Slash 300 4 User Manual

Thank you for purchasing a JL Audio amplifier for

your automotive sound system.

Your amplifier has been designed and manufactured to exacting

standards in order to ensure years of musical enjoyment in your

vehicle. For maximum performance and extended warranty

coverage, we highly recommend that you have your new amplifier

installed by an authorized JL Audio dealer. Your authorized

dealer has the training, expertise and installation equipment to

ensure optimum performance from this product. Should you

decide to install the amplifier yourself, please take the time

to read this manual thoroughly so as to familiarize yourself

with its installation requirements and setup procedures.

If you have any questions regarding the instructions in this

manual or any aspect of your amplifier’s operation, please contact

your authorized JL Audio dealer for assistance. If you need further

assistance, please call the JL Audio Technical Support Department at

[phone] during business hours (Eastern Time Zone).

JL AUDIO 300/4

four-channel full-range amplifier

owner’s manual

PLANNING YOUR INSTALLATION

It is important that you take the time to read
this manual and that you plan out your installation
carefully.The following are some considerations
that you must take into account when planning
your installation.

Cooling Efficiency Considerations:

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 back 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, but
you still need to follow some basic guidelines:

• Amplifier mounted vertically with heat sink fins

pointing up: Optimum

• Amplifier mounted horizontally,

right side up: Good

• Amplifier mounted horizontally, but upside down:

Fair (not recommended if there is less than 1 inch
(2.5 cm) clearance above the amplifier heat sinks)

• Amplifier mounted vertically with heat sink fins

pointing laterally: Fair

• Amplifier mounted vertically with heat sink fins

pointing down: Poor (not recommended)

If mounting the amplifier under a seat, make sure
there is at least 1 inch (2.5 cm) of space above the
amplifier heat sink fins to permit proper cooling.

Safety Considerations:

Your amplifier needs to be installed in a dry,
well-ventilated environment and in a manner
which does not interfere with your vehicle’s safety
equipment (air bags, seat belt systems,ABS brake
systems, etc.).You should also take the time to
securely mount the amplifier using the supplied
screws so that it does not come loose in the event
of a collision or a sudden jolt to the vehicle (15 lbs.
of aluminum traveling at 60 MPH will hurt you).

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.

JL AUDIO 300/4 3

Front Channel

Input Voltage

Range Selector

(pg. 6)

Front Channel

Filter Slope

Selection

(pg. 7)

Front Channel

Filter Frequency

Range Selector

(pg. 8)

Front Channel

Input Sensitivity

Control

(pg. 6)

Front Channel
Left and Right

Input Jacks

(pg. 6)

Front Channel

Input Mode

Selector

(pg. 6)

Front Channel

Speaker Outputs

(pg. 8)

Rear Channel

Speaker Outputs

(pg. 8)

Front Channel

Filter Cutoff

Frequency Selector

(pg. 8)

Front Channel

Filter Mode

Selector

(pg. 7)

Rear Channel
Left and Right

Input Jacks

(pg. 6)

Remote Turn-On

Connector

(pg. 6)

Chassis Ground

Connector

(pg. 5)

+12 V Power

Connector

(pg. 5)

Rear Channel

Input Voltage

Range Selector

(pg. 6)

Rear Channel

Filter Slope

Selection

(pg. 7)

Rear Channel

Filter Frequency

Range Selector

(pg. 8)

Rear Channel

Input Sensitivity

Control

(pg. 6)

Rear Channel

Filter Mode

Selector

(pg. 7)

Rear Channel

Filter Cutoff

Frequency Selector

(pg. 8)

PROTECT YOUR HEARING!

We value you as a long-term customer. For that
reason, we urge you to practice restraint in the
operation of this product so as not to damage your
hearing and that of others in your vehicle. Studies
have shown that continuous exposure to high
sound pressure levels can lead to permanent
(irreparable) hearing loss. This and all other high­power amplifiers are capable of producing such high
sound pressure levels when connected to a speaker
system. Please limit your continuous exposure to
high volume levels.

While driving, operate your audio system in a
manner that still allows you to hear necessary noises
to operate your vehicle safely (horns, sirens, etc.).

SERIAL NUMBER

In the event that your amplifier requires service
or is ever stolen, you will need to have a record of
the product’s serial number. Please take the time to
enter that number in the space provided below.
The serial number can be found on the bottom
panel of the amplifier and on the amplifier packaging.

Serial Number:

_______________________________

INSTALLATION APPLICATIONS

This amplifier is designed for operation in vehicles
with 12V, negative-ground electrical systems. Use of
this product in vehicles with positive ground and/or
voltages other than 12V may result in damage to the
product and will void 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.

2 JL AUDIO 300/4

11) Connect the speaker wires to the amplifier.

12) Carefully review the amplifier’s control

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

13) Install power wire fuse (40A for a

single 300/4) and reconnect the negative
battery post terminal.

14) Turn on the source unit at a low level

to double-check that the amplifier is configured
correctly. Resist the temptation to crank it up until
you have verified the control settings.

15) Make necessary adjustments to the input

sensitivity controls of the front and rear channel
sections to obtain the right overall output and the
desired balance between their outputs. See
Appendix B (page 14) for the recommended input
sensitivity setting method.

16) Enjoy the fruits of your labor with your

favorite music.

POWER CONNECTIONS

Before installing the amplifier, disconnect the
negative (ground) wire from the vehicle's battery.
This will prevent accidental damage to the system,
the vehicle and your body during installation.

The 300/4's “+12 VDC” and “Ground”
connections are designed to accept 8 - 4 AWG
power wire. 8 AWG is the minimum

recommended power wire size for
this amplifier.

If you are installing the 300/4 with other
amplifiers and wish to use a single main power wire,
use 2 AWG or 1/0 AWG main power wire
(depending on the overall current demands of all
the amplifiers in the system).This 2 AWG or 1/0
AWG power wire should terminate into a
distribution block mounted as close to the amplifiers
as possible and should connect to the 300/4 with
8 - 4 AWG power wire.

Please note that smaller AWG numbers mean

bigger wire and vice-versa (1/0 AWG is biggest, 2
AWG is smaller, then 4 AWG, then 8 AWG, etc.).

To connect the power wires to the amplifier, first
back out the set screw on the top of the amplifier,
using the supplied 2.5 mm hex wrench. Strip
1/2 inch (12 mm) of insulation from the end of
each wire and insert the bare wire into the
receptacle on the front panel of the amplifier, seating
it firmly so that no bare wire is exposed.While
holding the wire in place, tighten the set screw
firmly, taking care not to strip the head of the screw.

