car audio
power amplifier
owner’s manual
THANK YOU
for purchasing a JBL A6000GTi or A3000GTi amplifier.
Select Car Audio, then click on Support, and then click on Product Registration.
Also, please retain your original purchase receipt and packing crate
in case you must ship your unit back for service.
DESIGNING A SPEAKER SYSTEM FOR THE GTI AMPLIFIER
NOTE: Although the JBL A6000GTi or
A3000GTi amplifier will drive a system
made up of any subwoofers, we
recommend using JBL GTi subwoofers
with GTi amplifiers.
PARALLEL CONNECTIONS
To determine the impedance of a
system of three W15GTi (dual voice-
coil) subwoofers connected in series-
parallel, use the series connection
formula to determine the impedance
of each subwoofer with its voice coils
connected in series. Then insert the
calculated value into the parallel
connection formula to determine the
equivalent impedance for the three sub-
woofers connected in parallel.
ABOUT SPEAKER
POWER HANDLING
The formula for determining the
equivalent impedance of the voice coils
connected in parallel is:
The RMS power handling rating of
a speaker indicates the amount of
power it will handle continuously.
Although designing a subwoofer
system by considering the RMS rating
will ultimately provide you with the
most reliable system, your speakers
may be able to handle more power,
depending on what kind of music is
being reproduced.
Z
equivalent = 1/(1/Z1 + 1/Z2 + 1/Z3 …)
Where Zequivalent is the equivalent
impedance of the coils connected in
parallel. Z1, Z2 and Z3 (and so on) are
the nominal impedance ratings of the
individual speakers. The equivalent
impedance of the voice coils shown in
Figure 3 is 2 ohms.
Both the JBL A6000GTi and A3000GTi
amplifiers provide RMS power that
exceeds the RMS power-handling
rating of nearly every subwoofer
available. To use this amplifier
optimally, you should design a speaker
system made up of several identical
speakers, so that the power delivered
by the amplifier will be shared equally
among the speakers.
NOTE: Each W15GTi voice coil has an
impedance of 6 ohms.
For music with extended bass notes
(e.g., bass music, hip-hop or techno),
you should design a speaker system
based on the RMS power handling of
your speakers. For music with sharp
transient bass notes (e.g., rock,
country or jazz), the RMS power
handling rating is conservative, and you
can count on your speakers being able
to handle more power than the RMS
rating.
4 ohms
4 ohms
For example, in Figure 4, each woofer
will have an impedance of 12 ohms, by
Ztotal = Z1 + Z2 = 6 + 6 = 12
and the three woofers connected
in parallel will have an equivalent
impedance of 4 ohms, by
Zequivalent = 1/(1/Z1 + 1/Z2 + 1/Z3)
= 1/(1/12 + 1/12 + 1/12)
= 1/(3/12)
The JBL A6000GTi and A3000GTi
amplifiers support a wide range of
impedances, and any speaker system
with a total or equivalent impedance of
1 to 4 ohms will extract full power from
either amplifier. In order to connect
multiple woofers to the A6000GTi or
A3000GTi, you’ll need to connect your
speakers in series, parallel or series-
parallel. We’ve included diagrams for
each connection scheme and a pair of
formulas, which will help you.
Figure 3. Parallel connection of two
4-ohm voice coils yields a total
impedance of 2 ohms.
= 12/3 = 4
The total power output of your
amplifier will be divided among the
speakers connected to it. For example,
if you are using an A6000GTi and three
W15GTi subwoofers, each subwoofer
will receive 2,000 watts.
NOTE: All subwoofers connected to an
amplifier in a system must be identical
and, if they are dual voice-coil sub-
woofers, their coils must be wired iden-
tically. Do not connect the coils of one
subwoofer together in series and
another in parallel, since doing so will
cause uneven power distribution,
potential damage to the speakers, and
poor overall performance.
DUAL VOICE-COIL
CONNECTIONS
Dual voice-coil subwoofers, such as
JBL’s GTi series, may be connected
in series, as shown in Figure 2;
in parallel, as shown in Figure 3; or in
series-parallel, as shown in Figure 4.
