Slash 250 1 User 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

[phone] during business hours (Eastern Time Zone).

JL AUDIO 250/1

monoblock subwoofer amplifier

owner’s manual

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:

Your JL Audio amplifier employs an advanced
type of heat management, called RealSink™.This
feature takes advantage of convection and radiation
effects to remove heat from the amplifier circuitry.
For optimum cooling performance, the vertical heat
sinks located at the back of the amplifier 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, but
you still need to follow some basic guidelines:

• Amplifier mounted vertically with heat sink fins

pointing up: Optimum

• Amplifier mounted horizontally,

right side up: Good

• Amplifier mounted horizontally, but upside down:

Fair (not recommended if there is less than 1 inch
(2.5 cm) clearance above the amplifier heat sinks)

• Amplifier mounted vertically with heat sink fins

pointing laterally: Fair

• Amplifier mounted vertically with heat sink fins

pointing down: Poor (not recommended)

If mounting the amplifier under a seat, make sure
there is at least 1 inch (2.5 cm) of space above the
amplifier heat sink fins 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 using the supplied
screws so that it does not come loose in the event
of a collision or a sudden jolt to the vehicle (10 lbs.
of aluminum traveling at 60 MPH will hurt you).

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

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

JL AUDIO 250/1 3

PROTECT YOUR HEARING!

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 high­power 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 12V, 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.

2 JL AUDIO 250/1

JL AUDIO 250/1

monoblock subwoofer amplifier

Amplifier Input Section

Input Sens.

Input Voltage

Low/High

Left Ch.

Right Ch.

Signal Sensing

Off/On

Output Mode

Full-Range/Low-Pass/High-Pass

Left Ch.

Right Ch.

Amp LP Filter

Mode/Slope

Off/12dB/24dB

Filter Freq. (Hz)

Bass Control

LF Boost (dB)

Off/30Hz

Infrasonic Filter

+1

+13

+3

+7

+10

Preamp Output Section

Remote Turn-On

Connector

(pg. 6)

Chassis Ground

Connector

(pg. 5)

+12 V Power

Connector

(pg. 5)

+12VDC Ground Remote

Positive

Subwoofer

Outputs
(pg. 10)

Negative

Subwoofer

Outputs

(pg. 10)

Selects
Boost Level
for Bass EQ

(pg. 9)

Left and Right

Preamp Output Jacks

(pg. 8)

Left and Right

Input Jacks

(pg. 7)

Selects Low-Pass

Filter Frequency for

Amplifier Channel

(pg. 8)

Input Sensitivity

Control

(pg. 7)

Input Voltage

Range Selector

(pg. 7)

Infrasonic Filter

On/Off Switch

(pg. 9)

Signal Sensing

Turn-On

On/Off Switch

(pg. 6)

Amplifier Low­Pass Filter Slope
Selection/Defeat

(pg. 8)

Preamp Output
Mode Selector

(pg. 8)

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 person during installation.

The 250/1's “+12 VDC” and “Ground”
connections are designed to accept 8 AWG ­4 AWG power wire. 8 AWG is a minimum

power wire size for this amplifier.

If you are installing the 250/1 with other
amplifiers and wish to use a single main power wire,
use 4 AWG, 2 AWG or 1/0 AWG main power
wire (depending on the overall current demands of
all the amplifiers in the system).This 4 AWG,
2 AWG or 1/0 AWG power wire should terminate
into a distribution block mounted as close to the
amplifiers as possible and should connect to the
250/1 with 8 AWG or 4 AWG power wire.

Please note that smaller AWG numbers mean
bigger wire and vice-versa (1/0 AWG is biggest,
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
amplifier, 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
receptacle on the front panel of the amplifier,
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
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.The use of a star washer to lock
down the connection is advisable.

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 (or larger) when installing amplifier
systems with total fuse ratings exceeding 60A.

FUSE REQUIREMENTS

It is absolutely vital that the main power
lead 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 250/1 is being run from that power wire,
we recommend a 30A fuse be used. AGU (big glass
fuse) or MaxiFuse™ (big plastic-body fuse) types
are recommended.

No fuse is required directly before the amplifier
power connection. If one is desired, we recommend
the use of a 30A AGU fuse or MaxiFuse™ type.

IMPORTANT

!

