JL Audio JD400/4

400W RMS JD Series Class-D 4-Channel Car Amplifier

JL Audio
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• 75 watts x 4 channel @ 4 ohms
• 100 watts x 4 channel @ 2 ohms
• Bridged: 200 watts x 2 channel @ 4 ohms
• Total RMS Power: 400 watts
• Class D 2 ohms Stable 4-Channel Amplifier

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JL JD400/4 with Amplifier Wiring Kit

400W RMS JD Series Class-D 4-Channel Car Amplifier



Current Promotions (1 offer)

Expand your audio system and keep your factory stereo and features. These top-of-the-line LOCs help provide an audiophile-level listening experience with their noise isolation technology. This offer cannot be combined with any other coupons or offers.

JL Audio JD400/4

50% off

Priced separately $349 98

Promo Savings of $35 00

Total price:

$314 98


JL Audio

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Premium Engineering

Utilizing our exclusive NexD™ high-speed switching technologies, the JD400/4 amplifier is engineered to deliver loads of clean power, with excellent efficiency and low distortion. This little guy churns out 100 watts of audio from each of its four channels into 2 ohms (14.4V, 1% THD) and is fully bridgeable, so it can be used as a 3-channel amplifier, or as a 2-channel amplifier producing a whopping 200W x 2 into 4 ohms.

The JD400/4’s controls can be found on the input panel of the amplifier, with all speaker and power connections located along the opposite end of the extruded aluminum chassis. Signal processing features include high or low-pass 12 dB / octave filters (defeatable) for each channel pair, with continuously variable frequency selection from 50-500 Hz, and dual-range, differential-balanced inputs capable of accepting line-level or speaker-level signals. Automatic turn-on capability (via signal sensing or DC-offset sensing) is standard equipment.

Onboard LED-clipping indicators are also included surrounding each input sensitivity control. This convenient feature lets you set your amplifier’s input sensitivity, quickly and accurately, without special equipment. You will also find a set of buffered, pass-through preamp outputs on-board, so you can pass signals to another amplifier.

NexD Switching Technology

Let's get a little nerdy... A traditional PWM switching amp design uses a fixed switching frequency and varies the pulse width based solely on the audio input signal to the pulse modulator. This basic approach assumes some ideal conditions, like a rock-steady power supply, that do not necessarily occur in a real, in-car installation. Power supply sag with signal causes distortion at all power levels with these designs, even well below clipping. The cure for this is feedback (a corrective signal sent back to the input side), but this becomes impractical as the audio frequency increases, making it a good solution for band-limited (subwoofer) amps, but not for full-range amplifiers.

Taking the above into account when designing the NexD™ subwoofer amplifiers, we have taken the simple fixed PWM approach and enhanced it with a very high switching frequency: 240 kHz, which is about 4x higher than most Class D subwoofer amplifiers. This pushes the amplifier's bandwidth to at least 500 Hz with minimal distortion and improves efficiency, while keeping typically bulky circuity more compact. Your subwoofers will reward you with tight, rock-solid bass performance.

For the full-range NexD™ amplifiers and channels we applied a variable, ultra-high speed version of the NexD™ technology (switching at well over 400 kHz). In these designs, a self-oscillating modulator with "feed-forward" sends information about the instantaneous power supply voltage to the modulator, combining this with the input signal to cancel out any distortion due to supply voltage fluctuation. This reduces distortion prior to applying feedback, simplifying the overall feedback loop design.

Differential-Balanced Inputs

Today’s vehicles are equipped with sophisticated electronics capable of generating noise and interference that can intrude into the audio path, ruining the listening experience. Most audio equipment uses single-ended, ground-referenced RCA jacks to receive audio signals. This means that the RCA shield is connected directly to the signal ground. This is a simple, cost-effective input design that works well for short runs in noise-free environments. In noisier environments, this method cannot reject the common mode noise that could be on both RCA conductors (shield and center conductor).