SERIES CONNECTIONS
The formula for determining the total
impedance of the two woofers connect-
ed in series is:
It’s important to choose a system of
subwoofers that will handle all of the
power. To determine how much total
power your speaker system will
handle, simply multiply the RMS power
handling rating of one of your speakers
by the total number of speakers that
will be connected.
Ztotal = Z1 + Z2 + Z3 ...
Where Ztotal is the total impedance of
all woofers connected in series. Z1, Z2
and Z3 (and so on) are the nominal
impedance ratings of the individual
speakers. The total impedance of the
voice coils shown in Figure 2 is 8 ohms.
Figure 4. Series-parallel connections
of three W15GTi subwoofers (with a
voice coil impedance of 6 ohms) yields
a total series impedance of 12 ohms
for each subwoofer, and an equivalent
parallel impedance of 4 ohms for all
three subwoofers.
4 ohms
4 ohms
Remove
Terminal Jumper
Red
Black
Figure 2. Series connection of two
4-ohm voice coils yields a total
impedance of 8 ohms.
Remove
Terminal Jumper
3
SUPPLYING POWER TO THE GTI AMPLIFIER
POWER IN IS
POWER OUT
HOW YOUR CHARGING
SYSTEM WORKS
PROGRAM MATERIAL
AND CURRENT DEMAND
Few stock batteries can provide the
current required to reproduce even
short-duration musical peaks. Adding
a pair of batteries with cold-cranking
capacities of 600 amperes will provide
extra current for short music bursts, but
reserve power may still be
depleted over longer music intervals.
Adding more batteries will provide more
reserve power and current, but no mat-
ter how many are installed, the alterna-
tor will still have to recharge them all.
In order to get full power out of your
amplifier, you must provide full power to
your amplifier. That’s a basic rule
of physics. The A6000GTi amplifier
can draw nearly 800 amperes when
reproducing sine waves at full output.
Both JBL A6000GTi and A3000GTi ampli-
fiers can quickly exhaust the
factory-installed charging system of
any vehicle on the road today. With this
much available amplifier power, you will
need to beef up your vehicle’s
The battery’s job is to start your
vehicle. Running the electrical
Music is a combination of loud and
soft sounds, with varying durations
and rhythms that present unique
current demands during amplification.
For example, it may take full power
to reproduce the sound of a kick
drum. The peak power demand doesn’t
last very long, but it is repeated over
and over.
accessories is the alternator’s job.
The battery isn’t designed to be a
continuous source of power. It is a
renewable source and is charged by
the alternator when the engine runs.
Battery charging can only occur when
the current demand from the electrical
accessories is less than the total cur-
rent output capacity of the alternator.
If your charging system can’t provide all
the power your amplifier needs on
a continuous basis, it still may be
adequate. During the sound of the
kick drum, the battery can provide
the extra current that’s necessary,
and between kick drum beats, the alter-
nator will put some of the energy back
into the battery.
If you plan to use the A6000GTi or
A3000GTi in SPL competition, the charg-
ing system requirements will be much
greater than those for normal music lis-
tening. Be prepared to add additional
batteries and alternators to provide
continuous current required for contin-
uous duty.
electrical system to satisfy the
amplifier’s current demands. We
recommend adding at least two
12-volt batteries, connected in
parallel with cold-cranking capacities
of at least 600 amperes each, to the
factory-installed charging system.
See your authorized JBL car audio
dealer for help in designing and
installing an upgraded charging
system to support your GTi amplifier.
However, depending on the current rat-
ing of the alternator, the amplifier’s
maximum output power, the music
content, and the charging system’s
capability, the alternator may not be
able to keep up over time. In that case,
you’ll need to install a somewhat larger
alternator for more current, or adjust
your driving and listening habits, to give
the alternator time to catch up with the
amplifier’s current demand.
4
MAKING THE CONNECTIONS
POWER CONNECTIONS
Connect the source unit’s remote
turn-on lead to the REMOTE terminal on
the amplifier (see Figure 5). Use
any convenient gauge wire for the
connection.
SIGNAL CONNECTIONS
For gauges, varying voltages are output
on selected RJ45 pins to indicate
voltage, current and temperature.
Use 0-gauge cable to connect the
amplifier’s GND – terminal directly to
the vehicle’s chassis (see Figure 5).
