JBL GTS 100 (serv.man2) User Manual / Operation Manual ▷ View online
and 16 volts. Check that the power
wires are not reversed.
wires are not reversed.
If the GTS100 is operated at very high
power levels in a high ambient tempera-
ture situation, the unit may not be able
to radiate all the heat generated by
such operation. If the temperature of
the amplifier reaches a level that could
cause damage, the thermal overload
protection circuit will turn the amplifier
off. It will turn the amp back on again
when it cools off. Repeated activation of
the protection circuits indicates that the
system is being improperly operated or
that the amplifier should be relocated to
an area that either has a lower ambient
temperature or that allows more air cir-
culation around the unit.
power levels in a high ambient tempera-
ture situation, the unit may not be able
to radiate all the heat generated by
such operation. If the temperature of
the amplifier reaches a level that could
cause damage, the thermal overload
protection circuit will turn the amplifier
off. It will turn the amp back on again
when it cools off. Repeated activation of
the protection circuits indicates that the
system is being improperly operated or
that the amplifier should be relocated to
an area that either has a lower ambient
temperature or that allows more air cir-
culation around the unit.
Fuse Replacement – If the fuse on the
GTS100 must be replaced, DO NOT
use a fuse rated for higher current lev-
els. The fuse size for the GTS100 is 20
amps. Exceeding the standard fuse size
or bypassing the fuse holder will void
the warranty and may cause serious
damage. It is extremely rare for this
fuse to blow. If it blows repeatedly, it is
most likely that the amplifier has an
internal problem that will need to be
repaired by an authorized service cen-
ter. The only external cause for this
fuse to blow is reversed polarity of the
power wire connections.
GTS100 must be replaced, DO NOT
use a fuse rated for higher current lev-
els. The fuse size for the GTS100 is 20
amps. Exceeding the standard fuse size
or bypassing the fuse holder will void
the warranty and may cause serious
damage. It is extremely rare for this
fuse to blow. If it blows repeatedly, it is
most likely that the amplifier has an
internal problem that will need to be
repaired by an authorized service cen-
ter. The only external cause for this
fuse to blow is reversed polarity of the
power wire connections.
Solving Noise Problems
The power supply system of every vehi-
cle has some electrical “noise” that is
generated by the ignition system, the
alternator, the accessories, and their
wiring. High performance audio equip-
cle has some electrical “noise” that is
generated by the ignition system, the
alternator, the accessories, and their
wiring. High performance audio equip-
weather) before the amplifier will pro-
duce sound. This eliminates the chance
of annoying noises produced by the
radio or signal processors being ampli-
fied and passed to the speakers when
the system is first turned on.
duce sound. This eliminates the chance
of annoying noises produced by the
radio or signal processors being ampli-
fied and passed to the speakers when
the system is first turned on.
Power Consumption – Operating the
GTS100 when the vehicle is not running
may discharge the battery. Under nor-
mal operating conditions, the units will
draw an average of 5 amps from the
battery. At high volumes, the amplifier
can draw as much as 20 amps for brief
bursts. After even a short period of
time, this current drain can discharge
the battery to the point that it will not
start the vehicle. Power consumption
under “no signal” conditions is less than
1 amp for the GTS100. Even this small
power usage can discharge a battery
over several hours time. When the
GTS100 is turned off, there is no cur-
rent drawn from the battery despite the
direct-to-battery power connection.
GTS100 when the vehicle is not running
may discharge the battery. Under nor-
mal operating conditions, the units will
draw an average of 5 amps from the
battery. At high volumes, the amplifier
can draw as much as 20 amps for brief
bursts. After even a short period of
time, this current drain can discharge
the battery to the point that it will not
start the vehicle. Power consumption
under “no signal” conditions is less than
1 amp for the GTS100. Even this small
power usage can discharge a battery
over several hours time. When the
GTS100 is turned off, there is no cur-
rent drawn from the battery despite the
direct-to-battery power connection.