The ground connection should be made using
the same gauge wire as the power connection
and should be kept as short as possible, while
accessing a solid piece of sheet metal in the vehicle.
The surface of the sheet 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.The use of a star washer to lock
down the connection is advisable.

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

Many vehicles employ small (10 AWG - 6 AWG)
wire to ground the battery to the vehicle chassis and
to connect the alternator's positive connection to the
battery.To prevent voltage drops, these wires should
be upgraded to 4 AWG when installing amplifier
systems with main fuse ratings above 60A.

FUSE REQUIREMENTS

It is absolutely vital that the main power wire(s)
to the amplifier(s) in the system be fused within
18 inches (45 cm) of the positive battery post
connection.The fuse value at each power wire
should be high enough for all of the equipment
being run from that power wire. If only the
300/4 is being run from that power wire, we
recommend a 40A fuse be used. AGU (big glass
fuse) or MaxiFuse™ (big plastic-body fuse) types
are recommended.

No fuse is required or recommended directly
before the amplifier power connection. If one is
desired, we recommend the use of a 40A AGU fuse
or MaxiFuse™ type.

IMPORTANT

!

JL AUDIO 300/4 5

PRODUCT DESCRIPTION

The JL Audio 300/4 is a four-channel full-range
amplifier utilizing patented Absolute Symmetry™
Class AB technology for all channels.All channels
benefit from JL Audio's exclusive R.I.P.S. power
supply design which optimizes the output of each
channel pair for any impedance between 1.5 and 4
ohms per channel.

The 300/4 can be operated in the
following modes:

1) As a full-system amplifier in bi-amp mode with
one pair of channels driving subwoofers in low-pass
mode (75W x 2 or 150W x 1) and the other pair
of channels driving main speakers in high-pass mode
(75W x 2).

2) As a four-channel satellite amplifier in a bi­amplified system, delivering high-passed signals to
front and rear speaker systems.

The 300/4's flexible input and crossover sections
permit operation with a wide variety of source units
and system configurations.The 300/4 can operate
with a single pair of stereo inputs or with separate
inputs for front and rear channels, if the source unit
is equipped with front and rear outputs.

TYPICAL INSTALLATION SEQUENCE

The following represents the sequence for a
typical amplifier installation, using an aftermarket
source unit. Additional steps and different
procedures may be required in some applications. If
you have any questions, please contact your
authorized JL Audio dealer for assistance.

1) Disconnect the negative battery post

connection and secure the disconnected cable to
prevent accidental re-connection during installation.

This step is not optional!

2) Run power wire (minimum 8 AWG) from

the battery location to the amplifier mounting
location, taking care to route it in such a way that
it will not be damaged and will not interfere with
vehicle operation. Use 2 AWG or 1/0 AWG
power wire if additional amplifiers are being
installed with the 300/4.

3) Connect power wire to the positive battery

post. Fuse the wire with an appropriate fuse block
(and connectors) within 18 inches (45 cm) wire
length of the positive battery post. This fuse is

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

4) Run signal cables (RCA cables) and remote

turn-on wire from the source unit to the amplifier
mounting location.There are two ways to provide
input to the 300/4. Please read the rest of this manual
carefully to choose the best one for your system.

5) Run speaker wire from the speaker systems to

the amplifier mounting location.

6) Find a good, solid metal grounding point

close to the amplifier and connect the negative
power wire to it using appropriate hardware.
Use minimum 8 AWG power wire, no longer
than 36 inches (90 cm) from the amplifier to the
ground connection point. In some vehicles, it may
be necessary to upgrade the battery ground wire.
(See page 5 for important notice).

7) Securely mount the amplifier using the

supplied screws.

8) Connect the positive and negative power

wires to the amplifier. A fuse near the amplifier is
not necessary.

9) Connect the remote turn-on wire

to the amplifier.

10) Connect the RCA input cables

to the amplifier.

4 JL AUDIO 300/4

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 B (page 14) 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 B (page 14). 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
front and rear channels and any other amplifier
channels in the system.

CROSSOVER CONTROLS

Crossovers are groups of individual electronic filters
which allow only certain frequency ranges to pass
through them by attenuating frequencies outside
the selected range. These filters allow the user to
specify what frequency range will be sent out of
each channel section of the amplifier.This, in turn,
allows each speaker system to only reproduce a
range of frequencies it is well-suited for, resulting in
reduced distortion and improved fidelity.

Front and Rear Filter Section:

The 300/4 employs two separate, but identical filter
sections for its front and rear channel pairs.These
sections consist of the following controls

1) “Filter Mode” Control: This switch allows you to
configure the filter into one of two filter types or
defeat it completely:
“Off”: Defeats the filter for that channel section
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.
“LP” (Low-Pass): Configures the filter to attenuate
frequencies above the selected filter frequency.
Useful for connection of subwoofer(s) to that
channel section.
“HP” (High-Pass): Configures the filter to attenuate
frequencies below the selected filter frequency.
Useful for connection of component speakers to
that channel section in a bi-amplified system.

2) “Filter Slope” Control: This switch allows

you to select from two filter slopes for that
channel section.
“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

JL AUDIO 300/4 7

TURN-ON LEAD

The 300/4 uses a conventional +12V remote
turn-on lead, typically controlled by the source unit's
remote turn-on output.The amplifier will turn on
when +12V is present at its “Remote” input and
turn off when +12V is switched off. If a source unit
does not have a dedicated remote turn-on output,
the amplifier’s turn-on lead can be connected to
+12V via a switch that derives power from an
ignition-switched circuit.

The 300/4's “Remote” turn-on connector is
designed to accept 18 AWG – 8 AWG wire.
12 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 top of
the amplifier, using the supplied hex wrench. Strip
1/2 inch (12mm) of wire and insert the bare wire
into the receptacle on the front panel of the
amplifier, 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, taking care not to strip the head of
the screw and making sure that the wire is firmly
gripped by the set screw.

FRONT AND REAR INPUT SECTIONS

The 300/4 has two separate input sections, one
for its front channels and another for its rear
channels. Each section contains a pair of RCA-type
input jacks, an “Input Voltage” switch and an “Input
Sens.” rotary control.

The “Front Input Section” also contains an “Input
Mode” switch to allow operation of all four amplifier
channels with one or two pairs of input signals.