Scrape off all paint from the metal area
for a good, clean ground connection.
Make sure the ground wire is as short
as possible and is connected to metal
on the vehicle’s body. Do not connect
the GND – cable to the frame of the
vehicle. It is isolated from the chassis
using rubber shims and will not provide
an adequate ground. Instead, use the
trunk’s floor or cargo area as a suitable
location. Do not connect the GND –
cable to the battery’s negative (–)
terminal.
Use high-quality twisted-pair RCA audio
cables to connect your source unit’s
main stereo or subwoofer RCA output
jacks to the amplifier’s L/R INPUT jacks.
For a single subwoofer output, use an
RCA “Y” adapter to
For battery voltage, linear scale (pin 1):
2 volts = 8 volts at the battery
4.5 volts = 18 volts at the battery
For temperature, linear scale (pin 2):
0 volts = –10 degrees Celsius
5 volts = 110 degrees Celsius
For current, linear scale (pin 3):
0 volts = 0 amperes current draw
5 volts = 800 amperes current draw
The amplifier’s internal neon lights
require a separate switched power
connection with at least a 2-ampere cur-
rent capacity. If desired, install a switch
to turn on the neon lights or a relay trig-
gered by a circuit in the vehicle (e.g.,
door switch, trunk pin switch or other
turn-on source). If you want the amplifi-
er’s neon to light when the
connect its signal to both input jacks.
As a convenience, each JBL A6000GTi
or A3000GTi amplifier is also equipped
with a set of PASS-THRU L/R RCA audio
jacks. They will pass incoming audio
signals unaltered, and you can use
them to send stereo audio signals to
other components in your system.
Also, you can connect a power meter
using the pins for battery voltage and
current. Be sure to use a power meter
that multiplies the incoming voltage and
current signals (i.e., P = E x I) to convert
the data to watts.
amplifier is on, connect the LIGHTING
terminal to a relay triggered by the radio’s
remote turn-on lead (see Figure 5).
REMOTE LEVEL
CONTROL/ACCESSORY
GAUGE OUTPUTS
Source Unit
A6000GTi
Power Terminals
The A6000GTi and A3000GTi use an
RJ45 connector to output control
signals for the Remote Level Control
and accessory gauges. Use the 15'
RJ11 cable to connect the control to the
amplifier. For accessory gauges, use
the pinouts in Figure 6 to make custom
cables with materials found
Remote Turn-On
CONNECTING
THE SPEAKERS
IMPORTANT: As a safety feature and
due to the high output voltage
capability of the A6000GTi and
A3000GTi amplifiers, the SPEAKER
OUTPUTS are equipped with a cover
that must be in place in order for
the amplifier to operate. When the
cover is removed, the amplifier will
turn off and speaker connections
can be made safely.
+12 V
(or other
turn-on
85
87 87a
signal)
0-gauge
0-gauge
no nc
86
30
at most electronics supply stores or
home centers.
Ground
SPDT Relay
ANN-Type Fuse
(500 A or more)
Chassis
Ground
(Bare Metal)
18"
RJ45 Connector
(GTi Input Panel)
8
1
Figure 5. Power wiring
diagram for the JBL A6000GTi
amplifier. The A3000GTi is
wired in a similar way.
Batteries
Ground (also use for acc. gauges) = 8
No Connection = 7
1 = Battery Voltage (to acc. volt meter)
2 = Temperature (to acc. temp. gauge)
3 = Current (to acc. ampere meter)
4 = Remote Level Control
Remote Level Control = 6
Remote Level Control = 5
Use 0-gauge cable to connect the
BATT+ terminal directly to the vehicle’s
battery. If the battery is located in the
engine compartment and the BATT+
cable must be routed through the
firewall or any metal obstruction, install
a wafer-type (ANN) fuse with a current
rating of at least 500 amperes and an
appropriate fuse holder
Figure 6. Pinouts for the REMOTE LEVEL RJ45 connector on the
A6000GTi or A3000GTi amplifier.
IMPORTANT: Do not connect a jumper
directly between the REMOTE and
LIGHTING terminals. Doing so may burn
out the remote turn-on circuits
in your source unit.
within 18" of the vehicle’s battery
(see Figure 5).
