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Klipsch Reference R-121SW 12" Ported Subwoofer Review

by January 11, 2023
Klipsch R-121SW Subwoofer

Klipsch R-121SW Subwoofer

  • Product Name: R-121SW Subwoofer
  • Manufacturer: Klipsch
  • Performance Rating: StarStarStarhalf-star
  • Value Rating: StarStarStarhalf-star
  • Review Date: January 11, 2023 00:00
  • MSRP: $ 600
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  • 12" front-firing woofer made of spun-copper TCP (Thermoformed Crystalline Polymer)
  • Built-in digital amplifier delivers 200 watts RMS of continuous power (400 watts peak dynamic power)
  • Frequency response: 28-120 Hz
  • Bass-reflex (ported) cabinet design with rear-firing port
  • 3/4" MDF enclosure
  • Front LED power indicator
  • Weight: 35.2 lbs.
  • Dimensions: 16"W x 16-5/8"H x 20-15/16"D
  • Warranty: 5 years (woofer), 2 years (amplifier)


  • Relatively small for a ported 12” subwoofer
  • Bulletproof protection by limiter
  • 22Hz port tuning gives it deeper bass than expected
  • Very good time-domain performance


  • More output can be had from less expensive subwoofers


Klipsch R-121SW Introduction

As a byproduct of being one of the most popular loudspeaker brands in the world, Klipsch is also one of the most popular subwoofer manufacturers too. Their subs can be found in the home audio section of pretty much all major electronic retail chains in North America and throughout much of the world. That being so, it is long overdue for us at Audioholics to take a deep dive into a Klipsch powered subwoofer. So that is precisely what we will be doing today. We will be taking a look at the 12" ported R-1212SW subwoofer, which was recently released along with the launch of their updated Reference series speakers. As with their preceding subwoofer models, this one is bound to be a big seller and will inevitably find its way into many thousands of homes. But is it really a good subwoofer? Where does it stand among its competition? Does Klipsch invest as much effort into their subwoofer design as they do their loudspeakers? These are the questions we will be asking in today’s review…


R121SW grille2   R121SW no grille3

With its grille on, the R-121SW isn’t a very distinctive subwoofer. That isn’t to say it looks bad at all but rather it is a fairly routine black box like many other subs. It uses a black vinyl faux wood grain finish that can be seen in many other speakers and subs in this class. What is nice is that it is a fingerprint-resistant finish, unlike many satin or gloss finishes. All of the edges are hard angles and there is no edge rounding, so the cabinet doesn’t make much effort in hiding its boxiness. It disappears easily into a room corner for those who do not want something that attracts much attention. What helps in this respect is that it is on the smaller side of 12” ported subs, and it’s not a large subwoofer by most people’s standards, although it certainly wouldn’t be considered tiny either. It is only when the grille is removed that the sub visually separates itself from competitors. Removing the grille unveils Klipsch’s trademarked copper cone. To me, the copper cone design of Klipsch has always added a touch of class. Removing the grille also exposes a front-mounted LED power indicator that lets you know the sub’s power state. Overall, it is not a pretty subwoofer nor is it an ugly one. It just looks like a typical subwoofer.

Design Analysis

The R–121SW seems to be a simple ported subwoofer, and that’s  a good thing if it’s executed well. There is no need to reinvent the wheel when something works well. It uses a 12” front-firing driver in a box with a rear-firing port and is powered by a 200-watt (continuously rated) / 400-watt (peak) amplifier. That is the basic design overview, but let’s dig in a bit deeper to look at the specifics, and let’s start with the driver.

R121SW interior

The driver’s cone is made from a material that Klipsch calls copper-spun thermoforming crystalline polymer (TCP). That sounds fancy, but, as far as I can tell, it is really just polypropylene with artificial cosmetic copper coloring. That is OK since, as we have said, there is no need to reinvent the wheel, and polypropylene is a good cone material on account of its light weight and stiffness. Klipsch says this cone has steeper angling for “a smoother response and improved accuracy and transparency.” Creating a steeper cone might make it more rigid, at least for the back-and-forth plane of motion that it’s intended to move in, and that could push flexing modes out to higher frequencies, but that isn’t normally a problem with subwoofer cones since they are relegated to such a low frequency band. The cone is attached to a stamped steel basket with a 1” thick surround and a Nomex spider. The motor’s magnet is not huge with a 4” diameter and 1” thickness, but the most important aspect would be the magnetic flux, which we don’t know.

