JBL GTH400-20107 manual Adjusting the Gain, Ground Wire, 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.

Do not connect to the vehicle’s fuse block or to a wire feeding other accessories.

•To prevent electrical system damage or fire, a fuse holder and fuse (not included – maximum 60 Amp) must be installed in the power supply wire as close to the battery as possible, and before the wire travels through the firewall or other metal panel.

Ground Wire

•Proper grounding is extremely important. Use a heat- and oil- resistant stranded copper automotive wire equivalent to the size used for the +12V connection. Crimp or solder and insulate any wire-to-wire connections. Keep the ground wire as short as possible. A ground wire must be solidly connected to a major sheet metal structure of the vehicle such as a panel near the amp-mounting location. Scrape all paint and primer off the sheet metal at the grounding point to ensure a good electrical connection. Attach the wire to the grounding point with a nut, bolt and star washer. The high current demanded by high-powered amplifiers requires a more secure ground than the typical sheet-metal screw will provide.

The color code for the speaker-level input harness is as follows:

Speaker-Level Input Harness

Color Codes
Group 1 Left (+):		White
Group 1 Left (–):		White with
		Black Stripe
Group 1 Right (+):		Gray
Group 1 Right (–):		Gray with
		Black Stripe
Group 2	Left (+):	Green
Group 2	Left (–):	Green with
		Black Stripe
Group 2	Right (+):	Purple
Group 2	Right (–):	Purple with
		Black Stripe

5. Adjusting the Gain

Before operating the GTH400, recheck all wiring connections to make sure they are correct and secure. Be sure that a fuse (60 amps, not included) is installed in the +12V line near the battery. Reconnect the negative ground (–) terminal of the battery. Make sure that the mode switches, crossover switches, Group 2 & 3 Input switches, and crossover frequency modules, are properly set.

•The setting of the gain controls on the GTH400 is important to ensure proper performance, low noise levels, and maximum reliability in the system. As a general rule, controls on components at the front-end of the system (source, equalizers, electronic crossovers, etc.) should be set as high as possible, with the amplifier gain control set as low as possible while still providing adequate volume levels. Using a high signal level from the source and a low gain setting on the amplifier will help keep

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