5
MAKING THE CONNECTIONS
A6000GTi SPEAKER
CONNECTIONS
Figure 7. The JBL A6000GTi
subwoofer amplifier is set
to bridged mode to drive a
subwoofer system. Only use
this mode when the nominal
equivalent or total impedance
of the speaker system is
2 ohms or greater.
Set Output Mode A6000GTi Amplifier
The A6000GTi is a 2-channel amplifier
designed to drive subwoofers only.
The left and right input signals are com-
bined inside the amplifier to
provide a mono output signal, no
matter which output mode is selected.
to 2CH/BR
(partial output panel)
(on input panel)
See “Setting The Crossover”
on Page 8
to Adjust Crossover Controls
The A6000GTi can be connected to
two independent speaker systems in
2-channel mode. It can be connected to
a combination of subwoofers
Subwoofer
System
configured as a single load with its
channels bridged or connected in
parallel. Bridged channels will provide
high output voltage for driving loads
with a nominal impedance of 2 to 4
ohms. Connecting the channels in
parallel will provide the high current
necessary to drive loads of 1 to 2 ohms.
2 ohms
or more
Figure 8. The JBL A6000GTi
subwoofer amplifier is set
to parallel mode to drive a
subwoofer system. Only
use this mode when the
nominal equivalent or total
impedance of the speaker
system is less than 2 ohms.
Set Output Mode A6000GTi Amplifier
to PARALLEL
(partial output panel)
(on input panel)
Included below are three application
diagrams that will help you plan
your A6000GTi installation. Figures 7
through 9 show how to configure the
JBL A6000GTi subwoofer amplifier for
bridged-mono, parallel-mono and
2-channel operation (see Setting Up the
GTi Amplifier).
jumper
See “Setting The Crossover”
on Page 8
to Adjust Crossover Controls
Subwoofer
System
NOTE: A jumper is added
between the + terminals.
IMPORTANT: If the nominal impedance
of the speaker system is close to 2
ohms, you may try both bridged and
parallel configurations to determine
which one performs better. Remember
to set the output mode switch to the
appropriate setting when changing
configurations.
2 ohms
or less
Figure 9. The JBL A6000GTi
subwoofer amplifier is set
to 2-channel mode to drive
a pair of subwoofers or
subwoofer systems with
nominal equivalent or total
impedances of 2 to 4 ohms.
Set Output Mode A6000GTi Amplifier
to 2CH/BR
(partial output panel)
(on input panel)
NOTE: For simplicity, Figures 7 through
9 do not show power, remote and input
connections (see page 5).
See “Setting The Crossover”
on Page 8
to Adjust Crossover Controls
Subwoofer
System
Subwoofer
System
2 to 4
ohms
2 to 4
ohms
6
MAKING THE CONNECTIONS
A3000GTI SPEAKER
CONNECTIONS
Figure 10. The JBL A3000GTi
amplifier is set to bridged
mode to drive a subwoofer
system. Only use this mode
when the nominal equivalent
or total impedance of the
speaker system is 2 ohms
or greater.
Set Output Mode A3000GTi Amplifier
Included below are three application
diagrams that will help you plan your
A3000GTi installation. Figures 10
through 12 show how to configure
the JBL A3000GTi amplifier for
bridged-mono, parallel-mono and
2-channel operation (also see
Setting Up the GTi Amplifier).
to BRIDGE
(partial output panel)
(on input panel)
See “Setting The Crossover”
on Page 8
to Adjust Crossover Controls
Subwoofer
System
NOTE: For simplicity, Figures 10 through
12 do not show power, remote and input
connections (see page 5).
2 ohms
or more
OUTPUT LOAD SWITCH
Figure 11. The JBL A3000GTi
amplifier is set to parallel
mode to drive a subwoofer
system. Only use this mode
when the nominal equivalent
or total impedance of the
speaker system is less than
2 ohms.
The Output Load switch is used to
optimize amplifier performance when
driving a full-range signal. Set the
switch according to the nominal imped-
ance of the load: Use the 4-ohm mode
when driving loads with a nominal
impedance greater than 2 ohms and the
2-ohm mode when driving loads with a
nominal impedance of 2 ohms or less.
