KJ West One - Connoisseurs of Sound - Est. 1965
KJ West One - Connoisseurs of Sound - Est. 1965

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No.25 Reference

REL Acoustics

No. 25 commemorates and celebrates REL's quarter century of building the finest sub bass systems, while pointing to the future and their next 25 years as it employs their most advanced design, engineering and craftsmanship.

No. 25 combines the power of an ultra-reliable 1,000 watt amplifier, with a lightweight and perfectly balanced carbon fibre 15” driver. All this is controlled byREL's legendary filter sets and proprietary crossovers with 2 separate parametric equalizers permitting remarkably flat in-room response, while maintaining the speed and resolution for which modern RELs have become known.

REL want their customers to enjoy all this performance without being limited to only a few room locations, so they built-in LongBow™ wireless receivers into every No. 25. This design utilizes zero compression, resulting in stunning dynamics and bass extension without being tethered to a cable, while delivering sound quality comparable to competitor’s hardwired designs. It’s just another example of how REL strive to offer complete and thoughtful solutions.

No. 25 marks a new standard in cabinet execution, both for its physical beauty and the manner in which it manages the critical backwave propagating from the rear surface of the massive 15″ carbon fibre piston at its heart. The shape of No. 25 is designed to disturb and cancel much of the incredible force created by the inward stroke as No. 25 reloads for your music or film’s next set of demands. It is necessary to keep this backwave as silent as possible, while allowing the driver to “breathe” without compressing dynamics. The curvilinear cabinet walls deflect, diffuse and dissipate these waves into smaller cross plane waves. Minimising rear waves that eventually emerge as comb filtering — noise that cancels the primary bass — is what creates clear, purposeful bass that strides into a room with tremendous energy and clarity.

Comprised of 30mm thick (about 1 1/8″) Australian MDF, transected by hardwood spars that break up common mode resonances within the top surface of the cabinet and down its sidewalls, the bracing is not unlike the spars in a ship’s hull. Some may view this as excessive, but these are the lengths REL's design team goes to to deliver the finest subwoofer extant, fully fitting of the title No. 25.

When we experience bass in real time out in the world, it occurs with height to it. It strikes our sinuses, it kicks at our chest cavities, it rumbles along the floor conveying power authority and majesty. The Reference Line Arrays permits bass to emerge more naturally, adding a height component in how it propagates throughout the room. The bottom unit reinforces the deepest overtones, creeping and rumbling across the floor to produce room shake. The middle location provides crisp attack and articulation of kick drums or any transient-based event. The unit imparts the flutter and shimmer of all manner of instruments floating in air. Making Reference Line Arrays the Holy Grail of the REL experience and is only available with the Reference products.

Since 90 percent of the energy produced by a system resides in the bass regions, Reference Line Arrays are the magic element missing from so many otherwise state of the art systems. This air, transparency and, of course, effortless power that Reference Line Arrays convey can’t be imagined, it can only be experienced in person.

It takes huge power to invest the No. 25 with the shattering dynamics of which it is capable. The rugged beast of a 1,000 watt NextGen3 amplifier that powers No. 25 has already proven itself in the field in one of REL's previous designs, making them comfortable with not only its startling sonic performance but also its reliability.

However, No. 25 is no mere exercise in excess, but rather a thorough exposition in the art of rendering sub bass, totally, completely and with great deftness in tonality, expression and dynamics. It is this ability to not merely play loud, but to bring to life the contrast between loud and soft passages that makes REL owners so passionate about their designs. After all, dynamics are not merely the ability to play loud, but to bring to life the contrast between loud and soft passages in music or film. Ultimately, this is what makes the No. 25 the addiction it quickly becomes.

No. 25 has a heart of pure carbon, as we opted for a cone material that is stronger than steel, yet incredibly light. Carefully woven from pure carbon fibre, No. 25’s 15” cone structure weighs 70% less than a 10” cone of just two years ago. This combination of incredibly light weight coupled to remarkable structural integrity is what gives No. 25 its combination of speed and power.

Yet another benefit of the weight reduction strategy REL employs is that it permits near-perfect dynamic balancing of the driver, yielding ideal behavior throughout its incredible 4” of fore-and-aft stroke.

RRP - £6,500

REL Acoustics range

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