R121SW rearThe driver is powered by a 200-watt amplifier that Klipsch calls ‘all digital,’ which I presume means that it uses DSP processing. They don’t specify the amplifier’s type, but it looks like Class D. It only has a basic control set with a volume knob, a low-pass frequency knob that ranges from 50Hz up to filter deactivation, a 0/180 degree phase switch, and an off/on/auto switch. Inputs are only a pair of RCA jacks. It is a simple plate amp and doesn’t have any extraneous features, and that is fine since most modern AVRs do most of the subwoofer control anyway. For all the sophisticated subwoofer control methods on higher-end subs like touch-sensitive screen displays, apps, and remote controls, the vast majority of users just set the sub up and let the AVR deal with it- as they should.

The cabinet uses ½” thick MDF side panels with a ¾” thick front baffle and a center brace to reinforce the midsections. There is polyfill lining the sides to help damp internal acoustic energy. The rear-mounted port has a 3” diameter and a 14 ½” length. It is only flared on the front. Those port dimensions suggest a relatively low tuning frequency, but we will see for sure in the performance analysis. The grille uses plastic pegs and grille guides to connect with the front. It only hides the driver but since it is just a fabric-draped frame, it wouldn’t protect the fragile cone from any heavy or fast-moving objects. The feet are some simple ⅝” tall hard rubber cylinders that get the job done.

As was said, this is a fairly simple sub on the surface, so there isn’t a whole lot more to discuss with this design, and many of the most important aspects that will determine performance are not outwardly visible, such as amplifier configuration or driver parameters. Let’s now see how it plays out in some typical use…

Listening Sessions

The best placement for a single sub in my room gives me a relatively flat response for an un-EQ’d single subwoofer, with a window of +/- 4 dB from 25 Hz to 100 Hz with no broad dips in important ranges. This location trades low-end room gain for a relatively flat response, a worthwhile trade for my tastes. The receiver used was a Marantz AV7705. The crossover was set to 80Hz. The speakers used were some Mon Acoustics SuperMon Isobarics powered by a Monoprice Monolith 5x200-watt amplifier.

As always, I will note here that since room acoustics have a huge effect on low frequencies, the way these subwoofers sound in my room at my listening position is not necessarily going to be the way they sound anywhere else for anyone else, so readers would do well to keep that in mind, and not just for this subwoofer in this review but for any subwoofer in any review.

Music Listening

the Klipsch R-121SW provided a muscular footing which belied its modest size...

As one of the few acoustic instruments capable of serious bass in subwoofer band frequencies, I always start off listening to a subwoofer with an album focused on pipe organ music. Not every pipe organ album has an abundance of deep bass, but one that does have some powerful low-frequency content is “Organ Music from the St. Gallen Cathedral, Vol. 4.” The title is an apt description of the contents of the album, and a variety of works are used to demonstrate the musical capability of the organ of the St. Gallen Cathedral. The cathedral dates back to 1767, but the massive organ was installed in 1968. It has 5,465 pipes and 74 stops including a 32’ stop which should lead to a very deep fundamental frequency. I streamed this high-resolution recording from Qobuz.

Deep bass kicks in early in this album with very low notes underlining much of the first track, “Hymne Heroique.” Much as its title indicates, it was a grandiose piece with a number of stops pulled, and the R-121SW provided a muscular footing for the song. Subsequent tracks don’t go quite as hard on lower frequencies, but they still utilize subwoofer band frequencies abundantly, such as the midsection of “Fantasie Orange,” which was a certifiable pipe organ deep bass fest. This very unusual composition was given an energetic low-frequency handling by the R-121SW which belied its modest size. At some moments the bass was subtle but still present, and the R-121SW could deliver its presence without overdoing it. The R-121SW could effect a good blend with the speakers, and although that is largely a matter of set-up techniques rather than the sub itself, the sub still needs to be linear and controlled enough for a good integration to be possible. Of pipe organ albums, this one rides deep bass harder than most, and the organist Willibald Guggenmos definitely isn’t shy about showing off the low-frequency prowess of the Kuhn pipe organ in the St. Gallen Cathedral, but the Klipsch R-121SW made a good showing for itself, at least for the loudness levels that I listened to. I am sure that much higher loudness levels would find the limits of this sub, but I was happy with the performance that it could provide.

