JL Audio J2250.1 User Manual

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owner’s manual

250W Monoblock Subwoofer Amplifier

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 our Technical Support Department at (954) 443-1100during business hours.

Protect Your Hearing!

We value you as a long-termcustomer. 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 otherhigh-poweramplifiers 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-groundelectrical 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.

Remote Turn-On

Connector

(pg. 6)

Chassis Ground +12 V Power

Fuse

Connector

 

Connector

(pg. 5)

(pg. 5)

 

(pg. 5)

 

Ground

Remote

+ VDC

FUSE

 

 

 

30A

Made in China

Power Status

Left & Right

Input Sensitivity

 

 

 

 

Bass Boost

 

 

Protection Status

Indicator

Preamp Output Jacks

 

Control

 

 

 

 

Control

 

 

 

Indicator

(pg.

 

11) High-Level

(pg.

8) Left & Right

 

(pg. 7)

Filter

(pg. 9)

Remote (pg.

11)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Input Jack

 

 

Preamp Input Jacks

 

 

 

Frequency Selector

 

Level Port

 

 

 

 

 

(pg. 6,7)

 

 

 

(pg.

6)

 

 

 

 

 

(pg. 8)

 

 

 

 

(pg. 9)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Preamp

Amplifier

Outputs

Inputs

LEFT

LEFT

High-LevelInputs

Power

 

 

 

 

 

 

Protect

 

 

 

 

 

 

Remote

min

max

60

240

O

+9dB

Level Port

 

Input Sens.

LP Filter Frequency (Hz)

Bass Boost

RIGHT RIGHT

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JL Audio

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-upand 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-coolingis not necessary.

Speaker Outputs

(pg. 10)

Speaker Output (Mono)

! IMPORTANT

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-ventilatedenvironment 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 appropriate hardware 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 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 J2-250.1is a monoblock subwoofer amplifier utilizing Class A/B technology. Its frequency response is limited to the range below 100 Hz. It is not designed for driving midrange speakers or tweeters. It has been optimized forlow-frequencyamplification. For detailed specifications, please refer to Appendix B (page 13).

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Typical Installation Sequence

The following represents the sequence for a typical amplifier installation, using an aftermarket source unit or OEM Interface product. 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 accidentalre-connectionduring 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 J2-250.1.

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 remoteturn-onwire from the source unit to the amplifier mounting location.

5) Run speaker wire 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 minimum 8 AWG power wire, 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 appropriate hardware.

8)Connect the positive and negative power wires to the amplifier.

9) Connect the remoteturn-onwire

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 J2-250.1)and reconnect the negative battery post terminal.

14)Turn on the source unit at a low level

to double-checkthat 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.

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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.

Ground

Remote

+ VDC

The J2-250.1’s+12 VDC” (positive) and “Ground” (ground) connections are designed to accept up to 4 AWG power wire. 8 AWG is a minimum power wire size for this amplifier.

If you are installing the J2-250.1with other amplifiers and wish to use a single main power wire, use 2 AWG or 1/0 AWG main power wire (depending on the overall current demands of all the amplifiers in the system). This 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 theJ2-250.1with 8 or 4 AWG power wire.

Note: that smaller AWG numbers mean bigger wire andvice-versa(1/0 AWG is the largest,

2 AWG is smaller, then 4 AWG, then

8 AWG, etc.).

To connect the power and ground wires to the amplifier, strip 1/2-inch(12 mm) of insulation from each wire and insert the bare wire into the the appropriate terminal block positions on theJ2-250.1.Use a Phillips screwdriver to secure the wire via the screw on the top of each terminal.

The “Ground” connection should be made using 8 AWG or 4 AWG wire 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 insulating grommet to prevent damage to the insulation of the wire. Failure to do so may result in a dangerous short circuit.

! IMPORTANT

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 a J2-250.1.

Fuse Requirements

While the J2-250.1has a 30A ATC fuse on its power connection panel, this fuse does nothing to protect the vehicle from a dangerous short circuit in the power wire. It only protects the amplifier. 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 J2-250.1is being run from that power wire, we recommend a 30A fuse be used. AFS, ATC, AGU orMAXI-typefuses are recommended.

FUSE

30A

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“REMote” turn-On

The J2-250.1is turned on and off using a conventional +12V remote turnon lead, typically controlled by the source unit’s remoteturn-onoutput.

Ground

Remote

+ VDC

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 remoteturn-onoutput, the amplifier’sturn-onlead can be connected to +12V via a switch that derives power from an ignitionswitched circuit.

18 AWG wire is more than adequate for the remote turn-onconnection. To connect the remoteturn-onwire to the amplifier, strip1/2-inch(12 mm) of insulation from the wire

and insert it into the “Remote” receptacle on the power connector. Tighten the connector down using a Phillips screwdriver.

“AMPLIFIER InputS”

The J2-250.1offers two input connection methods, one forhigh-level(speaker level) signals and one forlow-level(preamp level) signals.