JL AUDIO 250/1 5

PRODUCT DESCRIPTION

The JL Audio 250/1 is a monoblock subwoofer
amplifier utilizing proprietary and patented Class D
technology. Its frequency response is limited to the
range below 500 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 E (page 19).

TYPICAL INSTALLATION SEQUENCE

The following represents the sequence for a
typical amplifier installation, using an aftermarket
source unit. 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 8 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 4 AWG, 2 AWG or
1/0 AWG power wire if additional amplifiers are
being installed with the 250/1.

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
connected to the amplifier.

4) Run signal cables (RCA cables) and remote

turn-on wire from the source unit to the amplifier
mounting location.

5) Run speaker wire from the speaker system 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 the same
size power wire as the wire connected to the
“+12V” connection (min. 8 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 using the

supplied screws.

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 RCA input cables to

the amplifier.

11) Connect the speaker wires 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 power wire fuse (30A for a single

250/1) 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 control to obtain the right overall output
and the desired balance between the subwoofer
output and the satellite (mid and high-frequency)
output. See Appendix B (page 13) for the
recommended input sensitivity setting method.

16) Enjoy the fruits of your labor with your

favorite music.

4 JL AUDIO 250/1

AMPLIFIER INPUT SECTION

The 250/1 employs a differential-balanced
input topology that provides the user with a high
degree of input flexibility while retaining superior
noise rejection.This type of circuit also allows the
250/1 to accept high-voltage inputs from factory
source unit outputs without excessive distortion
or noise problems.

1) Input Connections: A standard left/right pair

of RCA type jacks is used for input on the 250/1.
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 and for the “LP”
output mode of the “Preamp Output” section. In
“Full-Range” or “HP” mode, the “Preamp Output”
delivers a stereo signal if one is present at the
amplifier inputs.

If you plan to use the “Preamp Output” in
“Full-Range” or “HP” mode 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. (It's a great amplifier, but it
doesn't do magic).

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.

2) Input Voltage Range: A wide range of signal

input voltages can be accommodated by the
250/1's input section (200mV – 8V).This wide
range is split up into two sub-ranges, accessible via
switches located in the “Amplifier Input Section”
of the amplifier.

The “Low” position on the “Input Voltage”
switch selects an input sensitivity range between

IMPORTANT

!

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,
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 cer tain high­output preamp level signals as well as speaker-level
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 cables or plugs.

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.

3) Input Sensitivity Adjustment: Located next to
the “Input Voltage” switch, in the “Amplifier Input
Section”, is a rotary control labeled “Input Sens.”.
Once the appropriate “Input Voltage” range has
been selected, this rotary control 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).

To properly set the amplifier for maximum clean
output, please refer to Appendix B (page 13) in this
manual. After using this procedure, you can then
adjust the level of the amplifier by adjusting the
input sensitivity downward, if the amplifier requires
attenuation to achieve the desired system balance.

Do not increase the “Input Sens.” setting for
any amplifier in the system beyond the maximum
level established during the procedure outlined
in Appendix B (page 13). Doing so will result in
audible distortion and possible speaker damage.

IMPORTANT

!

JL AUDIO 250/1 7

TURN-ON OPTIONS

The 250/1 can be turned on and off using two
different methods:

1) A conventional +12V remote turn-on lead.

2) A signal sensing turn-on circuit.

To select between the two modes there is a

switch, marked “Signal Sensing”, located in the

“Amplifier Input Section” of the front panel.

1) Conventional Remote Turn-On Method:

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.To use this method, select

“Off” on the “Signal Sensing” switch in the
“Amplifier Input Section”.

The 250/1's “Remote” turn-on connector is

designed to accept 12 AWG – 8 AWG wire.
12 AWG is more than adequate for this purpose.
To connect the remote turn-on wire to the
amplifier, first back out the set screw on the top of
the amplifier, using the supplied hex wrench. Strip
1/2 inch (12mm) of wire and insert the bare wire
into the receptacle on the front panel of the
amplifier, seating it firmly so that no bare wire is
exposed. Smaller wire than 12 AWG can be used,
but it may be necessary to strip 1 inch of insulation
from the wire and fold the bare wire in half prior to
insertion. 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.

2) Signal Sensing Turn-On Method: A valuable

feature of the 250/1 is its ability to be turned on
and off by the presence or lack of signal at its audio
inputs.This allows you to operate the amplifier
without having to locate a remote turn-on lead at
the source unit.This can be ver y useful if interfacing
the amplifier with some OEM source units that do
not have conventional turn-on leads.

