JL Audio 300-2 User Manual

250.3 Kb

JL AUDIO 300/2 two-channelfull-rangeamplifier

o w n e r ’ s m a n u a l

Thank you for purchasing a JL Audio amplifier for your automotive sound system.

Your amplifier has been designed and manufactured to exacting standards in order to ensure years of musical enjoyment in your vehicle. For maximum performance and extended warranty coverage, we highly recommend that you have your new amplifier installed by an authorized JL Audio dealer. Your authorized dealer has the training, expertise and installation equipment to ensure optimum performance from this product. Should you decide to install the amplifier yourself, please take the time

to read this manual thoroughly so as to familiarize yourself with its installation requirements and setup procedures.

If you have any questions regarding the instructions in this manual or any aspect of your amplifier’s operation, please contact your authorized JL Audio dealer for assistance. If you need further assistance, please call the JL Audio Technical Support Department at (954) 443-1100during business hours (Eastern Time Zone).


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 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.).


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:



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.

Chassis Ground


(pg. 5)

+12 V Power

Remote Turn-On



(pg. 5)

(pg. 6)




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-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, 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-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 the supplied screws so that it does not come loose in the event of a collision or a sudden jolt to the vehicle (15 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.










Filter Slope






Input Sensitivity





































(pg. 8)






(pg. 7)






Preamp Output












Input Voltage









Filter Frequency














Signal Selector

Range Selector






Range Selector




Speaker Outputs


(pg. 9)


(pg. 8)







(pg. 7)






(pg. 9)

































































































































































































































































Left and Right



Preamp Output Jacks



(pg. 9)





(pg. 8)


(pg. 8)


Left and Right

Input Jacks

(pg. 7)


JL AUDIO 300/2

JL AUDIO 300/2



The JL Audio 300/2 is a two-channelfull-rangeamplifier utilizing patented Absolute Symmetry™ Class AB technology for both channels.These channels benefit from JL Audio's exclusive R.I.P.S. power supply design which optimizes the output of for any impedance between 1.5 and 4 ohms per channel (3 - 8Ω bridged).

The 300/2's flexible input and crossover sections permit operation with a wide variety of source units and system configurations.


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-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 2 AWG or 1/0 AWG power wire if additional amplifiers are being installed with the 300/2.

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-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 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-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 (40A for a

single 300/2) 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 B (page 13) for the recommended input sensitivity setting method.

16)Enjoy the fruits of your labor with your favorite music.






Before installing the amplifier, disconnect the


The ground connection should be made using

negative (ground) wire from the vehicle's battery.

the same gauge wire as the power connection

This will prevent accidental damage to the system,

and should be kept as short as possible, while

the vehicle and your body during installation.

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

The 300/2's “+12 VDC” and “Ground”

a dangerous short circuit.

connections are designed to accept 8 - 4 AWG





power wire. 8 AWG is the minimum









recommended power wire size for this


Many vehicles employ small (10 AWG - 6 AWG)


wire to ground the battery to the vehicle chassis and

If you are installing the 300/2 with other

to connect the alternator's positive connection to the

amplifiers and wish to use a single main power wire,

battery.To prevent voltage drops, these wires should

use 2 AWG or 1/0 AWG main power wire

be upgraded to 4 AWG when installing amplifier

(depending on the overall current demands of all

systems with main fuse ratings above 60A.

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 the 300/2 with





8 - 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.






JL AUDIO 300/2

JL AUDIO 300/2





It is absolutely vital that the main power wire(s)

The 300/2 uses a conventional +12V remote


The 300/2 has one input section, which contains a

to the amplifier(s) in the system be fused within

turn-onlead, typically controlled by the source unit's

pair of RCA-typeinput jacks, an “Input Voltage”

18 inches (45 cm) of the positive battery post

remote turn-onoutput.The amplifier will turn on

switch and an “Input Sens.” rotary control.

connection.The fuse value at each power wire

when +12V is present at its “Remote” input and



























should be high enough for all of the equipment

turn off when +12V is switched off. If a source unit



























being run from that power wire. If only the

does not have a dedicated remote turn-onoutput,














300/2 is being run from that power wire, we

the amplifier’s turn-onlead can be connected to



























recommend a 40A fuse be used. AGU (big glass

+12V via a switch that derives power from an














fuse) or MaxiFuse™ (big plastic-bodyfuse) types















are recommended.

