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SERIE S

S/850

$3,999

S/850 is built for uncompromising performance, blending power with refinement. Featuring an 850-watt Linear Class D amplifier, advanced CarbonAlloy™ drivers, and innovations from our Reference line, it delivers explosive dynamics, nuance, and effortless scale.

Premium Wood Grille orders ship the week of December 20th, 2025.

850-watt Linear Class D Amplifier
12" CarbonAlloy™ Active Driver with 12" Long-Stroke Passive Radiator
Music & Theater Systems, Medium-to-Large Rooms
Stereo Pairs & Line Arrays
Optional Premium Wood Grille Available. As a natural wood material, grain and color variations are expected and unique to each grille

Color:Black

Black
White

Setup:One Subwoofer

Single Subwoofer
Stereo Pair
Line Array

Add-On Grille:Cloth (included)

Cloth (included)
Premium Wood

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S/850

Single Subwoofer
Black
Cloth (included)

$3,999

Stunning Design Meets Raw Power

S/850 stands as the benchmark of the Serie S line, with its design innovations shaping and elevating its three stablemates. Every improvement is sweeping and comprehensive, ensuring the entire Serie S family benefits from the advancements pioneered in the S/850.

The results are spectacular: it delivers incredible attack and output beyond even the former Carbon Special at the very limits of performance, yet with the precision, quietness, and clarity that produce true dynamic range. Lightning-fast transients, deep effortless bass, and tonal richness combine to deliver nuance that elevates both music and theater.

Design

Designed to be Perfect

The S/850 cabinet is longer, lower, wider, and deeper—proportions that give it a naturally dynamic presence. Subtle design details refine its look and feel: clean creases that catch the light, warm silver-gold badges with a titanium-like finish, and stainless-steel handles recessed into graceful ellipses. Beneath each front rail, precision-milled billet cylinders provide exact leveling, while thick internal aluminum slabs secure the handles for safe stacking in Line Arrays. Designed to complement modern interiors, the S/850 also offers an optional Premium Wood Grille, adding warmth and individuality.

Driver

Driven to Perfection

The S/850 is the result of relentless refinement. This progress comes not only from exploring newer, finer materials, but also from the thousands of hours of critical listening our team undertakes each year—experience that transforms raw engineering into musical and theatrical performance of the highest order. With every detail carefully considered, the S/850 delivers a level of power, nuance, and scale that redefines what’s possible in its class.

S/850 drivers now feature lightweight pure carbon-fiber center caps, replacing the solid aluminum moldings of earlier models. These caps reduce moving mass while stiffening the cone, resulting in explosive dynamics and the ability to resolve the quietest passages with delicacy and nuance. Feather-light yet rigid, they extend performance at both extremes—a hallmark of REL design.

Passive Radiator

Supporting this advanced active driver is a newly engineered down-firing passive radiator. Purpose-built to handle the extreme throw distances produced by the S/850’s more powerful amplifier and driver system. Its flat, primary-piston surface—crafted from carbon, glass fibre, and light, stiff closed-cell foam, represents an evolution of prior designs but is now 40% stiffer and significantly lighter. With over 2.4" (60mm) of travel in each direction, it expands dynamics and low-frequency authority, unlocking the full scale and impact of the S/850.

Amplifier

Monoblock Slam, Class D Efficiency

The S/850’s amplifier delivers the slam of massive Class A/B monoblocks while harnessing the efficiency of a modern Class D output stage. Supported by a robust traditional power supply, it produces 850 watts of continuous output and can surge to 1,000 watts during demanding peaks, ensuring ample headroom for both music and theater. Upgraded input filters, equipped with the same thin-film capacitors used in our flagship designs, introduce a new level of transparency and refinement previously unheard of in this class. Together, these advancements create dramatic improvements in clarity, sound staging, and sheer authority—an amplifier that blends brute force with finesse to anchor the performance of the entire Serie S line.

Analog Filtered to Perfection:

We choose analog because it is the only way to achieve truly natural sound. All REL input filters are 100% analog—among the fastest ever offered in a subwoofer. At the core is our renowned High Level Input, which connects directly to the speaker outputs of your main amplifier. This doesn’t draw power; instead, it carries the full sonic signature of your system, allowing REL to blend seamlessly with your speakers—a quality reviewers have praised for decades.

For systems where High Level isn’t possible, our low-level input uses the same analog filter circuit, available via both RCA and XLR connections, to deliver the speed, naturalness, and integration REL is known for. And in theater or dual-use systems, REL uniquely allows High Level and .1/LFE to run together—so music benefits from natural integration, while movies deliver the full impact intended by the mix.

Line Array

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/850 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.)

Wireless

Wired For Sound…Wirelessly

Sometimes the best wire is no wire. Quality cables are a given in high-end audio systems, but there are occasions where it is impractical, unsafe, or unsightly to drape a cable across the room. REL delivers the ultimate solution with Airship Direct™, our optional wireless system that transmits wide-bandwidth, compound signals, carrying both High Level and .1/LFE simultaneously. Even with the scale and output of S/850, Airship Direct™ preserves the speed, transparency, and authority that define REL. It allows seamless transitions between music and movies without ever touching the controls, all from a single module that plugs neatly into the rear panel and stays invisible in your room. Simple, direct, uncompromised: Airship Direct™.

