REL S/812 Subwoofer Review

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Highly Recommended
REL S/812 Subwoofer Review
SRP: £2,399.99

What is the REL S/812?

The REL S/812 forms part of the pretentiously titled Serie S range of subwoofers, but never a company to do things by half, the latest additions are a total transformation of REL’s mid-sized class of subs. As a result, unlike the previously released 212/SE, the new S/812 represents a complete revision of the line-up that adds new upgrades and design features.

For a start, the cabinet has been revised, and the feet replaced with rails. The NextGen5 amplifier has also been upgraded to deliver more power, and the ultra-lightweight ContinuousCast alloy cone redesigned to handle the increase in slam. Improved filters tailor the LFE channel to deliver twice the output between 19 and 35Hz, while the high-level and low-level inputs use a new PerfectFilter. Finally, these redesigned subwoofers can also be stacked up to three units high.

The S/812 currently retails for £2,299 as at the time of writing (December 2019), but if that’s too expensive there’s also the smaller S/510 that can be picked up for £1,799. REL claims these new subwoofers represent the biggest leap in performance yet seen from the company’s mid-range models, so let’s plug the S/812 into our system and find out.


The REL S/812 has a completely redesigned cabinet that is lower, wider and deeper, using dimensions based on the company’s Reference Series. The build quality is superb, and despite essentially being a cube, the S/812 is unusually attractive for a subwoofer. This is the kind of sub you wouldn’t mind having on display, rather than hidden away in a dedicated home cinema.

REL S/812

There’s a gunmetal grey badge on the top and chrome handles at the sides, which are both attractive and practical, allowing you to move the heavy S/812 with relative ease. The 12-inch gunmetal driver proudly sports the REL logo, but if you’d rather cover it up there’s also a sizeable black fabric grille. The result is a high-end sub that oozes style and charm.

REL S/812

The more traditional chunky four feet have been replaced with ultra-stable rails that serve two purposes: first, they provide better support; and secondly, they cantilever the main cabinet forward allowing it to seemingly float in space. The S/812 offers a choice of two gorgeous finishes: gloss piano black or gloss white lacquer, both of which use a total of 12 coats. Finally, the sub measures 430 x 455 x 514mm (WxHxD) and weighs in at 34kg.

  The result is a high-end sub that oozes style and charm

Control and Connections

The REL S/812 has all of its controls located at the rear and, considering the price, it's a surprisingly minimal selection. There’s a main power switch and a connector for the three-pin power cable, along with two more switches for 'always on/standby' and '0-180˚ phase'. There are also knobs for high/low and LFE levels, and one for setting the crossover.

However that’s it, and there’s no remote control or smartphone app to make set up easier or more flexible. This does make the S/812 relatively straightforward to install, but also puts it at a disadvantage to some of the competition. I certainly prefer being able to sit at the sweet spot and control the sub, rather than having to peer down the back.

REL S/812

On a related note, the writing on the rear panel isn’t also printed upside down. This is something that REL does on its cheaper subwoofers, so I was surprised this wasn’t the case on the S/812. Another minor gripe is that it’s hard to tell where the control knobs are set; adding indentations or a raised line would certainly help when adjusting them.

The connections are better, with high-level Neutrik Speakon, low-level stereo phono, and LFE (phono and balanced XLR) inputs. There are also high-level Neutrik Speakon and LFE (phono and XLR) outputs. The Serie S subs are also compatible with the new AirShip wireless system, which REL claims is extremely stable due to its use of a bandwidth previously reserved for the military.’s hard to tell where the control knobs are set; adding indentations or a raised line would certainly help when adjusting them

Features and Specs

The REL S/812 includes a number of key improvements, starting with a 45% increase in power thanks to NextGen5 Class D amplification previously used in the company’s reference models. As a result, the power source is continuously rated at 800W but offers claimed peaks up to 1,000W. REL also employs special PureTheatre filters that were first used in the HT/1508, and these tailor the LFE channel to deliver almost twice the output between 19 and 35Hz.

Since this is a REL sub, there are high- and low-level inputs which allow the S/812 to deliver deep bass to a high-end two-channel music system, as well as a multichannel home cinema. The increase in power necessitated the development on the musical front of an all-new circuit termed PerfectFilter. This performs two functions: extending the response of the extreme low end frequencies, while simultaneously opening up the middle and high frequencies of the system.