1) Input Mode Switch: If you wish to operate all

four channels of the 300/4 with a single pair of
stereo inputs, select the “2ch”position on the
“Input Mode” switch and connect a single pair of
input cables to the input jacks in the “Front Input

Section”. In this mode, the amplifier will route the
signals connected to the front inputs to the rear
inputs as well.

If you wish to use separate inputs for the front
and rear channel cections (to allow front-to-rear
fading, for example) and the source unit is
equipped with front and rear outputs, select
“4ch” on the “Input Mode” switch. In this mode,
you must connect separate pairs of input cables
to each input section.

2) Input Voltage Range: A wide range of signal

input voltages can be accommodated by each of
the 300/4's input sections (200mV – 8V).This wide
range is split up into two sub-ranges, accessible via
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 conventional preamp-level outputs, this is most
likely the position that you will use.

The “High” position on each “Input Voltage”
switch selects an input sensitivity range between
800mV and 8V.This is useful for cer tain high-output
preamp level signals as well as speaker-level output
from source units and small amplifiers.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.

The output of the amplifier will decrease for a
given input voltage when the “Input Range” switch
is placed in the “High” position. Conversely, the
output will be higher with the switch in the “Low”
position.While this may sound counter-intuitive, it is
consistent with the descriptions above.

3) Input Sensitivity Adjustment: 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

IMPORTANT

!

6 JL AUDIO 300/4

For optimum power output at all four channels,
connect the same impedance (between 1.5-4Ω) on
all four channels. On pages 16 and 17 are charts
showing the continuous (RMS) power output
capability of the 300/4 into various combinations of
front and rear impedances (optimum output is
shown in bold type). Please refer to these charts so
you know what to expect in terms of power
output.

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
yellow “Low Ω” LED lights to indicate that this
has happened). See page 10 for details.

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.

IMPORTANT

!

IMPORTANT

!

IMPORTANT

!

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 300/4 has been designed for bridging
of its channel pairs without the need for input
inversion adaptors.

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”
(not included.) When bridged, each channel pair will
deliver optimum power into a 3-8Ω load. Operating
bridged channel pairs into a load lower than 3Ω is
not recommended.

Because a bridged pair of channels requires that
both channels receive input, you need to connect
both left and right RCA inputs to the bridged
channel pair’s inputs. Connection of only one RCA
input will result in reduced power output, increased
distortion and can cause the amplifier to overheat.
Do not do this! Instead, use a “Y-Adaptor” to split
the mono signal into both left and right RCA inputs.

Why a mono signal? If you are bridging a pair of
channels and use a stereo input, the only
information that will reach the amplifier stage is the
common-phase portion of the signal. This may be
useful for passively deriving a center-channel signal,
but is not going to give you a defined left or right
channel. If you are looking to reproduce a single
channel’s signal, you must split the mono signal with
a “Y-Adaptor” and connect it to both left and right
RCA inputs for the bridged channel pair.

JL AUDIO 300/4 9

frequency at a rate of 24 dB per octave (Linkwitz­Riley 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. Experiment to find
the slope which best matches the acoustic
requirements of the system.The sharper “24dB”
setting will do a better job of protecting small
speakers with limited power handling.The shallower
“12dB” octave setting allows the rear speakers to
reproduce more low-frequency content.

3) “Freq. Range” Control: When thrown to

the right, this switch multiplies the cutoff
frequency selected by the rotary “Filter Freq.
(Hz)” control by a factor of 10. In the “x1”
position, the range of the rotary control is
50 - 500 Hz (as marked). In the “x10”
position, the range of the rotary control is
500 Hz - 5 kHz (5000 Hz).

4) “Filter Freq. (Hz)” The filter frequency

markings surrounding this rotar y 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 A
(page 14) of this manual.

SPEAKER OUTPUTS

Even though you may have installed zillions of
amps in your day, please take the time to read this
section! The 300/4 is not a typical amplifier and care
must be taken to balance the front and rear channel
speaker impedances for optimum output from all
four channels.

The 300/4 employs JL Audio's exclusive
Regulated, Intelligent Power Supply (R.I.P.S.) design.
This sophisticated power supply allows the
amplifier to produce its optimum power (300
watts) over a wide range of speaker impedances.
Unlike conventional amplifiers that require a
specific impedance to produce optimum power,
the R.I.P.S.-equipped 300/4 gives you the freedom
to use a variety of speaker configurations that
achieve final impedances between 1.5 – 4 Ohms
nominal per channel (without sacrificing power
output or sound quality).

The operation of the R.I.P.S. circuitr y is entirely
automatic and adjusts itself every time the amplifier
is turned on according to the lowest impedance
present at either front or rear channels .There are
no user controls to configure.The system operates
through three stages of impedance optimization,
choosing the stage most appropriate to the actual
impedance of the speakers you connect to it.

Because the 300/4 utilizes a single power supply,
it will set itself up based on the lowest impedance
present at either the front or rear amplifier
channels. For example, if you connect a 2 ohm load
to each front channel and a 4 ohm load to each
rear channel, the amplifier will adjust itself to deliver
75 watts x 2 to the front 2 ohm loads, but will only
deliver half its optimum power (37.5 watts x 2) to
the rear 4 ohm loads. If you connect a 4 ohm load
to all four channels or a 2 ohm load to all four
channels, the amplifier will deliver 75 watts x 4. See,
we told you this amp was different... Read on, there
is more important information to follow.

8 JL AUDIO 300/4

SYSTEM CONFIGURATIONS

The 300/4 is a flexible amplifier, well-suited for a
multitude of system configurations. In this section, the
most likely configurations are explained in detail.

Once you have selected your desired
configuration, you can use the amplifier panel
drawings on the bottom of the following
pages to mark the required switch positions for
easy reference.

BI-AMPLIFIED SYSTEMS

Bi-amplified systems are defined as systems in
which separate amplifier channels drive low­frequency (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.

The 300/4 can be configured to drive a bi­amplified system by itself or with a separate
subwoofer amplifier.

BI-AMPLIFIED SYSTEM WITH ONE 300/4

In this configuration, the rear channels of the
300/4 will drive subwoofers (stereo 75W x 2 or
bridged 150W x 1) with low-pass filtering.The front
channels will drive component speakers in stereo
(75W x 2) with high-pass filtering.

Input connection options for a bi-amplified system
with one 300/4 are as follows:

A) No User Adjustability

Required: a basic source unit or processor with left

and right stereo outputs.
Input Connections: a single pair of stereo source
unit outputs connected to the front channel inputs
of the 300/4 (select “2ch” on the “Input Mode”
switch in the “Front Input Section”).

