REL Acoustics S/850

Overview

The REL Acoustics S/850 sits near the top of REL's high performance S line, a powered subwoofer engineered to disappear into a serious music system while adding weight, scale and air. Its defining tool is REL's signature high-level Speakon connection, which takes signal from your main amplifier's speaker terminals so the sub follows the exact character and timing of that amplifier. The result is bass that arrives with the same phase and voicing as your main speakers, so the low end feels like part of one coherent musical event rather than a separate box making noise.

Engineering centers on a stiff, fast forward-firing active driver supported by a large down-firing passive radiator, driven by a powerful onboard amplifier. That combination lets the S/850 move real air with control, tightening leading edges on kick drums and double bass while extending low into the room. A continuously variable crossover, gain and phase controls give you precise integration, and a separate .1/LFE input lets the same cabinet handle home theater duty when you want it.

The S/850 is for the listener who has a resolving pair of main speakers and wants deeper, larger, more effortless bass without disturbing midrange purity. It works as a single unit in most rooms, and REL owners frequently run two in a stereo pair or stack them in a line array for greater dynamic headroom in larger spaces.

Key Features

• REL high-level Speakon connection so the sub follows the character and timing of your main amplifier for music first
• Separate .1/LFE input for seamless home theater integration alongside music use
• Forward-firing active driver paired with a large down-firing passive radiator for speed and extension
• Powerful onboard amplification for controlled, dynamic bass with low distortion
• Continuously variable crossover, gain and phase for precise room and speaker integration
• Compatible with REL wireless options such as AirShip II and HT-Air MKII for a clean cable-free link
• Can be run as a single sub, a stereo pair, or stacked in a line array for larger rooms
• High-gloss reference finish and rigid cabinet construction to control resonance

How the S/850 Compares

REL S/850 vs REL S/550

The S/550 is the next model down in the S line and shares the same music-first high-level Speakon philosophy in a slightly more compact package. The S/850 steps up with greater driver and amplifier capability, delivering more low-frequency scale and dynamic headroom. Choose the S/550 for medium rooms and the S/850 when you want more effortless output in larger spaces or with bigger main speakers. See the REL S/550.

REL S/850 vs REL Carbon Special Black Label

The Carbon Special is a reference flagship built for the highest resolution and output, aimed at the most demanding rooms and systems. The S/850 offers much of the S line's speed and musical blending at a more attainable position in the range. Move to the Carbon Special when you need reference-level command; the S/850 is ideal for high performance music systems that value integration and control. See the REL Carbon Special Black Label.

REL S/850 vs REL Classic 99

The Classic 99 is part of REL's vintage-inspired line, pairing a 12 inch driver with retro styling and a warm musical presentation. The S/850 takes a more modern high performance approach with a passive radiator and greater dynamic headroom. Pick the Classic 99 for its aesthetic and character; choose the S/850 for tighter, more extended output in a resolving contemporary system. See the REL Classic 99.

Recommended System Pairings

A subwoofer adds to an existing system, so pair the S/850 with capable main speakers, an amplifier to drive them, and REL's own wireless and cabling for the cleanest connection.

• Spendor A4.2 Floorstanders These refined three-driver floorstanders offer a natural, coherent midrange that the S/850 extends below, adding weight and room-filling scale without disturbing their voicing.
• Klipsch Forte IV Dynamic and lively Heritage floorstanders that benefit from the S/850's deep, controlled foundation, especially in larger rooms where extra low-end headroom pays off.
• Advance Paris A12 APEX A capable integrated amplifier to drive your mains, with speaker terminals ready for REL's high-level Speakon connection so the S/850 follows the amp's character.
• REL AirShip II Wireless REL's high performance wireless system gives you a clean, cable-free link to the S/850 when running the cable across the room is impractical.
• REL Bassline Blue High Level Cable An upgraded high-level Speakon cable that refines the connection between your amplifier and the S/850 for the tightest, most articulate blend.

Frequently Asked Questions

What is the REL S/850?
It is a high performance active powered subwoofer from REL's S line, built to augment a music and home theater system with deep, fast, well-integrated bass.

What makes REL's high-level connection special?
REL's high-level Speakon cable takes signal from your main amplifier's speaker terminals, so the subwoofer follows the exact character and timing of that amplifier and blends for music first.

Does the S/850 work for home theater?
Yes. It has a separate .1/LFE input for home theater alongside its high-level connection for music, so a single sub can handle both roles.

What size driver does the S/850 use?
It uses a 12 inch forward-firing active driver supported by a 12 inch down-firing passive radiator.

Can I run two S/850 subwoofers?
Yes. REL subs are frequently run as a stereo pair or stacked in a line array to increase dynamic headroom and improve room coverage.

Can the S/850 be used wirelessly?
Yes. It is compatible with REL wireless systems such as AirShip II and HT-Air MKII for a clean, cable-free connection, sold separately.

What controls does the S/850 offer?
It has a continuously variable crossover, gain and phase, plus a level control for precise integration with your speakers and room.

How is the S/850 different from the S/550?
The S/850 sits above the S/550 in the same line, offering greater driver and amplifier capability for more scale and headroom in larger rooms.

Do I connect the S/850 to my amplifier or my speakers?
For music, you use the high-level Speakon connection from your amplifier's speaker terminals, which is REL's signature approach for musical blending.

Will the S/850 muddy my midrange?
No. Because it follows your main amplifier's character and offers precise crossover and phase control, it fills in below your speakers without disturbing midrange purity.

What finishes are available?
The S/850 is typically offered in high-gloss black and high-gloss white.

What amplifier power does the S/850 use?
It uses a powerful onboard 850 watt RMS Linear Class D amplifier designed for controlled, dynamic output with low distortion.

How many subwoofers do I need?
Most rooms are well served by a single S/850, but a stereo pair improves left-right bass coherence and adds headroom in larger spaces.

What speakers pair well with the S/850?
It complements resolving main speakers such as the Spendor A4.2 or Klipsch Forte IV, extending their low end without altering their character.

Do I need a special cable for the high-level connection?
The S/850 includes a high-level Speakon cable, and you can upgrade to REL's Bassline Blue high-level cable for a further refined connection.

Can the S/850 be positioned in a corner?
Yes. Corner placement can reinforce low-frequency output, and the variable controls let you tune gain, crossover and phase to suit the position.

Is the S/850 suitable for large rooms?
Yes. Its output and extension suit medium and larger rooms, and stacking or pairing units provides additional headroom where needed.

Does the S/850 include a warranty?
Yes. It carries REL Acoustics' 3 year parts and labor coverage for the original owner when purchased from an authorized dealer.

How does the S/850 compare to the Classic 99?
The Classic 99 is a vintage-inspired design with warm character, while the S/850 takes a modern high performance approach with more dynamic headroom and extension.

Why buy from All Elite Audio?
All Elite Audio is an authorized REL Acoustics dealer in Maryland, offering genuine products with full factory warranty, expert setup guidance and in-stock availability.