JBL GTH400 Owner's Manual
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JBL GTH400 Owner's Manual

JBL GTH400 Owner's Manual

6/5/4/3 channel automotive power amplifier
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GTH400-20107
06/03/98 15:49
Side 26

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Summary of Contents for JBL GTH400

  • Page 1 GTH400-20107 06/03/98 15:49 Side 26...
  • Page 2 GTH400-20107 06/03/98 15:49 Side 1 GTH400 6/5/4/3 CHANNEL AUTOMOTIVE POWER AMPLIFIER OWNER’S MANUAL...

  • Page 3: Table Of Contents

    1. Introduction... 3 1.1 Features ... 4 1.2 About Installation ... 4 2. Installation and use ... 5 3. System Design with the GTH400... 6 3.1 Speaker Requirements ... 6 3.2 Typical Applications... 7 4. Installation and Use ... 9 4.1 Controls and Connectors...

  • Page 4: Introduction

    In addition to conventional preamp- level inputs, the GTH400 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.

  • Page 5: Features

    JBL dealer. If you choose to install the GTH400 yourself, read all of the information in this manual before you start the installation. Pay particular attention to...

  • Page 6: Installation And Use

    GTH400-20107 06/03/98 15:49 Side 5 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. 1. Disconnect the negative cable from the battery.

  • Page 7: System Design With The Gth400

    8 ohms Nominal Impedance (–) ohms When a group of the GTH400 is in bridged mode, the combined impedance of the speaker (or speakers) connected to the bridged channels should be at least 4 ohms. As in the example above, sustained operation of...

  • Page 8: Typical Applications

    06/03/98 15:49 Side 7 3.2 Typical Applications The diagrams on pages 8 & 9 show the most common basic system configurations of the GTH400. One or more of these building blocks may be combined to form elaborate system designs. Application 1...
  • Page 9 GTH400-20107 06/03/98 15:49 Side 8 Application 3 4-Channel Full-Range or Bi-Amplified 4-Channel Full-Range Group 1 Input Mode Group 2 Input – Group 3 Input – Speaker Crossover Flat Preamp Output Crossover – 4-Channel Bi-Amplified with Fading Mono Subwoofers Group 1...

  • Page 10: Installation And Use

    See “Audio Input Connections” section (page 23) for wiring instructions. This input also includes JBL’s Common Sense input circuitry which turns the amplifier on as soon as the high powered head unit connected to this input is turned on.
  • Page 11 GTH400-20107 06/03/98 15:49 Side 10 to use in conjunction with a high- pass filtered input signal to create a bandpass crossover (for a midrange or midbass driver). Set the switch to H (high) to activate the high-pass filter for use with satellite speakers or tweeters on an amplifier group.
  • Page 12 GTH400-20107 06/03/98 15:49 Side 11 BOOST BASS BOOST BASS BOOST BASS...

  • Page 13: Internal Adjustments

    Side 12 4.2 Internal Adjustments Speaker-Level Input Impedance Adjustments The speaker level inputs of the GTH400 come factory set with 100k ohm input impedance. This will provide the lowest distortion operation from the speaker outputs of most modern head units by...

  • Page 14: Custom Chip Construction

    For further information on how to use the speaker output and preamp output crossovers for system building see the “Typical Applications” and “Add-On and Upgrade Steps” sections. Remote Chassis Installation The wired remote of the GTH400 can be installed either in dash or under dash.

  • Page 15: Unter-Dash Remote Installation

    GTH400 Front Rear Group 1 Group 2 The right and left inputs and outputs of the GTH400 must be reversed for proper functioning of the virtual center image enhancer when used in a right hand drive automobile. Power Supply Connections...
  • Page 16 GTH400-20107 06/03/98 15:49 Side 15 FACE PLATE SPACER PLATE (INCLUDED) Cassette/CD Tuner Antenna Input Power Cassette/Receiver Antenna Power Supply Wires Power Antenna Cassette/CD Preamp Output Relay Blue w/White Stripe - Remote On/Off Ignition Switch 60 Amp (Not Included) Fuse –...

  • Page 17: Simultaneous Speaker Stereo-Mono Connection Diagram

    GTH400-20107 06/03/98 15:49 Side 16 is heat- and oil-resistant whenever running wires through the engine compartment. All wire-to-wire connections should be soldered and insulated with heat shrink tubing, or connected through a high-quality Simultaneous Stereo-Mono Connection Diagrams A. Satellite/Subwoofer High Pass Satellite...

  • Page 18: Speaker-Level Input Harness Color Codes

    GTH400-20107 06/03/98 15:49 Side 17 •The GTH400 will draw as much as 60 amps from the vehicle’s electrical system, enough to overload conventional vehicle wiring. Therefore the +12 volt power supply must be taken directly from the positive side of the battery.
  • Page 19 Side 18 background noise levels in the system low. •To adjust a system using a single GTH400, start with all three of the amplifier gain controls fully counterclockwise and the Imaging Enhancer Remote set to “Bypass” mode. Some head units have additional output level controls or switches.

  • Page 20: Important Characteristics

    “Driver” position is slightly offset to the left or right side of the dashboard, switch the car-size switch located inside of the GTH400 under the bottom cover as shown below. This switch optimizes the Imaging Enhancer for standard or large cars.
  • Page 21 GTH400-20107 06/03/98 15:50 Side 20 and off, or does not work at all, a problem in installation or an abnormal electrical condition is indicated. Check speaker wiring for short circuits or impedance loads significantly below 2 ohms (4 ohms in bridged mode). Check the power supply voltage at the input of the amplifier to be sure that it is normal;...

  • Page 22: In Case Of Difficulty

    If the new fuses blow immediately, then check all the wiring connections. If no fault is found, consult your JBL dealer. • Remote-on wire between the head unit and the amplifiers is disconnected or defective; check for +12 volts between amplifiers remote-on input terminal and the ground wire with the head unit on.
  • Page 23 • Perform the adjustments as directed in the Imaging Enhancer Setup section. • Incorrectly connected or shorted speaker wires; check for shorts in wiring. • Defective GTH400; if there is no short on the speaker outputs, the GTH400 may be broken. Consult your JBL dealer.

  • Page 24: Specifications

    GTH400-20107 06/03/98 15:50 Side 23 8. Specifications Signal to Noise Ratio Frequency Response Damping Factor Slew Factor Line Level Input Sensitivity (For Rated Power) Line Level Input Impedance Speaker Level Input Impedance Speaker Level Input Sensitivity Preamp Output Sensitivity Preamp Input:...
  • Page 25 GTH400-20107 06/03/98 15:50 Side 24 Power Requirement 11 to 16V DC Negative Ground Fuse Size 30 Amp ATC Type Fuse (2 per Amplifier) Size (L x W x H) 15-1/4" x 11-1/4" x 2" (387mm x 286mm x 51mm) Weight...
  • Page 26 GTH400-20107 06/03/98 15:50 Side 25 Staple or clip your original bill of sale here.

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