JL Audio RD400/4 4 Ch. 400 Watt Amplifier – #98621

Brand: JL Audio
Model Number: RD400/4
UPC: 699440986212
JL Audio
Model Number: RD400/4
UPC: 699440986212

JL Audio RD400/4 #98621 Mono Subwoofer Amplifier

  • 4-channel car amplifier
  • 75 watts RMS x 4 at 4 ohms
  • 200 watts RMS x 2 bridged at 4 ohms
  • Class D amplifier design with NextD switching amp technology
  • Differential-balanced inputs help eliminate noise
  • Variable low- and high-pass filters
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Product Description

Features & Specifications



JL Audio RD400/4 #98621 4-Channel Car Amplifier

Utilizing our exclusive NexD high-speed switching technologies, the ultra-compact JL Audio 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.

Power your music

JL Audio’s RD400/4 4-channel amplifier will power each your car’s front and rear speakers with 75 watts RMS, so you’ll hear and feel your music clearly over the whistle of the wind and rumble of the road. For driving bass, you can switch the RD400/4 to 2-channel mode and run a couple of subwoofer with up to 200 watts RMS each.

This tiny amplifier packs a serious full-range punch, delivering a staggering 100 watts to each of its four channels into 2 ohms (14.4V, 1% THD). The breakthrough that makes this much power possible in such a small chassis is our NexD ultra-high-speed switching design, which allows for full bandwidth Class D operation with extremely low distortion and outstanding efficiency.

Low current demand, low distortion, and integrates well

The RD400/4 plays your music with true fidelity and impressive impact, without straining your car’s electrical system, thanks to JL Audio’s proprietary NexD™ amplifier technology. “Differential-balanced” inputs keep the incoming signals clear of outside noise, and allow you to connect this amp to just about any radio. The speaker-level inputs feature two auto turn-on modes so you can readily incorporate this amp into a factory system — no need for RCA connections or a remote turn-on lead for this setup.

For your convenience, the JL Audio 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.

LED clip lights and other cool features

High- and low-pass filters help you dial in the perfect tone for your speakers or subs. Onboard LED clip indicators let you set the amp gain quickly and accurately with the use of a test tone. A removable cover hides the amp’s controls, resulting in a handsome appearance and a tamper-resistant installation. Cool blue LED accent lighting adds some charm to this amp’s rugged good looks.

Onboard LED-clipping indicators are also included with your JL Audio 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 JL Audio 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.

Brand JL Audio   Model JL Audio RD400/4
Product: JL Audio RD400/4 4 Ch. 400 Watt Amplifier – #98621
Weight 3.17 kg
Dimensions 170 × 248 × 54 mm
Rated Continuous (RMS) Power @ 14.4 V

@ 4 Ω: 75 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: 60 W RMS x 4
@ 2 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
Channel Input Mode Switch: Yes (2/4 ch.)
Pass-Through Preamp Output: Buffered
Source Channel Selection for PreOuts: No

Physical Specifications

Height (H): 2.13 in / 54 mm
Width (W): 9.78 in / 248 mm
Depth (D): 6.96 in / 177 mm

Mobile Amplifier Channels

4 Channel

Mobile Amplifier Class

Class D

Mobile Amplifier Features

High-Pass Filter, Pre Amp Outputs, Speaker Level Inputs

Mobile Amplifier Fuse Rating


Mobile Amplifier RMS

351 to 750 watts

Mobile Min Impedance


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