Serie S


S/510 takes REL’s compact-medium chassis concept to reference-like levels of performance and does so with style, power and incredible speed. It delivers incredible levels of all ‘round performance. S/510 allows those with less space, or when pairing with high end speakers that are slightly less robust to have a perfect dance partner when the S/812 is simply too much of a great thing.

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Extreme Performance

Compact Package

For S/510, every aspect of the previous generation’s inner workings were examined without regard to its critical and customer-driven success. We turned a fresh eye to power requirements, driver improvements, and specialty filters, upgrading each-to extract all the extra performance possible. All this alongside the cabinet refinements necessary for those upgrades to emerge cleanly. This latest S range is a triumphant development that has exceeded every expectation of our design team.

Our requirements were for far stronger deep bass output between 20-35 Hz, vastly improved theatre dynamics, and an even more open and spacious soundfield which benefits both music and film. We turned to our NextGen3 amplifier, tuned to 500 watts with substantial reserves of power, added a light film of carbon fibre to the rear of the driver to handle the extra power, and developed two new sets of custom filters to extract the utmost in brute force and spaciousness. Finally, we imbued S/510 with the ability to be stacked in 4- or 6-unit line arrays, just like our reference models.


Invisibly Upgraded

S/510’s Bass Engine

S/510 required upgrades to its ContinuousCast™ Alloy Cone to allow it to survive its massive power upgrades. To permit its thin, aluminum cone to survive 500 watts and incredibly long stroke, we added an ultra-lightweight backing of pure carbon fibre strategically placed over portions of the rear surface of the cone. This produces two benefits; it strengthens and stiffens the cone and also eliminates reversion, wherein the backwave inside the cabinet is now prevented from interfering with the main launch of bass into the room. The result is more accurate and far louder deep bass.


Nothing Passive About This

SuperProgressive™ passive radiator

Our uniquely tuned passive radiators use special suspensions, now with an additional 8mm of linear travel, to produce performance unlike conventional subwoofers. Our new SuperProgressive™ passive radiator produces extremely long travel allowing for very loud output while retaining the variable stiffness of its suspension. This allows it to act like a sealed box compact 12” design at low volumes and a high output 14” design at its limit.


500 Watt Monoblock Within

NextGen3 Amplifier

At 500 watts the NextGen3 amplifier is borrowed from our former flagship model and produces huge reservoirs of power and current. The 20%+ increase in power (previous version was 400 watts) is needed to deliver the high output levels needed for modern theatre, as well as to produce the extremely deep bass in a high end 2-channel system. This increase in power is necessitated by our development on the musical front of an all-new circuit termed PerfectFilter™ that balance both frequency extremes.

PerfectFilter performs two seemingly disparate qualities; extending the strong, even response of the extreme low end of bass frequencies while simultaneously opening up air and delicacy in the middle and high frequencies of one’s system. Additionally, we applied customized PureTheatre™ filters to allow S/510 to keep up with modern theatre effects without breaking a sweat.


Stacked for Ultimate Performance

Serie S Line Arrays

In the real world, bass occurs with width, depth and height. By stacking up to three units per side (stereo or theatre main L-R speakers) the proper perspective and height of sonic events are illuminated. This elevates reproduction from conventional stereo or theatre to a floor to ceiling panoramic, full scale perspective of each sonic event. Reviewers are lining up to marvel at the transformation of music and film into the full-scale representation that REL Line Arrays uniquely deliver.

Customer Reviews

Based on 19 reviews
Great Experience, love the REL S/510

I have only had my REL subwoofer two weeks, but I am loving the sound of it and what it adds to the music and to home theatre. The direct buying experience was painless, it arrived in 5 days and set-up was simple. I am still tuning it into the room. but the buying experience could not have been easier. I am definitely a new REL fan .....It is definitely money well spent .....


