Name: JL Audio RD400/4
Brand: JL Audio
SKU: rd4004
Price: 379.99 USD
Availability: InStock
Rating: 4.9643 (28 reviews)

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JL Audio RD400/4 Image 1 — JL Audio RD400/4

JL Audio RD400/4 Image 2 — JL Audio RD400/4

JL Audio RD400/4 Image 3 — JL Audio RD400/4

JL Audio RD400/4 Image 4 — JL Audio RD400/4

JL Audio RD400/4 Image 5 — JL Audio RD400/4

Product videos

Product highlights

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

Learn more about the rd4004

Universal – fits most vehicles.

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$379.99

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In Stock

Brand new

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Additional conditions

Open Box, Great $322.99

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Current Promotions (3 offers)

30% Off an Amp Kit with Purchase!

This offer cannot be combined with any other coupons or offers.

JL Audio RD400/4

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$379 ⁹⁹

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JL Audio RD400/4

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50% off

JL Audio RD400/4

$379 ⁹⁹

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Product Highlights

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

Description

Authorized dealer

4-Channel Class D Full-Range Amplifier

The JL Audio RD400/4 is a sleek, modern 4-channel amplifier from the RD series, designed for "do-it-yourself" audiophiles who want high performance with an easy setup. Using NexD high-speed switching technology, it delivers 400 Watts of total RMS power in a compact, efficient design. The RD400/4 is known for its "all-on-one-side" connection layout and top-mounted controls, making it very installer-friendly.

It features integrated LED clipping indicators for every channel pair. These lights allow you to set the gain (input sensitivity) to the exact point of maximum clean power without needing an oscilloscope. It also includes a durable black powder-coated finish and a top-mounted LED light strip that indicates the amplifier's overall status.

Product Details:

RD Series Class D 2 ohm Stable 4-Channel Amplifier
RMS Power Rating:

4 ohm: 75 watts x 4 channel
2 ohm: 100 watts x 4 channel
Bridged: 200 watts x 2 channel @ 4 ohm

Total power output: 400 watts
Onboard LED clipping indicator rings
1 pair of preamp output
Speaker-level (high-level) inputs (Requires adapter like the JL Audio XD-CLRAIC2-SW)
Signal sensing remote turn-on
NextD switching amplifier technology
Differential-balanced inputs help eliminate noise
Advanced Rollback Protection System prevents thermal shut-down
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
Variable low-pass filter: 50 - 500 Hz
Fuse Rating: 40A (AFS, AGU or MaxiFuse)
4 AWG gauge amplifier wiring kit is recommended for installation
Dimensions: 9.78" L x 6.96" W x 2.13" H
Authorized Internet Dealer
2 Year Manufacturer's Warranty
MFR #: RD400/4

Product history:

	JL Audio RD400/4 (newest, current model)
	JL Audio JX400/4D (previous model, replaced by JL Audio RD400/4)
	JL Audio JX360/4 (previous model, replaced by JL Audio JX400/4D)

Frequently Asked Questions (FAQ)

My amplifier won't turn on and the status LED is completely dark. What should I check first?

Check your battery voltage and remote turn-on lead. The RD400/4 requires at least 10V to power up. If the voltage is lower, the amp will stay off. Also, verify that the 40A main fuse near the battery hasn't blown.

How do I use the built-in LED clipping indicators to set my gain without special tools?

Play a 1kHz test tone at 3/4 volume. Turn the "Input Sens." up until the LED turns red, then back it off slightly until it turns off. This ensures maximum clean power without risking speaker damage or distortion.

The status LED is alternating between Red and Blue. What does this mean?

This indicates a continuous "Over Current" condition, often caused by a short circuit in the speaker wiring or a speaker impedance that is too low. Check for loose wire strands touching the vehicle chassis or other terminals.

My factory radio doesn't have a remote turn-on wire. Can I still use this amplifier?

Yes. Set the "Turn-On Mode" switch to "DC" or "Signal." This allows the amp to sense the audio signal from your factory wires and turn on automatically, eliminating the need for a separate 12V remote lead.

Can I bridge this 4-channel amp to power two subwoofers?

Yes. Connect the positive (+) of the sub to the Left+ terminal and the negative (-) to the Right- terminal of each channel pair. Ensure each subwoofer has a minimum impedance of 4 ohms to prevent the amp from entering protection mode.