The sensitivity of the signal sensing turn-on circuit
has been designed for high-level (speaker level)
signals, not for low-level (preamp level) signals. Using
this feature with low-level (preamp level) signals is
not recommended.We do not recommend this
method of turning the amplifier on and off as a
default.Whenever possible, use the conventional
remote turn-on lead method.The signal sensing
circuit is designed to detect midrange frequency
signal presence. If the signal feeding the amplifier is
not full-range (for example, if there is an active
low-pass crossover in line before the amplifier),
this circuit will not operate properly.

To activate the signal sensing turn-on feature,
place the “Signal Sensing” switch in the “On”
position.This should only be done if there is no
conventional turn-on lead connected to the
amplifier's “Remote” connector.When in the “On”
position, the signal sensing circuit will monitor the
audio input signal and turn the amplifier on when
signal is present. After about 25 seconds of no
signal, the amplifier will shut off.

Turning on other amplifiers in signal sensing
mode: When the signal sensing circuit is turned on,

the “Remote” Connector on the amplifier may be
used as a remote turn-on source for other
amplifiers in the system. +12V will be present
at the connector when the amplifier turns on in
signal sensing mode and will not be present when
the amplifier turns off.

You cannot use the turn-on output to turn on
processors that are in the signal path before the
250/1. (Signal will not pass through most
processors when they are not powered up,
meaning that the amplifier will not turn on until
that processor is active).

IMPORTANT

!

IMPORTANT

!

6 JL AUDIO 250/1

This is primarily used for running additional 250/1’s
in a slave configuration from the master amplifier
as shown in Appendix C (page 14).

If the “Output Mode” switch is in the
“Low-Pass” position and the “Amp LP Filter”
switch is in the “Off” position, the preamp output
will be a 12 dB/octave low-pass with the

“Bass Control” processing added to it.
This is not a preferred operating mode. Do not
use this mode for master/slave configurations.

3) “High-Pass”: In this mode, the preamp

outputs deliver a high-pass signal with a cutoff
frequency identical to the low-pass frequency
selected at the “Amp LP Filter” and a filter
slope equivalent to the one selected with the
“Amp LP Filter” “Mode/Slope” switch .

Although it is not a preferred application, this
high-pass output feature will continue to operate at
a 12 dB/octave slope when the “Amp LP Filter” is
set to the “Off” position.

The signal level of the “Preamp Output” is
affected by the setting of the “Input Voltage Range”
switch (of the input section chosen by the
“Signal From” switch). See Appendix B (page 13)
for details on “Input Voltage” settings. All “slave”
amplifiers should get this switch set to “Low”.
See Appendix C (page 14) for details.

CAUTION

!!

CAUTION

!!

CAUTION

!!

BASS CONTROL SECTION

The 250/1 includes a basic bass processing
section consisting of two primary components: a
fixed-frequency, 24 dB/octave infrasonic filter and a
fixed-frequency/“Q”, single-band equalizer centered
at 48 Hz.

1) “Infrasonic Filter”: The infrasonic filter is a

24 dB/octave high-pass filter, with a fixed cutoff
frequency of 30 Hz.This filter is designed to
conserve amplifier power and protect subwoofer
systems without audibly affecting the sub-bass
output. With ported enclosures, the use of the
infrasonic filter is highly recommended to protect
the speaker(s) from excessive excursion below
box tuning.With sealed enclosures, the use of the
filter is less necessary, but can still help protect the
speaker system.

The infrasonic filter can be completely defeated
by selecting the “Off” position on the “Infrasonic
Filter” switch.This bypasses all signal from flowing
through the circuit.

2) “LF (Low-frequency) Boost”: This feature

allows the user to control the boost of a fixed “Q”,
fixed-frequency equalization band centered at
48 Hz.The “LF Boost” control knob determines
how much boost (in dB) you are adding to the bass
signal. A range of 0 - 15 dB of boost is available.
If no boost is desired, rotate the “LF Boost” knob
fully counterclockwise.

