JBL GT-BassPro12 Service Manual ▷ View online
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ConneCtIng the subWoofer to Your vehICle’s audIo
sYsteM
The JBL GT-BassPro12 is equipped with two line-level (RCA) input
The JBL GT-BassPro12 is equipped with two line-level (RCA) input
connectors and a high-level input connector. Consult the following
system application diagrams to help you plan the installation of your GT-
BassPro12. For additional installation suggestions, contact your local
authorized JBL car audio dealer.
If your car audio system’s head unit has front or rear stereo line-
level outputs:
Use a stereo RCA audio cable (not supplied) to connect the GT-
Use a stereo RCA audio cable (not supplied) to connect the GT-
BassPro12’s line-level input connectors to the head unit’s front or rear
left and right line-level outputs.
L. Front
Speaker
L. Rear
Speaker
Audio System
Head Unit
Left/Right
Line-Level
Outputs
Stereo RCA Audio Cable
(not supplied)
R. Front
Speaker
R. Rear
Speaker
If your car audio system’s head unit has a line-level subwoofer
output:
If the head unit has a line-level subwoofer output, you can connect it to
If the head unit has a line-level subwoofer output, you can connect it to
either of the GT-BassPro12’s line-level input connectors.
L. Front
Speaker
Use Either
Connector
L. Rear
Speaker
Audio System
Head Unit
Subwoofer
Output
Single RCA Audio Cable
(not supplied)
R. Front
Speaker
R. Rear
Speaker
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If your car audio system’s head unit does not have line-level
outputs:
Connect the GT-BassPro12’s high-level inputs to either the front or
Connect the GT-BassPro12’s high-level inputs to either the front or
the rear speaker outputs of your car audio system’s head unit (splice
crimps not included). Make sure to connect the car audio system’s “+”
speaker wires to the “+”wires on the GT-BassPro12’s high-level input
wiring harness (the gray and white leads without stripes); connect the car
audio system’s “–” speaker wires to the “–” wires on the GT-BassPro12’s
high-level input wiring harness (the leads with black stripes). Use least
#20 AWG (0.8128mm) speaker wire for speaker-level input connections.
Left
Speaker
Audio System
Head Unit
Splices
(not supplied)
White
Wire
Gray
Wire
Gray Wire
w/Black Stripe
White Wire
w/Black Stripe
High-Level Input Wiring
Harness (supplied)
Splices
(not supplied)
Right
Speaker
ConneCtIng the poWer and ground
Use at least #12 AWG (2.052mm) wire for the positive battery (“+12V”)
Use at least #12 AWG (2.052mm) wire for the positive battery (“+12V”)
and ground (“GND”) connections. Connect the GT-BassPro12’s “+12V”
terminal directly to the battery’s “+” (positive) terminal. Install a fuse
holder with a 20A fuse within 18” (46cm) of the battery’s “+” terminal.
Remote Turn-On
Audio System
Head Unit
Chassis Ground
(bare metal)
20A Fuse
18"
(46cm)
Battery
> #20 AWG
(0.8128mm) Wire
> #12 AWG (2.052mm) Wire
> #12 AWG (2.052mm) Wire
> #12 AWG (2.052mm) Wire
Route all power wires through grommets in the vehicle’s firewall. If
factory grommets are not available, install grommets yourself. Connect
a short ground wire from the GT-BassPro12’s ground terminal to the
nearest bare metal surface on the vehicle. For a good connection, use
sandpaper to clear the paint from the metal surface and use a screw with
a lock (star) washer.
reMote turn-on ConneCtIon
When using the line-level input connections, the GT-BassPro12 requires
When using the line-level input connections, the GT-BassPro12 requires
a +5V to +12V DC signal at the Remote (REM) connector to turn on.
Most head units with preamp outputs provide a remote turn-on wire that
supplies this remote voltage signal. (As an alternative, you can connect
the REM terminal to a switched ignition circuit.) Use at least #20 AWG
(0.8128mm) wire for the remote turn-on connection.
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note: The remote turn-on connection is not needed when using the
high-level input connections. See Auto Turn-On switch, on this page.
usInG The suBwOOfer
WarnIng: playing loud music in an automobile can hinder your
ability to hear traffic and permanently damage your hearing. We
recommend listening at low or moderate levels while driving
your car. We accept no liability for hearing loss, bodily injury or
property damage resulting from the use or misuse of this product.
Controls and funCtIons
The JBL GT-BassPro12’s control panel features controls and indicators
The JBL GT-BassPro12’s control panel features controls and indicators
that make it easy for you to integrate the subwoofer’s sound with almost
any vehicle’s unique acoustic properties.
