JL Audio RBC-1 User Manual

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, 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 [phone] during business hours.

PROTECT YOUR HEARING!

Bass Boost Controls

Input Voltage

Low | High

CH 1 (Left)

Input Sens. LP Filter

Filter Freq. (Hz)

40

45

55

65

80

100

200

Bass Boost

Remote

Bass Port

PowerProtect

CH 2 (Right)

Pre-Outs

Left & Right

Preamp Inp ut Jacks

(pg. 6)

Protectio n Status

Indicator

(pg. 9)

Left & Right

Preamp Out put Jacks

(pg. 8)

Input Voltage

Selection

(pg. 6)

Power Statu s

Indicator

(pg. 9)

Bass EQ

On/Off Switc h

(pg. 8)

Jack for
Remote Bass
Control K nob

(pg. 8)

Filter Mode

Selection

(pg. 7)

Filter

Frequenc y Selector

(pg. 7)

Input Sensitiv ity

Control

(pg. 6)

Remote Turn-On

Connector

(pg. 6)

Chassis Ground

Connector

(pg. 5)

+12 V Power

Connector

(pg. 5)

Speaker Outputs

(pg. 8)

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.

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.

Serial Number:

INSTALLATION APPLICATIONS

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
th e w ar ran ty.

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.

PLANNING YOUR INSTALLATION

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.

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.

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.

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 so that it does not
come loose in the event of a collision or a sudden
jolt to the vehicle.

Stupid Mistakes to Avoid

• 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.

• 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.

• Protect all system wires from sharp metal

edges and wear by carefully routing them,
tying them down and using grommets and
loom where appropriate.

• Do not mount the amplifier in the engine

2 JL AUDIO G-MAX JL AUDIO G-MAX 3

compartment, under the vehicle, on the roof
or in any other area that will expose the
amplifier circuitry to the elements.

PRODUCT DESCRIPTION

The JL Audio G-MAX 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).

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.

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 G-MAX.

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.

5) Run speaker cables from the speaker systems

to the amplifier mounting location.

6) Find a good, solid metal grounding point

close to the amplif ier and connect the
negative power wire to it using appropriate
hardware (use of the JL Audio ECS master
ground lug, XB-MGLU is recommended).
Use the same size power wire as the wire
connected to the “+12 VD C” 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).

7) Securely mount the amplifier.

8) Connect the positive and negative power

wires to the amplifier. A fuse near the
amplifier is not necessary.

9) Connect the remote turn-on wire

to the amplifier.

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 G-MAX) 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.

16) Enjoy the fruits of your labor with your

favorite music.

POWER CONNECTIONS

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 G-MAX’s “+12V DC ” 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 G-MAX 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 G-MAX
with 4 AWG power wire.

Note: 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.

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 (XB-MGLU).
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.

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.

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 G-MAX is being run from that power
wire, we recommend a 80A fuse be used. ANL
(big blade 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
ANL or MaxiFuse™ ty pe.

4 JL AUDIO G-MAX JL AUDIO G-MAX 5

Input Sens. LP Filter

Filter Freq. (Hz)

40

45

556580

100

200

TURNON LEAD

Bass Boost Controls

Input Voltage

Low | High

CH 1 (Left)

Input Sens. LP Filter

Filter Freq. (Hz)

40

45

556580

100

200

Bass Boost

Remote

Bass Port

PowerProtect

CH 2 (Right)

Pre-Outs

The G-MAX 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 G-MAX’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.

INPUT SECTION

The G-MAX’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-ty pe jacks.

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.

INPUT VOLTAGE RANGE:

A wide range of signal input voltages can be
accommodated by the G-MAX’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.

The “High” position on the “Input Voltage”
switch selects an input sensitivity range between
800mV and 8V. This is useful for certain high­output preamp level signals as well as speaker­level output from source units and
small amplifiers.

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.

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.

AMPLIFIER CONTROLS

1) “Input Sens.”: Once the appropriate “Input
Vol ta ge ” 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 counter­clockwise will result in lower sensitivity
(quieter for a given input voltage.)

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.

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.

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 mid­range 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 G-MAX 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 G-MAX 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.

2) Filter Operation: The low-pass filter in the

G-MAX 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 mid­bass speakers in the system. Experiment to
find the slope which best matches the acoustic
requirements of your system.

6 JL AUDIO G-MAX JL AUDIO G-MAX 7