JBL GTQ 360 User Manual / Operation Manual ▷ View online
G R A N D T O U R I N G S E R I E S
G E N U I N E J B L
4 / 3 / 2 C h a n n e l
A u t o m o t i v e P o w e r A m p l i f i e r
G T Q 3 6 0 , G T Q 2 4 0 O w n e r ’ s M a n u a l
GTQ 360 new 7/17/98 10:44 AM Page 1
2
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
1.1
Thanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
1.2
About Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
2. Installation and Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
2.1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
2.2
Controls and Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
3. System Design Using the GTQ360 and GTQ240 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
3.1
Speaker Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
3.2
Signal Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
4. Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
4.1
Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
4.2
Ground Wire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
4.3
Remote-In/Out Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.4
Mute Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.5
Speaker-Level Input Harness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Internal Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1
Speaker-Level Input Impedance Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.2
Crossover Frequency Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.3
Custom Chip Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6. Adjusting the Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Typical Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8. In Case of Difficulty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Warranty Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Owner’s Warranty Information
Model Number
Serial Number
Dealer Name
City, State, Zip
Sales Receipt Number
Date of Purchase
GTQ 360 new 7/17/98 10:44 AM Page 2
3
1. Introduction
1.1 Thanks
for purchasing your new
GT series automotive multi-channel
amplifier. Your GT series amplifier will
easily connect to virtually any car audio
system, whether it is factory installed or
purchased separately. The GTQ360 and
GTQ240 include an abundance of unique
features which are described in this man-
ual. The flexible design of their built-in
crossover circuitry allows elaborate sys-
tems to be built more simply than with
conventional components. For optimum
performance, the power amplifier circuit-
ry is a fully-discrete design notable for its
low distortion and unusually clean and
clear sound quality.
In addition to conventional preamp-level
inputs, the GTQ360 and GTQ240 feature
JBL’s Universal Interface™ design, which
facilitates simple connection to factory
radios with the low distortion that is usu-
ally only associated with preamp level
connection. With the Universal Interface
on the GTQ360 and GTQ240, a factory
radio can either be used as the main
music source or simultaneously com-
bined with a CD player or changer that
has volume-control capability. By provid-
ing this two-unit direct connection,
Universal Interface circuitry eliminates the
need for an FM modulator to interface a
CD player to factory radios, improving the
fidelity of digital playback.
In addition, when using a high-powered
(BTL) radio through the speaker-level
inputs, Common Sense turn-on circuitry
senses the common-mode voltage pres-
ent on the radio’s speaker wires, turning
the amplifier on without an additional
remote wire.
amplifier. Your GT series amplifier will
easily connect to virtually any car audio
system, whether it is factory installed or
purchased separately. The GTQ360 and
GTQ240 include an abundance of unique
features which are described in this man-
ual. The flexible design of their built-in
crossover circuitry allows elaborate sys-
tems to be built more simply than with
conventional components. For optimum
performance, the power amplifier circuit-
ry is a fully-discrete design notable for its
low distortion and unusually clean and
clear sound quality.
In addition to conventional preamp-level
inputs, the GTQ360 and GTQ240 feature
JBL’s Universal Interface™ design, which
facilitates simple connection to factory
radios with the low distortion that is usu-
ally only associated with preamp level
connection. With the Universal Interface
on the GTQ360 and GTQ240, a factory
radio can either be used as the main
music source or simultaneously com-
bined with a CD player or changer that
has volume-control capability. By provid-
ing this two-unit direct connection,
Universal Interface circuitry eliminates the
need for an FM modulator to interface a
CD player to factory radios, improving the
fidelity of digital playback.
In addition, when using a high-powered
(BTL) radio through the speaker-level
inputs, Common Sense turn-on circuitry
senses the common-mode voltage pres-
ent on the radio’s speaker wires, turning
the amplifier on without an additional
remote wire.
