Imaging Enhancer Setup

GTH400-20107 06/03/98 15:49 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. Set those to their maximum position.

•Set the level controls on any associated equipment such as equalizers and electronic crossovers as recommended by their manufacturers. Set all Bass/ Treble or equalizer controls to their centered or bypassed positions. While listening carefully to the system output, adjust the volume control of the radio/tape deck to the point where you first begin to hear audible distortion. Use caution: excessive distortion can damage loudspeakers. Reduce the level just to the point where the distortion goes away. This is the maximum undistorted output level of your head unit and signal processors, and should not be exceeded during use. If audible distortion does not occur, continue to increase the level until the head unit is turned all the way up. If this setting does not provide adequate volume levels, gradually increase (turn clockwise) the gain control for the main (usually front) speaker groups on the GTH400 until the system plays as loud as necessary or when the first signs of distortion are heard.

•After adjusting the main speaker’s gain control, you may then turn down

the head unit’s volume control to a comfortable level, and adjust the remaining channels for the desired system balance. You will find this easiest to do by adjusting the channels in the following order: 1) front speaker Group, 2) rear speaker Group, 3) subwoofer speaker Group. Elaborate systems incorporating tri- or quad-amplification can be complex to adjust. Your local authorized JBL installation specialist is the best person to help with such adjustment.

After the installation and set up is finished and all wiring is checked, proceed with the next few steps to set up the Imaging Enhancer on the GTH400.

Note: Since the Imaging Enhancer in the GTH400 is primarily designed to optimize the sound stage for the driver, all tests should be performed while sitting in the driver’s seat.

1.The Power Indicator LED on the GTH400 main chassis should light up when the head unit is turned on.

2.Make sure the “Front-Ambience/ Bypass/On” knob and “Rear- Ambience/Driver/All” knobs are pushed in and rotated completely counterclockwise.

3.Play a selection which has vocals and good “center” information.

4.Gently turn up the volume to a comfortable listening level. You should hear a very distinctive center image coming from the middle of your dashboard. If not, make sure the “Rear-Ambience/Driver/All” knob is pushed in to the “Driver”