The amplifier keeps shutting off during high-volume playback. Is it overheating?

If the LED is solid Red, it is in thermal protection. Ensure there is at least 1 inch of clearance above the amp for airflow. Avoid mounting it upside down or in small, unventilated spaces where heat can build up.

I’m hearing a constant ticking or thumping sound from my speakers. How do I fix it?

This usually signals a recurring over-current fault. Inspect your speaker wires for any "pinched" areas where the insulation might be worn, or use a multimeter to ensure your speakers aren't dropping below 2 ohms per channel.

Should I use 8 AWG or 4 AWG wire for this specific 400W model?

For the RD400/4, 4 AWG 100% pure copper wire is highly recommended to prevent voltage drops. While 8 AWG may work for very short runs (under 10ft), 4 AWG ensures the amp gets the current it needs to perform at its full 400W rating.

Specifications & Details

Key Features

Amplifier Key Features

Speaker Level Inputs

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

Series

RD Series

Amplifier Class

Number of Channels

4-Channel

Total RMS Power Output

400 watts

Maximum Input Gauge Size

4 AWG

Minimum Impedance Unbridged

2 ohm

Minimum Impedance Bridged

4 ohms

Frequency Response

12 - 22000 Hz

THD at Rated RMS Power

<1%

Speaker Level Inputs

Optional (Requires Accessory Adapter)

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

Fuse Rating

40A x 1

Total Fuse Rating

Strappable

Sonic Certified Amplifier

Yes

Amp Bluetooth Connectivity

Hi-Res Certified

Low-Level Input Sensitivity

200mV - 2 volts

High-Level Input Sensitivity

800mV - 8 volts

What is in the box?

Paperwork

User manual
Warranty/Registration card

WITB: Amplifiers

Amplifier
Adhesive brand badge
Allen wrench

Warranty and Return Policy

Parts Warranty Duration

2 years

Labor Warranty Duration

2 years

Warranty Provider

Manufacturer

Customer Ratings & Reviews

Overall rating distribution

5 star		96%
4 star		4%
3 star		0%
2 star		0%
1 star		0%

Filter by Star Rating

Show only Verified Purchases

By feature average rating

Durability		4.9
Value		4.9
Features		5
Design		5
Usability		5

Customer Photos & Videos

Customer Reviews

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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.

By Gerry on March 16, 2017 Checkmark Icon

Verified purchase

49 found this helpful

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Great Product

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

Cons:None.

By Dustin on February 8, 2018 Checkmark Icon

Verified purchase

46 found this helpful

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Amp

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

By Marc on September 24, 2017

42 found this helpful

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Nice

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

By Anonymous on March 30, 2019 Checkmark Icon

Verified purchase

42 found this helpful

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JL Audio Class-D 4-Channel RD400/4

Great prices on great equipment and Fast delivery thanx sonic

By Anonymous on March 6, 2019 Checkmark Icon

Verified purchase

41 found this helpful

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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.

By David on August 7, 2020 Checkmark Icon

Verified purchase

40 found this helpful

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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.

By Anonymous on December 14, 2018

40 found this helpful

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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.

By Christopher on March 19, 2020 Checkmark Icon

Verified purchase

39 found this helpful

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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.

By Christopher on January 24, 2021 Checkmark Icon

Verified purchase

34 found this helpful

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Sounds good for the money

Using this in conjunction with an RD1500 in a regular cab Silverado. Not yet installed but it is running on my test bench on a set of Kicker's bookshelf demo speakers. Good, clean sound and plenty of power while running in 2 channel mode.

Shipping and customer service experience was not what I expected; both were slower than promised. Product is great.

By Ryan on November 24, 2021 Checkmark Icon

Verified purchase

33 found this helpful

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See all 28 reviews

Add-ons

Belva BAK44

Complete 4-Channel CCA 4 Gauge Amp Kit with RCA Cables and Speaker Wire

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$49.99

List price $79.99

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JL Audio RD400/4

$379.99

Current Promotions (3 offers)

Product Highlights

Description

4-Channel Class D Full-Range Amplifier

Product Details:

Product history:

Frequently Asked Questions (FAQ)

Specifications & Details

Item Details

Product and How-to Videos

Customer Ratings & Reviews

Customer Photos & Videos

Customer Reviews

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