Set Output Mode A3000GTi Amplifier
to PARALLEL
(partial output panel)
(on input panel)
jumper
See “Setting The Crossover”
on Page 8
to Adjust Crossover Controls
Subwoofer
System
NOTE: A jumper is added
between the + terminals.
2 ohms
or less
Figure 12. The JBL A3000GTi
amplifier is set to stereo
mode to drive a pair of full-
range speaker systems with
nominal equivalent or total
impedances of 2 to 4 ohms.
Set Output Mode A3000GTi Amplifier
to STEREO
(partial output panel)
(on input panel)
See “Setting The Crossover”
on Page 8
to Adjust Crossover Controls
L Speaker
System
R Speaker
System
2 to 4
ohms
2 to 4
ohms
7
SETTING UP THE GTI AMPLIFIER
SETTING THE CROSSOVER
SETTING INPUT
SENSITIVITY
SETTING PHASE
SETTING DBO
IMPORTANT: If you plan to use the
A3000GTi to drive full-range speakers,
set the crossover mode switch to FLAT
and skip to the next section, “Setting
Input Sensitivity.”
1. Initially set the PHASE control to 0°.
Play a favorite audio track that has
significant bass output.
2. Continue listening to the music and
have another person slowly adjust
the PHASE control towards 180° and
back to 0° again.
3. Repeat Step 2 as needed until you
find a setting that produces the most
mid-bass output.
DBO (or Dynamic Bass Optimizer) is
a 12dB/octave high-pass filter with vari-
able frequency (20Hz to 80Hz)
and variable boost (0 to +12dB) at
the cutoff frequency.
NOTE: You can use the supplied
REMOTE LEVEL control to fine-tune
the input sensitivity or to adjust the
level of the bass according to the
program material after the amplifier’s
LEVEL control has been set properly.
Connect the remote module’s attached
cable to the REMOTE LEVEL (RJ45) jack
on the amplifier’s input panel. Start with
the REMOTE LEVEL Control in its maxi-
mum (clockwise) position.
1. Depending on your system plan,
set the A3000GTi’s crossover mode
switch to LP (low-pass) or HP (high-
pass). The A6000GTi is a low-pass
amplifier only, designed to drive
subwoofers. No crossover switch
is provided.
2. The crossover slope has two
settings: 12 (dB per octave) or
24 (dB per octave). Select the
slope that best suits your taste, but
consider that a steeper low-pass
filter will make the subwoofers
sound less directional (since more
midrange will be filtered from the
signal). A steeper high-pass filter will
reduce a small speaker’s
unnecessary cone excursion at
the lowest frequencies, which
will increase power handling
and reduce distortion.
3. Set the A3000GTi’s HP FREQ control
to allow the speakers to make
as much bass as possible while
minimizing distortion caused by
small speakers trying to reproduce
the lowest frequencies. The best
setting is one where the speakers
produce crisp, clear impact without
being overdriven.
NOTE: During DBO adjustment, you can
audition the effect by setting the DBO
switch to OFF and then back to ON.
NOTE: The A3000GTi can be used
to drive a pair of stereo mid-bass
speakers. In this case, use the DBO
to set the high-pass filter (from 20Hz to
80Hz) and use the crossover to set the
low-pass filter (from 80Hz to 320Hz).
NOTE: For applications using multiple
GTi amplifiers where the highest SPL
is desired at a single point in the
vehicle (i.e., SPL competition), adjust
the PHASE controls on all amplifiers
so all speakers are in phase at the
microphone position. This will pro-
vide the highest SPL when measured
with an SPL meter.
1. Initially, turn the amplifier’s LEVEL
control to the minimum (clockwise)
position.
2. Reconnect the (–) negative lead to
your vehicle’s battery. Apply power
to the audio system and play a
favorite music track.
3. Increase the source unit’s volume
control to the maximum listening
position. Slowly turn the amplifier’s
LEVEL control counterclockwise and
observe the I/OPT and E/OPT LEDs
(on the amplifier’s top).
