JL Audio Refurbished RD400/4 Class D 4-Channel Full-Range Amplifier

JL Audio

7 reviews Write a Review
You save $120.00
You save $120.00



4-Channel Class D Full-Range Amplifier, 100 W x 4 @ 2 Ω / 75 W x 4 @ 4 Ω - 14.4V

Utilizing our exclusive NexD™ high-speed switching technologies, the ultra-compact RD400/4 amplifier is engineered to deliver loads of audio output power, with incredible efficiency and low distortion. Don’t let its modern styling and small size fool you though, this little powerhouse churns out 100 watts of crystal-clear 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.
For your convenience, the RD400/4’s controls can be found on top of the amplifier, beneath a protective cover, with all connections located along one side of its chassis. Studio-grade 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 most input voltage levels. Automatic turn-on capability (via signal sensing or DC-offset sensing) is standard equipment, along with all-new input type switches for bridging of stereo output channels without needing to use Y-adaptors.
Onboard LED-clipping indicators are also included with your RD400/4. This all-new, innovative feature lets you easily set your amplifier’s input sensitivity settings, quickly and accurately, with no special equipment needed. You’ll also find a set of preamp outputs on-hand, so you can pass signals to another amplifier, almost effortlessly. The RD400/4 features a durable, black powder-coated finish and a top-mounted, dual-color LED light strip that reports the overall status and condition.

Rated Continuous (RMS) Power @ 14.4 V

@ 4 Ω 75 W RMS x 4
@ 3 Ω 100 W RMS x 4
Bridged @ 4Ω 200 W RMS x 2

Rated Continuous (RMS) Power @ 12.5 V

@ 4 Ω 60 W RMS x 4
@ 3 Ω 90 W RMS x 4
Bridged @ 4Ω 180 W RMS x 2

General Specifications

Frequency Response 12 Hz - 22 kHz (+0, -1dB)
S/N Ratio, referred to highest rated power >104 dB below rated power (A-weighted, 20 Hz - 20 kHz noise bandwidth)
S/N Ratio, referred to 1 W >84 dB (A-weighted, 20 Hz - 20 kHz noise bandwidth)
Damping Factor @ 4 Ω >150 / 50 Hz
Damping Factor @ 2 Ω >75 / 50 Hz
THD+N @ Rated Power <1% @ 2 Ω per Ch.
Input Voltage Range @ RCA Inputs Switchable from 200 mV - 2 V RMS (Low) to 800 mV - 8 V RMS (High)
Min.Copper Power / Ground Wire Gauge 4 AWG wire
Fuse Rating 40 A (AFS, AGU or MaxiFuse™)

Signal Processing

Filter Mode(s) Low-Pass or High-Pass
Filter Slope(s) 12 dB/octave
Filter Frequency Range 50 Hz - 500 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 Buffered
Source Channel Selection for PreOuts No

Physical Specifications

    <table class= Height (H) 2.13 in / 54 mm Width (W) 9.78 in / 372 mm Depth (D) 6.96 in / 177 mm

Refurbished FAQ

Refurbished Frequently Asked Questions

  • What does refurbished mean? Refurbished products may be unused customer returns that are essentially "new" items, or they may be defective products that were returned under warranty, and resold by the manufacturer after repairing the defects and ensuring proper function.
  • What is the warranty? All of our manufacturer refurbished items come with a 90-day warranty. Compared to the new products we carry generally having a 1-year or longer warranty. (JL Audio Amps are 2-years, and all of Wet Sounds carries a 2-year warranty when new)
  • What's it look like? A lot of the manufacturer refurbished products we sell generally look very good, and sometimes you can't even tell. However, these products can have some wear and tare on them, and we generally rate them an 8/10 cosmetically, and perfect 10/10 functionally.
  • What was wrong with it? We aren't told what is wrong with each and every product. Like stated above, they could have just been a return or they may have had an issue. Regardless, they are all combed over by their respective manufacturer to function as new before being shipped to us.
  • Have more questions? Call us, send us a chat, or an email. We'll be able to answer any additional questions you may have.

Extra Information

JL Audio
8.00 LBS
Number Of Channels:
4 Channel
RMS Power In Watts:
251-500 Watts
Manufacturer SKU:
8.0000 lbs
Special Offer:
This item includes a FREE CreativeCare 1-Year Warranty Upgrade at no additional cost!
Free 2-Day Shipping!

    7 Reviews

  • Posted by Matthew Heckman on 30th May 2020


    JL RD400/4

    To start, the shipping was super quick considering what's going on and second, for a refurbished item, I'm about 99% sure the one I got was a never used return. This this is in mint condition! I could not be more happy with what I got for the outstanding price! I will 100% be dealing with these guys again! Oh and if free sticker swag is your thing, dont worry, they got you covered on that too!

  • Posted by Ruben Estrella on 14th May 2020


    JL Audio rules

    Quality and powerful sound, Great amplifier, can't go wrong with JL Audio.

  • Posted by Ronald on 9th May 2020



    I had just finished my install of this wonderful amplifier. This is the only amplifier that does accept differential balanced input in this price range. I had pair this amplifier with a set of morel tempo Ultras and they sound phenomenal plus the soundstage is amazing.

  • Posted by Justin on 30th Apr 2020


    Great amp

    I’ve got this amp installed in the cabin of boat and it’s paired with JL M3 7.7” speakers. It’s a huge upgrade from my old “100 watt” amp. I was a little worried about getting a refurbished amp but it looked brand new and you couldn’t tell it apart from one that was not. This amp is a great value and the shipping was super fast!!

  • Posted by Richard Rodriguez on 3rd Feb 2020


    Perfect Condition

    Looks brand new, not one scratch. Even the packaging and accessories look untouched. Amazing bargain find. Oh, sounds great too.

  • Posted by Blake on 18th Nov 2019


    JL Audio RD/400

    Perfect like new but renewed amp looks like it was brand new and works awesome. Very impressed

  • Posted by Guy on 19th Apr 2019


    Take advantage

    The refurbished JL audio amp I received was exactly what I hoped it would be: appeared to be 100% new I could not find any signs use and it was an upgrade over the amp it replaced. I bought this amp to replace a $100 power acoustik 4-channel that I discovered was the cause of distortion and hissing in my setup. With the JL I no longer have annoying hissing. I also noted a nice improvement in sound quality; I'm not a real audio head but everything just sounded more musical. I also liked how easy to terminals are to use, nicely laid out and it uses sturdy hex screws instead of cheap Phillips head screws which tend to strip easily. So, if you're looking for a very nice 4 channel amp an extremely generous price level take advantage of this deal. Thank you Creative Audio!