Overload Protection – The GTS100
incorporates elaborate protection cir-
cuitry to prevent damage to the ampli-
fier circuitry and ensure reliable opera-
tion. This circuitry will turn the amplifier
off in the event of overheating, a short
circuit on the speaker output wiring, or
improper power supply connections. If
the amplifier cycles on and off, or does
not work at all, a problem in installation
or an abnormal electrical condition is
indicated. Check speaker wiring for
short circuits or impedance loads signif-
icantly below 2 ohms, (4 ohms in
bridged mode). Check the power supply
voltage at the input of the amplifier to
be sure that it is normal, between 11
incorporates elaborate protection cir-
cuitry to prevent damage to the ampli-
fier circuitry and ensure reliable opera-
tion. This circuitry will turn the amplifier
off in the event of overheating, a short
circuit on the speaker output wiring, or
improper power supply connections. If
the amplifier cycles on and off, or does
not work at all, a problem in installation
or an abnormal electrical condition is
indicated. Check speaker wiring for
short circuits or impedance loads signif-
icantly below 2 ohms, (4 ohms in
bridged mode). Check the power supply
voltage at the input of the amplifier to
be sure that it is normal, between 11
21
JBL 1394 Manual 7/17/98 11:49 AM Page 21
the amplifiers and signal processors are
all grounded to the same point on the
chassis. Usually the head unit does not
need to be grounded to the same point
as the rest of the system, but in some
instances grounding the head unit to
the same point will also help. If this
does not adequately reduce the noise
level, try another ground point on the
car frame. Some ground points may
work better than others. In some in-
stances with plastic-bodied vehicles,
grounding the source unit and/or
amplifier directly to the battery will
provide the best results, although,
usually, this provides the worst results
with most cars.
all grounded to the same point on the
chassis. Usually the head unit does not
need to be grounded to the same point
as the rest of the system, but in some
instances grounding the head unit to
the same point will also help. If this
does not adequately reduce the noise
level, try another ground point on the
car frame. Some ground points may
work better than others. In some in-
stances with plastic-bodied vehicles,
grounding the source unit and/or
amplifier directly to the battery will
provide the best results, although,
usually, this provides the worst results
with most cars.
In complex systems involving compo-
nents from different manufacturers, it
helps to know the type of power sup-
plies used in each component. For
low-level signal processors such as
equalizers or electronic crossovers, a
manufacturer may either use a power
supply which is isolated through a DC-
to-DC converter, or a simple regulated
supply from the +12V vehicle battery.
Components using the latter type of
supply can be identified by a direct con-
nection from power ground to the shield
of the RCA jacks (measured with no
other connections present). For these
components, the best ground connec-
tion may be one where the power
ground wire is not connected at all! The
RCA cables will provide the ground
connection to the source unit. Please
note that this is only appropriate for
units which draw less than 500mA of
current. Higher power units of this type
are best connected with their ground
nents from different manufacturers, it
helps to know the type of power sup-
plies used in each component. For
low-level signal processors such as
equalizers or electronic crossovers, a
manufacturer may either use a power
supply which is isolated through a DC-
to-DC converter, or a simple regulated
supply from the +12V vehicle battery.
Components using the latter type of
supply can be identified by a direct con-
nection from power ground to the shield
of the RCA jacks (measured with no
other connections present). For these
components, the best ground connec-
tion may be one where the power
ground wire is not connected at all! The
RCA cables will provide the ground
connection to the source unit. Please
note that this is only appropriate for
units which draw less than 500mA of
current. Higher power units of this type
are best connected with their ground
22
ment is more likely to pick up such
noise than conventional equipment
because it has wide frequency band-
width and high gain (amplification) cir-
cuits. The GTS100 has built-in power
supply filters to help prevent noise prob-
lems. If noise occurs it is probably the
result of improper installation. The
following suggestions will help you
eliminate most noise problems.
noise than conventional equipment
because it has wide frequency band-
width and high gain (amplification) cir-
cuits. The GTS100 has built-in power
supply filters to help prevent noise prob-
lems. If noise occurs it is probably the
result of improper installation. The
following suggestions will help you
eliminate most noise problems.
Source Noise – Often noise in a system
is picked up by the signal source.
Before attempting to eliminate noise
from the “amp” be sure it is not being
picked up by the signal source and then
passed on to the amp. To do this, con-
nect the signal source output to an
external amplifier which has no other
connection to the vehicle except for the
audio signal leads. A battery-powered
portable with line-inputs works well for
this. Listen to see if the noise is present
in the signal from the source unit. If so,
consult the manufacturer of the source
unit, or your JBL dealer, for help in elim-
inating this noise. If there is no noise in
this signal, it can be eliminated as the
source of the noise in your system.
is picked up by the signal source.
Before attempting to eliminate noise
from the “amp” be sure it is not being
picked up by the signal source and then
passed on to the amp. To do this, con-
nect the signal source output to an
external amplifier which has no other
connection to the vehicle except for the
audio signal leads. A battery-powered
portable with line-inputs works well for
this. Listen to see if the noise is present
in the signal from the source unit. If so,
consult the manufacturer of the source
unit, or your JBL dealer, for help in elim-
inating this noise. If there is no noise in
this signal, it can be eliminated as the
source of the noise in your system.
