23
Operation
Before operating the GTS100x,
recheck all wiring connections to
make sure they are correct and
secure. Be sure that a 20-amp
fuse (not included) is installed in
the
+
12V line next to the battery.
Reconnect the negative ground
(–) terminal of the battery. Make
sure that the input mode selector,
crossover switch and preamp
mode switch are properly set.
Gain Adjustments
The setting of the gain control on
the GTS100x is important to
ensure proper performance, low
noise levels, and maximum relia-
bility 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 ampli-
fier 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 back-
ground noise levels in the
system low.
To adjust a system using a single
amplifier, start with the amplifier
input sensitivity controls fully
counterclockwise. Some radio/
tape decks have additional output
level controls or switches. Set
these to their maximum position.
Set the level controls on any
associated equipment such as
equalizers and electronic
crossovers to the maximum
position or as recommended by
the manufacturer. Set all Bass/
Treble or equalizer controls to
their centered or bypassed posi-
tions. 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.
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 audi-
ble distortion does not occur, con-
tinue 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 clock-
wise) the gain control of the
GTS100x until the system plays
as loud as necessary or when the
first signs of distortion are heard.
When multiple amplifiers are
used in the system, it is best to
adjust the gain of the amplifier
driving the main (usually front)
speakers first. Then turn down
the head unit’s volume control to
a comfortable level, and adjust
the remaining amplifiers for the
desired system balance. You will
find this easiest to do by adjust-
ing the amplifiers in the following
order: 1) front channels, 2) rear
channels, 3) subwoofers. Complex
systems incorporating tri- or
quad-amplification can be time-
consuming to adjust. Your local
authorized JBL installation spe-
cialist is the best person to help
with such adjustment.
GTS100x OM 7/16/98 2:56 PM Page 23