The “Bass Control” section will only operate
when the amplifier's filter is activated with the
“Amp LP Filter” switch in the “12dB” or “24dB”
position. It will not work with this switch in the
“Off” position.This is to prevent cascading the
processing of multiple amplifiers when configured
in a master/slave arrangement as shown in
Appendix C (page 14). If you are using an external
active crossover and would like to use the “Bass
Control” features, set the “Amp LP Filter” switch

IMPORTANT

!

JL AUDIO 250/1 9

CROSSOVER CONTROLS

Crossovers are groups of individual electronic filters
which allow only certain frequency ranges to pass
through them by attenuating frequencies outside
the selected range. These filters allow the user to
specify what frequency range will be sent out of
each channel section of the amplifier. This, in turn,
allows each speaker system to only reproduce a
range of frequencies it is well-suited for, resulting in
reduced distortion and improved fidelity.

AMPLIFIER LOW-PASS FILTER

The 250/1 employs a sophisticated, state-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.

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

250/1 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.

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 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.

2) 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 the chart in
Appendix A (page 12) 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 ver y useful if
the amplifier is mounted in a location where you
can’t see the front panel markings easily.

3) 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 Control” section processing (see page 9 for
details). With the internal crossover turned off, the
250/1’s upper frequency response limit is 500 Hz,
due to its bass-specific Class D design.

PREAMP OUTPUT SECTION

The 250/1 incorporates a flexible preamp output
section, designed to make multiple amplifier systems
easy to set up.

The Preamp output can be configured in three
different “Output Modes”:

1) “Full-Range”: This is a pass-through mode for

the preamp output, delivering the same signal that is
being fed to the “Amplifier Input Section” (If the
input signal is full-range, the preamp output will be
full-range).This signal is not affected by the “Bass

Control” processing selected for the amplifier.

2) “Low-Pass”: The preamp output delivers the

same mono-summed signal that is feeding the
250/1's amplifier section when the “Amp LP
Filter” is engaged, including all the low-pass filtering
and “Bass Control” processing that is selected.

8 JL AUDIO 250/1

STATUS INDICATOR LIGHTS /
PROTECTION CIRCUITRY

There are three status indicator lights on the top

of the amplifier. These are as follows:

1) “Power” (Green): lights to indicate that the

amplifier is turned on and operating normally.

2) “Thermal” (Red): lights to indicate that the

amplifier has exceeded its safe operating
temperature, putting the amplifier into a self­protection mode, which reduces the power output
of the amplifier. The red light will shut off and the
amplifier will return to normal, full-power operating
mode if the heat sink temperature drops back to a
safe level.

3) “Low Ω” (Amber): lights to indicate that the

impedance of the speaker load connected to the
amplifier is lower than the optimum load impedance
range for the amplifier. When this light is on, a
protection circuit engages and reduces the power
output of the amplifier. The amber indicator will also
light when a short-circuit is detected in the speaker
wiring (this can be a short between the positive and
negative speaker wires or between either speaker
wire and the vehicle chassis).

There is only one condition that will shut
down an undamaged 250/1 completely…

If battery voltage drops below 10 volts, the entire

amplifier will shut itself off.The green “Power”
indicator on the top of the amplifier 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, have your charging system inspected to
make sure it is working properly. A 0.5 or 1.0 Farad
rapid-discharge capacitor connected in parallel to
the amplifier power connections may minimize
these short duration voltage dips in many systems
that are having this problem.

For information on troubleshooting this

amplifier, refer to Appendix D (page 16).

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 par ts 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 the

JL AUDIO Technical Department for assistance:

[phone]

9:00 AM – 5:30 PM Eastern Time,

Monday – Friday

JL AUDIO 250/1 11

on “12dB” and rotate the frequency selection
knob fully clockwise to the “200 Hz” position.This
will activate the “LF Boost” and “Infrasonic Filter”
controls without significantly affecting the crossover
point selected by the external active crossover.

SUBWOOFER OUTPUT

The 250/1 employs JL Audio's exclusive
Regulated, Intelligent Power Supply (R.I.P.S.) design.
This sophisticated power supply allows the amplifier
to produce its optimum power (250 watts x 1)
over a wide range of speaker impedances.

Unlike conventional amplifiers that require a
specific impedance to produce optimum power, the
R.I.P.S.-equipped 250/1 gives you the freedom to
use a variety of subwoofer configurations that
achieve final nominal impedances between

1.5 – 4Ω (without sacrificing power output or
sound quality).

