JBL A6000GTi User Manual

car audio  
power amplifier  
owner’s manual  
THANK YOU  
for purchasing a JBL A6000GTi or A3000GTi amplifier.  
For warranty support, please register your purchase at  
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  
subwoofers 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.  
Zequivalent = 1/(1/Z1 + 1/Z2 + 1/Z3 …)  
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.  
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.  
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  
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.  
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)  
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.  
DUAL VOICE-COIL  
CONNECTIONS  
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  
identically. 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 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  
connected 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 ...  
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.  
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.  
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 matter how many are installed, the  
alternator 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  
amplifiers 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  
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.  
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  
alternator will put some of the energy  
back into the battery.  
If you plan to use the A6000GTi or  
A3000GTi in SPL competition, the  
charging system requirements will be  
much greater than those for normal  
music listening. Be prepared to add  
additional batteries and alternators to  
provide continuous current required  
for continuous duty.  
However, depending on the current  
rating 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.  
See your authorized JBL car audio  
dealer for help in designing and  
installing an upgraded charging  
system to support your GTi amplifier.  
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  
connect its signal to both input jacks.  
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  
current capacity. If desired, install a  
switch to turn on the neon lights or a  
relay triggered by a circuit in the vehicle  
(e.g., door switch, trunk pin switch or  
other turn-on source). If you want the  
amplifier’s neon to light when the  
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  
at most electronics supply stores or  
home centers.  
CONNECTING  
THE SPEAKERS  
Remote Turn-On  
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  
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  
within 18" of the vehicle’s battery  
(see Figure 5).  
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.  
5
MAKING THE 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.  
A6000GTi SPEAKER  
CONNECTIONS  
Set Output Mode A6000GTi Amplifier  
The A6000GTi is a 2-channel amplifier  
designed to drive subwoofers only.  
The left and right input signals are  
combined 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  
Subwoofer  
System  
The A6000GTi can be connected to  
two independent speaker systems in  
2-channel mode. It can be connected  
to a combination of subwoofers  
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  
The Output Load switch is used to  
optimize amplifier performance when  
driving a full-range signal. Set the  
switch according to the nominal  
impedance 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.  
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.  
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  
variable 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  
maximum (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.  
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.  
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 provide  
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  
–12  
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.  
20  
80  
Freq. (Hz)  
BOOST  
configured in the parallel mode.  
DBO BOOST Control  
(adjusts boost amount  
at cut-off frequency)  
dB  
• In the parallel mode, at the ideal  
setting, the I/OPT LED should  
flash on musical peaks to indicate  
that the amplifier is producing  
maximum 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 532-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  
(see Figure 16 below). Disconnect  
the ribbon cable from display board.  
9. Using a small flat-blade screwdriver,  
disconnect the wiring for the neon  
tubes.  
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.  
Figure 16. Removing the fuse from the  
A6000GTi amplifier.  
Fasten the replacement fuse  
in place using the two fuse nuts.  
• To replace a neon tube (see  
Figure 17), use a T-15 screwdriver  
and pliers 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 pro-  
cedure 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  
JBL Consumer Products  
250 Crossways Park Drive, Woodbury, NY 11797 USA  
© 2004 Harman International Industries, Incorporated  
JBL and Crown are registered trademarks of  
Harman International Industries, Incorporated.  
Part No. GTIAMPOM4/04  
Features, specifications and appearance are subject to change without notice.  

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