Ground Loops – The vast majority of
noise problems in car audio systems
are caused by inadequate or improper
grounding. The head unit, the amplifier
and any other components must be
grounded to a major metal member of
the vehicle’s frame. Make sure to
choose a solid metal ground point. In
many new vehicles some structural ele-
ments are made of plastic.
noise problems in car audio systems
are caused by inadequate or improper
grounding. The head unit, the amplifier
and any other components must be
grounded to a major metal member of
the vehicle’s frame. Make sure to
choose a solid metal ground point. In
many new vehicles some structural ele-
ments are made of plastic.
Although not usually necessary, practi-
cal experience shows that often the
noise level in the system will be lower if
cal experience shows that often the
noise level in the system will be lower if
JBL 1394 Manual 7/17/98 11:49 AM Page 22
must cross, they should cross at right
angles. If you suspect that power line
noise is being induced in the signal
leads, you can repeat the test for
source noise described previously, but
perform the test at the amplifier end of
the signal cables.
angles. If you suspect that power line
noise is being induced in the signal
leads, you can repeat the test for
source noise described previously, but
perform the test at the amplifier end of
the signal cables.
Other Noise Sources – Common noise
problems will be solved by proper
grounding and power supply connec-
tions. However, there are many noise
suppression devices (such as spark
plug and coil lead suppressers and
rotor and coil bypass capacitors) avail-
able at auto parts or car stereo stores.
There are also noise suppressers that
can be connected directly to the alter-
nator that are effective in some situa-
tions. The use of any such suppressors
should be discussed with a JBL autho-
rized installation specialist. Certain
vehicles are particularly “noisy,” espe-
cially models that have solid state igni-
tion systems or that have non-metal
bodies. Such vehicles may require elec-
trical noise suppression devices which
are not normally needed.
problems will be solved by proper
grounding and power supply connec-
tions. However, there are many noise
suppression devices (such as spark
plug and coil lead suppressers and
rotor and coil bypass capacitors) avail-
able at auto parts or car stereo stores.
There are also noise suppressers that
can be connected directly to the alter-
nator that are effective in some situa-
tions. The use of any such suppressors
should be discussed with a JBL autho-
rized installation specialist. Certain
vehicles are particularly “noisy,” espe-
cially models that have solid state igni-
tion systems or that have non-metal
bodies. Such vehicles may require elec-
trical noise suppression devices which
are not normally needed.
Antenna – A common noise problem is
generated by a “ground loop” produced
by the antenna shielded cable being
grounded at both the antenna mounting
point and at the head unit input. In this
instance, insulate the antenna ground
from the chassis of the vehicle at the
antenna mounting point so the antenna
shield is grounded only at the radio’s
antenna input. Commercial antenna
ground-loop isolators are also available.
generated by a “ground loop” produced
by the antenna shielded cable being
grounded at both the antenna mounting
point and at the head unit input. In this
instance, insulate the antenna ground
from the chassis of the vehicle at the
antenna mounting point so the antenna
shield is grounded only at the radio’s
antenna input. Commercial antenna
ground-loop isolators are also available.
Switching Noise – The GTS100 has a
highly developed switching power sup-
ply which generates some RF interfer-
highly developed switching power sup-
ply which generates some RF interfer-
wires connected
directly to the chassis
of the head unit. The trickiest grounding
task is created when some components
of this type are mixed with other compo-
nents using isolated supplies. For this
type of system, the following grounding
scheme will
task is created when some components
of this type are mixed with other compo-
nents using isolated supplies. For this
type of system, the following grounding
scheme will
usually work:
1. Connect the head unit chassis to a
solid vehicle ground using a short,
heavy gauge wire (>AWG10). Do not
connect this to the vehicle’s wiring
harness, but go directly to a metal
part of the vehicle.
heavy gauge wire (>AWG10). Do not
connect this to the vehicle’s wiring
harness, but go directly to a metal
part of the vehicle.
2. Connect all non-isolated signal-
processor grounds directly to the
head unit chassis at the same point.
Run each wire individually. Due to
wire resistance connecting multiple
wires to a single wire, then running
the single wire to the head unit, is not
the same!
head unit chassis at the same point.
