JL Audio Car Stereo System A1800 User Manual

A1800  
monoblock subwoofer amplifier  
OWNER’S MANUAL  
Thank you for purchasing a JL Audio amplifier for  
your automotive sound system.  
Your amplifier has been designed and manufactured to exacting  
standards in order to ensure years of musical enjoyment in your vehicle.  
For maximum performance and extended warranty  
coverage, we highly recommend that you have your new amplifier  
installed by an authorized JL Audio dealer. Your authorized  
dealer has the training, expertise and installation equipment to ensure  
optimum performance from this product. Should you  
decide to install the amplifier yourself, please take the time  
to read this manual thoroughly so as to familiarize yourself  
with its installation requirements and setup procedures.  
If you have any questions regarding the instructions in this  
manual or any aspect of your amplifier’s operation, please contact your  
authorized JL Audio dealer for assistance. If you need further assistance,  
please call the JL Audio Technical Support Department  
at (954) 443-1100 during business hours.  
 
PROTECT YOUR HEARING!  
INSTALLATION APPLICATIONS  
PLANNING YOUR INSTALLATION  
We value you as a long-term customer. For  
that reason, we urge you to practice restraint in  
the operation of this product so as not to damage  
your hearing and that of others in your vehicle.  
Studies have shown that continuous exposure to  
high sound pressure levels can lead to permanent  
(irreparable) hearing loss. This and all other  
high-power amplifiers are capable of producing  
such high sound pressure levels when connected  
to a speaker system. Please limit your continuous  
exposure to high volume levels.  
This amplifier is designed for operation in  
vehicles with 12 volt, negative-ground electrical  
systems. Use of this product in vehicles with  
positive ground and/or voltages other than 12V  
may result in damage to the product and will void  
the warranty.  
This product is not certified or approved for  
use in aircraft.  
Do not attempt to “bridge” the outputs of this  
amplifier with the outputs of a second amplifier,  
including an identical one.  
It is important that you take the time to read  
this manual and that you plan out your  
installation carefully. The following are some  
considerations that you must take into account  
when planning your installation.  
Mounting the amplifier upside down is  
strongly discouraged.  
If mounting the amplifier under a seat,  
make sure there is at least 1 inch (2.5 cm) of  
space above the amplifier’s outer shell to permit  
proper cooling.  
Cooling Efficiency Considerations:  
The outer shell of your JL Audio amplifier  
is designed to remove heat from the amplifier  
circuitry. For optimum cooling performance,  
this outer shell should be exposed to as large a  
volume of air as possible. Enclosing the amplifier  
in a small, poorly ventilated chamber can  
lead to excessive heat build-up and degraded  
performance. If an installation calls for an  
enclosure around the amplifier, we recommend  
that this enclosure be ventilated with the aid  
of a fan. In normal applications, fan-cooling  
is not necessary.  
Safety Considerations:  
Your amplifier needs to be installed in a dry,  
well-ventilated environment and in a manner  
which does not interfere with your vehicle’s safety  
equipment (air bags, seat belt systems, ABS brake  
systems, etc.). You should also take the time to  
securely mount the amplifier using the supplied  
screws so that it does not come loose in the event  
of a collision or a sudden jolt to the vehicle.  
While driving, operate your audio system in  
a manner that still allows you to hear necessary  
noises to operate your vehicle safely (horns,  
sirens, etc.).  
SERIAL NUMBER  
In the event that your amplifier requires  
service or is ever stolen, you will need to have  
a record of the product’s serial number. Please  
take the time to enter that number in the space  
provided below. The serial number can be found  
on the bottom panel of the amplifier and on the  
amplifier packaging.  
Stupid Mistakes to Avoid  
Chassis Ground  
Connector  
(pg. 5)  
Check before drilling any holes in your vehicle  
to make sure that you will not be drilling  
through a gas tank, brake line, wiring harness or  
other vital vehicle system.  
Speaker Outputs  
(pg. 8)  
+12 V Power  
Connector  
(pg. 5)  
Remote Turn-On  
Connector  
(pg. 6)  
• Do not run system wiring outside or underneath  
the vehicle. This is an extremely dangerous  
practice which can result in severe damage to  
your vehicle and person.  
Serial Number:  
• Protect all system wires from sharp metal  
edges and wear by carefully routing them,  
tying them down and using grommets and  
loom where appropriate.  