Result: the relative level of the LF and HF
channels will be fixed by the 300/4’s “Input Sens.”
settings and will not be user adjustable from the
front of the vehicle.

B) Fade Subwoofer Level vs. HF Level

Required: a source unit or processor with front and

rear pairs of outputs.
Input Connections: the first stereo pair of source
unit outputs is connected to the front inputs of the
300/4.The second stereo pair of source unit
outputs is connected to the rear inputs (select

“4ch” on the “Input Mode” switch in the “Front
Input Section”).
Result: in this mode, the user has the ability to fade

or control the level of the LF channels relative to
the HF channels via the source unit’s fader control
without exceeding the maximum clean output level
set by each amplifier section’s “Input Sens.” controls.

C) Subwoofer Level Control Only

Required: a source unit or processor with left, right

and subwoofer outputs.
Input Connections: the main stereo pair of source
unit outputs is connected to the front inputs of the
300/4.The source unit’s dedicated subwoofer
output is connected to the rear inputs (select “4ch”
on the “Input Mode” switch in the “Front Input

Section”).
Result: in this mode, the user has the ability to

control the absolute level of the LF channels relative
to the HF channels.

Set the rear channel “Input Sens.” with the

source unit’s subwoofer level control set at 3/4 of full
output. See Appendix B (page 14) for details.

IMPORTANT

!

JL AUDIO 300/4 11

STATUS INDICATOR LIGHTS /
PROTECTION CIRCUITRY

There are three status indicator lights on the top

of the amplifier. These are as follows:

1) “Power” (Green): lights to indicate that the

amplifier is turned on and operating normally.

2) “Thermal” (Red): lights to indicate that the

amplifier has exceeded its safe operating
temperature, putting the amplifier into a self­protection mode, which reduces the power
output of the amplifier. The red light will shut off
and the amplifier will return to normal, full-power
operating mode if the heat sink temperature
drops back to a safe level.

3) “Low Ω” (Amber): 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 all four amplifier channels.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 shor t-circuit
by only connecting one of the amplifier sections at a
time (front or rear).The amber LED will light when
you connect the section that is experiencing the
problem and turn the volume up.

There is only one condition that will shut
down an undamaged 300/4 completely…

If battery voltage drops below 10 volts, the entire

amplifier will shut itself off.The green “Power”
indicator on the top of the amplifier will turn off
when this occurs.The amplifier will turn back on
when voltage climbs back above 10 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.A 0.5 or 1.0 Farad
rapid-discharge capacitor connected in parallel to
the amplifier power connections will minimize these
short duration voltage dips in most systems that are
having this problem.

For information on troubleshooting this

amplifier, refer to Appendix C (page 18).

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 par ts 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.

If you have any questions about the installation or

setup of the amplifier not covered in

this manual, please contact your dealer or the

JL AUDIO Technical Department for assistance:

[phone]

9:00 AM – 5:30 PM Eastern Time,

Monday – Friday

10 JL AUDIO 300/4

Input Connections: The main stereo pair of source
unit outputs is connected to the front inputs of the
300/4 (select “2ch” on the “Input Mode” switch in
the “Front Input Section”).The source unit’s
dedicated subwoofer output is connected to the
subwoofer amplifier inputs.
Result: with this option, the user has the ability to
control the absolute level of the subwoofer channel
relative to the HF channels, but cannot fade the
front and rear HF channels relative to each other.

Set the subwoofer amplifier’s “Input Sens.” with

the source unit’s subwoofer level control set at 3/4
of full output.

D) Front to Rear HF Fading and
Subwoofer Level Control
Required: a source unit or processor with front and

rear pairs of stereo outputs plus a dedicated
subwoofer output.
Input Connections: one stereo pair (front, typically)
of source unit outputs is connected to the front
inputs of the 300/4. The second stereo pair of
source unit outputs (rear, typically) is connected to
the rear inputs of the 300/4 (select “4ch” on the
“Input Mode” switch in the “Front Input Section”).
The source unit’s dedicated subwoofer output is
connected to the subwoofer amplifier inputs.
Result: with this option, the user has the ability to
fade the front and rear HF channels relative to each
other and also has the ability to control the
absolute level of the subwoofer channel relative to
the HF channels.

Set the subwoofer amplifier’s “Input Sens.” with

the source unit’s subwoofer level control set at 3/4
of full output.

IMPORTANT

!

IMPORTANT

!

Crossover Setup for Bi-Amplified System with one
300/4 and a separate subwoofer amplifier:

Once the input and preamp output sections have

been configured appropriately, go to the “Front
Filter Controls” and “Rear Filter Controls” You will
set both control sections identically to start:

Select “x1” on the “Freq. Range” switch, “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). Select the same settings for the
“Rear Filter Controls”.

After proper adjustment of the 300/4’s front and
rear “Input Sens.” controls, and the subwoofer
amplifier’s input sensitivity controls, 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 300/4 use the method shown in Appendix B
(page 14). For precise filter frequency information
for the 300/4 refer to Appendix A (page 14). Refer
to the subwoofer amplifier owner’s manual for
proper adjustments.

JL AUDIO 300/4 13

Crossover Setup for Bi-Amplified System
with one 300/4:

Once the input sections have been configured

appropriately, go to the “Rear Filter Controls”.
Select “x1” on the “Freq. Range” switch, “LP” (low­pass) 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 Filter
Controls” and select “x1” on the “Freq. Range”
switch, “HP” (high-pass) on the “Filter Type” switch
and “12dB” or “24dB” on the “Filter Mode/Slope”
switch and an appropriate “Filter Freq.” (again, 80-
90 Hz is a good starting point).

After proper adjustment of the front and rear
“Input Range” and “Input Sens.” controls using the
method shown in Appendix B (page 14), you can
fine tune filter frequencies and slopes and attenuate
either pair of channels to achieve proper balance.
For precise filter frequency information refer to
Appendix A (page 14).

BI-AMPLIFIED SYSTEM WITH ONE 300/4 IN
FOUR-CHANNEL MODE AND A SEPARATE
SUBWOOFER AMPLIFIER

This configuration requires that the separate
subwoofer amplifier has a built-in low-pass filter. All
JL Audio subwoofer amplifiers have this feature.

In this configuration, the front channels of the
300/4 will drive front component speakers (stereo
75W x 2) with high-pass filtering.The rear channels
will drive rear component speakers in stereo (75W
x 2), also with high-pass filtering.

The separate amplifier will drive the subwoofer
system with low-pass filtering (select a filter
frequency of 80-90 Hz to start).