I bought one from Up Scale audio; got it home; hooked it up....loved it....SO, i purchases a 2nd one from Up Scale....WOW, now I have my own bass section, or so it would seem. I am running all tube equipment (Prima Luna gear) and these two subs are augmenting my Klipsch Hersey 3's until i can get corner horns....but these subs add what i have been missing all my life.....just the right amount of bass.....i am not an audiophile nor do i have the greatest gear in the world....but I am sure I am getting $100K sound out of my $40K system....and the REL's bring it all home....these babies are not even broken in yet....hope to have them broke in so when i get the Khorns, my life long dream of having "the sytem" in my mind, anyways...is done.....great investment.

Easy setup and clear upgrade

I purchased a single S/812 at the end of 2020, as suggested by the subwoofer finder/speaker pairing. It's a lovely-looking piece of kit that screams outstanding fit-and-finish. I love the high level input that ensures that the S/812 blends perfectly with my speakers since I use it mostly for music. I upgraded to the Bassline Blue cable, which brought a subtle yet noticeable improvement over the standard cable in terms of naturalness. Placement and gain/crossover tweaks took few weeks. Counterintuitively, the S/812 works better when placed on the inside of the right speaker, halfway between said speaker and my equipment rack, aimed at the listener/seat. I settled with the gain one click over 9 o'clock, and the crossover about one click over 10 o'clock. Yes, some tracks can use a higher crossover or gain, but this particular setup works across all tracks in a long listening session. I listen to a lot of music across various genres. The S/812 has added depth and scale to many tracks, with more texture on voices and the midrange in general. And of course, segments with very low range (organ, synth, various drums, electric bass or double-bass) have become much more impressive without sounding overblown. Interestingly, this applies to recordings that used to sound "thin" including few piano albums that now sound fuller (but again, not artificially so). Very pleased.

Sonic foundation

I purchased the REL S/510 to supplement my aging Martinlogin Sequel II, electrostatic speakers.
These speakers are hybrid with the Electrostatic panel and 10" woofer in each speaker.
The 10" woofers in my speakers failed to produce the deep base in my two channel system.
The REL Sub replaced an older 12" Sub that never seemed to integrate sonically into my system. I would often leave it turned off; it was a store demo and may have had issues I was unaware of.
Stereo is the primary purpose of the Subwoofer purchase, but I may tie it into my theater system at some point because the REL can manage multiple sources.
I purchased the Airship with my Sub as recommended.
My Sub is 15-20 ft away from the stereo rack, and Airplay removed the long cable.
I have two Monoblock Tube amplifiers that required connecting the Airplay/Sub directly to my pre-amp using RCA cables for the Left and Right channels. Because I use an older Stereo pre-amp with one set of outputs for amplification, I used "Y" splitters to make the connection.
The room is in a basement with carpet, multiple bookshelves, 8ft ceiling, ~25ft width, and a depth shorter than the width of about 15ft. The room dimensions resulted in a wider than usual separation between my speakers. Some would call it "Near Field" listening.
The room is not a true rectangle; it has an alcove to the listener's left. The alcove creates a hole in the sonics that is compensated through speaker placement as much as possible.
Another essential detail of the room is that it is a multi-use family room; this also means I am limited, in speaker placement, including the Sub. All require the wife's seal of approval.
I listen to a variety of music: Jazz, Rock, Classical, & Pop:
Initial listening out of the box, immediately the sound stage become more crystallized, instruments found their place. This was before making any effort to optimize the sub location. The REL simply replaced the old Sub on the floor. The pluck of a Bass was better defined, less muffled; the drums crisper with a greater sense of impact. Notes meant to linger – seamed to lingered longer; those intended to be short and abrupt are quicker.

I've been listening to the new Sub for about 3 weeks now. The first week was time spent mostly attempting to get it placed as best I could in the room. I followed the instructional videos and tried my best to find the best spot. Because of the limitations of where I could place the Sub, it wasn't until the 2nd week I decided to make up for any lack of "synergy" with the room and my system by relying more on the Volume & Crossover adjustments on the Sub. I spent the 2nd week working on these adjustments.
I'm now at the end of my 3rd week. Last night, I discovered I had left my system on overnight, and this may have completed any burn in (with no music playing?). Maybe there is yet another level of burn in to complete; I don't know?
But, the music last night was sonically smoother, more energetic, alive more captivating. My system had a defined sound stage before; the REL fine tuned it, brought it into focus. It was like when the optometrist reaches the last series of lens flips, "which is better, this or this." The last "This" was differently better, way better than my old Sub, and clearer than it had been just a few days before.
I can read the sound stage without squinting. Each instrument/vocal has its location on the stage. No pointing and saying the drums are in that area, Now the drums are there with a firm finger point.
Subtle echoes in the recording are more obvious; the interaction between the instruments and their environment resonate, making the environment of the recording a more significant part of the listening experience.