Also, the built-in active cross-over pro-
vides either full-range, high-pass or low-
pass operation. This lets your GT series
amplifier power either subwoofer or com-
ponent speakers in a bi-amplified system,
or conventional full-range speakers in
simpler systems.
The GTQ360 and GTQ240 also include
preamp-level outputs which can provide
either full-range, high-pass or low-pass
signal to drive additional amplifiers. This
lets you build systems of virtually any
design without requiring a separate elec-
tronic crossover.
vides either full-range, high-pass or low-
pass operation. This lets your GT series
amplifier power either subwoofer or com-
ponent speakers in a bi-amplified system,
or conventional full-range speakers in
simpler systems.
The GTQ360 and GTQ240 also include
preamp-level outputs which can provide
either full-range, high-pass or low-pass
signal to drive additional amplifiers. This
lets you build systems of virtually any
design without requiring a separate elec-
tronic crossover.
1.2 About Installation
Although the GTQ360 and GTQ240 are
designed to make installation as easy as
possible, these are extremely sophisticat-
ed products that require proper installa-
tion and setup to realize their full perfor-
mance potential. If you feel you do not
have the necessary knowledge and skills,
we strongly recommend that the installa-
tion be done by your authorized JBL deal-
er.
If you choose to install the GTQ amplifier
yourself, read all of the information in this
manual before you start the installation.
Pay particular attention to the safety pre-
cautions and notes.
designed to make installation as easy as
possible, these are extremely sophisticat-
ed products that require proper installa-
tion and setup to realize their full perfor-
mance potential. If you feel you do not
have the necessary knowledge and skills,
we strongly recommend that the installa-
tion be done by your authorized JBL deal-
er.
If you choose to install the GTQ amplifier
yourself, read all of the information in this
manual before you start the installation.
Pay particular attention to the safety pre-
cautions and notes.
2. Installation and Use
2.1
Refer to the “Speaker-Level Input
Impedance Adjustments” and “Crossover
Frequency Adjustments” sections of this
manual (page 7) to see if you will need to
make alterations to the factory settings. If
you are not using the built-in crossover,
or the speaker-level inputs, you may skip
this step.
1. Disconnect the negative cable from the
battery. Note: If the vehicle’s radio fea-
tures a code-type security system, make
certain you know the code before discon-
necting the battery!
2. Run a power cable complete with a
fuse (not included) directly from the posi-
tive +12V battery terminal to the desired
amplifier location. Keep the fuse within 6"
of the battery terminal, and position it
before the wire runs through any metal
partition. A minimum of #10AWG is
required for the GTQ240 and #8AWG for
the GTQ360. The GTQ240 requires a 30A
fuse, the GTQ360 a 60A fuse.
Note: All wiring connections should be
made either by soldering with heatshrink
tubing insulation, by using commercially
available high-quality distribution blocks,
or with high-quality crimp-type insulated
connectors installed with a professional-
type, articulated crimping tool. Soldering
crimp-type terminals is recommended for
additional security. Never use wire nuts,
insulation-displacement connectors (i.e.,
ScotchLok type), or twist and tape con-
nections. Do not use electrical tape; it will
loosen with age and extreme
temperatures.
Frequency Adjustments” sections of this
manual (page 7) to see if you will need to
make alterations to the factory settings. If
you are not using the built-in crossover,
or the speaker-level inputs, you may skip
this step.
1. Disconnect the negative cable from the
battery. Note: If the vehicle’s radio fea-
tures a code-type security system, make
certain you know the code before discon-
necting the battery!
2. Run a power cable complete with a
fuse (not included) directly from the posi-
tive +12V battery terminal to the desired
amplifier location. Keep the fuse within 6"
of the battery terminal, and position it
before the wire runs through any metal
partition. A minimum of #10AWG is
required for the GTQ240 and #8AWG for
the GTQ360. The GTQ240 requires a 30A
fuse, the GTQ360 a 60A fuse.