The operation of the R.I.P.S. circuitry is entirely
automatic and adjusts itself every time the amplifier
is turned on according to the lowest impedance
present at the speaker load.There are no user
controls to configure.The system operates through
multiple stages of impedance optimization, choosing
the stage most appropriate to the actual impedance
of the speaker(s) you connect to it.

If you connect a load higher than 4Ω nominal
to the 250/1, power will drop by half with every
doubling of impedance above 4Ω. If you connect a
load lower than 1.5Ω nominal to the 250/1, the
amplifier protection circuitry activates a “safe”
mode which reduces amplifier power to protect
the circuitry from failure (the yellow LED on the
top of the amplifier will light to indicate that this
has happened). See page 11 for details.

IMPORTANT

!

Speaker loads below 1.5Ω nominal are not
recommended and may cause the amplifier output
to distort excessively.

Speaker connections to the 250/1 are
straightforward and take place at the far right of the
front panel.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.

Do not chassis ground any speakers connected
to this or any other JL Audio amplifier. Doing so will
cause the amplifier to go into protection and mute
the output.

The 250/1's speaker connectors are designed
to accept 12 AWG – 8 AWG wire.

To connect the speaker wires to the amplifier,
first back out the set screws on the top of the
amplifier, using the supplied 2.5 mm hex wrench.
Strip 1/2 inch (12 mm) of insulation from each wire
and insert the bare wire end into the receptacles
on the front panel of the amplifier, seating them
firmly so that no bare wire is exposed.While
holding each wire in place, tighten each 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.

Do NOT attempt to “bridge” two 250/1’s or
combine their output to a single load in any manner.
Doing so will damage the amplifier(s).

Before reconnecting the battery ground and
turning the system on, verify that all control settings
on the amplifier are set according to the needs of
the system.

IMPORTANT

!

IMPORTANT

!

IMPORTANT

!

10 JL AUDIO 250/1

APPENDIX B:

Input Sensitivity Level Setting

JL Audio amplifiers utilizing the Regulated
Intelligent Power Supply (R.I.P.S.) allow delivery of
their rated power when connected to any load
impedance from 1.5 - 4Ω per channel and when
connected to a charging system with any voltage
from 11 - 14.5V. This design is beneficial for many
reasons. One of these reasons is ease of setup.
Because each JL Audio amplifier will always deliver
the same amount of power within its operational
range of impedances and supply voltages, the
maximum, unclipped output is very predictable.
This makes setting the gain structure via the input
sensitivity controls very simple. Following the
directions below will allow the user to adjust the
input sensitivity of the amplifier(s) simply and easily
in just a few minutes using equipment which is
commonly available in installation bays.

Necessary Equipment

• Digital AC Voltmeter

• CD with a sine-wave test tone recorded at 0 dB

reference level in the frequency range to be
amplified (ex. 50 Hz for a subwoofer amplifier.
1 kHz for a midrange application). Do not use
attenuated test tones (-10 dB, -20 dB, etc.).

The Nine-Step Procedure

1) Disconnect the speaker(s) from the amplifier’s

“Subwoofer Output”connectors (you only need to

remove the negative or positive speaker wire).

2) Turn “Off ” all processing on the source unit

and amplifier (bass/treble, loudness, EQ, etc.).

3) Switch the “Input Voltage” to “Low” and

turn the “Input Sens.” control on the amplifier all
the way down.

4) Set the source unit volume to 3/4 of full

volume. If the amplifier is being driven by a source
unit’s dedicated subwoofer output, also adjust the
source unit’s subwoofer level control to 3/4 of
maximum output.This will allow for reasonable gain
overlap with moderate clipping at full volume.

5) Using the chart below, determine the target

voltage for input sensitivity adjustment according to
the nominal impedance of the speaker system
connected to the amplifier output.

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) at 3/4 source unit volume.

7) Connect the AC voltmeter to the

“Subwoofer Output” connectors of the amplifier.

8) Increase the “Input Sens.” control until the

target voltage is delivered. If multiple subwoofer
amps are being used, set each one to the same
exact voltage and you have also level matched
them. If excessive voltage is read with the control
at minimum (full counterclockwise), switch the

“Input Voltage” to “High” and re-adjust.

9) Once you have adjusted each amplifier to its

maximum unclipped output level, reconnect the
speaker(s).The “Input Sens.” can now be adjusted
downward if the amplifier requires attenuation to
achieve the desired system balance.