The 300/2's “Remote” turn-onconnector is














No fuse is required or recommended directly

designed to accept 18 AWG – 8 AWG wire.














before the amplifier power connection. If one is

12 AWG is more than adequate for this purpose.



























desired, we recommend the use of a 40A AGU fuse

To connect the remote turn-onwire to the














or MaxiFuse™ type.

amplifier, first back out the set screw on the top of


1) Input Voltage Range: A wide range of signal


the amplifier, using the supplied hex wrench. Strip

input voltages can be accommodated by the


1/2 inch (12mm) of wire and insert the bare wire

300/2's input section (200mV – 8V).This wide


into the receptacle on the front panel of the

range is split up into two sub-ranges,accessible via


amplifier, seating it firmly so that no bare wire is

a switch located in the “Amplifier Input Section”.


exposed.When using smaller wire, it may be


The “Low” position on the “Input Voltage”


necessary to strip 1 inch of insulation from the wire

switch selects an input sensitivity range between


and fold the bare wire in half prior to insertion.

200mV and 2V.This means that the “Input Sens.”


While holding the wire in the terminal, tighten the

rotary control will operate within that voltage


set screw firmly, taking care not to strip the head of

window. If you are using an aftermarket source unit,


the screw and making sure that the wire is firmly

with conventional preamp-leveloutputs, this is most


gripped by the set screw.

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 high-output



preamp level signals as well as speaker-leveloutput



from source units and small amplifiers.To use



speaker-levelsources, splice the speaker output



wires of the source unit or small amplifier onto a



pair of RCA 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.

2) Input Sensitivity Adjustment: Located next to the “Input Voltage” switch in the “Amplifier Input Section” nput section is a rotary control labeled

“Input Sens.”. Once the appropriate “Input Voltage” range has been selected, this control can be used to match the source unit's output voltage to the input stage of the 300/2 for maximum clean output. 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 B (page 13) in this manual. After using this procedure, you can then adjust the “Input Sens.” level downward if this is required 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.


JL AUDIO 300/2

JL AUDIO 300/2






Crossovers are groups of individual electronic filters

2) “Filter Slope” Control: This switch allows

The 300/2 incorporates a flexible preamp output


The 300/2 employs JL AUDIO's exclusive

which allow only certain frequency ranges to pass

you to select from two filter slopes for that

section, so that additional amplifiers can be added to

Regulated, Intelligent Power Supply (R.I.P.S.) design.

through them by attenuating frequencies outside

channel section.

the system.This pre-ampoutput can be configured

This sophisticated power supply allows the

the selected range.These filters allow the user to

“12dB”: Configures the filter to attenuate

three different ways using the switch labeled

amplifier to produce its optimum power (300

specify what frequency range will be sent to the

frequencies above or below the selected filter

“Output Mode” in the “Preamp Output Section”.

watts) over a wide range of speaker impedances.

each amplifier (or channels) in a system.This, in turn,

frequency at a rate of 12 dB per octave










Unlike conventional amplifiers that require a










allows each speaker system to only reproduce a

(Butterworth alignment).










specific impedance to produce optimum power,

range of frequencies it is well-suitedfor, resulting in

“24dB”: Configures the filter to attenuate










the R.I.P.S.-equipped300/2 gives you the freedom










reduced distortion and improved fidelity.

frequencies above or below the selected filter










to use a variety of speaker configurations that
























frequency at a rate of 24 dB per octave (Linkwitz-










achieve final impedances between 1.5 – 4Ω

Amp Filter Section:

Riley alignment).










nominal per channel (without sacrificing power















Depending on the speaker system and the










output or sound quality).






































vehicle, different filter slopes may be required to











The operation of the R.I.P.S. circuitry is entirely















produce a smooth transition between the sound of










automatic and adjusts itself every time the amplifier















1) “Full-Range”:The preamp output delivers





























different speakers in the system. Experiment to find

is turned on according to the lowest impedance





























the slope which best matches the acoustic

the same signal that is connected to the 300/2's

present at the speaker outputs .There are no user















requirements of the system.The sharper “24dB”

Amplifier Inputs.

