JBL GTS300
Owner's Manual

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 performance and utility. The power amplifier circuitry is a fully discrete design notable for its low distortion 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 Interface, 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 highpowered (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, highpass or low-pass operation. This lets your GT series amplifier power 1

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