slash 450 4 User Manual

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 (60A for a 

single 450/4) 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 1&2 and 3&4 channel

sections to obtain the right overall output and the

desired balance between their outputs. See

Appendix B (page 20) for the recommended input

sensitivity setting method.

16) Enjoy the fruits of your labor with your

favorite music.

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 450/4's “+12 VDC” and “Ground”

connections are designed to accept 4 AWG power

wire. 4 AWG is the only recommended

If you are installing the 450/4 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 450/4 with 

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 

(4 AWG) 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.

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 

450/4 is being run from that power wire, we

recommend a 60A 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 60A AGU fuse

or MaxiFuse™ type.

JL AUDIO 450/4

5

The JL Audio 450/4 is a four-channel system

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 staggered power distribution of the 1&2 and

3&4 channel pairs (150W x 2 for CH 1&2 and 

75 x 2 for CH 3&4) allows for a wide variety of

application options.The 450/4 can be operated in

the following modes:

1) As a full-system amplifier in bi-amp mode with

CH 1&2 driving subwoofers in low-pass mode

(150W x 1 or 300W x 1) and CH 3&4 driving

main speakers in high-pass mode (75W x 2).

2) As a high power four-channel satellite amplifier

in a bi-amplified system, delivering high-passed

signals to front and rear speaker systems. In this

mode, we recommend that CH 1&2 drive the front

speaker systems and CH 3&4 drive the rear speaker

systems. Preamp outputs permit connection of a

separate amplifier to drive the subwoofer system.

3) As a high power four-channel satellite amplifier

in a tri-amplified system, delivering band-passed

signals through CH 1&2 to mid-bass speakers and

high-passed signals through CH 3&4 to  mid-range/

tweeter speaker systems. Preamp outputs permit

connection of a separate amplifier to drive the

subwoofer system.

4) As a high power three-channel satellite

amplifier, delivering 150W x 3 at 4

Ω in high-pass

mode to left, center and right speaker systems.This

requires bridging the outputs of CH 3&4 to create

an equal power third channel to complement 

CH 1&2. Preamp outputs permit connection of a

separate amplifier to drive the subwoofer system.

The 450/4's flexible input and crossover sections

permit operation with a wide variety of source units

and system configurations.The 450/4 can operate

with a single pair of stereo inputs or with separate

inputs for CH 1&2 and CH 3&4, if the source unit is

equipped with front and rear outputs.The 450/4's

preamp output can send pass-through signals from

the CH 1&2 inputs only OR the CH 3&4 inputs

only OR it can sum all four input channels to feed a

subwoofer amplifier.This latter mode allows for non-

fading sub-bass with front to rear satellite fading.

As we said, it's very flexible.

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 4 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 450/4.

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 450/4. 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 4 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.

11) Connect the speaker wires to the amplifier.

4

JL AUDIO 450/4