Input Voltage  
Selection  
(pg. 6)  
Left & Right  
Preamp Output Jacks  
(pg. 8)  
Protection Status  
Indicator  
Bass EQ  
On/Off Switch  
(pg. 8)  
Filter Mode  
Selection  
(pg. 7)  
(pg. 9)  
Jack for  
Left & Right  
Preamp Input Jacks  
(pg. 6)  
Power Status  
Indicator  
(pg. 9)  
Remote Bass  
Control Knob  
(pg. 8)  
Input Sensitivity  
Control  
(pg. 6)  
Filter  
Frequency Selector  
(pg. 7)  
• Do not mount the amplifier in the engine  
compartment, under the vehicle, on the roof  
or in any other area that will expose the  
amplifier circuitry to the elements.  
CH 1 (Left)  
Pre-Outs  
Bass Boost Controls  
Bass Boost  
Filter Freq. (Hz)  
65  
Input Voltage  
Input Sens.  
LP Filter  
55  
45  
40  
80  
100  
200  
Power  
Protect  
|
Low High  
Remote  
Bass Port  
CH 2 (Right)  
2
JL AUDIO A1800  
JL AUDIO A1800  
3
 
PRODUCT DESCRIPTION  
POWER CONNECTIONS  
The JL Audio A1800 is a monoblock subwoofer  
amplifier utilizing proprietary and patented  
Class D technology. Its frequency response  
is limited to the range below 250 Hz. It is not  
designed for driving midrange speakers or  
tweeters. Every aspect of its operation has been  
optimized for low-frequency amplification.  
For detailed specifications, please refer to  
Appendix C (page 13).  
5) Run speaker cables from the speaker systems  
to the amplifier mounting location.  
6) Find a good, solid metal grounding point  
close to the amplifier and connect the  
negative power wire to it using appropriate  
hardware (use of the JL Audio ECS master  
ground lug, XA-MGL-1 is recommended).  
Use the same size power wire as the wire  
connected to the “+12VDC” connection  
(4 AWG), no longer than 36 inches (90 cm)  
from the amplifier to the ground connection  
point. In some vehicles, it may be necessary to  
upgrade the battery ground wire. (See page 5  
for important notice).  
Before installing the amplifier, disconnect the  
negative (ground) wire from the vehicle’s battery.  
This will prevent accidental damage to the system,  
the vehicle and your body during installation.  
The ground connection should be made using  
the same gauge wire as the power connection (4  
AWG) and should be kept as short as possible,  
while accessing a solid piece of sheet metal in the  
vehicle. The surface of the sheet metal should  
be sanded at the contact point to create a clean,  
metal-to-metal connection between the chassis  
and the termination of the ground wire. For  
optimal grounding, we recommend the use of a  
JL Audio ECS master ground lug (XA-MGL-1).  
Alternatively, a sheet metal screw or bolt can be  
used with a star washer.  
Any wires run through metal barriers (such  
as firewalls), must be protected with a high  
quality rubber grommet to prevent damage to the  
insulation of the wire. Failure to do so may result  
in a dangerous short circuit.  
TYPICAL INSTALLATION SEQUENCE  
The following represents the sequence  
for a typical amplifier installation, using an  
aftermarket source unit or OEM Interface  
processor (like the CleanSweep CL441dsp).  
Additional steps and different procedures may  
be required in some applications. If you have  
any questions, please contact your authorized  
JL Audio dealer for assistance.  
7) Securely mount the amplifier using the  
supplied screws.  
8) Connect the positive and negative power  
wires to the amplifier. A fuse near the  
amplifier is not necessary.  
The A1800’s “+12VDC” and “Ground”  
connections are designed to accept 4 AWG power  
wire. 4 AWG is a minimum power wire size for  
this amplifier.  
If you are installing the A1800 with other  
amplifiers and wish to use a single main power  
wire, use 2 AWG or larger main power wire for  
systems with total power between 700W and  
1400W or 1/0 AWG wire for systems with more  
than 1400W. This main power wire should  
terminate into a distribution block mounted as  
close to the amplifiers as possible. The output of  
the distribution block will connect to the A1800  
with 4 AWG power wire.  
9) Connect the remote turn-on wire  
to the amplifier.  
1) Disconnect the negative battery post  
connection and secure the disconnected cable  
to prevent accidental re-connection during  
installation. This step is not optional.  
2) Run power wire (minimum 4 AWG) from the  
battery location to the amplifier mounting  
location, taking care to route it in such a  
way that it will not be damaged and will  
not interfere with vehicle operation. Use  
2 AWG or 1/0 AWG power wire and a power  
distribution block if additional amplifiers are  
being installed with the A1800.  
3) Connect power wire to the positive battery  
post. Fuse the wire with an appropriate fuse  
block (and connectors) within 18 inches (45  
cm) wire length of the positive battery post.  
This fuse is essential to protect the vehicle.  
Do not install the fuse until the power wire  
has been securely connected to the amplifier.  
4) Run signal cables and remote turn-on wire  
from the source unit to the final amplifier  
mounting location.  
