Compact Power, Engineered for Precision and Control

S/550 delivers the speed, scale, and authority of Serie S in a more compact form. Powered by a 550-watt Pure Class D amplifier and advanced CarbonAlloy™ drivers, it brings refined dynamics and musical nuance to medium-sized rooms. Equally capable in high-end music systems or immersive theaters, S/550 proves that true performance is defined by control not size.

• 550-watt Pure Class D Amplifier for fast, articulate bass performance
• 10" CarbonAlloy Active Driver with 12" down-firing Passive Radiator for depth and speed
• Optimized for music and theater systems in medium-sized rooms
• Designed for stereo pairs and line-array configurations

A Massive Step Forward

S/550 is the gateway to the Serie S line, delivering the speed, depth, and nuance that define REL’s performance ethos. While its larger sibling, the S/850, sets the ultimate benchmark, the S/550 carries forward many of the same design innovations-ensuring the essence of Serie S is fully realized in a more compact form.

The results are remarkable: S/550 offers lightning-fast transients, deep articulate bass, and tonal balance that breathes life into both music and film. Its ability to combine authority with refinement makes it an ideal choice for those seeking a true high-end experience in medium-sized systems, with performance that consistently exceeds expectations.

For those seeking a more bespoke finish, S/550 is available with an optional Premium Wood Grille upgrade for added warmth and individuality.

Designed for Excellence

Take in the design as a whole: horizontal strakes carved into the side walls, elegant elliptical returns that cradle handles finished in a warm golden-silver, echoing raw titanium. Everywhere you look, thoughtful details emerge-but the purpose is clear. This generation delivers the seemingly impossible: a larger cabinet that is lower, wider, and deeper, yet visually lighter.

The added internal volume gives drivers greater freedom and amplifiers improved efficiency, while updated internal bracing keeps cabinet resonances firmly under control. Subtler touches also make a difference, badges that disappear into the grille cloth, silver accents that rest quietly within the cabinet plane, and model numbers etched discreetly into the front rails, visible only when stacked in a Line Array.

An optional Premium Wood Grille adds warmth and individuality, while front-rail leveling adjusters ensure effortless setup, even on uneven floors. Together, these refinements reflect REL’s philosophy that great design is as much about thoughtful usability as it is about beauty and performance.

Drive Faster. Drive Better

The new S/550 10” high-amplitude driver has been completely rebuilt-only the cast frame remains. Its CarbonAlloy™ cone, capped with pure carbon fiber, sharpens attack and smooths decay, letting notes fade naturally into silence. A redesigned suspension allows greater travel, easily handling the amplifier’s added power.

In listening, the driver feels supple and effortless, free from strain. Because it’s lighter, the amplifier works less, yet delivers more power, allowing the driver to move further and play louder than ever before. The result is nothing short of a revelation.

Passive Radiator

Supporting the active driver is an updated and redesigned down-firing passive radiator, purpose-built to handle the extreme throw distances created by the S/550’s upgraded amplifier and driver. Its flat, primary-piston surface, an evolution of carbon, glass fibre, and closed-cell foam construction-is now 40% stiffer and significantly lighter than before. With more than 2.4" (60mm) of travel in each direction, the passive extends dynamics, authority, and depth, completing a system that pushes well beyond expectations for its class

Amplified Excellence

Rated at 550-watts, the Pure Class D amplifier outpaces its predecessor, but numbers tell only part of the story. In laboratory testing, this unit delivers 600-watts continuous with no strain for extended periods, not simply for an instant. Its crest power is fully 50% greater than its predecessor. It delivers the fast, truly deep bass for which Serie S is known, producing performance that defies specification sheets.

Premium polypropylene capacitors, similar to those used in REL Reference models, feature in the input filters, resulting in a more open soundstage with greater transparency. Extensive testing and long-term development confirm this unit as a rugged and reliable amplifier. Fed by the second-generation PerfectFilter™, the deep bass performance remains remarkable for a subwoofer with such a compact footprint.

Analog Filtered to Perfection

Analog technology remains the only path to achieving truly natural sound. All REL input filters operate in a 100% analog domain, making them among the fastest ever offered in a subwoofer. At the core sits the renowned High Level Input, connecting directly to the speaker outputs of the main amplifier. Rather than drawing power, the connection carries the full sonic signature of the system, allowing REL to blend seamlessly with speakers-a quality praised by reviewers for decades.

For systems where High Level connections are not possible, the low-level input utilizes the same analog filter circuit, available through both RCA and XLR connections, delivering the speed, naturalness, and integration for which REL is recognized. In theater or dual-use systems, REL uniquely allows High Level and .1/LFE to operate simultaneously, enabling music to benefit from natural integration while movies deliver their full cinematic impact.

Serie S Line Array

REL’s Line Arrays are revered for producing sound staging and dynamics that rival the world’s finest systems. Designed to grow in pairs, a Line Array can begin with a simple stereo pair, expand with a second, and ultimately rise to three units per channel, delivering floor-to-ceiling authority and scale.

S/550 now features a precision-milled knurled aluminum adjustment knob integrated into the body rails. This knob allows the bottom subwoofer in a Line Array to achieve perfect level on uneven or soft flooring such as thick-pile carpets or dual-pad installations ensuring a safer, more stable foundation. Purpose-built exclusively for Line Array use, these adjustment knobs enable ideal setup and secure performance without compromise. (Note: 212 Black Label does not include these adjustment knobs.)

Wired For Sound…Wirelessly

Sometimes the best wire is no wire. Quality cables remain essential in high-end audio systems, yet certain situations make running cables across a room impractical, unsafe, or visually distracting. REL addresses this challenge with Airship Direct™, an optional wireless system that transmits wide-bandwidth compound signals while carrying both High Level and .1/LFE simultaneously.

Even with the scale and output of S/550, Airship Direct™ preserves the speed, transparency, and authority that define REL. Seamless transitions between music and movies occur without touching the controls, all from a single module that plugs neatly into the rear panel and remains visually hidden within the room. Simple, direct, uncompromised: Airship Direct™.