Note: All wiring connections should be
made either by soldering with heatshrink
tubing insulation, by using commercially
available high-quality distribution blocks,
or with high-quality crimp-type insulated
connectors installed with a professional-
type, articulated crimping tool. Soldering
crimp-type terminals is recommended for
additional security. Never use wire nuts,
insulation-displacement connectors (i.e.,
ScotchLok type), or twist and tape con-
nections. Do not use electrical tape; it will
loosen with age and extreme
temperatures.
3. Mount amplifier in the desired location
using the included screws.
4. Connect power wiring as shown in the
Wiring Diagram.
5. Connect the outputs from the head unit
to the appropriate inputs of the amplifier
according to the Wiring Diagram with
either (or both) high-quality low-level sig-
nal cables with RCA plugs, or the supplied
speaker-level input connector.
6. Connect the speakers to the amplifier
according to the Wiring Diagram.
7. Turn the gain controls to the
1/4-position for all groups.
8. Set the bass boost of each group to the
desired position.
9. Set the crossover switches for each
group as desired.
10. Set the Group 2 Input as desired.
11. Set the mode switches to Stereo,
Left + Right, or Left Input Only operation
for each group.
12. Double-check your switch settings.
Reconnect the negative battery cable.
Note: Incorrect switch settings can dam-
age your speakers!
13. Turn on the signal source at a low vol-
ume level, and check for the correct out-
put from each speaker.
14. Adjust the amplifier gain controls
using the procedure described in the
“Adjusting the Gain” section.
15. Read the rest of the manual to get
maximum use and enjoyment from your
amplifier.
using the included screws.
4. Connect power wiring as shown in the
Wiring Diagram.
5. Connect the outputs from the head unit
to the appropriate inputs of the amplifier
according to the Wiring Diagram with
either (or both) high-quality low-level sig-
nal cables with RCA plugs, or the supplied
speaker-level input connector.
6. Connect the speakers to the amplifier
according to the Wiring Diagram.
7. Turn the gain controls to the
1/4-position for all groups.
8. Set the bass boost of each group to the
desired position.
9. Set the crossover switches for each
group as desired.
10. Set the Group 2 Input as desired.
11. Set the mode switches to Stereo,
Left + Right, or Left Input Only operation
for each group.
12. Double-check your switch settings.
Reconnect the negative battery cable.
Note: Incorrect switch settings can dam-
age your speakers!
13. Turn on the signal source at a low vol-
ume level, and check for the correct out-
put from each speaker.
14. Adjust the amplifier gain controls
using the procedure described in the
“Adjusting the Gain” section.
15. Read the rest of the manual to get
maximum use and enjoyment from your
amplifier.
GTQ 360 new 7/17/98 10:44 AM Page 3
4
13. Mode Switches – These switches are
used to set the input mode for both pre-
amp and speaker-level inputs. Set the
switch to ST(ereo) for normal operation
on the group using individual left and
right inputs. Set this switch to R to drive
both the left and right outputs with only a
single input on the right jack. Set the
switch to L
used to set the input mode for both pre-
amp and speaker-level inputs. Set the
switch to ST(ereo) for normal operation
on the group using individual left and
right inputs. Set this switch to R to drive
both the left and right outputs with only a
single input on the right jack. Set the
switch to L
+
R to sum the left and right
inputs for a mono output on the group.
These switches do not affect the preamp
ouputs.
14. Bass EQ Switch – These switches acti-
vate a built-in Bass Boost circuit used to
increase low-bass output on the selected
group. These switches do not affect the
preamp outputs.
15. Group 2 Input Switch – This switch is
used to select which inputs will drive
Group 2 of the amplifier. Put the switch in
position “GR 1” to allow Group 2 to be
driven by the Group 1 inputs. Put the
switch in the “GR 2” position to drive
Group 2 with the Group 2 inputs.
Power Indicator LED (on amp chassis
top) – LED steadily illuminates for normal
operation. LED blinks when protection
circuitry or muting is engaged.