Do not increase any “Input Sens.” setting in

the system beyond the maximum level established
during this procedure. Doing so will result in
audible distortion and possible speaker damage.

IMPORTANT

!

JL AUDIO 250/1 13

Nom. Impedance Target AC Voltage

4Ω (or higher) 31.6 V

3Ω 27.4 V

2Ω 22.4 V

1.5Ω 19.4 V

APPENDIX A:

Precise Frequency Selection

AMPLIFIER LOW-PASS FILTER

Detent Panel Actual

Number Marking Freq.

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

12 JL AUDIO 250/1

out of the preamp outputs of the amplifier are
compatible with the “Low” setting on the
“Input Range” control.

The “Signal Sensing” turn-on feature will not
work on “slave” amplifiers, but “slave” amplifiers
can be turned on and off by a “master” amplifier
operating in signal sensing turn-on mode.
Simply connect the “master” amplifier’s

“Remote” connection, to the “slave” amplifier(s)
“Remote” connection(s).

Do not increase the “Input Sens.” setting for any
amplifier in the system beyond the maximum level
established during the procedure outlined in
Appendix B (page 13). Doing so will result in
audible distortion and possible speaker damage.

4) If you would like to run a third amplifier in

“Slave” configuration, select the “Full-Range”
position on the “Output Mode” switch of the first
“Slave” amplifier. Then, connect an RCA cable
from the first “Slave” amplifier’s preamp outputs to
the second “Slave” amplifier. As you did with the

first “Slave” amplifier, set the second “Slave”
amplifier’s “Amp LP Filter” to the “Off” position.
Then, calibrate the third amplifier’s “Input Range”
and “Input Sens.” controls in the same manner as
you did for the second amplifier.

Additional amplifiers may be added to this
“Master/Slave” configuration following the same
procedure as in step 4.

Once you match the input sensitivities of all the
amplifiers, you can use the “Master” amplifier’s

“Amp LP Filter”,“Infrasonic Filter” and “Bass
Boost” features to control the “Slave” amplifier(s).

Below is a diagram showing a Master/Slave
configuration with one “Master” (top amplifier)
and two “Slave” amplifiers. Switches and controls
that are defeated in the “Slave” amplifiers are
printed in gray.

JL AUDIO 250/1 15

Connect Master 250/1 Preamp Output
to Slave A 250/1 Input

Connect Slave A 250/1 Preamp Output to Slave B 250/1 Input

Connect Master 250/1 Input to Signal Source

APPENDIX C:

Master/Slave Configurations

With the flexible on-board crossovers and
processing incorporated into the 250/1, it is
possible to connect multiple 250/1’s in a
“Master/Slave” configuration, with each amplifier
driving its own speaker system but controlled by
the processing and filtering of only one amplifier.
This is very useful when driving multiple
subwoofers with multiple amplifiers.

To create a Master/Slave configuration, first
determine which amplifier will be the “Master”
amplifier and connect the main input signal to that
amplifier (from the source unit or from an
outboard processor).This amplifier’s “Amp LP

Filter” section “Infrasonic Filter” and “Bass
Boost” features will process the signal for the

“Slave” amplifier or amplifiers.

Here is the procedure for implementing a
“Master/Slave” configuration:

1) Set the “Master” amplifier’s “Output Mode”

switch to the center “Low-Pass” position.This will
send a parallel, mono-summed signal from the
“Master” amplifier’s “Amp LP Filter” section to its
preamp outputs.

2) Connect an RCA cable from the “Master”

amplifier’s preamp outputs to the main input of the
first “Slave” amplifier. Set the “Slave” amplifier’s
“Amp LP Filter” to the “Off” position.This will
defeat the LP filter and the bass processing of this
“Slave Amplifier”.

3) The input sensitivity of the two amplifiers

needs to be adjusted independently.To properly
calibrate the amplifiers for maximum, identical, clean
output, please refer to Appendix B (page 13).
After using this procedure, you can then adjust the
level of the amplifiers by adjusting the input
sensitivities downward, if the amplifiers require
attenuation to achieve the desired system balance.
If the input sensitivities are adjusted, the amplifiers
must be recalibrated to ensure identical power
output levels.

