JL 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 batter y 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 certain 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” r ange 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