Many vehicles employ small (10 AWG -  
6 AWG) wire to ground the battery to the  
vehicle chassis and to connect the alternator’s  
positive connection to the battery. To prevent  
voltage drops, these wires should be upgraded  
to 4 AWG when installing amplifier systems  
with main fuse ratings above 60A.  
10) Connect the input cables to the amplifier.  
11) Connect the speaker cables to the amplifier.  
12) Carefully review the amplifier’s control  
settings to make sure that they are set  
according to the needs of the system.  
13) Install the power wire fuse (80A for a  
single A1800) and reconnect the negative  
battery post terminal.  
14) Turn on the source unit at a low level  
to double-check that the amplifier is  
configured correctly. Resist the temptation  
to crank it up until you have verified the  
control settings.  
15) Make necessary adjustments to the input  
sensitivity controls to obtain the right  
overall output and the desired balance  
in the system. See Appendix A (page 12)  
for the recommended input sensitivity  
setting method.  
FUSE REQUIREMENTS  
It is absolutely vital that the main power  
wire(s) to the amplifier(s) in the system be  
fused within 18 inches (45 cm) of the positive  
battery post connection. The fuse value at each  
power wire should be high enough for all of the  
equipment being run from that power wire. If  
only the A1800 is being run from that power wire,  
we recommend a 80A fuse be used. ANL (big  
blade fuse), AGU (big glass fuse) or MaxiFuse™  
(big plastic-body fuse) types are recommended.  
No fuse is required or recommended directly  
before the amplifier power connection. If one is  
desired, we recommend the use of a 80A AGU,  
AFS or MaxiFuse™ type.  
Note: that smaller AWG numbers mean bigger  
wire and vice-versa (1/0 AWG is the largest, 2  
AWG is smaller, then 4 AWG, then  
8 AWG, etc.).  
To connect the power wires to the amplifier,  
first back out the set screw on the top of the  
terminal block, using the supplied 2.5 mm hex  
wrench. Strip 1/2 inch (12 mm) of insulation from  
the end of each wire and insert the bare wire into  
the terminal block, seating it firmly so that no  
bare wire is exposed. While holding the wire in  
place, tighten the set screw firmly, taking care not  
to strip the head of the screw.  
16) Enjoy the fruits of your labor with your  
favorite music.  
4
JL AUDIO A1800  
JL AUDIO A1800  
5
 
TURN-ON LEAD  
AMPLIFIER CONTROLS  
The A1800 uses a conventional +12V remote  
turn-on lead, typically controlled by the source  
unit's remote turn-on output. The amplifier will  
turn on when +12V is present at its “Remote”  
input and turn off when +12V is switched off. If  
a source unit does not have a dedicated remote  
turn-on output, the amplifier’s turn-on lead can  
be connected to +12V via a switch that derives  
power from an ignition-switched circuit.  
The A1800’s “Remote” turn-on connector is  
designed to accept 18 AWG – 12 AWG wire. To  
connect the remote turn-on wire to the amplifier,  
first back out the set screw on the top of the  
terminal block, using the supplied 2.5 mm hex  
wrench. Strip 1/2 inch (12mm) of wire and insert  
the bare wire into the terminal block, seating it  
firmly so that no bare wire is exposed. While  
holding the wire in the terminal, tighten the set  
screw firmly, taking care not to strip the head of  
the screw and making sure that the wire is firmly  
gripped by the set screw.  
You may run a stereo or a mono signal into  
the inputs of the amplifier. The amplifier’s input  
section automatically sums stereo signals to mono  
for the internal amplifier section. The amplifier  
will operate with only one input connection (left  
or right), but will require an increase in input  
sensitivity to overcome the loss of signal. If a  
mono input signal is to be run, we recommend  
that you use a “Y-adaptor” to split the mono  
signal into both inputs of the amplifier.  
1) “Input Sens.”: Once the appropriate “Input  
Voltage” range has been selected, the control  
labeled “Input Sens.” located in the “Amplifier  
Controls” section can be used to match the  
source unit’s output voltage to the input  
stage of the amplifier for maximum clean  
output. Rotating the control clockwise will  
result in higher sensitivity (louder for a given  
input voltage). Rotating the control counter-  
clockwise will result in lower sensitivity  
(quieter for a given input voltage.)  
Filter Controls  
Most speakers are not designed to reproduce  
the full range of frequencies audible by the  
human ear. For this reason, most speaker  
systems are comprised of multiple speakers, each  
dedicated to reproducing a specific frequency  
range. Filters are used to select which frequency  
range is sent to each section of a speaker system.  