Preamp

Amplifier

Outputs

Inputs

LEFT

LEFT

High-LevelInputs

RIGHT RIGHT

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 into the RCA jacks, we recommend that you use a “Y-adaptor” to split the mono signal into both the Left and Right inputs of the amplifier.

1)Low-LevelInputs:A standard left/ right pair of RCA type jacks in the

“Amplifier Inputs” section is used for preamp level(low-level)signal input on theJ2-250.1.This is the preferred connection method whenever available.

2)High-Level Inputs: If your system does not offer a preamp level signal option, you can connect speaker level signals directly to the

“High-LevelInputs”connector using the supplied mating connector and wire harness. Simply splice the appropriate left/right and positive/negative wires to the included harness and plug the harness into the “High-LevelInputs”connector on the amplifier. The J2-250.1 will attenuate the high-level signal to make it compatible with its input stage.

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JL Audio

! IMPORTANT

Make sure you observe correct polarity in making the “High-LevelInput” connections. Failure to do so will result in a complete loss of signal (no bass).

The connections for the “High-Level Inputs” plug wires are as follows from left to right on the plug:

White: Left Positive (+) White/Black: Left Negative (–)

Black: Common Ground (rarely used)* Gray: Right Positive (+)

Gray/Black: Right Negative (–)

*The only time you will use the “Common Ground” connection is with some older (pre1980’s) factory systems or head units that ground their speakers to chassis ground. To use this connection, ground the black wire on the plug to chassis ground and only connect the Left and Right Positive plug wires to the factory radio outputs.

! IMPORTANT

If you plan to use the preamp outputs 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.

“INPUT SENSITIVITY” (GAIN) ADJUSTMENT

Located next to the input connectors is a rotary control labeled “Input Sens.”. 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.

plifier nputs

LEFT

min

max

60

Input Sens.

LP Filter Fr

RIGHT

Rotating the control clockwise will result in higher sensitivity (louder for a given input

voltage). Rotating the control counter-clockwisewill 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 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 A (page 12). Doing so will result in audible distortion and possible speaker damage.

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“LP FILTER” (CroSSOVER) Control

The J2-250.1employs a 12dB/octavelow-pass(LP) 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.

The low-passfilter in theJ2-250.1is fully variable between 60 Hz and 240 Hz via the“LP Filter Frequency” control knob. The “10 o’clock” position corresponds to 80 Hz and is a good starting point for system tuning.

“PREAmP OUTPUTS”

The J2-250.1incorporates a preamp output section, designed to make multiple amplifier systems easy to set up. This section consists of a pair ofRCA-typejacks marked

“Preamp Outputs”.

Preamp

Outputs

LEFT

max

60

240

O

t Sens.

LP Filter Frequency (Hz)

Bass

RIGHT

The Preamp outputs deliver the same signal that is being fed to the inputs. (If the input signal are full-range,the preamp outputs will befull-range).This signal is not affected by the bass boost or LP FIlter processing selected for the amplifier.

! IMPORTANT

The signal level of the preamp output is always low-levelregardless of whether you are using the“High-LevelInputs” or theLow-Level(RCA-jack)Inputs.

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JL Audio

“BASS BOost” Control

The J2-250.1includes a single band, boostonly bass equalizer controlled by a rotary knob marked“Bass Boost”. This control has a boost range of 0dB(full-counterclockwise)to +9dB(full-clockwise)and is centered at 45 Hz.

REMOTE LEVEL Control

The J2-250.1includes a remote level control that can be mounted in the front of the vehicle. This control allows the owner to adjust the overall subwoofer level to taste. To connect the remote bass control knob, insert its plug into the jack labeled“Remote Level Port” on the amplifier and route the cable and control to the desired location in the front of the vehicle.

 

O +9dB

Hz)

Bass Boost

Protect

Remote Level Port

+9dB s Boost

Care should be taken to securely mount this control in a manner that does not interfere with vehicle operation.

When setting the amplifier’s input sensitivity, the Remote Level Control should be unplugged or at full clockwise rotation (maximum level).

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SPEAKER OUTPUT

Speaker connection to the J2-250.1is straightforward and takes place at the far right of the power/speaker connection panel. Two positive (“+”) connections and two negative(“”)connections are available via a connector labeled“Speaker Output (Mono)”. The dual connections allow for two separate speaker wire runs to be parallelconnected to the amplifier’s mono output.

Speaker Output (Mono)

! IMPORTANT

Speaker loads below 2Ω nominal are not recommended and will cause the amplifier to enter into a protection mode.

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.

To connect the speaker wires to the amplifier, strip 1/2-inch(12 mm) of insulation from

each speaker wire and insert them into their appropriate connector (observing correct polarity). Then, tighten each connector using a Phillips screwdriver.

! IMPORTANT

Do NOT attempt to “bridge” two J2-250.1’stogether or combine their output to a single load in any manner. Doing so will damage the amplifier(s).

! IMPORTANT

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.

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JL Audio