The REL S/550 is the entry point to REL Acoustics' Serie S line, a range engineered to bridge the gap between their versatile Serie T/x models and the flagship Reference Series. Designed for medium-sized rooms of 250 to 500 square feet, the S/550 brings the hallmarks of the Serie S to a compact, elegantly finished cabinet: speed, depth, and musicality in equal measure. It is equally at home anchoring a high-resolution two-channel music system as it is delivering cinematic impact in a dedicated home theatre.
CarbonAlloy Driver System
At the heart of the S/550 is a 10-inch (250mm) long-throw active driver built on a CarbonAlloy cone structure, a composite of pure carbon fibre chosen for its exceptional stiffness-to-weight ratio. Mounted in a die-cast alloy chassis, this driver delivers fast, highly controlled bass transients. Working in concert is a 12-inch (305mm) down-firing passive radiator with a Carbon/Carbon flat cone structure and a steel chassis, which extends low-frequency reach while keeping the cabinet dimensions compact.
Linear Class D Amplification
Power is provided by a 550-watt (RMS) Linear Class D amplifier, fed by REL's second-generation PerfectFilter analogue filtering system. The Linear Class D topology is chosen for its combination of high output, low distortion, and compact form factor. Low frequency extension reaches -6dB at 19Hz, making the S/550 capable of resolving the deepest musical and cinematic content.
Connectivity and Integration
The S/550 provides REL's full suite of connection options. High Level input via a Neutrik Speakon connector (with a 10-metre cable supplied) allows the subwoofer to receive the same amplified signal as the main speakers, preserving the character and timing of the partnering amplifier. Low Level inputs include two RCA sockets for stereo operation and a dedicated .1/LFE RCA input for home theatre processors. An XLR LFE input is provided for balanced connections. Outputs mirror the inputs: High Level Speakon for daisy-chaining, Low Level RCA, and LFE RCA or XLR. High Level and .1/LFE inputs may be used simultaneously, making the S/550 a natural fit for combined music and home theatre systems. Wireless operation is supported via the optional REL AirShip Direct system, which transmits both High Level and .1/LFE signals simultaneously.
Line Array Capability
The S/550 is one of the few subwoofers at this price point capable of operating in a line array configuration, a feature inherited from REL's Reference Series. Integrated aluminium adjustment knobs allow up to three units to be stacked per channel, dramatically increasing output, bass evenness, and room-filling capability for larger spaces or more demanding listening requirements.
Cabinet and Finish
The cabinet is finished in Piano Black Lacquer, applied to a high-gloss standard. A cloth grille is included; an optional Premium Wood grille is available separately. The S/550's compact footprint (445mm wide by 372mm tall by 500mm deep) belies its output capability, making it a practical choice where space is at a premium without compromising on performance.
