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 distor-
tion 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 lev-
els, gradually increase (turn clockwise)
the gain control of the GTS100 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 comfort-
able level, and adjust the remaining
amplifiers for the desired system bal-
ance. You will find this easiest to do by
adjusting the amplifiers in the following
order: 1) front-channels, 2) rear-chan-
nels, 3) subwoofers. Complex systems
incorporating tri-or quad-amplification
can be time consuming to adjust. Your
local authorized JBL installation special-
ist is the best person to help with such
adjustment.
Other Characteristics
Turn-On Delay – When installed as
described in this manual, the GTS100
will turn on and off with the head unit or
the vehicle’s ignition switch. When the
amplifier is turned on, there is a time
delay of several seconds (longer in cold
20
Operation
Before operating the GTS100, 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
GTS100 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 ade-
quate volume levels. Using a high sig-
nal level from the source and a low
gain setting on the amplifier will help
keep background noise levels in the
system low.
To adjust a system using a single
amplifier, start with the amplifier input
sensitivity controls fully counterclock-
wise. Some radio/tape decks have addi-
tional 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 to the maximum
position or as recommended by the
manufacturer. Set all Bass/Treble or
equalizer controls to their centered or
bypassed positions. While listening
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