The division of frequency ranges to different  
speakers can be done with passive filters (coils  
and/or capacitors between the amplifier outputs  
and the speakers), which are acceptable and  
commonly used for filtering between mid-  
range speakers and tweeters. Filtering between  
subwoofer systems and satellite speaker systems  
is best done with active filters, which cut off  
frequency content at the input to the amplifier.  
Active filters are more stable than passive filters  
and do not introduce extraneous resistance,  
which can degrade subwoofer performance.  
The active filter built into the A1800 can be  
used to eliminate potentially harmful and/or  
undesired frequencies from making their way  
through the amplifier sections to the speaker(s).  
This serves to improve tonal balance and to avoid  
distortion and possible speaker failure. Correct  
use of these filters can substantially increase the  
longevity and fidelity of your audio system.  
The A1800 employs a sophisticated, variable,  
low-pass active filter for its internal channel.  
This feature is designed to attenuate frequencies  
above its filter frequency, so that the system’s  
subwoofers do not reproduce any audible  
midrange content.  
INPUT VOLTAGE RANGE:  
A wide range of signal input voltages can be  
accommodated by the A1800’s input section  
(200mV – 8V). This wide range is split up into  
two sub-ranges, accessible via a switch located to  
the left of the Input Connectors.  
The “Low” position on the “Input Voltage”  
switch selects an input sensitivity range between  
200mV and 2V. This means that the “Input  
Sens.” rotary control will operate within that  
voltage window. If you are using an aftermarket  
source unit or an OEM interface processor with  
conventional preamp-level outputs, this is most  
likely the position that you will use.  
Filter Freq. (Hz)  
65  
Input Sens.  
LP Filter  
55  
45  
40  
80  
100  
200  
INPUT SECTION  
The A1800’s input section allows you to send  
signal to the amplifier section through the use  
of two differential-balanced inputs, one for the  
left channel signal and one for the right channel  
signal. Connection is via RCA-type jacks.  
To properly set the amplifier for maximum  
clean output, please refer to Appendix A (page  
12) in this manual. After using this procedure,  
you can then adjust any or all “Input Sens.”  
levels downward if this is required to achieve  
the desired system balance.  
The “High” position on the “Input Voltage”  
switch selects an input sensitivity range between  
800mV and 8V. This is useful for certain high-  
output preamp level signals as well as speaker-  
level output from source units and  
small amplifiers.  
Do not increase any “Input Sens.” setting  
for any channel(s) of any amplifier in the  
system beyond the maximum level established  
during the procedure outlined in Appendix  
A (page 12). Doing so will result in audible  
distortion and possible speaker damage.  
To use speaker-level sources, splice the speaker  
output wires of the source unit or small amplifier  
onto a pair of RCA plugs. No line output  
converter is needed in most cases.  
CH 1 (Left)  
Input Voltage  
|
Low High  
2) Filter Operation: The low-pass filter in the  
A1800 is fully variable between 40 Hz and  
200 Hz via the “Filter Freq.” control knob  
and features the ability to select between a  
moderate “12dB” per octave or a steep “24dB”  
per octave slope via the “Mode/Slope” switch.  
Depending on the subwoofer system and  
the vehicle, different slopes may be required  
to produce a smooth transition to the mid-  
bass speakers in the system. Experiment to  
find the slope which best matches the acoustic  
requirements of your system.  
CH 2 (Right)  
The output of the amplifier will decrease for  
a given input voltage when the “Input Range”  
switch is placed in the “High” position.  
Conversely, the output will be higher with the  
switch in the “Low” position. While this may  
sound counter-intuitive, it is consistent with the  
descriptions above.  
6
JL AUDIO A1800  
JL AUDIO A1800  
7
 
BASS BOOST CONTROLS  
Tuning Hint: A trunk mounted sub whose  
output has to “fight” through a rear deck or a  
back seat often benefits from the 12 dB/octave  
slope which lets more upper bass content pass  
through. A sub that fires directly into the  
listening environment is more likely to benefit  
from a 24 dB/octave slope.  
The preamp output signal is not affected by the  
Bass Boost” processing selected for the amplifier  
or by any crossover filter selected (if the input  
signal is full-range, the preamp output will be  
full-range).  
The signal level of the “Preamp Output” is  
line-level (low voltage), regardless of the position  
selected via the A1800’s “Input Voltage” switch.  
An additional amplifier connected to these  
preamp outputs should have its input voltage  
switch set to the “Low” position.  
Speaker loads below 2 ohms nominal are not  
recommended and may cause the amplifier  
to initiate a protection mode which reduces  
power output.  
Bass Boost Controls  
Bass Boost  
Protect  
You will notice that there are two “+” positive  
connections and two “” negative connections.  
This is to facilitate multiple speaker wiring.  