Input connection options for a bi-amplified system
with one 300/4 and a separate subwoofer amplifier
are as follows:

A) No User Adjustability
Required: a basic source unit or processor with left

and right stereo outputs.
Input Connections: a single pair of stereo source
unit outputs is connected to the front inputs of the
300/4 (select “2ch” on the “Input Mode” switch in
the “Front Input Section”) and also connected to
the subwoofer amplifier inputs (via a “Y-Adaptor”).
Alternatively, the 300/4 can receive its input from
the subwoofer amplifier’s preamp output set to “full­range” mode.
Result: the relative level of the LF and front and rear
HF channels will be fixed by the 300/4’s “Input
Sens.” settings (as well as the subwoofer amplifier’s
settings) and will not be user adjustable from the
front of the vehicle.

B) Fade Subwoofer Level vs. HF Level

Required: a source unit or processor with front and

rear pairs of stereo outputs.
Input Connections: one stereo pair of source unit
outputs is connected to the front inputs of the
300/4 (select “2ch” on the “Input Mode” switch in
the “Front Input Section”).The second stereo pair
of source unit outputs is connected to the
subwoofer amplifier inputs.
Result: with this option, the user has the ability to
fade the level of the subwoofer amplifier’s input
relative to the HF channels, but cannot control
front-to-rear fading of the HF channels. The relative
level of the front and rear HF channels will be fixed
by the 300/4’s “Input Sens.” settings and will not be
user adjustable from the front of the vehicle.
fading the signal to the subwoofer amplifier.

C) Subwoofer Level Control Only

Required: a source unit or processor with left, right

and dedicated subwoofer outputs.

12 JL AUDIO 300/4

JL AUDIO 300/4 15

The Nine-Step Procedure
(follow this procedure for each pair of channels)

1) Disconnect the speaker(s) from the
amplifier’s “Front Speaker Outputs” and
“Rear Speaker Outputs”connectors.

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 300/4).

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.

5) Using the listings on the following pages
(pages 16 & 17), find the configuration that
matches your specific speaker impedance as
connected to the 300/4. Make sure you note
whether your channels are in stereo or bridged
and use the appropriate listing section. Once you
have found your configuration, note the target
voltage for input sensitivity adjustment for each
channel section.This target voltage is listed in
parentheses as “(set to “x” volts)”.

6) Verify that you have disconnected the
speakers 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.

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. 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),
switch the appropriate “Input Voltage” switch to

“High” and re-adjust.

9) Once you have adjusted each set of

channels to its maximum low-distortion 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.

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, including source unit tone controls or EQ
circuits. EQ cuts will not require re-adjustment.

TARGET VOLTAGE

CHARTS ARE ON THE

NEXT TWO PAGES

IMPORTANT

!

(continued on next page)

14 JL AUDIO 300/4

APPENDIX A:

Precise Frequency Selection Chart

“FILTER FREQ” FRONT / REAR FILTERS

Detent Panel Actual

Number Marking Freq.

Full counter-clockwise: 58

01 . . . . . . . . . . . . . . . . . . . . . . . .58

02 . . . . . . . . .“50” . . . . . . . . .58

03 . . . . . . . . . . . . . . . . . . . . . . . .58

04 . . . . . . . . . . . . . . . . . . . . . . . .58

05 . . . . . . . . . . . . . . . . . . . . . . . .59

06 . . . . . . . . . . . . . . . . . . . . . . . .60

07 . . . . . . . . . . . . . . . . . . . . . . . .61

08 . . . . . . . . .“60” . . . . . . . . .63

09 . . . . . . . . . . . . . . . . . . . . . . . .65

10 . . . . . . . . . . . . . . . . . . . . . . . .67

11 . . . . . . . . . . . . . . . . . . . . . . . .69

12 . . . . . . . . . . . . . . . . . . . . . . . .71

13 . . . . . . . . . . . . . . . . . . . . . . . .74

14 . . . . . . . . .“75” . . . . . . . . .77

15 . . . . . . . . . . . . . . . . . . . . . . . .80

16 . . . . . . . . . . . . . . . . . . . . . . . .82

17 . . . . . . . . . . . . . . . . . . . . . . . .85

18 . . . . . . . . . . . . . . . . . . . . . . . .90

19 . . . . . . . . . . . . . . . . . . . . . . . .93

20 . . . . . . . . .“95” . . . . . . . . .97

21 . . . . . . . . . . . . . . . . . . . . . . .102

22 . . . . . . . . . . . . . . . . . . . . . . .107

23 . . . . . . . . . . . . . . . . . . . . . . .113

24 . . . . . . . . . . . . . . . . . . . . . . .120

25 . . . . . . . . . . . . . . . . . . . . . . .127

26 . . . . . . . . .“130” . . . . . . . .135

27 . . . . . . . . . . . . . . . . . . . . . . .143

28 . . . . . . . . . . . . . . . . . . . . . . .153

29 . . . . . . . . . . . . . . . . . . . . . . .171

30 . . . . . . . . . . . . . . . . . . . . . . .182

31 . . . . . . . . . . . . . . . . . . . . . . .201

32 . . . . . . . . .“200” . . . . . . . .223

33 . . . . . . . . . . . . . . . . . . . . . . .253

34 . . . . . . . . . . . . . . . . . . . . . . .289

35 . . . . . . . . . . . . . . . . . . . . . . .337

36 . . . . . . . . . . . . . . . . . . . . . . .404

37 . . . . . . . . . . . . . . . . . . . . . . .474

38 . . . . . . . . .“500” . . . . . . . .514

39 . . . . . . . . . . . . . . . . . . . . . . .525

Full-clockwise: 542

APPENDIX B:

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 - 4Ω per channel (3 - 8Ω
bridged) 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. 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 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). Do not use attenuated test tones
(-10 dB, -20 dB, etc.).

