JL Audio RD400/4 | 400 Watt Class-D 4-Channel Amplifier

JL Audio Class-D 4-Channel RD400/4

400W RMS RD-Series NexD™ Class-D 4-Channel Amplifier

400W RMS RD-Series NexD™ Class-D 4-Channel Amplifier

• 75 Watts RMS x 4 @ 4 ohms
• 100 Watts RMS x 4 @ 2 ohms
• Total Peak Power: 800 Watts
• Variable Bass Boost: 0 to +12 dB bass boost at 45 Hz
• Heavy duty aluminum alloy heat-sink
• 7"W x 9-3/16"L x 2-1/8"H

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JL Audio's RD Series Amplifiers
Class D Power for Days

JL Audio RD400/4 4-Channel Class D Amplifier

Lots of power, installer-friendly design and options for every audio enthusiast, all make it easy to choose a JL Audio RD Series amplifier.


The RD400/4 has the do-it-yourself audiophile completely in mind. Capable of pushing out up to 100 watts of clean power to 4 channels at 2 ohms, this amp has the flexibility to push your cabin speakers, your subwoofers, or a combination of them depending on your needs. The RD multi-channel amps have built-in 12 dB/octave low-pass filters and three turn-on modes: Traditional 12-volt trigger, signal sensing and DC offset. Top off the package with a sleek, single-cast piece of aluminum in black powdercoat and blue LEDs, and your power looks as clean as it sounds.

Designed For Installers


JL Audio’s engineers had professional and at-home installers in mind with the RD Series. All of the inputs and controls are on the same side of the chassis, simplifying the setup whether you’re in a shop or in your driveway. The output clipping indicators on each channel section mean you don’t need specialized tools to accurately set the gain. A remote level control input gives you the option to install a bass level knob, sold separately, in the front seat, giving you full control over the bass output for every song you play.

NexD™ Switching Technology

NexD™ Switching Technology

The RD Series also incorporates JL Audio’s NexD Switching Tehnology. Since Class D amplifiers have a tendency to produce distortion at some ranges, NexD Switching helps cancel it out before feedback is ever applied. All of this helps ensure the some of the cleanest possible signal to your subwoofer and speakers from your brand new Class D amplifier.

For an amp that delivers power, utility, simplicity and plenty of options, take a look at all of the JL Audio RD Series amps at Sonic Electronix. We’re sure you’ll end up with one in your cart.

General Features:

  • JL Audio RD-Series RD400/4
  • Class-D 4-Channel Amplifier
  • RMS Power Rating:
    • 4 ohms: 75 watts x 4 chan.
    • 2 ohms: 100 watts x 4 chan.
    • 1 ohm: ------------N/A------------
    • Bridged, 4 ohms: 200 watts x 2 chan
  • Total power output: 800 watts
  • NexD™ Technology delivers outstanding sound quality, efficiency and reliability
  • LED clipping indicators
  • Pulse Width Modulated MOSFET power supply
  • LED power (green) and protect (red) indicators
  • Soft start turn-on
  • DC Offset-Sensing and Signal-Sensing (auto-on)
    • Designed for high-level (speaker level) signals, not for lowlevel (preamp level) signals.
    • The circuit senses the input signal from CH. 1 only.
  • Mono channel operation
  • Speaker-level (high-level) inputs
  • Bridging switch for each channel pair
  • Preamp RCA outputs to daisy chain multiple amps
  • 3-way protection circuitry (thermal, overload, and speaker short protection)
  • Dual speaker terminals simplify the hookup of multiple speakers
  • Heavy duty aluminum alloy heat-sink for extreme heat dissipation
  • Input sensitivity:
    • Low level: 200mV - 2V
    • High level: 800mV - 8V
  • Frequency Response: 12 - 22,000Hz
  • Total Harmonic Distortion (THD): <1%
  • Variable low-pass filter: 50 - 500 Hz, 12 dB/octave
  • Variable high-pass filter: 50 - 500 Hz, 12 dB/octave
  • Low-Pass Slope (dB/octave): 12 dB/octave
  • Variable Bass Boost: 0 to +12 dB bass boost at 45 Hz
  • Fuse Rating: 40 A x 1
  • 4-8 gauge power and ground wiring is recommended for installation. Contact us for information regarding a discount on select amplifier kits from our website when purchased together with this amplifier. Click Here for our contact information.
  • Dimensions: 7"W x 9-3/16"L x 2-1/8"H
  • Authorized Internet Dealer
  • 1-year Manufacturer's Warranty

Check out the JL Audio Class-D 4-Channel RD400/4 Owner's Manual

Product history:

