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SYSTEM CONFIGURATIONS
The G4500 is a flexible amplifier, well-suited
for a multitude of system configurations. In
this section, the most likely configurations are
explained in detail.
Once you have selected your desired
configuration, you can use the amplifier panel
drawing on pages 18 & 19 to mark the required
switch positions for easy reference.
BIAMPLIFIED SYSTEMS
Bi-amplified systems are defined as systems
in which separate amplifier channels drive low-
frequency (LF) and high-frequency (HF) speakers
and are separately filtered to send appropriate
frequency ranges to each speaker system.
The most common application of
bi-amplification in mobile audio is to drive a
subwoofer system from one or more amplifiers or
channels and component speakers from separate
amplifiers or channels.
The G4500 can be configured to drive a
bi-amplified system by itself or with a separate
subwoofer amplifier.
Bi-Amplified System with one G4500
In this configuration, channels 3&4 of the
G4500 will drive subwoofers (stereo or bridged)
with low-pass filtering. Channels 1&2 will
drive component speakers in stereo with
high-pass filtering.
Input connection options for a bi-amplified system
with one G4500 are as follows:
A) No User Adjustability:
R e q u i r e d : a basic source unit or processor
with one pair of stereo outputs.
Inp ut Connections: a single pair of stereo source
unit outputs connected to the “CH 1 (Left)”
and“CH 2 (Right)” inputs of the G4500 (select
“1&2” on the “CH 3&4 Input From” switch.
R e s u l t : the relative level of the LF and HF
channels will be determined by the G4500’s
“Input Sens.” settings and will not be user
adjustable from the front of the vehicle.
B ) Fade Subwoofer Level vs. HF Level
R e q u i r e d : a source unit or processor with two
pairs of stereo outputs.
Inp ut Connections: the first stereo pair source
unit outputs is connected to the “CH 1 (Left)”
and “CH 2 (Right)” inputs of the G4500. The
second stereo pair of source unit outputs is
connected to the “CH 3 (Left)” and “CH 4
(Right)” inputs (select “Discrete” on the “CH
3&4 Input From” switch).
R e s u l t : in this mode, the user has the ability to
fade or control the level of the LF channels
relative to the HF channels via the source
unit’s fader control without exceeding the
maximum clean output level set by each
amplifier section’s “Input Sens.” controls.
C) Subwoofer Level Control Only:
R e q u i r e d : a source unit or processor with
one pair of stereo outputs and dedicated
subwoofer outputs.
Inp ut Connections: the main stereo pair of
source unit outputs is connected to the “CH
1 (Left)” and “CH 2 (Right)” inputs of the
G4500. The source unit’s dedicated subwoofer
output is connected to the “CH 3 (Left)” and
“CH 4 (Right)” inputs (select “Discrete” on
the “CH 3&4 Input From” switch).
R e s u l t : in this mode, the user has the ability to
control the absolute level of the LF channels
relative to the HF channels.
Set the “Input Sens.” in the “Channel 3 & 4
Controls” section with the source unit’s
subwoofer level control set at 3/4 of full output.
See Appendix A (page 14) for details.
Crossover Setup for Bi-Amplified System
with one G4500:
Once the input sections have been configured
appropriately, go to the “Channel 3 & 4
Controls”. Select “LP” (low-pass) on the “Filter
Mode” switch and an appropriate “Filter Freq.”
(80 Hz is a good starting point).
AMPLIFIER STATUS INDICATOR LIGHTS &
PROTECTION CIRCUITRY
There are two status indicator lights on the
input / control end of the amplifier.
1) “Power” (Green): lights to indicate that the
amplifier is turned on and operating normally.
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 stereo (4 ohms bridged) 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.
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.
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.
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.
JL Audio Technical Support:
(9 5 4) 4 43 -110 0
9:00 AM – 5:30 PM (Eastern Time Zone)
Monday - Friday
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