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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) 443-1100 during business hours (Eastern Time Zone).

JL AUDIO 

450/4 

four-channel system amplifier

o w n e r ’ s   m a n u a l

Summary of Contents for 450/4

Page 1: ... 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...

Page 2: ... 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 20 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 d...

Page 3: ... pair for any impedance between 1 5 and 4 ohms per channel The staggered power distribution of the 1 2 and 3 4 channel pairs 150W x 2 for CH 1 2 and 75 x 2 for CH 3 4 allows for a wide variety of application options The 450 4 can be operated in the following modes 1 As a full system amplifier in bi amp mode with CH 1 2 driving subwoofers in low pass mode 150W x 1 or 300W x 1 and CH 3 4 driving mai...

Page 4: ...4 s Remote turn on connector is designed to accept 18 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 wir...

Page 5: ...mited to 0 or 6 dB allowing a range of 0 15 dB of boost to be selected The Bass EQ and Infrasonic Filter features will only operate when the CH 1 2 filter is activated and in low pass mode If you are using an external active crossover and would like to use the Bass EQ and Infrasonic Filter features set the IMPORTANT JL AUDIO 450 4 9 24dB Configures the filter for CH1 2 to attenuate frequencies abo...

Page 6: ...up 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 450 4 11 Filter Mode Slope switch on 12dB and rotate the frequency selection knob fully clockwise to the 500 Hz position This will activate the bass controls without significantly affecting the crossover point...

Page 7: ... 4 13 SYSTEM CONFIGURATIONS The 450 4 is a very flexible amplifier well suited for a multitude of system configurations In this section the most likely configurations are explained in detail Once you have selected your desired configuration you can use the amplifier panel drawings on the bottom of the following pages to mark the required switch positions for easy reference BI AMPLIFIED SYSTEMS Bi ...

Page 8: ...mp outputs are not used JL AUDIO 450 4 15 outputs is connected to the CH 1 2 inputs of the 450 4 select 2ch on the Input Mode switch in the CH 1 2 Input Section The second stereo pair of source unit outputs is connected to the subwoofer amplifier inputs In this mode the 450 4 s preamp output is not used Result with this option the user has the ability to fade the level of the subwoofer amplifier s...

Page 9: ...ls are unused User adjustability of left center and right channels depends on source unit processor Subwoofer level is user adjustable Set the subwoofer amplifier s Input Sens with the source unit s subwoofer level control set at 3 4 of full output Refer to the subwoofer amplifier owner s manual for proper adjustment The Summed Center Channel methods outlined below do not create a true center chan...

Page 10: ... a subwoofer system from one or more amplifiers or channels LFchannels mid range speakers from a separate amplifier or set of channels MFchannels and high frequency speakers from a separate amplifier or set of channels HFchannels One such configuration is to run subwoofers off the LFchannel s mid bass speakers off the MF channels and a passively crossed over mid high frequency component speaker sy...

Page 11: ...ult in audible distortion and possible speaker damage It will be necessary to re adjust the 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 the amplifier s Bass EQ and source unit tone controls or EQ circuits EQ cuts will not require re adjustment IMPORTANT JL AUDIO 450 4 21 CHA...

Page 12: ...LY SETTHE INPUT SENSITIVITY ON MY AMPLIFIER Please refer to Appendix B page 20 to set the input sensitivity for maximum unclipped output MY AMPLIFIER DOESN TTURN 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 ...

Page 13: ...e as a bandpass filter for tri amp configurations Defeatable LF Boost Single band fixed frequency 48 Hz fixed Q 6 dB boost Defeatable Port for optional remote bass control to provide variable boost control from 0 to 15 dB Infrasonic Filter 24 dB octave 30Hz defeatable CHANNELS 3 4 Amplifier Topology Class AB with patented Absolute Symmetry dual N Channel MOSFET output design Power Supply Independe...

Page 14: ...JL AUDIO 450 4 27 26 JL AUDIO 450 4 INSTALLATION NOTES Use this diagram to document your amplifier s switch and control positions ...

Page 15: ...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 origi...

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