JL Audio JX-400.4D - 400W 4 Channel Class D Subwoofer Amplifier

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Quick Summary:
The JX400/4D employs a highly-efficient Class D design with a robust MOSFET power supply to deliver a strong 100 watts to each of its four channels into 2 ohms (14.4V, 1% THD).
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Key Features

JL Audio JX-400.4D - 400W 4 Channel Class D Subwoofer Amplifier

Use the JX400/4D in combination with our JX500/1D or JX1000/1D monoblocks to build an amazing amplification system at a very affordable price. Or, use the JX400/4D by itself to power two satellites, plus a subwoofer.
The JX400/4D includes a defeatable 12 dB / octave filter for each channel bank, which can be configured as a low-pass or high-pass filter and offers continuously variable cutoff frequency selection from 50-200 Hz. Dedicated hi-level inputs are included, in addition to conventional low-level RCA inputs, making it easy to integrate with a variety of OEM and aftermarket head units.
Technical Specifications

Rated Continuous (RMS) Power @ 14.4 V:

  • @ 4 Ω - 70 W RMS x 4
  • @ 2 Ω - 100 W RMS x 4
  • Bridged @ 4Ω - 200 W RMS x 2

Rated Continuous (RMS) Power @ 12.5 V:

  • @ 4 Ω - 50 W RMS x 4
  • @ 2 Ω - 80 W RMS x 4
  • Bridged @ 4Ω - 160 W RMS x 2

General Specifications:

  • Frequency Response - 20 Hz - 20 kHz (+0, -1dB)
  • S/N Ratio, referred to highest rated power - >93 dB below rated power (A-weighted, 20 Hz - 20 kHz noise bandwidth)
  • S/N Ratio, referred to 1 W - >76 dB (A-weighted, 20 Hz - 20 kHz noise bandwidth)
  • Damping Factor @ 4 Ω - >60 / 50 Hz
  • Damping Factor @ 2 Ω - >30 / 50 Hz
  • THD+N @ Rated Power - <1% @ 2 Ω per Ch.
  • Input Voltage Range @ RCA Inputs - 200 mV - 4 V RMS
  • Input Voltage Range @ High-Level Inputs - 2 V - 10 V RMS
  • Min.Copper Power / Ground Wire Gauge - 4 AWG wire
  • Fuse Rating - 40 A (AFS, AGU or MaxiFuseâ„¢)

Signal Processing:

  • Filter Mode(s) - Low-Pass or High-Pass
  • Filter Slope(s) - 12 dB/octave
  • Filter Frequency Range - 50 Hz - 200 Hz
  • Detented, Calibrated Filter Freq. Potentiometers - No
  • Filter Defeat Function - Yes
  • Remote Level Control - No
  • Remote Level Modes - N/A
  • Channel Input Mode Switch - Yes (2/4 ch.)
  • Pass-Through Preamp Output - Unbuffered
  • Source Channel Selection for PreOuts - No (always 2 Ch)

Physical Specifications:

  • Height (H) - 2.15 in / 55 mm
  • Width (W) - 9.05 in / 230 mm
  • Depth (D) - 7.68 in / 195 mm
  • Net Weight - 4.80 lb / 2.18 kg
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Questions/Answers About This Product

Question: 01 August 2016

Car: Peugeot -

model - partner how much is fitting kit for this stereo to Peugeot partner 2004. thnaks


Hi, thanks for your question, prices may vary at the time of ordering a fitting kit or indeed any parts from our supplier, we may however have all the parts required in one of our stores. Please contact your local Car Audio Centre for a correct quote.

Question: 30 August 2016

Car: BMW 3 Series (E46) - 2005> (E90) -

Hi, Will this fit a 2007 BMW 318i MSport?


hi yes it will fit the bmw 318 2007 however you will need some parts to fit it . BMW 3 / 1 series Facia Plate CT27AA06 Fakra to Din aerial adapter CTSBM009 BMW Mini Steering wheel control interface

Question: 12 October 2016

Car: Peugeot 206 - 2002 > -

Just wondering, would this fit into my peugeot 206(2005) and would I need to purchase a harness to install this?


Hi, thanks for your question, we have shown a fitting kit below to fit the KMM-202, if you have steering wheel controls then you need a CANBUS harness, if not then you would need an ISO harness. CTKPE01 Complete Head Unit Replacement Kit

Question: 22 October 2016

Car: Seat Ibiza - <2008 -

hi Can you advise what extras i would need with stereo for it to fit my seat ibiza reg fe57 xjt.. and i would like it to work with the steering wheel controls aswell. thanks nathan


hi there, all you should should need to fit this unit are the below listed parts. CT24ST33 Single Din Facia CTSVW002.2 Steering Control Adaptor Single Wire Kenwood patch lead CT27AA14 Aerial Adaptor

Question: 08 February 2017

Car: -

What other extras will I need to install in 2003 Mercedes C200K SE ?


Good afternoon these are the other parts you will require to complete the installation: CT24MB01 Mercedes Fascia Plate (Black) Frame & Pocket CTSMC006.2 Mercedes Steering Wheel Control Interface CTKENWOODLEAD2 Patch connection CT27AA08 Antenna adapter CT24MB01 Single Din Facia CTSMC006.2 Steering Control Adaptor Single Wire Kenwood patch lead CT27AA08 Aerial Adaptor

Question: 18 February 2017

Car: Suzuki Ignis - 2002 > -

Hello, Are any other parts required to install this unit in a 2002 Suzuki Ignis? Thanks!


Hi there, Please see the links provided for parts listed on our system for a 2002 Suzuki Ignis. If possible please drive the vehicle to one of our stores to confirm these are the corrects parts for your vehicle as there are 2 types of fascia listed for the Ignis. I have provided a link for the most common fascia but please do check if the fascia shape matches upto the vehicles dash. Also your vehicle 'may' have iso connections as standard so you might not need the harness but you can check this by removing the unit and checking the type of connector plugged into the current radio. CT24SZ06 Single Din Facia CT20HD02 ISO Adaptor

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Fitting Services

Need help with Installation?

Here at CarAudioCentre we offer a professional and reputable fitting service in all our stores. For all fitting enquiries and bookings please visit or call one of our nationwide stores. Our fitters can install your new car stereo, DAB radio, audio visual, speakers, subwoofers or amplifier. We can also help to connect your iPod or MP3 player to you existing audio unit and can offer the best advice on the right in-car entertainment for your vehicle, to further this more we also offer a total 100% custom installation service for demo and show vehicles. So if you have an idea come on in and run it past us, the possibilities are endless and we are never too busy for an enthusiastic chat about our favourite subject.

Please note:

"That our two year warranty on products is only applicable to purchases made directly from us and that have been fitted in one of our stores."

Our Stores:

542 546 Mansfield Road, Sherwood NG5 2FR
Tel: 0115 9624 986
743-745 Eastern Ave, Newbury Park, London, IG2 7RT
Tel: 0208 599 2368
835 Garratt Lane, Tooting, London, SW17 0PG
Tel: 0208 971 9181