REL Acoustics has long been a powerhouse in the subwoofer world, and the newly reimagined Serie S line proves just how far they’ve come since early legacy models like the Strata III, introduced in 1998. Once considered among the best subwoofers of their time, those designs have been surpassed over the years by successive Serie S generations—2014, 2016, and 2019—earning REL a reputation for creating some of the finest subwoofers for two-channel music systems.
The 2025 Serie S lineup features four models: the S/550, S/850, Carbon Special Black Label, and 212 Black Label, each engineered for faster, deeper, and more articulate bass. As REL lead designer John Hunter explains: “Serie S is our boldest statement yet. We took everything we’ve learned over three decades and re-engineered the line from the ground up—including drivers, amplifiers, cabinetry, and even wireless connectivity.”
The Serie S Sessions: Exploring REL’s 2025 Subwoofers
To mark its 35th anniversary and the launch of the Serie S, REL hosted a two-day experience in Berkeley, California—the hub of REL’s North America operations and home to its design and development team. The event gathered a select group of journalists, creators, and hi-fi enthusiasts for exclusive first listens of the new models, intimate music experiences across the Bay Area, and a behind-the-scenes recording session. (Our invitation must have gotten lost in the mail.)
As REL lead designer John Hunter explains: “REL has always been about connecting people to the emotional truth of music and film. Serie S Sessions gave guests a chance to feel that for themselves and to see how REL’s craft translates into real-world experiences.”
Sound and Space: How REL Serie S 2025 Subwoofers Transform Music and Room Dynamics
The Serie S subwoofers are engineered not just to amplify sound—they turn it into an immersive experience. With their refined, architectural design, REL says the Serie S can seamlessly integrate into any space.
Here’s a brief overview of how each Serie S model fits into REL’s implementation strategy:
S/550 ($3,200): The “entry-level” model in the Serie S line, the S/550 is a reinvention of REL’s previous S/510. It delivers greater scale and richer dynamics, powered by a 550-watt Pure Class D amplifier, a 10-inch driver, and a 12-inch passive radiator. Its compact footprint makes it ideal for both music and home theater systems.
S/850 ($3,999): Positioned in the “sweet spot” of the Serie S lineup, the S/850 is slightly larger than the S/550 and features an 850-watt amplifier, a 12-inch driver, and a 12-inch passive radiator. Engineered for detail, speed, and impact, it excels in music, home theater, and even gaming applications.
Carbon Special Black Label ($4,999): This model features a 12-inch pure carbon-fiber driver and 12-inch passive radiator, delivering ultra-fast, transparent bass powered by a 900-watt amplifier. It also includes a premium wood grille, standard on this model, whereas it is optional on the other Serie S models.
212 Black Label ($5,999): The flagship of the Serie S line, the 212 Black Label features 12-inch twin active drivers and 12-inch twin passive radiators, all powered by a 1,000-watt amplifier. Designed for large rooms, it delivers commanding bass that excels in home theater and music applications alike.
All four Serie S models feature faster, lighter drivers with carbon-fiber refinements, redesigned passive radiators, and amplifiers with expanded headroom and control. They are compatible with REL’s Airship Direct high-resolution wireless system, which has an excellent track record and makes it easier for integrators to add these subwoofers to home theater setups without long and costly runs of cabling. Cabinet designs are wider and lower on select models for improved presence and are available with classic cloth or optional handcrafted wood grilles, combining architectural beauty with high-performance sound.
Line Array: REL Serie S 2025 Subs for Controlled, Immersive Low-End Performance
One intriguing way to set up the Serie S subwoofers (except the 212 Black Label) is in a Line Array configuration. Up to three subs can be stacked using REL Couplers (Line Array Connectors included with each compatible Serie S subwoofer), which link lower units to upper units. The couplers are solid, milled aluminum and, combined with the substantial rails on the underside of each cabinet, form an extremely heavy, sturdy bass tower.
When set up correctly—with dealer assistance, which should be a given at this price—the benefit isn’t just more low-end output: the system delivers better-balanced bass with fewer room issues. For those willing to invest in the experience, this setup will shake more than just the room—neighbors beware.