• In the bridged or 2-channel mode,
at the ideal setting, the E/OPT LED
should flash on musical peaks to
indicate the amplifier is producing
maximum voltage. If the I/OPT LED
flashes in bridged mode, this
For a vented box where a subwoofer
is prone to overexcursion below the
tuned frequency, set DBO to ON and set
the DBO HP FREQ control 10Hz below
the box’s resonant (tuned)
frequency (e.g., 30Hz for a vented
box tuned to 40Hz). Power typically
wasted in this region will now be
conserved and instead be available
for frequencies the enclosure can
reproduce. Use the DBO BOOST
control to boost the bass at the set
frequency by as much as 12dB, as
shown in Figure 13.
HP FREQ
DBO HP FREQ Control
(adjusts cut-off
frequency)
80Hz 20Hz
dB
0
–3
–6
–9
indicates the speaker system’s
impedance is lower than 2 ohms
and the amplifier should be
For a sealed enclosure, use DBO to
enhance the middle of the bass region.
Set DBO to ON, and then set the DBO
HP FREQ control to 35Hz to 40Hz. Adjust
the DBO BOOST control for a big and
full bass sound. Alternatively, for a
tighter-sounding bass, set the DBO HP
FREQ control between 45Hz to 50Hz and
also adjust the DBO BOOST control
according to your preference.
–12
20
80
Freq. (Hz)
BOOST
configured in the parallel mode.
DBO BOOST Control
(adjusts boost amount
at cut-off frequency)
dB
4. For either amplifier, set the LP FREQ
control so vocal information is not
reproduced by the subwoofers, and
the subwoofers’ sound blends with
the sound of the midrange speakers
without any missing information.
• In the parallel mode, at the ideal
setting, the I/OPT LED should
flash on musical peaks to indicate
that the amplifier is producing max-
imum current.
MIN
MAX
12
6
If either the I/OPT or E/OPT LED is
on steadily, the amplifier is being
overdriven and your speakers may
be in jeopardy. Turn the LEVEL
control back slightly until the I/OPT or
E/OPT LED flashes on musical peaks.
0
NOTE: The LP FREQ control can be
set to any frequency between 32Hz
and 320Hz.
For an infinite baffle application,
set DBO to ON, and then set the
HP FREQ control to the speaker’s Fs
value (to keep the subwoofer from
trying to create bass below the
resonant frequency). Adjust the DBO
BOOST control according to your taste.
–6
–12
20
80
Freq. (Hz)
Figure 13. Frequency response curves
show typical DBO control ranges for
the JBL A6000GTi or A3000GTi amplifier.
8
SETTING UP THE GTI AMPLIFIER
REPLACING THE FUSE
OR NEON TUBES
Figure 14. Removing bottom screws and
the clear cover from the A6000GTi
amplifier. NOTE: Do not remove the logo
badge assembly.
The JBL A6000/A3000GTi amplifier
is equipped with an internal fuse, a
20-inch neon tube and two 6-inch neon
tubes. Should the fuse or a neon tube
fail, perform the following steps
to replace the part:
NOTE: For neon tube replacement, see
your authorized JBL car audio dealer to
®
purchase new StreetGlow neon tubes
in 6- or 20-inch sizes.
NOTE: Although the following
steps discuss and illustrate how
to disassemble a JBL A6000GTi,
the disassembly procedure for a
JBL A3000GTi is similar.
1. Disconnect and unmount the
amplifier from the vehicle. On a
soft surface, turn the amplifier over
to view the bottom. Using a T-25
screwdriver, remove the four large
Torx-head screws along the bottom
edges and set them aside (see
Figure 14).
2. Turn the amplifier over to view the
top. Using a 5⁄32-inch Allen wrench,
remove the four cap screws on the
clear cover and set them aside (see
Figure 14).
4. Using a T-15 screwdriver, remove the
four Torx-head screws around the
output panel and set them aside (see
Figure 15).
5. Repeat Step 4 for the input panel
(see Figure 15).
6. Remove the cover and set it aside
(see Figure 15).
Figure 15. Removing the input and
output screws and the cover from the
A6000GTi amplifier.
3. Slide the clear cover off and set it
aside (see Figure 14).
9
SETTING UP THE GTI AMPLIFIER
7. Using a T-15 screwdriver, remove the
two Torx-head screws on the display
board and set them aside
9. Using a small flat-blade screwdriver,
disconnect the wiring for the neon
tubes.