It's hard to describe; my system was not horrible before, and I know the improvement I hear in my system is just that, an improvement to my system.

Audio is very subjective, with many variables related to equipment, rooms, and listener.
We audiophiles have an inadequate vocabulary to describe what we hear or feel. Such as "Crystal," what does that mean. I know what I'm trying to describe, but the reader may have a completely different interpretation. What I hear and feel is my experience, and I find it very hard to explain to another person.

I have a theory now. The Sub's frequency is the platform for all of the other notes to adhere. The old saying, "if the foundation of a build is poor, there is nothing you can do to prevent the building from having a structural problem." I believe my old Sub had issues; therefore, the rest of the notes suffered as well. Not that my system was terrible before my REL, but it has dramatically improved my listening experience. The solid bass frequency of the REL is the foundation of the rest of my system's sonic performance.


The S-812 has an excellent quality, after breaking in as recommended on the web-site.
The only complain I would have is the following:

I understand and agree that Rel builds very high quality sub-woofers. I watched many video from John Hunter and do trust his engineering and expertise. Very impressive guy!!!

However, as far as packaging, there should be more dedicated engineering on this aspect, PLEASE COMMUNICATE THIS EMAIL TO MR HUNTER...
Packaging seems weak and not be adequate for such units. I own several McIntosh equipment and was impressed with their packaging…

After the package was delivered and left at my door (too late to complain), I found after unpacking that one of the vertical side edges got busted (by some lift?). The cardboard had a large cut on each vertical side for about 4 or 5 inches.
It seems that the vertical side edges are not protected at all. The top and bottom were indeed solid, vertical side edges had no protection. See attached picture.

Some to think in the future with your development Team and Mr. Hunter. It is unfortunate for me, such a beautiful unit. And… this was my second unit ordered this month.

Reviews + Awards

"With the S/510 I found a few more quieter spaces in the music as if it was truer to the acoustic space and more refined in how it allowed the synergy of itself and the main speakers to behave in a more three-dimensional manner, dealing with layers more intelligently."

HiFi Pig
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Suggested Retail: $2,499

S/510 takes REL’s compact-medium chassis concept to reference-like levels of performance and does so with style, power and incredible speed. It delivers incredible levels of all ‘round performance. S/510 allows those with less space, or when pairing with high end speakers that are slightly less robust to have a perfect dance partner when the S/812 is simply too much of a great thing.



Front-firing active woofer, down-firing passive radiator

Active Driver Size & Material

10 in., 250mm long-throw, die cast aluminium chassis

Passive Radiator Size & Material

12 in., 300mm

Low Frequency Extention

-6 dB at 20hz

Input Connectors

High Level Neutrik Speakon, Low Level stereo RCA, LFE RCA, LFE XLR

Output Connectors

Hi Level Neutrik Speakon, LFE RCA, LFE XLR

Power Output

500 watts (RMS)

Amplifier Type

NextGen3 Class D

Wireless Capability

Yes- REL AirShip system [required]. Sold separately.

Protection System

Fully Electronic Set Safe


D.C. Fault


Output Short


Mains Input Voltage

220-240 volts, 110-120 volts for certain markets


5 Amp semi delay 220 volts operation 9 Amp semi delay 120 volts operation


W x H x D

15.7 x 16 x 18.25 in., (400 x 410 x 464 mm) Add 1.75in (44.5mm) in depth when using Hi Level connector

Net Weight

70 lbs. (31.7 kg)


Piano Black Lacquer, White Lacquer, 10 coats

Supplied Accessories

Mains Lead


Neutrik Speakon



Users Manual


In the interest of product development, REL Acoustics Limited reserve the right to vary these specifications without notice.