Please note that the “Input Range” switch on

all “slave” amplifiers needs to be set to “Low”,
even if the “master” amplifier is high voltage and
its switch is set to “High”. All signals passed

14 JL AUDIO 250/1

MASTER:

The Master amplifier’s

“Bass Control” section is

active and affects

all three amplifiers equally.

The last Slave amplifier’s

“Bass Control” section,

AMP LP Filter and “Preamp

Output” are inactive.

This Slave amplifier’s

“Bass Control”section and

AMP LP Filter are inactive,

but the Full-Range (pass-through)

feature of its “Preamp Output”

feeds the input of the

next Slave amplifier.

SLAVE (A):

SLAVE (B):

JL AUDIO 250/1 17

“MY AMPLIFIER SHUTS OFF ONCE IN A WHILE, USUALLY AT HIGHER VOLUMES”

Check your voltage source and grounding point.The R.I.P.S. power

supply is rated to operate with source voltages between
11 - 14.5V. Shutdown problems at higher levels can occur
when the charging system voltage drops below 10-volts.These
dips can be of very shor t duration making them extremely
difficult to detect with a common DC voltmeter. To ensure
proper voltage, inspect all wiring and termination points. It is
also a good idea to improve the vehicle’s factory ground wire
and termination point. Grounding problems are the leading
cause of mis-diagnosed amplifier failures.

“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 RCA
cables from the amplifier prior to this test).The frequency
used should be in the range that is to amplified by the
channels being tested (example: 50 Hz for a sub bass
amplifier channel and 1 kHz for a full-range amplifier
channel). A steady voltage should be present at the output
of the RCA cables. If you are receiving a sufficient voltage
(between 0.2 and 8.0-volts), check to ensure that the
speaker wires are making a good connection with the metal
inside the amplifier. The connectors are designed to accept
up to an 8 AWG wire. If you are using significantly smaller
wire (14 AWG or smaller), you may have difficulty making
an adequate connection. In this case, you may find it
necessary to “fold” the wire over once (or twice!) so as to
make a solid connection. Make sure to strip the wire to
allow for a sufficient connection with the input or output
of the amplifier.

Check the output of the amplifier. Using the procedure explained in

the previous check item (after plugging the RCA 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.
5-volts 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 above.

(continued on next page)

“MY AMPLIFIER DOESN’T TURN ON”

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 “+12V”
wire to the “Remote” terminal to see if the amplifier turns on.
If this does not work, proceed to the next step.

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 “Signal Sensing” switch to make sure it is in the desired

position. If you are using a remote wire, this switch should be
in the “Off” position. If you are using the signal sensing
feature, make sure there is a full-range signal being sent to the
RCA inputs of the amplifier. If you continue to have trouble
with the signal sensing feature, test the amplifier’s ability to turn
on by throwing the “Signal Sensing” switch to the “Off”
position and jumping the “+12V” wire to the “Remote”
terminal. If this turns the amplifier on, check your input signal
and connections.

“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 or between a speaker lead and the
vehicle’s chassis ground. If a shor t is present you will
experience distorted and/or attenuated output.The
“Low Ω” light may also 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 the amplifier is

driving a load between 1.5 - 4Ω. JL Audio monoblock
amplifiers have 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. In this case, each of the two loads
should have a nominal impedance between 3 - 8Ω.

Check the input signal and input signal cables to make sure signal is

present at the “Amplifier Input Section” 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.

16 JL AUDIO 250/1

APPENDIX D: TROUBLE SHOOTING

JL AUDIO 250/1 19

APPENDIX E:

250/1 Specifications

GENERAL SPECIFICATIONS:

Recommended Fuse Value: 30A

Recommended Fuse Type: AGU or MaxiFuse™

INPUT SECTION:

Input Type: Differential-balanced with RCA jack inputs

Input Range: Switchable from 200mV - 2V RMS to

800mV - 8V RMS

AMPLIFIER SECTION:

Amplifier Topology: H-Bridge , Class D Mono

with impedance optimization and patented

discrete drive circuitry

Power Supply: Pulse width modulation-regulated

switching power supply

Rated Power: 250W RMS x 1 @ 1.5 - 4Ω (11 - 14.5V)

THD at Rated Power: <0.05% @ 4Ω, 50 Hz

Signal to Noise Ratio: >95 dB referred to rated power

(A-weighted, 20 Hz - 20 kHz noise bandwidth)