REL Serie S Subwoofers Comparison
| Rel Serie S Model | S/550 | S/850 | Carbon Special Black Label | 212 Black Label |
| Price | $3,299 | $3,999 | $4,999 | $5,999 |
| Product Type | Subwoofer | Subwoofer | Subwoofer | Subwoofer |
| Driver Configuration | 1 x Front-firing active driver 1 x down-firing passive radiator | 1 x Front-firing active driver 1 x down-firing passive radiator | 1 x Front-firing active driver 1 x down-firing passive radiator | 2 x Front-firing active drivers 1 x rear passive radiator 1 x down-firing passive radiator |
| Driver | 1 x 10 in. (250mm) long-throw, CarbonAlloy™ cone structure, die cast alloy chassis | 1 x 12 in. (305mm) long-throw, CarbonAlloy™ cone structure, die cast alloy chassis | 1 x 12 in. (305mm) long-throw, carbon fibre cone with inverted carbon fibre centre cap, die cast alloy chassis | 2 x 12 in. (305mm) long-throw, CarbonAlloy™ cone structure, die cast alloy chassis |
| Passive Radiator Size and Material | 1 x 12 in. (305mm), Carbon/Carbon flat cone structure, steel chassis | 1 x 12 in. (305mm), Carbon/Carbon flat cone structure, steel chassis | 1 x 12 in. (305mm) long-throw, carbon fibre cone with inverted carbon fibre centre cap, die cast alloy chassis | Rear: 1 x 12 in. (305mm)CarbonAlloy™ cone structure, die cast alloy chassis Down: 1 x 12 in. (305mm) CarbonAlloy™ cone structure, die cast alloy chassis |
| Low Frequency Extension | -6 dB at 19Hz | -6 dB at 19Hz | -6 dB at 19Hz | -6dB at 18 Hz |
| Inputs | High Level: 1 x Neutrik Speakon Low Level 2 x RCA 1 x LFE RCA 1 x LFE XLR | High Level: 1 x Neutrik Speakon Low Level 2 x RCA 1 x LFE RCA 1 x LFE XLR | High Level: 1 x Neutrik Speakon Low Level 2 x RCA 1 x LFE RCA 1 x LFE XLR | High Level: 1 x Neutrik Speakon Low Level 2 x RCA 1 x LFE RCA 1 x LFE XLR |
| Outputs | High Level: 1 x Neutrik Speakon Low Level: 1 x RCA 1 x LFE RCA 1 x LFE XLR | High Level: 1 x Neutrik Speakon Low Level: 1 x RCA 1 x LFE RCA 1 x LFE XLR | High Level: :1 x Neutrik Speakon Low Level: 1 x RCA 1 x LFE RCA 1 x LFE XLR | High Leve:l :1 x Neutrik Speakon Low Level: 1 x RCA 1 x LFE RCA 1 x LFE XLR |
| Amplifier Type | Linear Class D | Linear Class D | Linear Class D | Linear Class D |
| Power Output | 550 watts (RMS) | 850 watts (RMS) | 900 watts (RMS) | 1,000 watts (RMS) |
| Wireless Copability | REL AirShip Direct (sold separately) | REL AirShip Direct (sold separately) | REL AirShip Direct (sold separately) | REL AirShip Direct (sold separately) |
| Protection System | Fully Electronic Set Safe D.C. Fault Output Short | Fully Electronic Set Safe D.C. Fault Output Short | Fully Electronic Set Safe D.C. Fault Output Short | Fully Electronic Set Safe D.C. Fault Output Short |
| Mains Input Voltage | 220-240 volts, 110-120 volts for certain markets | 220-240 volts, 110-120 volts for certain markets | 220-240 volts, 110-120 volts for certain markets | 220-240 volts, 110-120 volts for certain markets |
| Fuses | 8 Amp semi delay 220 volts operation 15 Amp semi delay 120 volts operation | 8 Amp semi delay 220 volts operation 15 Amp semi delay 120 volts operation | 8 Amp semi delay 220 volts operation 15 Amp semi delay 120 volts operation | 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) | Mains Lead: Yes Neutrik Speakon: Yes (10 Meters Nominal) | Mains Lead: Yes Neutrik Speakon: Yes (10 Meters Nominal) | Mains Lead: Yes Neutrik Speakon: Yes (10 Meters Nominal) |
| Dimensions (WHD) | 17.5 x 14.75 x 19.75 in. 445 x 372 x 500 mm | 19.25 x 16.125 x 21.25 in 488 x 410 x 540 mm | 19.25 x 16.125 x 22.25 in. 488 x 410 x 565 mm | 14.25 x 33 x 20.5 in. 362 x 840 x 523.3 mm |
| Weight | 68 lbs. (31 kg) | 93.5 lbs. (42.5 kg) | 98 lbs. (44.5 kg) | 134 lbs. (60.8 kg) |
| Finish | Piano Black Lacquer, Gloss White Lacquer 8 coats | Piano Black Lacquer, Gloss White Lacquer 8 coats | Piano Black Lacquer 8 coats | Piano Black Lacquer 8 coats |
| What’s in the box | Serie S/550 Subwoofer Power Cord 32′ Neutrik Speakon cable Cloth Grille Line Array Mounting Hardware User Manual and Warranty Information | Serie S/850 Subwoofer 6′ AC Power Cord 32′ Neutrik Speakon cable Line Array Mounting Hardware Cloth Grille User Manual and Warranty Information | Carbon Special Black Label Subwoofer 6′ AC Power Cord 32′ Neutrik Speakon cable Line Array Mounting Hardware Premium Wood Grille User Manual & Warranty Information | 212 Black Label Subwoofer Power Cord Standard Black Cloth Grille User Manual and Warranty Information |
The Bottom Line
The REL Serie S subwoofers combine state-of-the-art design, exceptional performance, and thoughtful features like premium wood grilles and hardware for Line Array setups—but they come at a premium price. While REL remains a benchmark for high-end two-channel and home theater subwoofers, the category is fiercely competitive.
Brands such as Neumann, DALI, Velodyne, and SVS also offer models capable of delivering impressive bass performance at various price points. For buyers willing to invest, the Serie S provides unmatched refinement and flexibility, but savvy shoppers should weigh alternatives before committing.
Price & Availability
Serie S is now available through authorized REL dealers around the world and via REL Website:
- S/550: $3,299
- S/850: $3,999
- Carbon Special Black Label: $4,999
- 212 Black Label: $5,999
- Airship Direct: $399
Since its founding in 1990, REL has elevated subwoofer performance with breakthrough engineering and craftsmanship. It’s a small but passionate Berkeley team, headed up by CEO Alex Broday and Chief Designer John Hunter. The team is not only responsible for maintaining leadership in subwoofer design that continually redefines what is possible in Low-Frequency Sound, but they also handle all U.S. customer service directly, no bots, and no outsourcing.
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