JL Audio RD400/4 thumbnail
(newest, current model)
JL Audio JX400/4D thumbnail
(previous model, replaced by JL Audio Class-D 4-Channel RD400/4)
JL Audio JX360/4 thumbnail
(previous model, replaced by JL Audio JX400/4D)
Power Specifications - Full Range Channels
RMS Power @ 4 ohms
75 watts x 4 channels
RMS Power @ 2 ohms
100 watts x 4 channels
Bridged RMS Power
200 watts x 2 channels
Amplifier Specifications
Amplifier Series
RD (JL Audio)
Marine Certified
Amplifier Class
Number of Channels
Total Peak Power Output
800 watts
Total RMS Power Output
400 watts
Maximum Input Gauge Size
Minimum Impedance Unbridged
2 ohms
Minimum Impedance Bridged
4 ohms
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
84 dB
Channel Separation
12 dB
Bass Boost
0 - 12 dB
Bass/Gain Remote
Optional (Accessory required and sold separately)
Fan Cooled
Fuse Rating
40A x 1 
Total Fuse Rating
CEA-2006 Compliant
Sonic Certified Amplifier
Not Tested
Amp Bluetooth Connectivity
Hi-Res Certified
Authorized Dealer
Authorized Dealer
Authorized Dealer
What is in the box?
WITB: Amplifiers
User manual
Specials with this Item
Warranty and Return Policy
Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider
  • JL Audio RD Series Car Amplifiers | Clipping LED Demonstration | CES 2017
  • JL Audio RD Amplifier Product Spotlight
  • How To Install an Amplifier: Car Amplifier Basics Part 2
JL Audio Class-D 4-Channel RD400/4

JL Audio Class-D 4-Channel RD400/4



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By feature average rating



March 16, 2017

Great Deal on a great product

I could not be happier with this amp. True quality from top to bottom. The sound is fantastic. I used this as a full range four channel amp to drive four kicker speakers. It gets its signal from the factory Nissan HU which is a very low quality HU in my opinion. I decided to try to keep the factory HU due to the factory steering wheel controls, bluetooth and stock look for theft deterrent appearance. I found the front channels on the HU clipped out way early compared to the rear when setting up the amp. So i switched the amp to 2 channel input / four channel output the set it up with the clip lights ....and perfection! What a great feature. I am very happy.


found this helpful.


March 6, 2019

JL Audio Class-D 4-Channel RD400/4

Great prices on great equipment and Fast delivery thanx sonic


found this helpful.


January 24, 2021

Open box saved me $70

JL lives up to their reputation again. Replaced my kicker 4 channel with this amp. A smaller footprint operates at a cooler temperature, and all of the wirings is on one side for cleaner wire installation.


found this helpful.


February 8, 2018

Great Product

Pros: Easy to install, all the needed features, underrated.



found this helpful.


August 7, 2020

Excellent app at a great price. Fast delivery also!

I needed the amp I bought quickly and Sonic Electronix was the only company that had it in stock and at the right price.

Great amp, shipped fast. 100% satisfied.


March 19, 2020

Excellent price Great power

This amp was a great price and I love the convenience in size. I replaced my factory amp and the Boston acoustic speakers now sound like high-end audio. Very easy to install and with the new clipping feature I have no issues. Will be buying another soon.


March 30, 2019


Very good sound quality amp and small enough to put under the seats


December 14, 2018

JL Audio Class-D 4-Channel RD400/4

I would recommend this amp it sounds so clean!!!! I have it running 4 6.5 Phoenix gold coaxal speakers I have had this amp for 6 months and works perfectly.


September 3, 2018

Great amp

Got this amp to replace old one. This amp is very powerful, clean, and sounds great.


September 24, 2017


Very pleased so far.. sounds just as my amp that I replaced.. easily installed, with a very small space required for installation... don't know about durability yet.. but we will see.. for the $$ and power/size ratio I would recommend this amp to anybody.. JL makes some of the best


December 31, 2016

Great amp

Works as advertised and put out the power. Looks good too!


April 11, 2018

JL AUDIO Quality absolutely

Clear sound, power and quality on my jl audio c2-650 components


January 28, 2017

Great Amp

Purchased amp to power focal 6.5 components, and 6.5 coaxial door speakers. Sounds wonderful, works like a charm.


found this helpful.

This product is temporarily out of stock. May we recommend...

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400W RMS RD-Series NexD™ Class-D 4-Channel Amplifier


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JL Audio XD-PCS4-1B 4 Gauge Wiring Kit

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Bass Remote

A bass remote made specifically for the this amplifier.


JL Audio XD-CLRAIC4-18 Core Series RCA Interconnect Cable

18 Ft (5.49 m) Core Series 4 Channel Audio Interconnect Cable



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