Frequency Response: 5 - 300 Hz (+0, -1 dB) /

5 - 500 Hz (+0, -3 dB)

Damping Factor: >500 @ 4Ω/50 Hz, >250 @ 2Ω/50 Hz

CROSSOVER SECTION:

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

PREAMP OUTPUT:

2-Channel, selectable as full-range (pass-through) or

low-pass or high-pass filtered (tracks with the amplifier

low-pass filter cutoff frequency)

BASS CONTROL SECTION:

Bass EQ: Single-band, fixed frequency/“Q” centered at 48 Hz

with boost adjustment from 0 dB to +15 dB, defeatable

Infrasonic Filter: 24 dB/octave Butterworth high-pass filter

with 30 Hz cutoff frequency, defeatable

DIMENSIONS: (LxWxH):

10.25" x 9.25" x 2.36" (260mm x 235mm x 60mm)

Due to ongoing product development, all specifications are

subject to change without notice.

18 JL AUDIO 250/1

“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 amplifier terminal.

Check the RCA connectors to ensure that both the center pin and

the outer shield are making good contact with the input jacks
on the amplifier.

“HOW DO I PROPERLY SET THE INPUT SENSITIVITY ON MY AMPLIFIER”

Please refer to Appendix B (page 13) to set the input sensitivity for

maximum, unclipped output.

APPENDIX D: TROUBLE SHOOTING (CONT.)

INSTALLATION NOTES:

Use this diagram to document your amplifier’s switch and control positions.

LIMITED WARRANTY - AMPLIFIERS (USA)

JL AUDIO warrants this product to be free of defects in materials and workmanship for a period of ninety
(90) days from the original date of purchase. The warranty term is extended to two (2) years if installation is
performed or approved by an authorized JL AUDIO dealer (proof of installation or approval required on
purchase receipt).

This warranty is not transferrable and applies only to the original purchaser from an authorized JL AUDIO
dealer. Should service be necessary under this warranty for any reason due to manufacturing defect or
malfunction, JL AUDIO will (at its discretion), repair or replace the defective product with new or remanufactured
product at no charge. Damage caused by the following is not covered under warranty: accident, misuse, abuse,
product modification or neglect, failure to follow installation instructions, unauthorized repair attempts,
misrepresentations by the seller.This warranty does not cover incidental or consequential damages and does not
cover the cost of removing or reinstalling the unit(s). Cosmetic damage due to accident or normal wear and tear
is not covered under warranty.

Warranty is void if the product’s serial number has been removed or defaced.

Any applicable implied warranties are limited in duration to the period of the express warranty as provided
herein beginning with the date of the original purchase at retail, and no warranties, whether express or implied,
shall apply to this product thereafter. Some states do not allow limitations on implied warranties, therefore these
exclusions may not apply to you.This warranty gives you specific legal rights, and you may also have other rights
which vary from state to state.

If you need service on your JL AUDIO product:

All warranty returns should be sent to JL AUDIO ’s Amplifier Service Facility freight-prepaid through an
authorized JL AUDIO dealer and must be accompanied by proof of purchase (a copy of the original sales receipt).
Direct returns from consumers or non-authorized dealers will be refused unless specifically authorized by
JL AUDIO with a valid return authorization number.

Warranty expiration on products returned without proof of purchase will be determined from the
manufacturing date code. Coverage may be invalidated as this date is previous to purchase date. Non-defective
items received will be returned freight-collect. Customer is responsible for shipping charges and insurance in
sending the product to JL AUDIO. Freight damage on returns is not covered under warranty.

For Service Information in the U.S.A. please call:

JL Audio customer service: [phone]

during normal business hours (9:00 AM – 5:30 PM Eastern Time)

JL Audio, Inc

10369 North Commerce Pkwy.

Miramar, FL 33025

(do not send product for repair to this address)

International Warranties:

Products purchased outside the United States of America are covered only

by that country’s distributor and not by JL Audio, Inc.

JL2501MAN-CH-09-2002

Patented Class D Amplifier Circuit (U.S. Patent #6,441,685) is Patent-Pending in the following
countries: Austria, Belgium, Brazil, Canada, China,France, Germany,Indonesia, Italy, Japan, Republic of Korea,

Mexico, Netherlands, Norway, Russian Federation, Singapore, Sweden, Switzerland, United Kingdom, and all
other PCT countries.