JBL GTH 400 (serv.man2) User Manual / Operation Manual ▷ View online
16
is heat- and oil-resistant whenever
running wires through the engine
compartment. All wire-to-wire
connections should be soldered and
insulated with heat shrink tubing, or
connected through a high-quality
running wires through the engine
compartment. All wire-to-wire
connections should be soldered and
insulated with heat shrink tubing, or
connected through a high-quality
insulated crimp-on connector or
secure set-screw-type terminal
blocks. Never leave bare wire
exposed. Terminate wires with crimp-
or solder-on lug terminals whenever
appropriate.
secure set-screw-type terminal
blocks. Never leave bare wire
exposed. Terminate wires with crimp-
or solder-on lug terminals whenever
appropriate.
High Pass Satellite
Crossover Frequency: 100Hz
Crossover Frequency: 100Hz
C:
300
µ
F capacitor
100V, non-polorized
Subwoofer Lowpass
Crossover Frequency: 100Hz
Crossover Frequency: 100Hz
L:
6.2mH air core inductor
(+)
(+)
(–)
(–)
(+)
(–)
C
Subwoofer (Low-Pass)
Tweeter/Midrange Satellites
(High Pass)
Right
Left
C
L
POWER
BATT(+)
REM OUT
REM IN
GND
SPEAKER LEVEL
INPUTS
FUSE
30A
FUSE
30A
_
_
_
_
+
+
L 1 R
L 2 R
L 3 R
+
+
+
+
L
R
+ – – +
+ – – +
R 2 L
R 1 L
+
–
1
2
3
1
2
3
LINE LEVEL INPUTS
PREAMP OUTPUTS
SPEAKER OUTPUTS
30A
30A
GTH400
A. Satellite/Subwoofer
POWER
BATT(+)
REM OUT
REM IN
GND
SPEAKER LEVEL
INPUTS
FUSE
30A
FUSE
30A
_
_
_
_
+
+
L 1 R
L 2 R
L 3 R
+
+
+
+
L
R
+ – – +
+ – – +
R 2 L
R 1 L
+
–
1
2
3
1
2
3
LINE LEVEL INPUTS
PREAMP OUTPUTS
SPEAKER OUTPUTS
30A
30A
Stereo, Non-Bridged
Speaker Connection*
Speaker Connection*
Center Channel
Bridged Speaker Connection*
* Center Channel Speaker Minimum 8 Ohms, Main
Speakers Minimum 4 Ohms When Used Simultaneously.
Speakers Minimum 4 Ohms When Used Simultaneously.
8
Ω
L-Pad
(Optional but Recommended)
4
Ω
Minimum
4
Ω
Minimum
GTH400
(+)
(–)
(+)
(+)
(–)
(–)
8
Ω
Minimum
B. Center Channel
*You may change the subwoofer satellite crossover frequency by using the
Inductor and Capacitor values calculated with the following formulas:
High-Pass (Satellite Crossover): = New Capacitor Value in
µ
F
Low-Pass(Subwoofer Crossover): = New Inductor Value in mH
30,000
Desired crossover Frequency in Hz
620
Desired crossover Frequency in Hz
Simultaneous Stereo-Mono
Connection Diagrams
Connection Diagrams
GTH400-20107 06/03/98 15:49 Side 16
17
•The GTH400 will draw as much as 60
amps from the vehicle’s electrical
system, enough to overload
conventional vehicle wiring. Therefore
the +12 volt power supply must be
taken directly from the positive side of
the battery.
Do not connect to the vehicle’s fuse
block or to a wire feeding other
accessories.
system, enough to overload
conventional vehicle wiring. Therefore
the +12 volt power supply must be
taken directly from the positive side of
the battery.
Do not connect to the vehicle’s fuse
block or to a wire feeding other
accessories.
•To prevent electrical system damage
or fire, a fuse holder and fuse (not
included – maximum 60 Amp) must be
installed in the power supply wire as
close to the battery as possible, and
before the wire travels through the
firewall or other metal panel.
included – maximum 60 Amp) must be
installed in the power supply wire as
close to the battery as possible, and
before the wire travels through the
firewall or other metal panel.
Ground Wire
•Proper grounding is extremely
important. Use a heat- and oil-
resistant stranded copper automotive
wire equivalent to the size used for the
+12V connection. Crimp or solder and
insulate any wire-to-wire connections.
Keep the ground wire as short as
possible. A ground wire must be
solidly connected to a major sheet
metal structure of the vehicle such as
a panel near the amp-mounting
location. Scrape all paint and primer
off the sheet metal at the grounding
point to ensure a good electrical
connection. Attach the wire to the
grounding point with a nut, bolt and
star washer. The high current
demanded by high-powered amplifiers
requires a more secure ground than
the typical sheet-metal screw will
provide.
resistant stranded copper automotive
wire equivalent to the size used for the
+12V connection. Crimp or solder and
insulate any wire-to-wire connections.
Keep the ground wire as short as
possible. A ground wire must be
solidly connected to a major sheet
metal structure of the vehicle such as
a panel near the amp-mounting
location. Scrape all paint and primer
off the sheet metal at the grounding
point to ensure a good electrical
connection. Attach the wire to the
grounding point with a nut, bolt and
star washer. The high current
demanded by high-powered amplifiers
requires a more secure ground than
the typical sheet-metal screw will
provide.
