JL Audio RD1500/1 RD Series 1 Channel Monoblock Subwoofer Amplifier 1500w RMS

The JL Audio RD1500/1 is a monoblock Class D subwoofer amplifier rated at 1500 W RMS at 1 or 2 ohms (14.4 V), from JL Audio's RD Series. It uses JL Audio's NexD™ switching technology to deliver high power output with low distortion from a compact, slim chassis.

This listing is the RD1500/1. The RD Series monoblock range is also available as the RD500/1 at 500 W RMS.

Key specifications

• Channels: 1 (monoblock), Class D
• RMS power at 14.4 V: 750 W at 4 Ω, 1000 W at 3 Ω, 1500 W at 2 Ω, 1500 W at 1 Ω
• RMS power at 12.5 V: 750 W at 4 Ω, 1000 W at 3 Ω, 1200 W at 2 Ω, 1500 W at 1 Ω
• Frequency response: 7 Hz to 500 Hz (+0, −1 dB)
• Low-pass filter: 50 Hz to 500 Hz, 12 dB/octave, with variable bass boost EQ
• Fuse rating: 150 A (AFS or AGU); minimum 2 AWG power and ground wire
• Dimensions (H × W × D): 54 × 458 × 177 mm
• Remote level control: optional RBC-1 (sold separately)

The rated power figures require the "Low Z" switch to be set for the load: the "2Ω" position for 4, 3 and 2 Ω loads, and the "1Ω" position for 1 Ω loads.

RD1500/1 Monoblock Class D Subwoofer Amplifier

1500 W x 1 @ 1–2 Ω / 750 W x 1 @ 4 Ω — 14.4 V

The RD1500/1 is built for high-power subwoofer applications. A special low-impedance circuit allows 1500 W output at 1 or 2 ohms (14.4 V, 1% THD). JL Audio's exclusive NexD™ Class D technology sits at the core, delivering high efficiency and low distortion from a slim, compact chassis.

All controls are located on top of the amplifier beneath a protective cover, with all connections running along one side of the chassis. Signal processing includes a 12 dB/octave low-pass filter with continuously variable frequency selection from 50–500 Hz, plus a variable bass boost EQ.

Dual-range, differential-balance inputs accept most input voltage levels. Automatic turn-on (via signal sensing or DC-offset sensing) is standard, and a set of preamp outputs lets you pass signals to a second amplifier.

An onboard LED clipping indicator allows accurate input sensitivity setting without special equipment. A top-mounted dual-colour LED light strip reports overall amplifier status and condition. The RD1500/1 has a durable black powder-coated finish. Subwoofer level can be controlled from the driver's seat using the optional RBC-1 remote level control (sold separately).

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 the original 'Slash' subwoofer amplifiers. NexD™ stems from that expertise to deliver outstanding fidelity and efficiency, producing compact amplifiers with high power output and strong value.

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 do not always occur in a real car installation. Power supply sag causes distortion at all power levels in these designs, even well below clipping.

Feedback can correct this, but becomes impractical as audio frequency increases. This makes it a practical solution for band-limited subwoofer amplifiers, but not for full-range designs.

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

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

The result is clean, powerful and reliable audio.