(see Figure 16 below). Disconnect
the ribbon cable from display board.
10. Remove the perforated shield and
set it aside.
8. Using a T-15 screwdriver, remove the
16 Torx-head screws on the
perforated shield and set them aside
(see Figure 16).
11. Replace the fuse or a neon tube as
follows:
• To replace the fuse on the ampli-
fier circuit board (see Figure 16),
use a 7⁄16-inch hex-socket driver
to remove the two fuse nuts and
then discard the failed fuse. Fasten
the replacement fuse
Figure 16. Removing the fuse from the
A6000GTi amplifier.
in place using the two fuse nuts.
• To replace a neon tube (see Figure
17), use a T-15 screwdriver and pli-
ers to remove the two
Torx-head screws, nuts and
washers on the two clamps that
hold each neon tube in place.
Remove the failed neon tube
and unscrew its wires.
On the replacement neon tube, clip off
the cigarette lighter adapter. Then strip
the wires and screw the ends to the
connector. Refasten the two clamps
with hardware in place around the
neon tube. If needed, repeat this proce-
dure for another failed neon tube.
Figure 17. Neon tube locations on the
A6000GTi amplifier.
Failed
Fuse
6" Neon Tubes
20" Neon Tube
(under shield)
12. Reassemble the amplifier in reverse
order, as discussed in Steps 1
through 10.
10
TROUBLESHOOTING
SYMPTOM
LIKELY CAUSE
SOLUTION
Power
No audio
(Power LED is off)
No voltage at power
or remote terminal
Check BATT+, REMOTE and
GND – terminals with VOM for
blown fuse or poor connection
6000 Watts Parallel Bridge
A6000GTi
A3000GTi
Thermal
Signal -18 dB
-9 dB
E Opt
I Opt
Fault
Internal fuse blown
(incorrect power
connections)
Low or high voltage
at power terminal
Replace internal fuse
(see Replacing the Fuse
or Neon Tubes section)
Check BATT+ terminal with
VOM for voltage between
10 and 16 Vdc; if not within
limits, check vehicle’s
electrical system
No audio
(Power LED
is flashing)
3000 Watts Parallel Bridge
Power
Fault
CH 1
CH 2
Thermal
Signal -18 dB
-9 dB
E Opt
I Opt
No audio
(Power and
Fault LEDs
are on)
Direct current on
speaker output(s)
Disconnect cable from
REMOTE terminal; if Fault LED
is still on, contact local JBL
service center
Figure 18. Display indicates Power Output and Protection status.
No audio
Internal amplifier
temperature is over
85° C
Check for blocked vents
or whether the ambient
temperature is above 85° C
(Power and
Thermal LEDs
are on)
Distorted audio
(I OPT and/or
E OPT LED[s]
are on more
than off)
Amplifier’s gain is
set to High
Properly adjust the
LEVEL control (see
Setting Input
Sensitivity section)
Distorted audio
(I OPT and/or
E OPT LED[s]
work correctly)
Defective source unit
Try new source unit
Shorted speaker
wires
Disconnect wires from
SPEAKER OUTPUTS and
check for shorts between
wires, or between a wire and
the vehicle’s chassis
Music lacks
“punch”
Speakers are out
of phase
Check speaker connections
(see sections on speaker
connections)
Wrong output mode
Verify output mode setting
(see Making the Connections
section)
Neon tubes do
not light
No voltage to neon tubes
for +12 Vdc
Check LIGHTING
terminal with VOM
Neon tubes are dead
Replace neon tubes
(see Replacing the Fuse
or Neon Tubes section)
11
Features, specifications and appearance are subject to change without notice.
Declaration of Conformity
We, Harman Consumer Group International
2, route de Tours
72500 Chateau-du-Loir
France
declare in own responsibility that the products
described in this owner’s manual are in compliance
with technical standards:
JBL Consumer Products
250 Crossways Park Drive, Woodbury, NY 11797 USA
EN 55013:2001
EN 55020:2002
© 2004 Harman International Industries, Incorporated
JBL and Crown are registered trademarks of
Harman International Industries, Incorporated.
Emmanuel Millot
Harman Consumer Group International
Chateau-du-Loir, France 05/04
Part No. GTIAMPOM4/04
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