These switches do not affect the preamp
ouputs.
14. Bass EQ Switch – These switches acti-
vate a built-in Bass Boost circuit used to
increase low-bass output on the selected
group. These switches do not affect the
preamp outputs.
15. Group 2 Input Switch – This switch is
used to select which inputs will drive
Group 2 of the amplifier. Put the switch in
position “GR 1” to allow Group 2 to be
driven by the Group 1 inputs. Put the
switch in the “GR 2” position to drive
Group 2 with the Group 2 inputs.
Power Indicator LED (on amp chassis
top) – LED steadily illuminates for normal
operation. LED blinks when protection
circuitry or muting is engaged.
2.2 Controls and Connectors
1. Preamp-Level Input Connector – Use
these connectors for line-level (preamp)
inputs to the amplifier.
2. Preamp-Level Output Connector – Use
these outputs to send signal to additional
amplifiers.
3. Speaker-Level Input Connector – Use
this connector for speaker-level input sig-
nals. A wire harness is supplied for use
with this connector. This input also
includes JBL’s Common Sense input cir-
cuitry which turns the amplifier on as
soon as the high-powered head unit con-
nected to this input is turned on.
4. Speaker Output Connectors – Connect
speaker wiring to these connectors. See
wiring directions for more information.
5., 6., 7., 8. Power Connector –
Connection for power wires REM IN/OUT
and Mute. See wiring directions for infor-
mation on proper connections.
9. Fuses – GTQ240: 30A ATC type.
GTQ360: 2 x 30A ATC type.
10. Gain Controls – Use these controls to
adjust the gain of the amplifier channel
group. See the “Adjusting the Gain” sec-
tion for tips on proper setup.
these connectors for line-level (preamp)
inputs to the amplifier.
2. Preamp-Level Output Connector – Use
these outputs to send signal to additional
amplifiers.
3. Speaker-Level Input Connector – Use
this connector for speaker-level input sig-
nals. A wire harness is supplied for use
with this connector. This input also
includes JBL’s Common Sense input cir-
cuitry which turns the amplifier on as
soon as the high-powered head unit con-
nected to this input is turned on.
4. Speaker Output Connectors – Connect
speaker wiring to these connectors. See
wiring directions for more information.
5., 6., 7., 8. Power Connector –
Connection for power wires REM IN/OUT
and Mute. See wiring directions for infor-
mation on proper connections.
9. Fuses – GTQ240: 30A ATC type.
GTQ360: 2 x 30A ATC type.
10. Gain Controls – Use these controls to
adjust the gain of the amplifier channel
group. See the “Adjusting the Gain” sec-
tion for tips on proper setup.
11. Preamp Crossover Switches – These
switches control the built-in crossovers
that are directed to the preamp-output
connectors. Set the switch to F (flat) for
full-band operation for that group. Set the
switch to L (low) to activate the low-pass
filter on the pre-amp output group (for
subwoofer use or to use in conjunction
with a high-pass filtered input signal to
create a band-pass crossover for a
midrange or midbass driver). Set the
switch to High-Pass to activate the high-
pass filter for use with satellite speakers
or tweeters on the pre-amp output group.
12. Speaker Crossover Switches – These
switches control the built-in crossovers
that are connected to each group's power
amplifier circuitry. Set the switch to F
(flat) for full band operation on a group.
Set this switch to L (low) to activate the
low-pass filter on the selected amplifier
group for subwoofer use or to use in con-
junction with a high-pass filtered input
signal to create a band-pass crossover
(for a midrange or midbass driver). Set
the switch to H (high) to activate the high-
pass filter for use with satellite speakers
or tweeters on an amplifier group.
switches control the built-in crossovers
that are directed to the preamp-output
connectors. Set the switch to F (flat) for
full-band operation for that group. Set the
switch to L (low) to activate the low-pass
filter on the pre-amp output group (for
subwoofer use or to use in conjunction
with a high-pass filtered input signal to
create a band-pass crossover for a
midrange or midbass driver). Set the
switch to High-Pass to activate the high-
pass filter for use with satellite speakers
or tweeters on the pre-amp output group.