Organ St Gallen  Bottesini

the R-121SW achieved a seamless blend with my speakers without much fuss.

Another acoustic instrument that can dig into deep bass is the double bass, and a good illustration of that can be heard in “Bottesini: Revolution of Bass.” The title refers to the 19th-century Romantic composer Giovanni Bottesini who revolutionized the use of the double bass. Before his time, many instrumentalists regarded the double bass as unwieldy, but he demonstrated its versatility and subtlety, which changed how it was approached by musicians afterward. On this album, double bass virtuoso Dominik Wagner plays a selection of pieces by Bottesini which aren’t often performed because of their technical demands. He is backed by the Wurttemburg Chamber Orchestra Heilbronn as well as the accomplished cellist Jeremias Fliedl and violinist Benjamin Schmidt. I also streamed this album from Qobuz in a 96kHz/24-bit resolution.

Much of the lower bass in this album didn’t come from the double bass itself but rather other orchestral elements, although when the double bass did dive into subwoofer range frequencies, the R-121SW acquitted itself nicely. This album, more than anything else, would require good integration between the subwoofer and main speakers, since only the fundamental frequency of the double bass lay in the subwoofer’s range, and the speakers are playing nearly all the harmonic components above that range. That means that timing and level matching between speakers and subwoofer will be very important in getting the sound of the double bass to sound unified and singular. Again, achieving a good fusion between speakers and subwoofer is largely a calibration issue, but by the end, the R-121SW achieved a seamless blend with the speakers without much fuss. It gave the double bass an authoritative and lifelike low end without sounding unnatural or boomy. It gave a natural-sounding extension to the speakers that I was using, and the fact that it could provide a meaningful contribution to a pair of Mon Acoustics SuperMon Isobarics, a beefy $25k standmount speaker set, is impressive coming from this $600 subwoofer.

For an entirely different musical bass experience, I found a dark ambient album titled “Labryntia” by Caldon Glover. This grim music uses sound to sculpt gloomy atmospheres and bleak soundscapes. This is like relaxation music for the Cenobites from the Hellraiser films. Glover uses very deep bass to help achieve his sonic panoramas; at times the low frequencies can be subtle but at other times they can be quite thick and give the impression of a monstrous setting. It’s an album that will keep any subwoofer busy, but it will expose the shortcomings of a poor performer. This is a brand-new release on the Cyclic Law label, again streamed from Qobuz.

The first track has a subtle drone that builds into some very low-pitched and prominent kettle drums, and the R-121SW deftly handled the subtlety of the drones while giving the drums enough thump to rattle the room doors. The next track featured a massive low-frequency rumble abetted by more deep bass percussion, and it all sounded positively thunderous on the R-121SW. The sub gave a visceral foundation to this music thereby heightening the realism of the nightmare world intended by the artist. Gigantic cathedral bells rang with a low-frequency buzz that gave it a physical presence instead of just an aural one. The sound gave the impression of being in an abyssal space, and the bass produced by the sub was critical in establishing the monumental scope of this soundscape. I would guess that most listeners use headphones to enjoy this music; however, that wouldn’t do this sound justice, primarily because headphones can’t produce the physical dimension of sound like a competent subwoofer can. The R-121SW proved itself to be a very competent sub with “Labryntia,” and I think that anyone who buys one for demanding music of this nature will be happy with the results. 

Labryntia  Outer Edges

For content to see how far the R-121SW can be pushed, I threw in “Outer Edges” by Noisia. Anyone who knows electronic music will know Noisia as one of the biggest drum’n’bass acts in the genre. Though they recently dissolved, Noisia still leaves behind a tremendous body of work that will keep drum’n’bass fans raving for decades to come. “Outer Edges” is a 2016 album that has 18 tracks yet is less than an hour long, so it is chocked full of short bangers that would be sure to get you evicted from any apartment if played at a healthy volume. I cranked the volume to see how much punishment the R-121SW could take; would it be enough to net me a citation for a noise complaint?

