REL S/550 subwoofer

The new REL S/550 subwoofer benefits from research and results derived from the previous generation of REL S. Numerous improvements have been made to the speakers, amplifier, and filtering. The enclosure has been completely redesigned and optimized. The REL S/550 incorporates many of the same design innovations as the S/850, the absolute reference in the S series, in a more compact format.

REL S/550: Enclosure

The REL S/550 subwoofer presents a very compact yet relatively “massive” and rigid shape. It is essentially a cube measuring 40 cm on all sides and weighs over 31 kg! Its shape has been modified to give it a more attractive design. The finish features eight layers of piano black or white lacquer.

On the front, there is a 25 cm Continuous CastAlloy™ cone speaker with a die-cast alloy chassis. At the bottom of the enclosure, there is another speaker (passive radiator) measuring 305 mm with a flat carbon-carbon cone and a 30 cm steel chassis.

The S/550 comes with a speaker grille covered in jersey. REL offers this subwoofer in two high-gloss finishes: black or white.

REL S/550: Settings and Connections

At the back of the REL S/550 enclosure, there is a connection and control panel. It features a high-level input in Speakon format and an XLR LFE input. Additionally, there is a low-level stereo input in RCA. These inputs are paired with outputs to chain multiple subwoofers.

The adjustments are standard for this type of product: a Hi/Low level, LFE level, a filtering adjustment (20/120 Hz), and a phase adjustment (0/180°).

REL S/550: Technology

This new version allows an increase of over 10% in power (the previous version was 500 watts). The amplification chosen by REL is Pure Class D, surpassing its predecessor by delivering a continuous power of 600 watts effortlessly for extended periods. Its peak power is 50% higher than the previous model.

High-end polypropylene capacitors, similar to those used in reference models, have been integrated into the input filters.

The REL S/550 is equipped with two PerfectFilter™ second-generation filters optimized for the speaker. All REL input filters are 100% analog, among the fastest ever offered in a subwoofer.

The new S/550 25 cm high-amplitude speaker has been completely rethought, retaining only the cast chassis. The CarbonAlloy™ membrane is layered with pure carbon fiber. The redesigned suspension allows for greater excursion, handling the amplifier’s power more easily.

It is not paired with a closed or bass reflex load, as is often the case. The main speaker is supported by a passive radiator, specifically designed to handle the extreme excursions generated by the amplifier and the S/550’s main speaker. Its flat surface, made of a primary piston, is an evolution of carbon/fiberglass and foam construction. It is 40% stiffer yet significantly lighter than the previous model, allowing an incredible travel of over 60 mm in each direction.

This technology has enabled deep and powerful bass in the extreme low range between 19 and 35 Hz.

Finally, the S/550 subwoofer can be stacked in line arrays of four or six units to complement exceptional systems.

REL S/550: Testing and Listening

The REL S/550 delivers fast and deep bass that has established the reputation of the S series. Adding this subwoofer immediately results in a more open soundstage and greater transparency in the lower spectrum. The bass produced is absolutely remarkable for a subwoofer of this size. The reproduction of bass is very flexible and smooth, with no distortion or compression.

The S/550 offers ultra-fast transients, articulated bass, and remarkable tonal balance.

After spending a few days (or hours?!) with it, it's hard to imagine disconnecting it. Its ability to combine power and finesse makes it an ideal choice for those seeking a true high-end experience in medium-sized systems.

The S/550 is the entry-level model of the S series, but it is a genuinely high-end subwoofer! The new REL S/550 offers dynamics, power, and depth that far exceed our expectations in this price range.

Of course, it is possible to use just one S/550, or two, four, or even six (three on each side)!

Highly recommended!