REL S/812

The S/812 uses a forward-firing 12-inch driver with a lightweight ContinuousCast alloy cone that’s been upgraded to handle the increased power. An ultra-lightweight backing of pure carbon fibre has been strategically placed at the rear to stiffen and strengthen it, while also eliminating reversion, wherein the back wave inside the cabinet is now prevented from interfering with the projection of bass into the room. REL claims the aluminium cone and carbon fibre backing are so incredibly light that the heaviest element is actually the glue between them.

  ...the power source is continuously rated at 800W but offers claimed peaks up to 1,000W

There’s also a downward-firing 12-inch carbon “SuperProgressive” passive radiator that uses a new design to produce extremely long travel allowing for very loud output while retaining the variable stiffness of its suspension. This enables the S/812 to act like a sealed-box compact 12-inch design at low volumes, but also act like a 14-inch design at its limit, thus helping deliver deep bass down to 19Hz (-6dB).

Set-up and Operation

The REL S/812 is easy to set up and, in terms of the connections, you have a choice of using the high-level or low-level inputs, including a mono LFE channel.

The high-level input is an unbalanced dual channel (stereo) input that uses a professional 'touch-proof' Neutrik Speakon connector (REL includes a 10m cable). You need to attach this to the sub and turn it until it locks, and then use the three wires at the other end to connect to the main left and right terminals on your amplifier: red wire to the red right terminal and yellow wire to the red left terminal, with a black wire that can be connected to either black terminal.

In effect, you are bi-wiring the sub to your power amplifier, and the use of three cables is designed to preserve the earthing. The advantage of this approach is that the sub receives exactly the same signal that is being sent to the front left and right speakers. This means the character and tonal balance of the bass from the main speakers are reflected in the bass from the subwoofer, resulting in a more integrated approach for music that results in faster bass.

REL S/812

If you're installing the S/812 in a home cinema setup then you're more likely to use the low-level input. You can either use stereo RCA connectors to connect the left and right output on your amplifier to the left and right input on the sub or, if your receiver or processor has a dedicated .1/LFE/Sub output, you can use the balanced XLR or RCA mono inputs. The latter is the most likely connection for the majority of home cinema setups.

  In the real world, bass has width, depth and height, so by stacking these subs, you create a bigger bass presence from a smaller footprint

Then all you need to do is set the phase, crossover and level controls correctly (depending on the kind of system you are running and how it's set up). The only other setting is the switch for ‘always on/standby’, which you can set depending on your preference. If you choose the latter, the S/812 will automatically turn off after 30 minutes without a signal and will switch back on once a signal is received on an input.

There's often some experimentation when it comes to positioning a sub but the better you know your room, the easier it is to avoid any major issues. I placed the review sample at the front of my room, between the centre and left speakers in a spot that I knew was reasonably balanced – with the side handles and rails on the bottom of the S/812 making this process easier. I tested the REL using the high-level and mono LFE connections at different times.

REL S/812

The S/812 is the first mid-sized REL subwoofer designed to be stackable, thanks to special fixtures and included metal plates. You can safely stack and lock multiple S/812s up to three units high, and run a total of six in two stacks. If that sounds crazy, REL claims there is logic in its madness. In the real world, bass has width, depth and height, so by stacking these subs, you create a bigger bass presence from a smaller footprint.

  ...the character and tonal balance of the bass from the main speakers are reflected in the bass from the subwoofer

I only had one sample to review, so I couldn’t put this theory to the test. However, even if REL did send me multiple samples, I'd find it difficult to accommodate two line arrays at the front of my home cinema. This approach is definitely for hardcore bass fans, and the cost and space required for two stacks of three subs will put most people off. It’s also better suited to stereo, for home cinema you’ll get more balanced bass by putting a sub in each corner of the room.


The REL S/812 is a genuinely impressive subwoofer that manages to combine low-end extension with powerful amplification to produce a performance that’s responsive, controlled and highly effective. This sub goes deep and, even on its own, had absolutely no trouble filling my home cinema with low frequency energy. However, this is no blunt instrument, and the S/812 is capable of astonishing deep bass that’s delivered with a surprising amount of subtlety and grace.

I decided to start with the massive bass notes that hit over the opening credits of Edge of Tomorrow. These particular low-end effects are famous for extending well below 20Hz, and are capable of reducing less capable subs to quivering wrecks. Not so the S/812, which took these particular infrasonic tests in its stride. It mined the depths with remarkable control and precision, delivering the desired effect of unnerving me before the film had even started.

The majority of films use low frequency effects to give certain scenes greater impact, but there are some films that use bass as a narrative tool. Aquaman is a good example, with a soundtrack that’s as bold and hard-hitting as the title character. In the scene where Aquaman takes out the submarine pirates, every punch feels like a sledgehammer, and when he throws that hatch, you’ll be diving for cover.