controls to configure.The system operates through















setting will do a better job of protecting small

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

multiple stages of impedance optimization, choosing





























speakers with limited power handling.The shallower

the same signal that is connected to the 300/2's

the stage most appropriate to the actual impedance











































“12dB” octave setting allows the rear speakers to

Amplifier Inputs with Low-Passfiltering applied to

of the speakers you connect to it.





























reproduce more low-frequencycontent.

it at the “Filter Freq.” and “Filter Slope” selected














1) “Filter Mode” Control: This switch allows you to

3) “Freq. Range” Control: When thrown to

in the “Amplifier Filter” section. This mode can














configure the filter into one of two filter types or

the right, this switch multiplies the cutoff

be useful for feeding a subwoofer amplifier














defeat it completely:

frequency selected by the rotary “Filter Freq.

when the 300/2 is being used to drive the














“Off”: Defeats the filter for that channel section

(Hz)” control by a factor of 10. In the “x1”

main speaker system.














completely, allowing the full range of frequencies

position, the range of the rotary control is

3) “High-Pass”:The preamp output delivers














present at the inputs to feed the amplifier.This is

50 - 500 Hz (as marked). In the “x10”

the same signal that is connected to the 300/2's



























useful for systems utilizing outboard crossovers or

position, the range of the rotary control is

Amplifier Inputs with High-Passfiltering applied to














requiring full-rangereproduction from the 300/2.

500 Hz - 5 kHz (5000 Hz).

it at the “Filter Freq.” and “Filter Slope” selected














“LP” (Low-Pass):Configures the filter to attenuate

4) “Filter Freq. (Hz)” The filter frequency

in the “Amplifier Filter” section. This mode can



























frequencies above the selected filter frequency.

markings surrounding this rotary control are for

be useful for feeding a second satellite amplifier














Useful for connection of subwoofer(s) to the 300/2.

reference purposes and are generally accurate to

when the 300/2 is being used to drive the main











If you connect a load higher than 4Ω nominal

“HP” (High-Pass):Configures the filter to attenuate

within 1/3 octave or better. If you would like to

speaker system.



frequencies below the selected filter frequency.

select the filter cutoff frequency with a higher level










per channel in stereo mode (or 8Ω in bridged

Useful for connection of component speakers to

of precision, consult the chart in Appendix A

NOTE: The signal level of the “Preamp Output” is

mode), power will drop by half with every

the 300/2 in a bi-amplifiedsystem.

(page 12) of this manual.

affected by the setting of the “Input Voltage Range”

doubling of impedance above 4Ω stereo / 8Ω
















switch of the amplifier. See the “Input Voltage

mono. If you connect a load lower than 1.5Ω
















Range” section (page 7) for details on “Input

nominal per channel in stereo mode (or 3Ω in
















Voltage” settings.The preamp output level is not

bridged mode, the amplifier protection circuitry
















affected by the “Input Sens.” rotary control.

activates a “safe” mode which reduces amplifier

























power to protect the circuitry from failure (the

























yellow “Low Ω” LED lights to indicate that this

























has happened). See page 10 for details.































































































Speaker loads below 1.5Ω nominal per channel

























in stereo or 3Ω nominal in bridged mode are not

























recommended and may cause the amplifier output

























to distort excessively.


JL AUDIO 300/2

JL AUDIO 300/2



Bridging is the practice of combining the output of two amplifier channels to drive a single load. When bridged, each channel produces signals of equal magnitude, but opposite polarity.The combined output of the two channels provides twice the output voltage available from a single channel.The 300/2 has been designed for bridging of its channel pairs without the need for input inversion adaptors.

To bridge a pair of channels, use the “Left +” and

“Right –”speaker connectors only (the “Left–”and “Right +” remain unused).When bridged, the 300/2 will deliver optimum power into a 3 - 8Ω load. Operating a bridged 300/2 into a load lower than 3Ω is not recommended.

Because a bridged pair of channels requires that both channels receive input, you need to connect both left and right RCA inputs to the source unit. Connection of only one RCA input will result in reduced power output, increased distortion and can cause the amplifier to overheat. Do not do this!

Instead, use a “Y-Adaptor”to split the mono signal into both left and right RCA inputs.