The two positive and two negative connections  
are connected in parallel inside the amplifier.  
Connecting two speakers, each to one set of  
positive and negative terminals, will result in a  
parallel speaker connection. If only connecting  
one pair of speaker wires, it is not necessary to  
use both sets of connections.  
Remote  
Bass Port  
Note: The above hint is not “set-in-stone”… You  
should always listen to the system carefully to  
determine the best choice as vehicle acoustics and  
other factors play a big role in choosing the most  
appropriate filter slope.  
1) “Bass Boost”: This switch allows the user  
to activate a 6 dB boost centered at 48 Hz.  
The “Filter Mode” switch in the Amplifier  
Controls” section must be in the “LP” position  
for the bass boost to be functional.  
3) Precise Frequency Selection: The filter  
frequency markings on the front panel of  
the amplifier are for reference purposes and  
are generally accurate to within 1/3 octave  
or better. If you would like to select the filter  
frequency with a higher level of precision,  
consult Appendix B (page 13) of this manual.  
This chart gives you a more accurate frequency  
for each of the forty detented positions of the  
frequency selection control. This method can  
be very useful if the amplifier is mounted in  
a location where you can’t see the front panel  
markings easily.  
If you plan to use the “Pre-Outs” to feed  
a stereo amplifier, you must connect a  
stereo signal to the input of the amplifier.  
A mono signal into the amplifier will result  
in a mono signal out of the preamp output.  
2) “Remote Bass Port”: This port allows you to  
connect an optional remote boost knob (sold  
separately, JL Audio Model RBC-1) that can  
be mounted in the front of the vehicle. With  
the RBC-1 connected, the boost is no longer  
limited to 0 or +6 dB, allowing a range of  
0 - 12 dB of boost to be selected.  
SPEAKER OUTPUTS  
The A1800’s speaker outputs are designed to  
accept 16 AWG - 8 AWG wire.  
The A1800 is designed to deliver power into  
speaker loads equal to or greater than 2 ohms.  
To connect the speaker wires to the amplifier,  
first back out the set screws own the top of the  
terminal block, using the supplied 2.5 mm hex  
wrench. Strip 1/2 inch (12 mm) of insulation from  
the end of each wire and insert the bare wire into  
the terminal block, seating it firmly so that no  
bare wire is exposed. While holding the wire in  
place, tighten the set screw firmly, taking care not  
to strip the head of the screw.  
PRE-OUTS  
The A1800 incorporates a pass-through  
preamp output section, so that additional  
amplifiers can be easily added to the system.  
The preamp output delivers the same signal that  
is connected to the A1800’s inputs.  
4) Defeating the Amplifier Filter: The Low-  
Pass filter can also be defeated completely,  
by switching the “Mode/Slope” switch to  
the “Off” position. This is useful if you are  
using an external active crossover in the  
system. Keep in mind that turning the internal  
crossover off also defeats the “Bass Boost”  
processing (see next section for details). With  
the internal crossover turned off, the A1800’s  
upper frequency response limit is 250 Hz, due  
to its bass-specific Class D design.  
CH 1 (Left)  
Pre-Outs  
Power  
CH 2 (Right)  
8
JL AUDIO A1800  
JL AUDIO A1800  
9
 
AMPLIFIER STATUS INDICATOR LIGHTS &  
PROTECTION CIRCUITRY  
There are two status indicator lights on the  
input / control end of the amplifier.  
SERVICING YOUR JL AUDIO AMPLIFIER  
If your amplifier fails or malfunctions, please  
return it to your authorized JL Audio dealer so  
that it may be sent in to JL Audio for service.  
There are no user serviceable parts or fuses inside  
the amplifier. The unique nature of the circuitry  
in the JL Audio amplifiers requires specifically  
trained service personnel. Do not attempt  
to service the amplifier yourself or through  
unauthorized repair facilities. This will not only  
void the warranty, but may result in the creation  
of more problems within the amplifier.  
Low-Voltage protection:  
If the car’s supply voltage drops below 10  
volts, the entire amplifier will shut itself off to  
protect its internal circuitry. The green “Power”  
indicator will turn off when this occurs. The  
amplifier will turn back on when voltage climbs  
back above 10 volts. This may happen in a rapid  
cycle when bass-heavy program material causes  
a weak charging system to dip below 10 volts  
momentarily. If this is happening in your system,  
turn your audio system off and have your power  
wiring, ground connections and charging  
system inspected.  
Power  
Protect  
If you have any questions about the installation or  
setup of the amplifier not covered in this manual,  
please contact your dealer or technical support.  
1) “Power” (Green): lights to indicate that the  
amplifier is turned on and operating normally.  