JL AUDIO 300/4 17

SUB-OPTIMUM CONFIGURATIONS (Stereo/Bridged):
First Pair of Channels (Stereo) 2nd Pair of Channels (Bridged)

Stereo 8Ω: 38W x 2 (set to 17.3V / ch.).........................................................Bridged 16Ω: 75W x 1 (set to 34.6V)

Stereo 8Ω: 38W x 2 (set to 17.3V / ch.).........................................................Bridged 12Ω: 100W x 1 (set to 34.6V)

Stereo 8Ω: 38W x 2 (set to 17.3V / ch.).........................................................Bridged 8Ω: 150W x 1 (set to 34.6V)

Stereo 8Ω: 25W x 2 (set to 15.0V / ch.).........................................................Bridged 6Ω: 150W x 1 (set to 30.0V)

Stereo 8Ω: 19W x 2 (set to 12.3V / ch.).........................................................Bridged 4Ω: 150W x 1 (set to 24.6V)

Stereo 8Ω: 14W x 2 (set to 10.6V / ch.).........................................................Bridged 3Ω: 150W x 1 (set to 21.2V)

Stereo 4Ω: 75W x 2 (set to 17.3V / ch.).........................................................Bridged 16Ω: 75W x 1 (set to 34.6V)

Stereo 4Ω: 75W x 2 (set to 17.3V / ch.).........................................................Bridged 12Ω: 100W x 1 (set to 34.6V)

Stereo 4Ω: 50W x 2 (set to 15.0V / ch.).........................................................Bridged 6Ω: 150W x 1 (set to 30.0V)

Stereo 4Ω: 38W x 2 (set to 12.3V / ch.).........................................................Bridged 4Ω: 150W x 1 (set to 24.6V)

Stereo 4Ω: 28W x 2 (set to 10.6V / ch.).........................................................Bridged 3Ω: 150W x 1 (set to 21.2V)

Stereo 3Ω: 75W x 2 (set to 15.0V / ch.).........................................................Bridged 16Ω: 50W x 1 (set to 30.0V)

Stereo 3Ω: 75W x 2 (set to 15.0V / ch.).........................................................Bridged 12Ω: 75W x 1 (set to 30.0V)

Stereo 3Ω: 75W x 2 (set to 15.0V / ch.).........................................................Bridged 8Ω: 100W x 1 (set to 30.0V)

Stereo 3Ω: 50W x 2 (set to 12.3V / ch.).........................................................Bridged 4Ω: 150W x 1 (set to 24.6V)

Stereo 3Ω: 38W x 2 (set to 10.6V / ch.).........................................................Bridged 3Ω: 150W x 1 (set to 21.2V)

Stereo 2Ω: 75W x 2 (set to 12.3V / ch.).........................................................Bridged 16Ω: 38W x 1 (set to 24.6V)

Stereo 2Ω: 75W x 2 (set to 12.3V / ch.).........................................................Bridged 12Ω: 50W x 1 (set to 24.6V)

Stereo 2Ω: 75W x 2 (set to 12.3V / ch.).........................................................Bridged 8Ω: 75W x 1 (set to 24.6V)

Stereo 2Ω: 75W x 2 (set to 12.3V / ch.).........................................................Bridged 6Ω: 100W x 1(set to 24.6V)

Stereo 2Ω: 56W x 2 (set to 10.6V / ch.).........................................................Bridged 3Ω: 100W x 1(set to 21.2V)

Stereo 1.5Ω: 75W x 2 (set to 10.6V / ch.) .....................................................Bridged 16Ω: 28W x 1(set to 21.2V)

Stereo 1.5Ω: 75W x 2 (set to 10.6V / ch.) .....................................................Bridged 12Ω: 38W x 1(set to 21.2V)

Stereo 1.5Ω: 75W x 2 (set to 10.6V / ch.) .....................................................Bridged 8Ω: 56W x 1(set to 21.2V)

Stereo 1.5Ω: 75W x 2 (set to 10.6V / ch.) .....................................................Bridged 6Ω: 75W x 1(set to 21.2V)

Stereo 1.5Ω: 75W x 2 (set to 10.6V / ch.) .....................................................Bridged 4Ω: 112W x 1(set to 21.2V)

SUB-OPTIMUM CONFIGURATIONS (Bridged/Bridged):
First Pair of Channels (Bridged) 2nd Pair of Channels (Bridged)

Bridged 16Ω: 75W x 1 (set to 34.6V)...............................................................Bridged 16Ω: 75W x 1 (set to 34.6V)

Bridged 16Ω: 75W x 1 (set to 34.6V)...............................................................Bridged 12Ω: 100W x 1 (set to 34.6V)

Bridged 16Ω: 75W x 1 (set to 34.6V)...............................................................Bridged 8Ω: 150W x 1 (set to 34.6V)

Bridged 16Ω: 50W x 1 (set to 30.0V)...............................................................Bridged 6Ω: 150W x 1 (set to 30.0V)

Bridged 16Ω: 38W x 1 (set to 24.6V)...............................................................Bridged 4Ω: 150W x 1 (set to 24.6V)

Bridged 16Ω: 38W x 1 (set to 21.2V)...............................................................Bridged 3Ω: 150W x 1 (set to 21.2V)

Bridged 12Ω: 100W x 1 (set to 34.6V)............................................................Bridged 12Ω: 100W x 1 (set to 34.6V)

Bridged 12Ω: 100W x 1 (set to 34.6V)............................................................Bridged 8Ω: 150W x 1 (set to 34.6V)

Bridged 12Ω: 100W x 1 (set to 30.0V)............................................................Bridged 6Ω: 150W x 1 (set to 30.0V)

Bridged 12Ω: 100W x 1 (set to 24.6V)............................................................Bridged 4Ω: 150W x 1 (set to 24.6V)

Bridged 12Ω: 100W x 1 (set to 21.2V)............................................................Bridged 3Ω: 150W x 1 (set to 21.2V)

Bridged 8Ω: 100W x 1 (set to 30.0V)...............................................................Bridged 6Ω: 150W x 1 (set to 30.0V)

Bridged 8Ω: 50W x 1 (set to 24.6V)..................................................................Bridged 4Ω: 150W x 1 (set to 24.6V)

Bridged 8Ω: 50W x 1 (set to 21.2V)..................................................................Bridged 3Ω: 150W x 1 (set to 21.2V)

Bridged 6Ω: 100W x 1 (set to 24.6V)...............................................................Bridged 4Ω: 150W x 1 (set to 24.6V)

Bridged 6Ω: 100W x 1 (set to 21.2V)...............................................................Bridged 3Ω: 150W x 1 (set to 21.2V)

16 JL AUDIO 300/4

APPENDIX B (CONT.):

Input Sensitivity Level Setting Reference Listings
Step 1: Define your front/rear channel configuration (Stereo/Stereo, Stereo/Bridged or Bridged/Bridged
Step 2: Look in the “Optimum Configurations” listing for your channel configuration. If it does not appear here,

look for it in the “Sub-Optimum Configurations” listing for your channel configuration.

Step 3: Once you have found your specific combination of impedances, use the target voltage listed in

parentheses for each set of channels to set the “Input Sens.” controls of the 300/4.

