JBL GTS600 Owner's Manual

either subwoofer or component

speakers in a bi-amplified system,

or conventional full-range speakers

in simpler systems.

The GTS300 and 600 also include

preamp-level outputs which can

provide either full-range, high-pass

or low-pass signal to drive

additional amplifiers. This lets you

build systems of virtually any

design without requiring a

separate electronic crossover.

1.2 About Installation

Although the GTS300 and GTS600

are designed to make installation

as easy as possible, they are

sophisticated products that require

proper installation to realize their

full performance potential.

If you feel you do not have the

necessary knowledge and skills we

strongly recommend that the

installation be done by your

authorized JBL dealer.

If you choose to install the GTS300

or GTS600 yourself read 

all

of the

information in this manual

before

you start the installation.

Pay particular attention to the

safety precautions and notes.

2. Installation and Use

Refer to the “Crossover Frequency

Adjustments” and “Speaker Level

Input Impedance Adjustments”

sections of this manual to see if

you will need to make alterations

to their factory settings. If you are

not using the built-in crossover, or

the speaker level inputs, you may

skip this step.

1. Disconnect the negative cable

from the battery. 

Note: If the

vehicle’s radio features a code

type security system, make

certain you know the code

1

1. Introduction

Thanks for purchasing your new

GT series automotive amplifier.

The GT series amplifier you have

chosen includes many unique

features to enhance its perfor-

mance and utility. The power amp-

lifier circuitry is a fully discrete

design notable for its low dis-

tortion and unusually clean and

clear sound quality. Your GT series

amplifier will easily connect to

virtually any car audio system,

whether it is factory installed or

one purchased separately.

In addition to conventional

preamplevel inputs, this model

features JBL’s Universal Interface

design, which facilitates simple

connection to factory radios with

the low distortion that is usually

only associated with preamp level

connection. With Universal Inter-

face, a factory radio can be used

either as the main music source or

combined with a CD player or

changer, which includes volume

control capability, simultaneously

connected to the amplifier. By

providing this two-unit direct

connection, Universal Interface

circuitry eliminates the need for an

FM modulator to interface a CD

player to factory radios, improving

the fidelity of digital playback.

In addition, when using a high-

powered (BTL) radio through the

speaker-level inputs, Common

Sense turn-on circuitry senses the

common-mode voltage present on

the radio’s speaker wires, turning

the amplifier on without an

additional “remote” wire.

Also, the built-in active crossover

provides either full-range, high-

pass or low-pass operation. This

lets your GT series amplifier power