JL Audio Technical Support:  
(954) 443-1100  
9:00 AM – 5:30 PM (Eastern Time Zone)  
Monday - Friday  
2) “Protect” (Red): Indicates that the amplifier  
protection circuitry has been activated to  
prevent product failure due to a short-circuit or  
a dangerously low impedance connected to the  
amplifier output(s). Connecting the speaker  
outputs to an impedance lower than 2 ohms  
will cause this protection mode to activate.  
When this protection mode is activated, the  
amplifier will reduce it maximum power  
output to protect its circuitry, which will  
manifest itself as increased distortion. When  
the problem is corrected, the amplifier will  
return to normal operation.  
Advanced Rollback Thermal protection  
Unlike conventional thermal protection  
systems, which shut down an amplifier when it  
overheats, this system protects the amplifier by  
gradually reducing power output if the amplifier’s  
safe operating temperature is exceeded. The  
amplifier will continue to operate and return  
to normal power output once its temperature  
returns to a normal range.  
10  
JL AUDIO A1800  
JL AUDIO A1800  
11  
 
APPENDIX A:  
APPENDIX B:  
APPENDIX C:  
Input Sensitivity Level Setting  
8) Increase the “Input Sens.” control until the  
target voltage is observed with the voltmeter.  
9) Once you have adjusted the A1800 to its  
maximum low-distortion output level,  
reconnect the speaker(s). The “Input Sens.”  
controls can now be adjusted downward if the  
amplifier requires attenuation to achieve the  
desired system balance.  
Precise Frequency Selection Chart  
A1800 Specifications  
Following the directions below will allow the  
installer to adjust the input sensitivity of each  
amplifier channel pair simply and easily in just a  
few minutes using equipment which is commonly  
available in installation bays.  
“FILTER FREQ” AMP FILTER  
General Specifications:  
Recommended Fuse Value: 80A  
Detent  
Number  
Panel  
Marking  
Actual  
Freq.  
Recommended Fuse Type: AGU, AFS, ANL or MaxiFuse™  
Full counter-clockwise: 42  
01 . . . . . . . . . . . . . . . . . . . . . . . . . . . .42  
02 . . . . . . . . . . . . . . . . . . . . . . . . . . . .42  
03 . . . . . . . . . . . . . . . . . . . . . . . . . . . .42  
04 . . . . . . . . . . . “40” . . . . . . . . . . . .42  
05 . . . . . . . . . . . . . . . . . . . . . . . . . . . .43  
06 . . . . . . . . . . . . . . . . . . . . . . . . . . . .44  
07 . . . . . . . . . . . . . . . . . . . . . . . . . . . .46  
08 . . . . . . . . . . . “45” . . . . . . . . . . . .47  
09 . . . . . . . . . . . . . . . . . . . . . . . . . . . .49  
10 . . . . . . . . . . . . . . . . . . . . . . . . . . . .50  
11. . . . . . . . . . . . . . . . . . . . . . . . . . . . .52  
12 . . . . . . . . . . . . . . . . . . . . . . . . . . . .53  
13 . . . . . . . . . . . . . . . . . . . . . . . . . . . .55  
14 . . . . . . . . . . . “55” . . . . . . . . . . . .57  
15 . . . . . . . . . . . . . . . . . . . . . . . . . . . .58  
16 . . . . . . . . . . . . . . . . . . . . . . . . . . . .60  
17 . . . . . . . . . . . . . . . . . . . . . . . . . . . .63  
18 . . . . . . . . . . . . . . . . . . . . . . . . . . . .65  
19 . . . . . . . . . . . “65” . . . . . . . . . . . .67  
20 . . . . . . . . . . . . . . . . . . . . . . . . . . . .70  
21 . . . . . . . . . . . . . . . . . . . . . . . . . . . .73  
22 . . . . . . . . . . . . . . . . . . . . . . . . . . . .76  
23 . . . . . . . . . . . . . . . . . . . . . . . . . . . .79  
24 . . . . . . . . . . . “80” . . . . . . . . . . . .83  
25 . . . . . . . . . . . . . . . . . . . . . . . . . . . .87  
26 . . . . . . . . . . . . . . . . . . . . . . . . . . . .92  
27 . . . . . . . . . . . . . . . . . . . . . . . . . . . .96  
28 . . . . . . . . . . . . . . . . . . . . . . . . . . . 102  
29 . . . . . . . . . . .“100” . . . . . . . . . . 108  
30 . . . . . . . . . . . . . . . . . . . . . . . . . . . 114  
31 . . . . . . . . . . . . . . . . . . . . . . . . . . . 122  
32 . . . . . . . . . . . . . . . . . . . . . . . . . . . 131  
33 . . . . . . . . . . . . . . . . . . . . . . . . . . . 143  
34 . . . . . . . . . . . . . . . . . . . . . . . . . . . 157  
35 . . . . . . . . . . . . . . . . . . . . . . . . . . . 184  
36 . . . . . . . . . . .“200” . . . . . . . . . . 193  
37 . . . . . . . . . . . . . . . . . . . . . . . . . . . 198  
38 . . . . . . . . . . . . . . . . . . . . . . . . . . . 198  
39 . . . . . . . . . . . . . . . . . . . . . . . . . . . 198  
Full-clockwise: 198  
Input Sections:  
No. of Inputs: One Stereo Pair  
Necessary Equipment  
• Digital AC Voltmeter  
Input Type: Differential-balanced with RCA jack inputs  
Input Range: Switchable from 200mV - 2V RMS to  
800mV - 8V RMS  
• CD with a sine-wave test tone recorded at  
0 dB reference level in the frequency range  
to be amplified for that set of channels  
(50 Hz for subwoofer channels, 1 kHz for a  
midrange application). Do not use attenuated  
test tones (-10 dB, -20 dB, etc.).  
