REL Acoustics No.35 and No.36 Reference Subwoofers Would Like a Word With Your Foundation

Reference-quality bass is not cheap. SVS might have something to say about that, but REL Acoustics has spent decades building some of the best subwoofers in the business, so it has more than earned the right to take another shot at the title.

And before anyone starts clutching their wallet, the new Reference No.35 and No.36 are not even close to being the most expensive subwoofers you can buy. There are models on the market that cost four or five times as much. Whether anyone actually needs to spend that kind of money to rearrange the furniture from the listening chair is another question.

REL last refreshed the top end of its Reference lineup in 2022 with the No.31 12-inch and No.32 15-inch subwoofers, both of which established themselves firmly in the ultra-high-end category. Four years later, REL is replacing them with the Reference No.35 and No.36, its next-generation flagship subwoofers.

The names may have changed only slightly, but these are not minor updates. REL is positioning the No.35 and No.36 as full-blown statement products designed for systems where bass extension, scale, speed, and integration are expected to be every bit as serious as the loudspeakers sitting in front of them.

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• REL Serie S 2025 Subwoofers Bring State-of-the-Art Bass Honoring 35 Years of Subwoofer Innovation

17 Pounds of Transformer Says REL Is Serious About Bass

At the heart of the new Reference No.35 and No.36 is REL’s new Class AB/D amplifier architecture, which combines the current delivery of a traditional Class A/B power supply with the speed and efficiency of Class D.

The No.35 delivers 900 watts RMS, while the No.36 increases output to 1,000 watts RMS. Both amplifiers are built around a massive 17-pound toroidal transformer, which should tell you rather quickly that REL was not aiming for lightweight engineering here.

“The new amplifiers were the starting point,” says John Hunter, REL President and Lead Designer. “Once we heard what they were capable of, it became clear the drivers had to evolve with them.”

Bigger Excursion and a Serious Carbon Fibre Upgrade

The No.36 applies REL’s new 12K Pure Carbon Fibre technology to its 15-inch (380mm) Reference driver, along with a revised suspension designed to allow greater cone movement.

The No.35 uses a 12-inch (300mm) driver with a new cast-aluminium frame and redesigned suspension, giving it an additional 12mm of travel in each direction compared with the No.31. REL has also adopted a finer 12K carbon fibre weave, intended to produce a quieter and more controlled cone.

The payoff is significant: REL says the No.35 can now play louder than the outgoing No.32, despite the latter being the previous 15-inch Reference flagship.

Statement Bass Deserves More Than a Black Box

The engineering inside the new No.35 and No.36 Reference models is only part of the story. REL has paid just as much attention to the cabinets housing all of that hardware.

Inspired by classic wooden runabouts, the enclosures reflect the influence of Franco Serblin, John Hunter’s mentor, and require 12 coats of hand-rubbed lacquer to achieve their final finish. Extensive internal bracing is designed to keep the cabinets inert, allowing the improvements in driver and amplifier control to come through without the enclosure adding its own unwanted contribution.

One REL Is Apparently Never Enough

The No.36 retains the same dimensions as REL’s previous 15-inch Reference models, while the No.35 matches the No.31 exactly. That means existing owners can integrate either model into a Reference Line Array alongside earlier-generation Reference subwoofers.

For more than two decades, Line Arrays have represented REL’s ultimate expression of deep bass. The concept involves vertically stacking and distributing multiple subwoofers within the room, which REL says allows the main loudspeakers to operate with greater scale, clarity, and freedom from low-frequency demands.

Up to three subwoofers can be stacked using REL Couplers (Line Array Connectors), which secure the lower and upper cabinets together. The solid, milled-aluminum couplers bolt directly to each subwoofer and work with the substantial rails underneath the cabinets to create an extremely heavy and rigid bass tower.

As with the outgoing No.31 and No.32, the new models provide the necessary wired connectivity and can also be configured for wireless operation. System settings can be controlled using REL’s Reference wireless remote control.

Comparison

The Bottom Line 

The No.31 and No.32 were already formidable subwoofers, which makes the No.35 and No.36 interesting for a different reason. REL did not simply install larger amplifiers, fiddle with the DSP, and declare victory. The new models combine revised carbon-fibre drivers, substantially reworked Class AB/D amplification, increased excursion, extensive cabinet construction, and compatibility with REL’s existing Reference Line Array ecosystem.

That last point might be the most unusual part of the entire upgrade. The No.35 and No.36 retain the dimensions of their predecessors, allowing existing Reference owners to integrate the new models with earlier REL subwoofers in a Line Array rather than starting over. At this level, where someone could conceivably have three very expensive subwoofers stacked on top of one another, backward compatibility suddenly becomes a rather meaningful feature.

At $10,000 for the No.35 and $12,000 for the No.36, none of this comes cheaply. There are also some extremely capable alternatives for considerably less money. The SVS 17-Ultra R|Evolution models deliver enormous output from 17-inch drivers for less than $3,000, while the PS Audio Foundry F12 offers a 12-inch driver, 1,000-watt amplifier, DSP, wireless capability, and even stackability for $2,749. MartinLogan and DALI also offer serious alternatives for high-end music and home theater systems.

What REL is selling for the additional money is not simply more bass. The Reference models are built around REL’s particular approach to integration, high-current amplification, high-level connectivity, elaborate cabinetry, and the ability to create a vertically stacked Reference system that can grow with an existing installation. There are cheaper ways to reach subterranean frequencies and shake the drywall. Quite a few of them, actually.

The No.35 and No.36 are aimed at listeners who want REL’s interpretation of statement-level bass and have a system capable of exposing the differences. Whether that refinement is worth $10,000 or $12,000 will require a serious audition, but at least REL is offering something more distinctive than another gigantic driver attached to an even more gigantic Class D amplifier.

And if a single No.36 somehow fails to satisfy you, REL will happily let you stack three of them. At that point, the limiting factor may no longer be bass response. It may be your homeowner’s insurance.

Price & Availability

All REL Subwoofers and related accessories are available through Authorized Dealers, including optional AirShip Direct for an extra $399.

• REL Reference No.36 (15-inch) – $12,000
• REL Reference No.35 (12-inch) – $10,000

Related Reading:

• REL Serie S 2025 Subwoofers Bring State-Of-The-Art Bass Honoring 35 Years Of Subwoofer Innovation
• REL’s Classic 99 Subwoofer Offers a Vintage Look With High-End Performance
• REL Planar On-Wall Subwoofers Could Change Where Bass Lives In Your Room