GTH400-20107 06/03/98 15:49 Side 18
background noise levels in the systemthe head unitOs volume control to a
low.comfortable level, and adjust the
YTo adjust a system using a singleremaining channels for the desired
GTH400, start with all three of thesystem balance. You will find this
easiest to do by adjusting the
amplifier gain controls fullychannels in the following order: 1)
counterclockwise and the Imagingfront speaker Group, 2) rear speaker
Enhancer Remote set to OBypass�
mode. Some head units haveGroup, 3) subwoofer speaker Group.
additional output level controls orElaborate systems incorporating tri- or
quad-amplification can be complex to
switches. Set those to their maximumadjust. Your local authorized JBL
position.installation specialist is the best
YSet the level controls on anyperson to help with such adjustment.
associated equipment such asImaging Enhancer Setup
equalizers and electronic crossovers
as recommended by theirAfter the installation and set up is
manufacturers. Set all Bass/ Treble orfinished and all wiring is checked,
proceed with the next few steps to set
equalizer controls to their centered orup the Imaging Enhancer on the
bypassed positions. While listening
carefully to the system output, adjustGTH400.
the volume control of the radio/tapeNote: Since the Imaging Enhancer in
deck to the point where you first beginthe GTH400 is primarily designed to
to hear audible distortion. Use caution:optimize the sound stage for the driver,
excessive distortion can damageall tests should be performed while
loudspeakers.Reduce the level just tositting in the driverOs seat.
the point where the distortion goes1. The Power Indicator LED on the
away. This is the maximum
undistorted output level of your headGTH400 main chassis should light
up when the head unit is turned on.
unit and signal processors, and should2. Make sure the OFront-Ambience/
not be exceeded during use. If audibleBypass/On� knob and ORear-
distortion does not occur, continue toAmbience/Driver/All� knobs are
increase the level until the head unit is
turned all the way up. If this settingpushed in and rotated completely
counterclockwise.
does not provide adequate volume 3. Play a selection which has vocals
levels, gradually increase (turnand good Ocenter� information.
clockwise) the gain control for the
main (usually front) speaker groups on4. Gently turn up the volume to a
the GTH400 until the system plays ascomfortable listening level. You
should hear a very distinctive center
loud as necessary or when the firstimage coming from the middle of
signs of distortion are heard.your dashboard. If not, make sure
YAfter adjusting the main speakerOsthe ORear-Ambience/Driver/All�
gain control, you may then turn downknob is pushed in to the ODriver�
18 |
ACEC