Why a mono signal? If you are bridging a pair of channels and use a stereo input, the only information that will reach the amplifier stage is the common-phaseportion of the signal.This may be useful for passively deriving acenter-channelsignal, but is not going to give you a defined left or right channel. If you are looking to reproduce a single channel’s signal, you must split the mono signal with a“Y-Adaptor”and connect it to both left and right

RCA inputs for the bridged channel pair.



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-poweroperating 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-circuitis 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).This can be used to diagnose ashort-circuitby only connecting one of channel at a time.The amber LED will light when you connect the section that is experiencing the problem and turn the volume up.

There is only one condition that will shut

down an undamaged 300/2 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-heavyprogram 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 Faradrapid-dischargecapacitor connected in parallel to the amplifier power connections will minimize these short duration voltage dips in most systems that are having this problem.

For information on troubleshooting this amplifier, refer to Appendix C (page 14).


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 the

JL AUDIO Technical Department for assistance:

(954) 443-1100

9:00 AM – 5:30 PM Eastern Time,

Monday – Friday


JL AUDIO 300/2

JL AUDIO 300/2



Precise Frequency Selection Chart








Full counter-clockwise:58

01 . . . . . . . . . . . . . . . . . . . . . . . .58 02 . . . . . . . . .“50” . . . . . . . . .58 03 . . . . . . . . . . . . . . . . . . . . . . . .58 04 . . . . . . . . . . . . . . . . . . . . . . . .58 05 . . . . . . . . . . . . . . . . . . . . . . . .59 06 . . . . . . . . . . . . . . . . . . . . . . . .60 07 . . . . . . . . . . . . . . . . . . . . . . . .61 08 . . . . . . . . .“60” . . . . . . . . .63 09 . . . . . . . . . . . . . . . . . . . . . . . .65 10 . . . . . . . . . . . . . . . . . . . . . . . .67 11 . . . . . . . . . . . . . . . . . . . . . . . .69 12 . . . . . . . . . . . . . . . . . . . . . . . .71 13 . . . . . . . . . . . . . . . . . . . . . . . .74 14 . . . . . . . . .“75” . . . . . . . . .77 15 . . . . . . . . . . . . . . . . . . . . . . . .80 16 . . . . . . . . . . . . . . . . . . . . . . . .82 17 . . . . . . . . . . . . . . . . . . . . . . . .85 18 . . . . . . . . . . . . . . . . . . . . . . . .90 19 . . . . . . . . . . . . . . . . . . . . . . . .93 20 . . . . . . . . .“95” . . . . . . . . .97 21 . . . . . . . . . . . . . . . . . . . . . . .102 22 . . . . . . . . . . . . . . . . . . . . . . .107 23 . . . . . . . . . . . . . . . . . . . . . . .113 24 . . . . . . . . . . . . . . . . . . . . . . .120 25 . . . . . . . . . . . . . . . . . . . . . . .127 26 . . . . . . . . .“130” . . . . . . . .135 27 . . . . . . . . . . . . . . . . . . . . . . .143 28 . . . . . . . . . . . . . . . . . . . . . . .153 29 . . . . . . . . . . . . . . . . . . . . . . .171 30 . . . . . . . . . . . . . . . . . . . . . . .182 31 . . . . . . . . . . . . . . . . . . . . . . .201 32 . . . . . . . . .“200” . . . . . . . .223 33 . . . . . . . . . . . . . . . . . . . . . . .253 34 . . . . . . . . . . . . . . . . . . . . . . .289 35 . . . . . . . . . . . . . . . . . . . . . . .337 36 . . . . . . . . . . . . . . . . . . . . . . .404 37 . . . . . . . . . . . . . . . . . . . . . . .474 38 . . . . . . . . .“500” . . . . . . . .514 39 . . . . . . . . . . . . . . . . . . . . . . .525



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 (3 - 8Ω bridged) 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-wavetest tone recorded at 0 dB reference level in the frequency range to be amplified for that set of channels (50 Hz for subwoofer channels, 1 kHz for a midrange application). Do not use attenuated test tones(-10dB,-20dB, etc.).

The Nine-StepProcedure

1)Disconnect the speaker(s) from the amplifier’s “Speaker Outputs”connectors.

2)Turn off all processing on the source unit (bass/treble, loudness, EQ, etc.). Set fader control to center position and subwoofer level control to 3/4 of maximum (if used to feed the 300/2).

