REL S/850 Subwoofer

The new REL S/850 subwoofer benefits from research and results based on the previous REL S generation.
Thanks to this, numerous improvements have been made to the drivers, amplifier, and filtering. The cabinet has been completely redesigned and optimized.

REL S/850: Cabinet

The REL S/850 subwoofer features a very compact yet relatively "massive" and rigid form. Its design takes inspiration from the REL Reference range. It is essentially a 50 cm by 50 cm cube, weighing over 42 kg! Its shape has been modified to give it a more attractive visual. The finish includes 8 layers of piano lacquer, black or white.
On the front, there is a 305 mm driver with a Continuous CastAlloy™ cone and a die-cast alloy frame. Underneath the cabinet and towards the floor, there is another driver (passive radiator), also 305 mm, with a flat carbon/carbon cone and a steel frame of 30 cm diameter.
The S/850 is supplied with a speaker grille covered in jersey. REL offers this subwoofer in two piano lacquer finishes: white or black.

REL S/850: Controls and Connections

On the rear panel of the REL S/850 cabinet, there is a connection and control panel. Inputs include a high-level Speakon connection, an LFE input via XLR, and stereo low-level RCA inputs.
These inputs are doubled by outputs to allow chaining multiple subwoofers. The controls are typical for this product category: Hi/Low level, LFE level, crossover adjustment (20/120 Hz), and phase adjustment (0/180°).

REL S/850: Technology

This new version allows an increase of more than 8% in power (the previous version was 800 watts). The amplification chosen by REL is a Pure Class D that surpasses its predecessor, delivering a continuous power of 900 watts effortlessly for long periods. Its peak power is 50% higher than the previous model.
Premium polypropylene capacitors, similar to those used in reference models, have been integrated into the input filters.
The REL S/850 is equipped with two second-generation PerfectFilter™ filters optimized for the driver. All REL input filters are 100% analog, among the fastest ever offered on a subwoofer.
The new 305 mm high-excursion S/850 driver has been completely redesigned, only the cast frame was retained. The CarbonAlloy™ diaphragm is coated with pure carbon fiber. The redesigned suspension offers greater excursion, more easily handling the amplifier's power. It is not loaded in a sealed or bass reflex configuration as is often the case. The main driver is supported by a passive radiator. It has been specially designed to handle the extreme excursions generated by the amplifier and the main S/850 driver. Its flat surface, made from a primary piston, is an evolution of the carbon/fiberglass and foam construction. It is 40% stiffer yet significantly lighter than the previous model, allowing an incredible excursion of more than 80 mm in each direction.
This technology has enabled deep and powerful bass reproduction in the extreme low range between 19 and 40 Hz.
Finally, the S/850 subwoofer offers the possibility to be used in pairs or stacked in line arrays of 4 or 6 units to complement exceptional systems.

REL S/850: Tests and Listening

The REL S/850 is reminiscent of its predecessor the S/812, but from the very first measurements, it clearly marks a real and noticeable difference.
The dynamics are thunderous and the transients ultra-fast. It quickly blends into the room showing no directivity or coloration.
The breadth and presence it gives to bass and music are remarkable. The most surprising aspect is the texture and harmonic richness it adds to the midrange. Voices seem more realistic and organic, while showing less harshness and aggression. The musical reproduction is tied to tonal balance, and in this context, the REL S/850 is a blessing!
Whatever style of music is played, the bass is remarkably fluid and natural. The reproduction shows no compression or distortion.
After a few days (or hours!?) with the REL S/850, it seems impossible to do without or forget it. Its ability to combine power and finesse makes it a remarkable choice for those seeking a true very high-end experience in mid-sized systems.

For us, the S/850 is undoubtedly a reference in this range.

Highly recommended +++!