For easy reference, channels achieving optimum power have their power output listed in bold type.

OPTIMUM CONFIGURATIONS (Stereo/Stereo):
1st Pair of Channels (Stereo) 2nd Pair of Channels (Stereo)

Stereo 4Ω: 75W x 2 (set to 17.3 V / ch.)........................................................Stereo 4Ω: 75W x 2 (set to 17.3 V / ch.)

Stereo 3Ω: 75W x 2 (set to 15.0 V / ch.)........................................................Stereo 3Ω: 75W x 2 (set to 15.0 V / ch.)

Stereo 2Ω: 75W x 2 (set to 12.3 V / ch.)........................................................Stereo 2Ω: 75W x 2 (set to 12.3 V / ch.)

Stereo 1.5Ω: 75W x 2 (set to 10.6 V / ch.)....................................................Stereo 1.5Ω: 75W x 2 (set to 10.6 V / ch.)

OPTIMUM CONFIGURATIONS (Stereo/Bridged):
1st Pair of Channels (Stereo) 2nd Pair of Channels (Bridged)

Stereo 4Ω: 75W x 2 (set to 17.3 V / ch.)........................................................Bridged 8Ω: 150W x 1 (set to 34.6 V)

Stereo 3Ω: 75W x 2 (set to 15.0 V / ch.)........................................................Bridged 6Ω: 150W x 1 (set to 30.0 V)

Stereo 2Ω: 75W x 2 (set to 12.3 V / ch.)........................................................Bridged 4Ω: 150W x 1 (set to 24.6 V)

Stereo 1.5Ω: 75W x 2 (set to 10.6 V / ch.)....................................................Bridged 3Ω: 150W x 1 (set to 21.2 V)

OPTIMUM CONFIGURATIONS (Bridged/Bridged):
1st Pair of Channels (Bridged) 2nd Pair of Channels (Bridged)

Bridged 8Ω: 150W x 1(set to 34.6 V) ................................................................Bridged 8Ω: 150W x 1 (set to 34.6 V)

Bridged 6Ω: 150W x 1(set to 30.0 V) ................................................................Bridged 6Ω: 150W x 1 (set to 30.0 V)

Bridged 4Ω: 150W x 1(set to 24.6 V) ................................................................Bridged 4Ω: 150W x 1 (set to 24.6 V)

Bridged 3Ω: 150W x 1(set to 21.2 V) ................................................................Bridged 4Ω: 150W x 1 (set to 21.2 V)

SUB-OPTIMUM CONFIGURATIONS (Stereo/Stereo):
1st Pair of Channels (Stereo) 2nd Pair of Channels (Stereo)

Stereo 8Ω: 38W x 2 (set to 17.3 V / ch.)........................................................Stereo 8Ω: 38W x 2 (set to 17.3 V / ch.)

Stereo 8Ω: 38W x 2 (set to 17.3 V / ch.)........................................................Stereo 6Ω: 50W x 2 (set to 17.3 V / ch.)

Stereo 8Ω: 38W x 2 (set to 17.3 V / ch.)........................................................Stereo 4Ω: 75W x 2 (set to 17.3 V / ch.)

Stereo 8Ω: 28W x 2 (set to 15.0 V / ch.)........................................................Stereo 3Ω: 75W x 2 (set to 15.0 V / ch.)

Stereo 8Ω: 19W x 2 (set to 12.3 V / ch.)........................................................Stereo 2Ω: 75W x 2 (set to 12.3 V / ch.)

Stereo 8Ω: 14W x 2 (set to 10.6 V / ch.)........................................................Stereo 1.5Ω: 75W x 2 (set to 10.6 V / ch.)

Stereo 6Ω: 50W x 2 (set to 17.3 V / ch.)........................................................Stereo 4Ω: 75W x 2 (set to 17.3 V / ch.)

Stereo 6Ω: 38W x 2 (set to 15.0 V / ch.)........................................................Stereo 3Ω: 75W x 2 (set to 15.0 V / ch.)

Stereo 6Ω: 25W x 2 (set to 12.3 V / ch.)........................................................Stereo 2Ω: 75W x 2 (set to 12.3 V / ch.)

Stereo 6Ω: 19W x 2 (set to 10.6 V / ch.)........................................................Stereo 1.5Ω: 75W x 2 (set to 10.6 V / ch.)

Stereo 4Ω: 50W x 2 (set to 15.0 V / ch.)........................................................Stereo 3Ω: 75W x 2 (set to 15.0 V / ch.)

Stereo 4Ω: 38W x 2 (set to 12.3 V / ch.)........................................................Stereo 2Ω: 75W x 2 (set to 12.3 V / ch.)

Stereo 4Ω: 28W x 2 (set to 10.6 V / ch.)........................................................Stereo 1.5Ω: 75W x 2 (set to 10.6 V / ch.)

Stereo 3Ω: 50W x 2 (set to 12.3 V / ch.)........................................................Stereo 2Ω: 75W x 2 (set to 12.3 V / ch.)

Stereo 3Ω: 38W x 2 (set to 10.6 V / ch.)........................................................Stereo 1.5Ω: 75W x 2 (set to 10.6 V / ch.)

Stereo 2Ω: 56W x 2 (set to 10.6 V / ch.)........................................................Stereo 1.5Ω: 75W x 2 (set to 10.6 V / ch.)

JL AUDIO 300/4 19

“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 RCA
cables from the amplifier prior to this test).The frequency
used should be in the range that is to amplified by the
channels being tested (example: 50 Hz for a sub bass
amplifier channel and 1 kHz for a full range amplifier
channel). A steady voltage should be present at the output
of the RCA cables. If you are receiving a sufficient voltage
(between 0.2 and 8.0-volts), check to ensure that the
speaker wires are making a good connection with the metal
inside the amplifier. The connector s are designed to accept
up to an 8 AWG wire. If you are using significantly smaller
wire (14 AWG or smaller), you may have difficulty making
an adequate connection. In this case, you may find it
necessary to “fold” the wire over once (or twice!) so as to
make a solid connection. Make sure to strip the wire to
allow for a sufficient connection with the input or output
of the amplifier.

Check the output of the amplifier. Using the procedure explained in

the previous check item (after plugging the RCA 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 wires from the amplifier while
doing this. Turn the volume up approximately half way.
5 volts 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 above.

“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 amplifier terminal.

Check the RCA connectors to ensure that both the center pin and

the outer shield are making good contact with the input jacks
on the amplifier.