Specifications

Technical Specifications

Type

Front-firing active driver, down-firing passive

Active Driver Size & Material

12 in. (305mm) long-throw, CarbonAlloy™ cone structure, die cast alloy chassis

Passive Radiator Size & Material

12 in. (305mm), Carbon/Carbon flat cone structure, steel chassis

Low Frequency Extension

-6 dB at 19Hz

Input Connectors

High Level Neutrik Speakon, Low Level (2) RCA, (1) LFE RCA, (1) LFE XLR

Output Connectors

High Level Neutrik Speakon, (1) Low Level RCA, (1) LFE RCA or (1) LFE XLR

Power Output

850 watts (RMS)

Amplifier Type

Linear Class D

Wireless Capability

REL AirShip Direct (sold separately)

Dual Parametric Filter

N/A

Finish

Piano Black Lacquer, Gloss White Lacquer 8 coats

Protection System

Fully Electronic Set Safe

Yes

D.C. Fault

Yes

Output Short

Yes

Mains Input Voltage

220-240 volts, 110-120 volts for certain markets

Fuses

8 Amp semi delay 220 volts operation, 15 Amp semi delay 120 volts operation

Supplied Accessories

Mains Lead

Yes

Neutrik Speakon

Yes (10 Meters Nominal)

Interconnect

User Manual

Yes

In the interest of product development, REL Acoustics Limited reserve the right to vary these specifications without notice.

Dimensions

DIMS

W x H x D
19.25 x 16.125 x 21.25 in.
(488 x 410 x 540 mm)

Net Weight

93.5 lbs. (42.5 kg)

Faq

How does my audio system benefit from the S/850 Subwoofer?

The REL S/850 is the flagship of the Serie S, created to deliver scale, depth, and refinement that expand the entire listening experience. Its bass arrives with both authority and grace — fast, controlled, and seamlessly woven into the performance. The result is an experience that feels larger, more dynamic, and more alive. From the intimacy of a quiet passage to the sweep of a cinematic score, the S/850 turns every moment into something richer, more immersive, and more real.

What makes REL Serie S subwoofers different from other REL subwoofers?

REL’s Serie S subwoofers strike a unique balance between high-end performance and compact elegance. Compared to Serie T/x, Serie S models offer upgraded components, faster filters, and more powerful amplifiers—resulting in greater speed, clarity, and dynamic output. Comparing Serie S to the home theater–focused HT range, Serie S is engineered for both reference-grade two-channel music and cinematic immersion. Carbon Special Black Label, S/850 & S/550 are among the few REL subwoofers designed for line array stacking, a feature borrowed from REL’s flagship Reference Series.

Is the S/850 subwoofer compatible with wireless systems?

Yes — the REL S/850 Black Label is fully compatible with REL’s new Airship Direct wireless system, allowing for wireless placement without sacrificing performance. Airship Direct preserves the speed, scale, and refinement that make the S/850 Black Label the flagship of the Serie S, delivering bass that is every bit as immediate, powerful, and seamlessly integrated as a wired connection.

What room size is ideal for S/850?

The S/850 is the flagship of Serie S, built for those who want their system to deliver both scale and refinement. Ideal for medium to larger rooms (300–700 sq. ft.), it has the size and authority to anchor a system, while remaining fast enough to disappear into the music.
At the heart of the S/850 are its redesigned, lightweight drivers, engineered to deliver greater speed, snap, and agility. This means bass that doesn’t just go deep—it starts and stops with absolute precision, keeping pace with the finest loudspeakers and adding energy that feels alive.
When paired with capable speakers, the S/850 does more than extend bass—it reveals new layers of detail and space, expanding the soundstage and allowing instruments and voices to bloom with natural presence.
The result is a subwoofer that’s both powerful and graceful, one that transforms not just what you hear, but how completely you experience the music.

Can I stack S/850 subwoofers in a line array?

Yes—the S/850, flagship of Serie S, was designed with stacking in mind. Starting with stereo pairs, it already delivers commanding scale, authority, and refinement that elevate a system well beyond expectation. As more units are added, the sound grows in presence, weight, and effortless ease, unveiling new layers of musical expression and cinematic impact that bring performances vividly to life.
What makes the S/850 remarkable is how it maintains its poise and balance no matter the scale. Whether enjoyed as pairs or expanded into a full Line Array, it combines power and elegance in a way that feels both natural and immersive. It is bass with stature—able to grow with ambition while always serving the music first.

View S/850 in Your Space

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What's in the box

Serie S/850 Subwoofer
6' AC Power Cord
32' Neutrik Speakon cable
Line Array Mounting Hardware
Cloth Grille
User Manual and Warranty Information
*The Premium Wood Grille is NOT included in your subwoofer purchase but is available for purchase.

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