JL Audio RD500/1 Monoblock 1 Channel Class D Sub Subwoofer Amplifier 500w RMS

The JL Audio RD500/1 is a monoblock Class D subwoofer amplifier from JL Audio's RD Series, rated at 500W RMS at 2 ohms, 350W at 3 ohms, and 250W at 4 ohms (14.4V). It uses JL Audio's proprietary NexD™ switching technology and features an onboard LED clipping indicator for straightforward setup.

This listing is the RD500/1. The RD Series is also available in RD1500/1 (1500W RMS).

Key specifications

• Output power: 250W x 1 at 4 ohms, 350W x 1 at 3 ohms, 500W x 1 at 2 ohms (14.4V)
• Frequency response: 7Hz to 500Hz (+0, -1dB)
• Low-pass filter: 12dB/octave, variable 50Hz to 500Hz
• THD+N at rated power: less than 1% at 2 ohms
• Input voltage range: switchable 200mV to 2V RMS (low) or 800mV to 8V RMS (high)
• Minimum power and ground wire: 4 AWG
• Fuse rating: 50A
• Remote level control: optional RBC-1

RD500/1 monoblock Class D subwoofer amplifier: 500W x 1 at 2 ohms, 250W x 1 at 4 ohms (14.4V)

The RD500/1 delivers 500W into 2 ohms (14.4V, 1% THD) from an ultra-compact chassis, powered by JL Audio's proprietary NexD™ switching technology for high output, precise efficiency and very low distortion.

Controls are located on top of the amplifier beneath a protective cover, with all connections along one side of the chassis. Signal processing includes a 12dB/octave low-pass filter variable from 50Hz to 500Hz, a variable bass boost EQ, and dual-range differential-balanced inputs compatible with most input voltage levels. Automatic turn-on via signal sensing or DC-offset sensing is standard, along with preamp outputs to pass signals to a second amplifier.

An onboard LED clipping indicator lets you set input sensitivity quickly and accurately without special equipment. The RD500/1 has a black powder-coated finish and a top-mounted dual-colour LED strip showing overall status. An optional RBC-1 remote level control (sold separately) allows subwoofer level adjustment from the driver's seat.

NexD™ switching technology

NexD™ technology delivers exceptional audio quality, high efficiency and high power from compact amplifier designs.

JL Audio has been at the forefront of Class D amplifier design since its original "Slash" subwoofer amplifiers. NexD™ stems from this expertise to deliver outstanding fidelity and efficiency in a compact, high-value package.

A traditional PWM switching amplifier uses a fixed switching frequency and varies pulse width based solely on the audio input signal. This assumes ideal conditions — such as a steady power supply — that don't always occur in a real car installation. Power supply sag causes distortion at all power levels, even well below clipping. Feedback can correct this, but becomes impractical at higher audio frequencies, making it better suited to band-limited subwoofer amplifiers than full-range designs.

For the NexD™ subwoofer amplifiers, JL Audio uses a fixed PWM approach enhanced with a switching frequency of 240kHz. This extends bandwidth to at least 500Hz with minimal distortion, improves efficiency, and keeps circuitry compact for tight, controlled bass performance.

For full-range NexD™ amplifiers and channels, JL Audio applies a variable, ultra-high-speed version of NexD™ technology switching at well over 400kHz. A self-oscillating modulator with feed-forward sends information about the instantaneous power supply voltage to the modulator, combining it with the input signal to cancel distortion caused by supply voltage fluctuation — reducing distortion before feedback is even applied, and simplifying the overall feedback loop design.

The result is clean, powerful and reliable audio.