By having more than one chassis-grounded RCA shield on a device, single-ended input designs are also more susceptible to ground loops. If noise is present on both conductors while the shield is connected to ground, the input amplifier will amplify the noise relative to the grounded RCA shield. When there are multiple RCA connections or any other conductors subjected to a magnetic field, this will cause a difference in potential across the RCA loop to be amplified at the grounded RCA as noise (a classic ground loop).

JL Audio’s Differential-Balanced Input circuits measure the center pin of the RCA connection relative to the RCA shield, even when the shield is not connected to ground, and even when the voltages at both conductors are moving relative to ground. Because both the center conductor and the shield see high impedance to ground at the input, a ground loop cannot be formed, as there is no current flow to induce a voltage as noise. This works equally well with differential-balanced, or unbalanced signal sources, making this input architecture compatible with all standard car and marine audio equipment, using standard, unshielded, twisted-pair RCA cables. No special cables are required, unlike the fully balanced connections used in professional audio.

Another benefit of the Differential-Balanced Input design is that it easily accepts low-level and high-level signals from a variety of factory head unit outputs and amplifiers, including single-ended “ground referenced” sources, as well as Balanced or Unbalanced “Bridged or BTL” sources. This eliminates the need for Line Output Converters (LOCs) in most installation scenarios. The obvious question is: “Why don’t all car audio amplifiers use Differential-Balanced Inputs?” The answer is simple: it costs more. Executing a proper differential-balanced input section requires more components and better quality components than a basic single-ended design, so you generally won’t find them on less expensive amplifiers.

Product Details:

  • JD Series Class D 2 ohms Stable 4-Channel Amplifier
  • RMS Power Rating:
    • 4 ohms: 75 watts x 4 channel
    • 2 ohms: 100 watts x 4 channel
    • Bridged, 4 ohms: 200 watts x 2 channel
  • Total power output: 400 watts
  • 3-way protection circuitry (thermal, overload, and speaker short protection)
  • Turn-on Mode Switch: remote, offset, and signal turn-on options
  • Input Mode Switch: allows the amp to be used in a 2-channel or 4-channel configuration
  • Input sensitivity:
    • Low level: 200mV - 2 volts
    • High level: 800mV - 8 volts
  • Frequency Response: 12 - 22000 Hz
  • Total Harmonic Distortion (THD): >1%
  • Signal to Noise Ratio: 104 dB
  • Variable high-pass filter: 50 - 500 Hz, 24 dB/octave
  • Variable low-pass filter: 50 - 500 Hz, 24 dB/octave
  • 4 AWG gauge power and ground wiring is recommended for installation.
  • Dimensions: 9-7/8" W x 7-1/2" L x 2-1/8" H
  • Authorized Internet Dealer
  • 1 Year Manufacturer's Warranty

Specifications & Details

Power Specifications - Full Range Channels
RMS Power @ 4 ohms
75 watts x 4 channel
RMS Power @ 2 ohms
100 watts x 4 channel
Bridged RMS Power
200 watts x 2 channel
Amplifier Specifications
JD Series
Marine Certified
Amplifier Class
Number of Channels
Total RMS Power Output
400 watts
Maximum Input Gauge Size
Minimum Impedance Unbridged
2 ohms
Minimum Impedance Bridged
4 ohms
Frequency Response
12 - 22000 Hz
THD at Rated RMS Power
Speaker Level Inputs
Preamp Outputs
1 pair
Built-in Crossover
Low-Pass (LP)
High-Pass (HP)
High-Pass Crossover Frequency
50 - 500 Hz
Low-Pass Crossover Frequency
50 - 500 Hz
Signal-to-Noise Ratio
104 dB
Remote bass/level controller
Fan Cooled
CEA-2031 Compliant
Sonic Certified Amplifier
Not Tested
Amp Bluetooth Connectivity
Hi-Res Certified
Low-Level Input Sensitivity
200mV - 2 volts
High-Level Input Sensitivity
800mV - 8 volts
Authorized Dealer
Authorized Dealer
Authorized Dealer
What is in the box?
WITB: Amplifiers
Mounting screws (4)
Washers (4)
Allen wrench
User manual
Warranty/Registration card
Warranty and Return Policy
Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider

Item Details


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Customer Ratings & Reviews

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Amazing sound!