Do not increase any Input Sens.setting for  
any amplifier channel or channel pair in the  
system beyond the maximum level established  
during this procedure. Doing so will result in  
audible distortion and possible speaker damage.  
Amplifier Section:  
Amplifier Topology: H-Bridge, Class D Mono  
with patented discrete drive circuitry  
Power Supply: Unregulated MOSFET switching type  
Rated Power at 12.5 V with less than  
0.08% THD+Noise (20-250 Hz):  
The Nine-Step Procedure  
1) Disconnect the speaker(s) from the  
It will be necessary to re-adjust the  
Input Sens.” for the affected channels if any  
equalizer boost is activated after setting the  
Input Sens.” with this procedure. This applies  
to any EQ boost circuit, including source unit  
tone controls or EQ circuits. EQ cuts will not  
require re-adjustment.  
amplifier’s speaker output connectors.  
2) Turn off all processing (bass/treble, loudness,  
EQ, etc.) on the source unit, processors (if  
used) and amplifier. Set fader control to center  
position and subwoofer level control to 3/4 of  
maximum (if used to feed the A1800).  
3) Switch the “Input Voltage” switch to “Low”  
and turn the “Input Sens.” control all the  
way down.  
4) Set the source unit volume to 3/4 of full  
volume. This will allow for reasonable gain  
overlap with moderate clipping at full volume.  
5) Using the chart on this page, determine the target  
voltage for input sensitivity adjustment according  
to the nominal impedance of the speaker system  
connected to the amplifier outputs.  
6) Verify that you have disconnected the speakers  
before proceeding. Play a track with an  
appropriate sine wave (within the frequency  
range to be amplified by the A1800) at 3/4  
source unit volume.  
7) Connect the AC voltmeter to the speaker output  
connectors of the amplifier. Make sure you test  
the voltage at the correct connectors (+ and –).  
480W RMS x 1 @ 4 ohms, 800W RMS x 1 @ 2 ohms  
Rated Power @ 14.4V with less than  
1% THD + Noise (20-250 Hz):  
640W RMS x 1 @ 4 ohms, 1000W RMS x 1 @ 2 ohms  
Signal to Noise Ratio: >95 dB referred to rated power  
(A-weighted, 20 Hz - 20 kHz noise bandwidth)  
Frequency Response: 10 - 250 Hz (+0, -1 dB)  
Damping Factor: >500 @ 4 ohms/50 Hz, >250 @ 2  
ohms/50 Hz  
Nom. Impedance  
Target AC Voltage  
43.8 V  
4Ω  
3Ω  
2Ω  
Amplifier Filter:  
42.0 V  
Amplifier Low-Pass Filter: State-variable, 12 dB/octave  
Butterworth or 24 dB/octave Linkwitz-Riley with  
continuously variable cutoff frequency selection  
from 40 - 200 Hz. Defeatable.  
40.0 V  
Preamp Output:  
Buffered pass-through type.  
Dimensions(LxWxH):  
15.75" x 9.25" x 2.50" (400mm x 235mm x 63.5mm)  
Due to ongoing product development, all specifications are subject to  
change without notice.  
12  
JL AUDIO A1800  
JL AUDIO A1800  
13  
 
APPENDIX D: TROUBLE SHOOTING  
“How do I properly set the input sensitivity on my amplifier”  
“My amplifier shuts off once in a while, usually at higher volumes”  
Check your voltage source and grounding point. The power supply  
Please refer to Appendix A (page 12) to set the input sensitivity for  
maximum, low-distortion output.  
of the A1800 will operate with charging system voltages  
down to 10V. Shutdown problems at higher volume levels  
can occur when the charging system voltage drops below  
10V. These dips can be of very short duration making them  
extremely difficult to detect with a common DC voltmeter.  