The color code for the speaker-level
input harness is as follows:
input harness is as follows:
Speaker-Level Input Harness
Color Codes
Group 1 Left (+):
White
Group 1 Left (–):
White with
Black Stripe
Black Stripe
Group 1 Right (+):
Gray
Group 1 Right (–):
Gray with
Black Stripe
Black Stripe
Group 2 Left (+):
Green
Group 2 Left (–):
Green with
Black Stripe
Black Stripe
Group 2 Right (+):
Purple
Group 2 Right (–):
Purple with
Black Stripe
Black Stripe
5. Adjusting the Gain
Before operating the GTH400, recheck
all wiring connections to make sure they
are correct and secure. Be sure that a
fuse (60 amps, not included) is installed
in the +12V line near the battery.
Reconnect the negative ground (–)
terminal of the battery. Make sure that
the mode switches, crossover switches,
Group 2 & 3 Input switches, and
crossover frequency modules, are
properly set.
all wiring connections to make sure they
are correct and secure. Be sure that a
fuse (60 amps, not included) is installed
in the +12V line near the battery.
Reconnect the negative ground (–)
terminal of the battery. Make sure that
the mode switches, crossover switches,
Group 2 & 3 Input switches, and
crossover frequency modules, are
properly set.
•The setting of the gain controls on the
GTH400 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 adequate
volume levels. Using a high signal level
from the source and a low gain setting
on the amplifier will help keep
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 adequate
volume levels. Using a high signal level
from the source and a low gain setting
on the amplifier will help keep
GTH400-20107 06/03/98 15:49 Side 17
18
background noise levels in the system
low.
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.
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.
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.
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.
Imaging Enhancer Setup
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.
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.
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.
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.
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.
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”
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”
GTH400-20107 06/03/98 15:49 Side 18
19
position for driver-optimized sound
stage.
stage.
5.
Proceed to push and pull the Rear-
Ambience knob to hear the effects
of “Driver” and “All” modes. You
should hear imaging coming from
the middle of the dashboard when
the knob is pushed in (“Driver”
mode). You should hear stereo with
ambience recovery when the knob
is pulled out (“All” mode). If you find
that the center imaging in the
“Driver” position is slightly offset to
the left or right side of the
dashboard, switch the car-size
switch located inside of the
GTH400 under the bottom cover as
shown below. This switch optimizes
the Imaging Enhancer for standard
or large cars.
Ambience knob to hear the effects
of “Driver” and “All” modes. You
should hear imaging coming from
the middle of the dashboard when
the knob is pushed in (“Driver”
mode). You should hear stereo with
ambience recovery when the knob
is pulled out (“All” mode). If you find
that the center imaging in the
“Driver” position is slightly offset to
the left or right side of the
dashboard, switch the car-size
switch located inside of the
GTH400 under the bottom cover as
shown below. This switch optimizes
the Imaging Enhancer for standard
or large cars.
6.
Slowly turn the “Front-Ambience”
knob in the clockwise direction to
increase ambience. You should
begin to hear slight reverberation in
the music and a sense of a
widening front sound stage in both
the “Driver” and “All” modes.
knob in the clockwise direction to
increase ambience. You should
begin to hear slight reverberation in
the music and a sense of a
widening front sound stage in both
the “Driver” and “All” modes.
7.
Slowly turn the “Rear-Ambience”
knob in the clockwise direction to
increase rear ambience (only in
knob in the clockwise direction to
increase rear ambience (only in
systems with rear speakers). You
should begin to hear an increase in
reverberation and get a feeling of
being in a very large auditorium.
Note: The GTH400 converts the
rear channels into true rear-fill
surround channels which cancel
all center information (vocals, lead
instruments, etc.) and lets only true
ambience information come out.
This same process is used in more
expensive “Surround Sound”
systems used in theaters.
should begin to hear an increase in
reverberation and get a feeling of
being in a very large auditorium.
Note: The GTH400 converts the
rear channels into true rear-fill
surround channels which cancel
all center information (vocals, lead
instruments, etc.) and lets only true
ambience information come out.
This same process is used in more
expensive “Surround Sound”
systems used in theaters.
8.
Adjust the front and rear ambience
as desired. For optimum center
imaging, it is recommended that
ambience be used sparingly on the
front channels.
as desired. For optimum center
imaging, it is recommended that
ambience be used sparingly on the
front channels.
9.
To bypass the effects of the
Imaging Enhancer in the GTH400,
simply pull on the “Front-
Ambience” knob until it clicks to the
“Bypass” position. The “Enhancer
On” LED on the remote control
panel will turn off and your sound
system should revert back to
normal stereo sound without
ambience enhancement. The
Imaging Enhancer is also bypassed
when the remote control is
unplugged from the amplifier.
Imaging Enhancer in the GTH400,
simply pull on the “Front-
Ambience” knob until it clicks to the
“Bypass” position. The “Enhancer
On” LED on the remote control
panel will turn off and your sound
system should revert back to
normal stereo sound without
ambience enhancement. The
Imaging Enhancer is also bypassed
when the remote control is
unplugged from the amplifier.
6. Important Characteristics
Overload Protection – The GTH400
incorporates elaborate protection cir-
cuitry to prevent damage to the
amplifier circuitry and ensure reliable
operation. 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
incorporates elaborate protection cir-
cuitry to prevent damage to the
amplifier circuitry and ensure reliable
operation. 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
IMAGE
ENHANCER
MODULE
ENHANCER
MODULE
FRONT
PLATE
PLATE
IMAGING ENHANCER
REMOTE PLUG
Standard Large
Imaging Enhancer
Car Size Switch
GTH400-20107 06/03/98 15:50 Side 19
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