  ...this is no blunt instrument, and the S/812 is capable of astonishing deep bass that’s delivered with a surprising amount of subtlety and grace

The S/812 delivers all these low frequency effects with perfectly timed precision, giving the fight scenes greater impact. It’s a controlled performance, and remarkably nimble for subwoofer of this size. This agility extends to even deeper effects, such as the descent into the Trench, or the leviathan that guards the trident. Here the use of bass provides this underwater monster with added low-end slam that gives it greater weight and size. Speaking of size, that brings us on to the next test.

REL S/812

If you’ll pardon the pun, Godzilla: King of the Monsters is another film with a monstrous amount of bass in its soundtrack. The film opens with Godzilla's massive roar, and the low frequency effects that accompany every footstep will literally shake the room. The S/812 digs deep, producing an infrasonic assault of epic proportions as the titular hero squares up against successive titans. Each encounter pummels you into submission with staggering amounts of bass, as buildings crumble and volcanoes erupt. At one point a nuclear device is detonated, sending a low frequency seismic shockwave through the room.

The S/812 is a very responsive subwoofer, delivering the kind of fast and precise bass that not only suits music, but also picks out key low frequency effects in complex movie soundtracks. The parachute drop at the beginning of Overlord is just such a mix, with a lot of different effects competing for your attention. There's the exploding flak that hits all around you with incredible precision, and you can clearly pick out individual effects despite the constant low frequency drone of the Dakota’s engines.

Ultimately, the plane carrying our heroes explodes in a fireball of destruction, and as the flames move up the fuselage, so the bass heads towards you in waves. The low frequencies seem to move through the room, and when the main protagonist tumbles through the air, ordinance explodes all around with a percussive thump you can feel. It’s an engagingly immersive sequence that is perfectly enhanced by the S/812's ability to deliver deep and controlled bass.

  It’s a controlled performance, and remarkably nimble for subwoofer of this size

This sense of commanding low frequency delivery, combined with responsive poise really came to the fore during the tank battle in Fury. This fantastic sequence involves three Shermans and a Tiger, with the S/812 ensuring the bass is delivered with a precision that is both visceral and exciting. The sub's detailed delivery ensures each tank has a distinctive and incredibly deep low-end rumble and yet, within the cacophony of battle, the REL clearly delineates the powerful impact of high explosive shells smashing into plate armour. It's a beautiful mix that makes full use of a modern system's low frequency extension, and the S/812 rises to the occasion with bass that is as composed as it is brutal.



  • Deep bass extension
  • Powerful amplification
  • Superior build quality
  • High level connections
  • Stackable option
  • Gorgeous design


  • No remote control
  • It's pricey

REL S/812 Subwoofer Review

The REL S/812 is an impressive subwoofer that effortlessly combines style, build quality and performance into a mid-range model that can hold its own against any of the competition. The combination of the 12-inch driver and matching 12-inch passive radiator ensures some serious low-end extension, and the amplification has power to spare. The S/812 delivers deep and controlled bass that’s handled with speed and agility, seamlessly blending with the other speakers in your system to create a fully integrated soundstage. The lack of a remote control is disappointing, and it’s fairly expensive, but the S/812 is a consummate infrasonic performer.

What are my alternatives?

SVS SB-3000

The excellent SVS SB-3000 is an obvious alternative and can be picked up for nearly a grand less – depending on which finish you choose. This sealed unit has a 13-inch driver combined with 800W of Sledge amplification, resulting in subwoofer that delivers a massive amount of bass from a relatively small footprint. Whether you are watching TV or movies, playing games or listening to music, the SB-3000 has you covered with the kind of responsive bass that is both controlled and precise. The S/812 can go a smidge lower, and the SVS doesn’t have the connectivity of the REL, but it has everything you need for a home cinema, and there’s even an excellent smartphone app.

BK Electronics P12-300SB-PR

It’s a testament to how good the BK Electronics P12-300SB-PR is that it can even be considered a viable alternative to a subwoofer that costs five times as much. Not only does this budget sub have a forward-firing 12-inch driver and matching downward-firing passive radiator, but it also has a similar set of connections that includes high-level inputs. The S/812 is prettier, better made and boasts considerably more power, but the BK can give it a serious run for its money in terms of bass extension. Ultimately, the REL is the superior subwoofer but, given the price difference, you could literally buy four P12-300SB-PRs and still have change for some high-quality cables.

MORE: Further subwoofer reviews here


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