To ensure proper voltage, inspect all wiring and termination  
points. It may also be necessary to upgrade the ground  
wire connecting the battery to the vehicle’s chassis and the  
power wire connecting the alternator to the battery. Many  
vehicles employ small (10 AWG - 6 AWG) wire to ground the  
battery to the vehicle’s chassis and to connect the alternator to  
the battery. To prevent voltage drops, these wires should be  
upgraded to 4 AWG when installing amplifier systems with  
main fuse ratings above 60A. Grounding problems are the  
leading cause of misdiagnosed amplifier “failures.”  
“My amplifier doesn’t turn on”  
Check the fuse, not just visually, but with a continuity meter. It is  
possible for a fuse to have poor internal connections that  
cannot be found by visual inspection. It is best to take the  
fuse out of the holder for testing. If no problem is found with  
the fuse, inspect the fuse-holder.  
Check the integrity of the connections made to each of the  
+12VDC”, “Ground”, and Remote” terminals. Ensure  
that no wire insulation is pinched by the terminal set screw  
and that each connection is tight.  
Check to make sure there is +12V at the “Remote” connection of the  
amplifier. In some cases, the turn-on lead from the source unit  
is insufficient to turn on multiple devices and the use of a relay  
is required. To test for this problem, jump the “+12VDC” wire  
to the “Remote” terminal to see if the amplifier turns on. If this  
does not work, proceed to the next step.  
“My amplifier turns on, but there is no output”  
Check the input signal using an AC voltmeter to measure the  
voltage from the source unit while an appropriate test tone is  
played through the source unit (disconnect the input cables  
from the amplifier prior to this test). The frequency used  
should be in the range that is to be amplified by the amplifier  
(example: 50 Hz for a sub bass application or 1 kHz for a full  
range / high-pass application). A steady, sufficient voltage  
(between 0.2 and 8.0-volts) should be present at the output of  
the signal cables.  
Check the output of the amplifier. Using the procedure explained in  
the previous check item (after plugging the input cables back  
into the amplifier) test for output at the speaker outputs of  
the amplifier. Unless you enjoy test tones at high levels, it is  
a good idea to remove the speaker wires from the amplifier  
while doing this. Turn the volume up approximately half  
way. 5V or more should be measured at the speaker outputs.  
This output level can vary greatly between amplifiers but it  
should not be in the millivolt range with the source unit at  
half volume. If you are reading sufficient voltage, check your  
speaker connections as explained below.  
“I get a distorted / attenuated sound coming out of the speaker(s)”  
Check the speaker wires for a possible short, either between the  
positive and negative leads or between either speaker lead  
and the vehicle’s chassis ground. If a short is present, you  
will experience distorted and/or attenuated output. The  
Protect” light will illuminate in this situation. It may be  
helpful to disconnect the speaker wires from the amplifier  
and use a different set of wires connected to a test speaker.  
Check the nominal load impedance to verify that of the amplifier is  
driving a load equal to or greater than 2 ohms.  
Check the input signal and input signal cables to make sure signal  
is present at the Amplifier Inputs” and the cables are not  
pinched or loose. It may be helpful to try a different set of  
cables and/or a different signal source to be sure.  
“My amplifier’s output fluctuates when I tap on it or hit a bump”  
Check the connections to the amplifier. Make sure that the  
insulation for all wires has been stripped back far enough to  
allow a good contact area inside the terminal block.  
Check the input connectors to ensure that they all are making good  
contact with the input jacks on the amplifier.  
Check to ensure that the speaker wires are making a good  
connection with the metal inside the terminal block. The  
speaker wire connectors are designed to accept up to 8 AWG  
wire. Make sure to strip the wire to allow for a sufficient  
connection with the metal inside the terminal block.  
14  
JL AUDIO A1800  
JL AUDIO A1800  
15  
 
INSTALLATION NOTES:  
Use this diagram to document your amplifier’s switch and control positions.  
CH 1 (Left)  
Pre-Outs  
Bass Boost Controls  
Filter Freq. (Hz)  
65  
Bass Boost  
Input Voltage  
Input Sens.  
LP Filter  
55  
45  
40  
80  
100  
200  
Power  
Protect  
|
Low High  
Remote  
Bass Port  
CH 2 (Right)  
16  
JL AUDIO A1800  
JL AUDIO A1800  
17  
 
INSTALLATION NOTES:  
INSTALLATION NOTES:  
18  
JL AUDIO A1800  
JL AUDIO A1800  
19  
 

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