12. Speaker Crossover Switches – These
switches control the built-in crossovers
that are connected to each group's power
amplifier circuitry. Set the switch to F
(flat) for full band operation on a group.
Set this switch to L (low) to activate the
low-pass filter on the selected amplifier
group for subwoofer use or to use in con-
junction with a high-pass filtered input
signal to create a band-pass crossover
(for a midrange or midbass driver). Set
the switch to H (high) to activate the high-
pass filter for use with satellite speakers
or tweeters on an amplifier group.
30A
30A
3
2
1
4
9
8
7
6
5
GR1
R GR1 L
LINE LEVEL
INPUT
SPEAKER LEVEL INPUTS
SPEAKER OUTPUTS (BRIDGED: R+TOL–)
POWER
GR2
GR1
GR2
BATT(+)
GND
MUTE
FUSE
30A
FUSE
30A
REM
IN/OUT
L
+ –
– +
+ –
– +
+
+
–
–
–
–
R
PREAMP
OUTPUTS
R GR2 L
L GR1 R
+
+
L GR2 R
15
14
13
13
12
12
11
11
10
10
14
BASS EQ
OFF ON
BASS EQ
OFF ON
CROSSOVER
SPEAKER PREAMP
SPEAKER PREAMP
MODE
INPUT
MODE
R ST L+R
R ST L+R
L
MIN MAX
GAIN
MIN MAX
GAIN
L
F
F
H
H
L
GR2
GR1
L
F
F
H
H
GROUP 1
GROUP 2
CROSSOVER DESIGNATIONS
F = FLAT (BYPASS)
L = LOW PASS
H = HIGH PASS
F = FLAT (BYPASS)
L = LOW PASS
H = HIGH PASS
CROSSOVER
SPEAKER PREAMP
SPEAKER PREAMP
3. System Design Using
the GTQ360 and GTQ240
the GTQ360 and GTQ240
3.1 Speaker Requirements
When used in the non-bridged mode, a
group-channel of the GTQ360 or GTQ240
can easily drive two 2-ohm speaker loads.
When only one speaker is connected to
the left and right outputs of a group, virtu-
ally any conventional speaker may be
used. Although the amplifier will not be
damaged, load impedances lower than 2
ohms will eventually cause the amplifier
to overheat, activating the protection cir-
cuits and causing the unit to shut off until
it cools down sufficiently.
When a group is in bridged mode, the
combined impedance of the speaker (or
speakers) connected to the bridged chan-
nels should be at least 4 ohms. Sustained
operation of the unit in bridged mode
with less than 4 ohms will likely cause
overheating.
The GTQ360 or GTQ240 must not be used
with speakers that have either one of
their input terminals wired to the frame
of the speaker or to the chassis of the
vehicle.
group-channel of the GTQ360 or GTQ240
can easily drive two 2-ohm speaker loads.
When only one speaker is connected to
the left and right outputs of a group, virtu-
ally any conventional speaker may be
used. Although the amplifier will not be
damaged, load impedances lower than 2
ohms will eventually cause the amplifier
to overheat, activating the protection cir-
cuits and causing the unit to shut off until
it cools down sufficiently.
When a group is in bridged mode, the
combined impedance of the speaker (or
speakers) connected to the bridged chan-
nels should be at least 4 ohms. Sustained
operation of the unit in bridged mode
with less than 4 ohms will likely cause
overheating.
The GTQ360 or GTQ240 must not be used
with speakers that have either one of
their input terminals wired to the frame
of the speaker or to the chassis of the
vehicle.
GTQ 360 new 7/17/98 10:44 AM Page 4