Power
Indicator
Auto Turn-On
Switch
Phase
Switch
Protect
Indicator
Low Pass
Control
Level
Control
Bass Boost
Control
power indicator: This LED will glow green when the JBL GT-BassPro12
is operating.
auto turn-on switch: If you connected your GT-BassPro12 using
the high-level connectors and did not connect the Remote Turn-On
connector, set the Auto Turn-On switch to the “On” position (in). If you
did connect the Remote Turn-On connector, set the Auto Turn-On switch
to the “Off” position (out).
protect indicator: This indicator will light up (and the subwoofer will
stop operating) to indicate the following conditions:
• Battery voltage too high/too low
• Subwoofer amplifier over temperature
• Short-circuit in the subwoofer driver or wiring
Correct the condition before attempting to use the subwoofer again.
• Subwoofer amplifier over temperature
• Short-circuit in the subwoofer driver or wiring
Correct the condition before attempting to use the subwoofer again.
phase switch: This switch will reverse the phase of the GT-BassPro12’s
output with respect to its input. When you install the GT-BassPro12 with
an existing factory or aftermarket system, changing the Phase switch
setting to reverse the subwoofer’s phase may produce a discernable
increase or decrease in the amount of upper bass that the system
reproduces, depending on the GT-BassPro12’s location in the vehicle
and the distance between it and the other speakers in the vehicle.
level control: Use this control to balance the relative volume of the GT-
BassPro12 with the other speakers in the vehicle.
low pass control: Use this control to adjust the amount of high-
frequency information present in the GT-BassPro12’s output. A lower
value allows less high-frequency content.
bass boost control: Use this control to increase the amount of low
bass output from the GT-BassPro12. The Bass Boost control provides
up to 12dB of boost at 45Hz.
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settIng the Controls
1. Make sure the head-unit power is off and the GT-BassPro12’s Level
1. Make sure the head-unit power is off and the GT-BassPro12’s Level
control is set to minimum.
2. Set the GT-BassPro12’s Low Pass control to its maximum frequency
of 120Hz and set the Bass Boost control to the 12 o’clock setting.
note: If you are using the Remote Level control, set it to maximum.
3. Turn the head unit on and play a selection of your favorite music track
that has substantial bass.
4. Adjust the Low Pass control counterclockwise until you hear only bass
information coming from the GT-BassPro12. For example, you should
not hear vocals coming from the subwoofer when you are seated in
the normal listening position.
5. Adjust the Bass Boost control either clockwise or counterclockwise to
suit your taste. Be sure to find a setting that does not create audible
distortion in the subwoofer’s sound.
6a. If you installed the remote level control, set the subwoofer’s Level
control to its maximum and set the remote level control’s knob to
the maximum level that provides undistorted output from the GT-
BassPro12 with the head unit’s volume control at its 3 o’clock
setting. Use the remote level control to adjust the subwoofer volume
according to your taste while avoiding distortion from the GT-
BassPro12.
6b. If you did not install the remote level control, adjust the subwoofer’s
Level control to the maximum level that provides undistorted output
from the GT-BassPro12 with the head unit’s volume control at
its 3 o’clock setting. After using the subwoofer for a while, if you
find that this setting produces too much bass, you can reduce the
subwoofer’s Level control setting.
7. With the Phase switch set at 0°, play a music track that has impactful
drums, and listen for the upper bass content, paying attention to the
impact of the drums. Then set the Phase switch to 180°, and listen
to the same music again. There may be more upper bass, less upper
bass or no change at all. The Phase switch position that provides the
most upper bass is technically correct, but you can choose either
setting according to your taste.
note: In most cases the above steps will provide you with satisfactory
results. However, the actual process may require several readjustments
of each control, since the settings will interact with one another. If
necessary, consult your authorized JBL car audio dealer for help in
tuning your system.
sPecIfIcaTIOns
Amplifier power:
150 watts RMS; 450 watts max power
Frequency response:
35Hz – 120Hz
Fuse rating:
25A
Max current draw:
13.5A
Idle current draw:
<500mA
Input sensitivity:
50mV – 4V (line-level input);
0.4V – 16V (speaker-level input)
Crossover frequency:
70Hz – 120Hz
Crossover slope:
12dB
Dimensions (W x H x D):
22-7/16” x 14-1/2” x 12”
(570mm x 369mm x 305mm)
Weight:
38.6 lb (17.5kg)
Click on the first or last page to see other GT-BassPro12 service manuals if exist.