3)Switch the “Input Voltage” to “Low” and turn the “Input Sens.” control all the way down.

4)Set the source unit volume to 3/4 of full volume. This will allow for reasonable gain overlap

with moderate clipping at full volume.

5) Using the chart below, determine the target voltage for input sensitivity adjustment according to the nominal impedance of the speaker system connected to the amplifier outputs.

6)Verify that you have disconnected the speakers before proceeding. Play a track with an appropriate sine wave (within the frequency range to be amplified by the 300/2) at 3/4 source unit volume.

7)Connect the AC voltmeter to the “Speaker Outputs” connectors of the amplifier. If the channel pair is operating in stereo, it is only necessary to measure one channel. If bridged, make sure you test the voltage at the correct connectors (L+ and R–).

8)Increase the “Input Sens.” control until the target voltage is observed with the voltmeter. If excessive voltage is read with the control at minimum (full counterclockwise), switch the “Input Voltage” switch to “High” and re-adjust.

9)Once you have adjusted the 300/2 to its maximum low-distortionoutput level, reconnect the speaker(s).The “Input Sens.” controls can now be adjusted downward if the amplifier requires attenuation to achieve the desired system balance.


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.

It will be necessary to re-adjustthe “Input Sens.” for the affected channels if any equalizer boost is activated after setting the “Input Sens.” with this procedure.This applies to any EQ boost circuit, including source unit tone controls or EQ circuits. EQ cuts will not requirere-adjustment.


Target AC Voltage





24.5 V

49.0 V


24.5 V

42.4 V


24.5 V

34.6 V


21.2 V

30.0 V


17.3 V

not recommended


15.0 V

not recommended


JL AUDIO 300/2

JL AUDIO 300/2




Check to make sure there is +12V at the “Remote” connection of the amplifier. In some cases, theturn-onlead 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 thefuse-holder.


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 short 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 each channel of the amplifier is driving a load between 1.5 - 4Ω

(3 - 8Ω bridged).

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.


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 short 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-diagnosedamplifier failures.


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 amplifier (example: 50 Hz for a sub bass application or

1 kHz for a full range / high-passapplication). 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.


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.


Please refer to Appendix B (page 13) to set the input sensitivity for maximum,low-distortionoutput.


JL AUDIO 300/2

JL AUDIO 300/2



300/2 Specifications


Recommended Fuse Value: 40A

Recommended Fuse Type: AGU or MaxiFuse™


No. of Inputs: One Stereo Pair

Input Type: Differential-balancedwith RCA jack inputs

Input Range: Switchable from 200mV - 2V RMS to 800mV - 8V RMS


Amplifier Topology: Class AB with patented Absolute Symmetry™ dual N-ChannelMOSFET output design

Power Supply: Independent, pulse width modulationregulated switching power supply with multistage impedance optimizing circuitry.

Rated Power (Stereo):

150W RMS x 2 @ 1.5-4Ω(11V - 14.5V)

Rated Power (Bridged):

300W RMS x 1 @ 3-8Ω(11V - 14.5V)

THD at Rated Power: <0.03% @ 4Ω per channel (20 Hz-20kHz)

Signal to Noise Ratio: >108.5 dB referred to rated power (A-weighted,20Hz-20kHz noise bandwidth)

Frequency Response: 5 Hz - 30 kHz (+0, -1dB)

Damping Factor: >200 @ 4Ω per ch. / 50 Hz, >100 @ 2Ω per ch. / 50 Hz

Slew Rate: ± 25V/µs


Filter Type: State-variable,12 dB/octave Butterworth or 24 dB/octaveLinkwitz-RileyLow-PassorHigh-Passwith continuously variable cutoff frequency from 50 - 500 Hz, switchable to a range of 500 - 5000 Hz, via x10 switch. Defeatable.


2-Channel,switch-selectableaspass-throughtype, trackingHigh-Pass,or trackingLow-Passlinked to Amplifier Filter.


13.4" x 9.25" x 2.36" (340mm x 235mm x 60mm)

Due to ongoing product development, all specifications are subject to change without notice.


JL AUDIO 300/2

JL AUDIO 300/2



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


JL AUDIO 300/2

JL AUDIO 300/2