desired system balance.
5) Using the chart below, determine the
target voltage for input sensitivity
adjustment according to the nominal
impedance of the speaker system
necessary equipment
• Digital AC Voltmeter
• CD with a sine-wave test tone recorded at
0 dB reference level in the frequency range
to be amplified for that set of channels
(50 Hz for subwoofer channels, 1 kHz for
a midrange 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.).
connected to each set of outputs.
6) Verify that you have disconnected the Speaker
Connector Plugs before proceeding. Play a
track with an appropriate sine wave (within the
frequency range to be amplified by each set of
channels) at 3/4 source unit volume.
Front CHannels
nom.
rear CHannels
impedance
stereo
24.5 V
24.5 V
24.5 V
21.2 V
17.3 V
15.0 V
bridged
stereo
24.5 V
24.5 V
24.5 V
21.2 V
17.3 V
15.0 V
bridged
49.0 V
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.
8Ω
6Ω
49.0 V
42.4 V
42.4 V
4Ω
34.6 V
34.6 V
3Ω
30.0 V
30.0 V
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.
not recommended
not recommended
not recommended
not recommended
2Ω
1.5Ω
18 | JL Audio - HD600/4 Owner’s Manual
19
aPPendix d: troublesHooting
“How do i properly set the input sensitivity on my amplifier”
Please refer to Appendix C (pages 18, 19) to set the input sensitivity
“my amplifier shuts off once in a while, usually at higher volumes”
Check your voltage source and grounding point. The power supply
for maximum, low-distortion output.
“my amplifier doesn’t turn on”
of the HD600/4 will operate with charging system voltages
down to 10V. Shutdown problems at higher volume levels
can occur when the charging system voltage drops below
10V. These dips can be of very short duration making them
extremely difficult to detect with a common DC voltmeter.
To ensure proper voltage, inspect all wiring and termination
points. It may also be necessary to upgrade the ground
wire connecting the battery to the vehicle’s chassis and the
power wire connecting the alternator to the battery. Many
vehicles employ small (10 AWG - 6 AWG) wire to ground the
battery to the vehicle’s chassis and to connect the alternator 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. Grounding problems are the
leading cause of misdiagnosed amplifier “failures.”
Check the fuse(s), not just visually, but with a continuity meter. It
is possible for a fuse 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 a relay
is required. To test for this problem, jump the “+12VDC” wire
to the “Remote” terminal to see if the amplifier turns on.
“i get a distorted / attenuated sound coming out of the speaker(s)”
Check the speaker wires for a possible short, either between the
“my amplifier turns on, but there is no output”
Check the input signal using an AC voltmeter to measure the
voltage from the source unit while an appropriate test tone is
played through the source unit (disconnect the input cables
from the amplifier prior to this test). The frequency used
should be in the range that is to be amplified by the amplifier
(example: 50 Hz for a sub bass application or 1 kHz for a full
range / high-pass application). A steady, sufficient voltage
(between 200mV and 8.0-volts) should be present at the
output of the signal cables.
Check the output of the amplifier. Using the procedure explained
in the previous check item (after plugging the input cables
back into the amplifier) test for output at the speaker outputs
of the amplifier. Unless you enjoy test tones at high levels,
it is a good idea to remove the Speaker Connector Plugs
from the amplifier while doing this. Turn the volume up
approximately half way. 5V or more should be measured
at the speaker outputs. This output level can vary greatly
between amplifiers but it should not be in the millivolt
range with the source unit at half volume. If you are reading
sufficient voltage, check your speaker connections as
explained below.
positive and negative leads or between either speaker lead
and the vehicle’s chassis ground. If a short 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 a different set of wires connected to a test
speaker.
Check the nominal load impedance to verify that each channel
of the amplifier is driving a load equal to or greater than
1.5 ohms in stereo mode (3 ohms bridged).
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 a different set of
cables and/or a different signal source to be sure.
“my amplifier’s output fluctuates when i tap on it or hit a bump”
Check the connections to the amplifier. Make sure that the
insulation for all wires has been stripped back far enough to
allow a good 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.
Check to ensure that the speaker wires are making a good
connection with the metal inside the Speaker Connector
Plugs. The speaker wire connectors are designed to accept up
to 12 AWG wire. Make sure to strip the wire to allow for a
sufficient connection with the metal inside each terminal.
20 | JL Audio - HD600/4 Owner’s Manual
21
installation notes:
use this diagram to document your amplifier’s switch and control positions.
22 | JL Audio - HD600/4 Owner’s Manual
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