This amp is phenominal. I am blown away with how well it performs. I believe in name brands when it comes to sound, and J/L hit the nail on the head with this one. I am running two subs bridged in two channel mode and it has a punch. QUALITY like this is meant to be heared. I wonder how great it would sound on my 6x9's. Makes me wish i still had my jl1000/1 to pair it with. Thanks sonicelectronics! You made my day.

By Ethan on August 7, 2021 checkmarkIcon Verified purchase


found this helpful.

Awesome Service

Was able to order a rush order and this amp in a breeze... Travis was so friendly and helpful, will highly recommend Sonic Electronix.

By Cody on August 23, 2020


found this helpful.

JL Audio JD400/4

Clear sound, very pleased.. Easy install, instructions need to be worked on a little..

By Barton on August 10, 2020 checkmarkIcon Verified purchase


found this helpful.

You cannot go wrong with this one.

I had been driving around in my Tundra for 3 years with the stock system. Friend picked my up one day with a proper system installed and I started researching parts the next day. Ended up completely stripping the interior out and upgraded from front to back.
Kenwood DDX9907XR HU, Focal Focal ES 165K components up front, JL coaxes in the rear, JL Audio CS112LG-TW3 Sub powered by a JD500/1 and this amazing little JD400/4 pushing the components and rear fill.
To say I am impressed by this amp is an understatement. JL made setting the gain idiotproof and this will play as loud and clear as my 51 Y/O ears can handle.
Cannot recommend enough.

By Ken on March 3, 2022 checkmarkIcon Verified purchase


found this helpful.

Very happy!

Paired with my JL C2 650's, this thing rocks! Super easy to install and delivers that JL quality that you know you're always gonna get. For the price, you can't beat this baby!

By Pico on May 23, 2022


found this helpful.

Nice amp.

Wow! I'm amazed at how this amp got highs & mids sounding crispy and very detailed. I highly recommend this 4 channel amplifier to anyone who looking for one. And the price is very reasonable as well. Two thumbs!!

By Anthony on May 2, 2022 checkmarkIcon Verified purchase


found this helpful.

Looks and Feels Awesome!

Have not installed this amplifier yet, but based on JL's reputation for quality and the look and feel of this amplifier I know it will perform well.

By Roberto on August 3, 2020 checkmarkIcon Verified purchase


found this helpful.


JL Audio has always been an awesome brand and even better when you can get it at a great price!!! Thank you Sonic Electronix!!!!

By Eddie on October 6, 2022 checkmarkIcon Verified purchase


found this helpful.

Installed on 2 cars 1994 Miata and 2005 Scion XB

I installed both amp in both cars and the installation was very easy do to great electrical connectors both cars sound is very good using Pioneer double din touch screen head unit. Sound is very clean and has plenty of power both Amos was installed in the back 94 Miata in the trunk and on the 05 Scion XB also in t h e back. I love the quality of the J&L amps would buy again.

By Marco on March 11, 2023 checkmarkIcon Verified purchase

Sonic is the only place I do business with after initial order

This amp is outstanding, clipping feature allows you to get the most out of your amplifier

By Dominick on April 29, 2022 checkmarkIcon Verified purchase


found this helpful.


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JL Audio JD400/4

• 75 watts x 4 channel @ 4 ohms
• 100 watts x 4 channel @ 2 ohms
• Bridged: 200 watts x 2 channel @ 4 ohms
• Total RMS Power: 400 watts
• Class D 2 ohms Stable 4-Channel Amplifier



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