Run each wire individually. Due to
wire resistance connecting multiple
wires to a single wire, then running
the single wire to the head unit, is not
the same!
3. Connect all amplifier and isolated
signal processor grounds directly to
the vehicle chassis at the same point
as each other, but not necessarily to
the same point as the head unit.
the vehicle chassis at the same point
as each other, but not necessarily to
the same point as the head unit.
Power-line Noise – The built-in power
supply filter of the amplifier makes
external filters unnecessary. In some
cases, power supply noise can enter
the system through the head unit power
supply or the supply of an equalizer or
other signal processor. Putting a filter
on the head unit or signal processor
power supply input may then be helpful.
supply filter of the amplifier makes
external filters unnecessary. In some
cases, power supply noise can enter
the system through the head unit power
supply or the supply of an equalizer or
other signal processor. Putting a filter
on the head unit or signal processor
power supply input may then be helpful.
Power wires carrying high currents may
induce noise in nearby signal wires.
Make sure that power wires and signal
wires do not run together for long dis-
tances. When power and signal leads
induce noise in nearby signal wires.
Make sure that power wires and signal
wires do not run together for long dis-
tances. When power and signal leads
23
JBL 1394 Manual 7/17/98 11:49 AM Page 23
Additional System
Configurations for Add-On
or Upgrade
Configurations for Add-On
or Upgrade
The features and capabilities of the
GTS100 provide tremendous system
design flexibility. The diagrams on the
following pages illustrate some of the
system possibilities. They are in order
of increasing complexity, showing the
way a system may be upgraded in
logical steps. Although the systems are
shown using speaker-level connection
from the head-unit, they may be built
using any combination of speaker or
preamp level inputs, depending on the
capability of your head unit. (See
pages 25-26.)
GTS100 provide tremendous system
design flexibility. The diagrams on the
following pages illustrate some of the
system possibilities. They are in order
of increasing complexity, showing the
way a system may be upgraded in
logical steps. Although the systems are
shown using speaker-level connection
from the head-unit, they may be built
using any combination of speaker or
preamp level inputs, depending on the
capability of your head unit. (See
pages 25-26.)
24
ence as a result of its switch-mode
operation. Although this is internally
filtered and shielded by the GTS100
chassis, some unusually sensitive
installations may pick up switching
noise, especially when listening to weak
AM radio stations. If this unusual situa-
tion occurs, one of the following installa-
tion corrections will typically eliminate
the problem. 1) Relocate the amplifier
to a position farther away from the radio
or radio antenna. 2) Move the electrical
ground of the head unit and/or amp to a
different point on the vehicle’s chassis.
3) Keep the amplifier power supply
wiring away from the radio or antenna
wiring. 4) Wrap the +12 volt power sup-
ply wires for the radio/tape deck with
metallized shielding tape or ground
braid and ground the tape to the chas-
sis of the vehicle.
operation. Although this is internally
filtered and shielded by the GTS100
chassis, some unusually sensitive
installations may pick up switching
noise, especially when listening to weak
AM radio stations. If this unusual situa-
tion occurs, one of the following installa-
tion corrections will typically eliminate
the problem. 1) Relocate the amplifier
to a position farther away from the radio
or radio antenna. 2) Move the electrical
ground of the head unit and/or amp to a
different point on the vehicle’s chassis.
3) Keep the amplifier power supply
wiring away from the radio or antenna
wiring. 4) Wrap the +12 volt power sup-
ply wires for the radio/tape deck with
metallized shielding tape or ground
braid and ground the tape to the chas-
sis of the vehicle.
Maintenance
The GTS100 does not require any regu-
lar maintenance. Periodically checking
the main power supply and grounding
points and terminal connections is
advisable. Be sure the connections are
solid and corrosion-free. Loose or cor-
roded connections can cause annoying
intermittent noise or unusual opera-
tional problems. Do not allow dust to
accumulate on the amplifier heat sinks.
It will reduce the amplifier’s ability to
dissipate heat. Occasional vacuum
cleaning will prevent dust accumulation.
lar maintenance. Periodically checking
the main power supply and grounding
points and terminal connections is
advisable. Be sure the connections are
solid and corrosion-free. Loose or cor-
roded connections can cause annoying
intermittent noise or unusual opera-
tional problems. Do not allow dust to
accumulate on the amplifier heat sinks.
It will reduce the amplifier’s ability to
dissipate heat. Occasional vacuum
cleaning will prevent dust accumulation.
JBL 1394 Manual 7/17/98 11:49 AM Page 24
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