“HOW DO I PROPERLY SET THE INPUT SENSITIVITY ON MY AMPLIFIER”

Please refer to Appendix B (page 14) to set the input sensitivity for

maximum, low-distortion output.

“MY AMPLIFIER DOESN’T TURN ON”

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 “+12V”
wire to the “Remote” terminal to see if the amplifier turns on.
If this does not work, proceed to the next step.

Check the fuse, 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.

“I GET A DISTORTED / ATTENUATED SOUND COMING OUT OF THE SPEAKER(S)”

Check the speaker wires for a possible short, either between the

positive and negative or between a speaker lead and the
vehicle’s chassis ground. If a shor t is present you will
experience distorted and/or attenuated output.The
“Low Ω” light may also illuminate 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 between 1.5 - 4Ω
(3 - 8Ω bridged).

Check the input signal and input signal cables to make sure signal is

present at the “Front Input Section” and “Rear Input
Section” 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 SHUTS OFF ONCE IN A WHILE, USUALLY AT HIGHER VOLUMES”

Check your voltage source and grounding point.The R.I.P.S. power

supply is rated to operate with source voltages between
11 - 14.5V. Shutdown problems at higher levels can occur
when the charging system voltage drops below 10 volts.These
dips can be of very shor t duration making them extremely
difficult to detect with a common DC voltmeter.To ensure
proper voltage, inspect all wiring and termination points. It is
also a good idea to improve the vehicle’s factory ground wire
and termination point. Grounding problems are the leading
cause of mis-diagnosed amplifier failures.

18 JL AUDIO 300/4

APPENDIX C: TROUBLE SHOOTING

JL AUDIO 300/4 21

APPENDIX D:

300/4 Specifications

GENERAL SPECIFICATIONS:

Recommended Fuse Value: 40A

Recommended Fuse Type: AGU or MaxiFuse™

INPUT SECTIONS:

No. of Inputs: Two Stereo Pairs (Front, Rear)

Input Type: Differential-balanced with RCA jack inputs

Input Range: Switchable from 200mV - 2V RMS

to 800mV - 8V RMS

AMPLIFIER SECTIONS:

Amplifier Topology: Class AB with patented Absolute

Symmetry™ dual N-Channel MOSFET output design

Power Supply: Independent, pulse width modulation-

regulated switching power supply with multistage

impedance optimizing circuitry.

Rated Power (Stereo):

75W RMS x 4 @ 1.5-4Ω (11V - 14.5V)

Rated Power (Bridged):

150W RMS x 2 @ 3-8Ω (11V - 14.5V)

THD at Rated Power: <0.03% @ 4Ω per channel

(20 Hz-20 kHz)

Signal to Noise Ratio: >108.5 dB referred to rated power

(A-weighted, 20 Hz-20 kHz noise bandwidth)

Frequency Response: 5 Hz - 30 kHz (+0, -1dB)

Damping Factor: >200 @ 4Ω per ch. / 50 Hz, >100 @ 2Ω

per ch. / 50 Hz

Slew Rate: ± 25V/µs

FILTER SECTIONS:

Front and Rear Filters (2): State-variable, 12 dB/octave

Butterworth or 24 dB/octave Linkwitz-Riley low-pass or

high-pass with continuously variable cutoff frequency from

50 - 500 Hz, switchable to a range of 500 - 5000 Hz, via

x10 switch. Defeatable.

DIMENSIONS (LxWxH):

13.4" x 9.25" x 2.36" (340mm x 235mm x 60mm)

Due to ongoing product development, all specifications are

subject to change without notice.

20 JL AUDIO 300/4

JL AUDIO 300/4 23

22 JL AUDIO 300/4

INSTALLATION NOTES:

Use this diagram to document your amplifier’s switch and control positions.

LIMITED WARRANTY - AMPLIFIERS (USA)

JL AUDIO warrants this product to be free of defects in materials and workmanship for a period of ninety
(90) days from the original date of purchase. The warranty term is extended to two (2) years if installation is
performed or approved by an authorized JL AUDIO dealer (proof of installation or approval required on
purchase receipt).

This warranty is not transferrable and applies only to the original purchaser from an authorized JL AUDIO
dealer. Should service be necessary under this warranty for any reason due to manufacturing defect or
malfunction, JL AUDIO will (at its discretion),repair or replace the defective product with new or remanufactured
product at no charge. Damage caused by the following is not covered under warranty: accident, misuse, abuse,
product modification or neglect, failure to follow installation instructions, unauthorized repair attempts,
misrepresentations by the seller.This warranty does not cover incidental or consequential damages and does not
cover the cost of removing or reinstalling the unit(s). Cosmetic damage due to accident or normal wear and tear
is not covered under warranty.

Warranty is void if the product’s serial number has been removed or defaced.

Any applicable implied warranties are limited in duration to the period of the express warranty as provided
herein beginning with the date of the original purchase at retail, and no warranties, whether express or implied,
shall apply to this product thereafter. Some states do not allow limitations on implied warranties, therefore these
exclusions may not apply to you.This warranty gives you specific legal rights, and you may also have other rights
which vary from state to state.

If you need service on your JL AUDIO product:

All warranty returns should be sent to JL AUDIO ’s Amplifier Service Facility freight-prepaid through an
authorized JL AUDIO dealer and must be accompanied by proof of purchase (a copy of the original sales receipt).
Direct returns from consumers or non-authorized dealers will be refused unless specifically authorized by
JL AUDIO with a valid return authorization number.

Warranty expiration on products returned without proof of purchase will be determined from the
manufacturing date code. Coverage may be invalidated as this date is previous to purchase date. Non-defective
items received will be returned freight-collect. Customer is responsible for shipping charges and insurance in
sending the product to JL AUDIO. Freight damage on returns is not covered under warranty.

For Service Information in the U.S.A. please call:

JL Audio customer service: [phone]

during normal business hours (9:00 AM – 5:30 PM Eastern Time)

JL Audio, Inc

10369 North Commerce Pkwy.

Miramar, FL 33025

(do not send product for repair to this address)

International Warranties:

Products purchased outside the United States of America are covered only

by that country’s distributor and not by JL Audio, Inc.

JL3004MAN-04-2003

Absolute Symmetry™Class AB Amplifier Circuit is covered by U.S. Patent #6,294,959 and is
pending in the countries listed below. Austria, Belgium,Brazil, Canada, China,France, Germany,Indonesia,

Italy, Japan, Republic of Korea, Mexico, Netherlands, Norway, Russian Federation, Singapore, Sweden,
Switzerland, United Kingdom, and all other PCT countries.