The R-121SW could get loud for sure, but I did find its limits in “Outer Edges.” There was a point at which it refused to get louder, but that point was not accompanied by audible distortion artifacts, thankfully. The DSP simply restricted the woofer from getting into any troublesome amplitudes. This was at a pretty loud level, and I don’t think most users would typically play anything this loud. It did have some punch and thump at these levels. The track “Collider” sounded just killer. “Stonewalled” had a wild bassline that sounded great with R-121SW. Likewise, the bassline in “Motion Blur” was given a satisfyingly thick grunt by the sub as well. Kick drums had a nice amount of punch, and while I have experienced more violent bass from other subs on this particular album, for a small 12” subwoofer, it did well. In my approximately 3,700 cubic foot room with hallway openings into other sections of my home, the R-121SW could render a strong sound, although it was not an absolute monster. In a smaller room such as a closed bedroom, this thing would stomp pretty hard. I had fun listening to “Outer Edges” on the R-121SW, and I think most users would be happy with the headroom it has. However, those who are into heavy-duty electronic bass music might want to spring for two of them rather than a single unit.

Movie Watching

Disaster movie auteur Roland Emmerich can always be counted on for something with loads of bass, and his latest opus, “Moonfall,” had just arrived on the HBO Max streaming service, so I thought it would be a good opportunity to see what the R-121SW could do with an effects-driven Hollywood mega-movie. “Moonfall” is about the moon being knocked out of its orbit by a mysterious force and ending up in a collision course with Earth. I hadn’t previously seen it, but my guess was that it probably wasn’t a leading candidate for a Nebula award for best screenplay, but few people go to see a movie like this for scientific enlightenment. So long as it has well-executed scenes of mass destruction, no one can say it didn’t deliver what it advertises.

After watching “Moonfall,” I have to say that it delivered the goods in terms of mass destruction, and the R-121SW gave it the bombast to make that mass destruction palpable. Some highlights include a space shuttle launch that narrowly outraces a tidal wave, the moon skimming the tops of mountains, and a nanotechnology blob attacking any manned space vehicle that it encounters. The R-121SW gave all of the earthquakes, tidal waves, and explosions enough oomph to give the movie a true big-screen feel. Larger and more expensive subs might have been capable of more deep bass output, but the R-121SW did surprisingly well considering its size and cost. I watched “Moonfall” at a healthy volume but not an extremely loud one, and I didn’t detect any problems or shortcomings. Those who are setting up subwoofers for dedicated home theater rooms for THX Reference level listening are going to want something beefier, but the R-121SW proved on “Moonfall” that it could competently charge a medium-sized room with plenty of bass. It should go without saying that “Moonfall” was absolutely preposterous, but anyone who watches a trailer for it or reads the plot synopsis should be prepared for that. Since this movie is primarily an excuse for epic effects scenes, technical aspects of visual and audio reproduction become that much more important to achieving its intended aims. The R-121SW was able to do this much better than I would have expected, and I think that a lot of people are going to be as pleasantly surprised as I was when they find out what it can do.

 Moonfall  The Void

One movie that I watched using the R-121SW was “The Void”, a 2016 cosmic horror film. I had seen it previously when it was first released, and I remember the sound mix being fairly heavy in bass. I quite liked it and had always intended to rewatch it, and it seemed like a good opportunity to see what the R-121SW could do with a very different type of sound mix. “The Void” is about a group of people in a rural hospital who find themselves under siege by a bizarre group of cultists. Things go from bad to worse when corpses in the hospital begin to transform into grotesque monsters. I like siege movies, I like horror movies about cults, and I like Lovecraftian mysticism, so this movie is right up my alley.

Much like I remembered, there was a lot of bass in this movie, but most of it was in the music score. However, it was a hell of a score. Much of it was created by Blitz//Berlin with additional tracks by Menolon, Brian Wiacek, and the director Jeremy Gillespie. With that many different contributors, one would expect the sound to be all over the place, but the music was cohesive. It was largely electronic with some traditional acoustical instruments, and the bass demands were intense at times. Any AV system that tries to reproduce this film is going to need some real power in low frequencies, and the R-121SW was able to meet the demands of the sound mix. I was likely pushing it near its limits, but I didn’t notice it running up against any limits during my viewing. Low-pitched synth sweeps relayed the on-screen horror with fervor by the R-121SW. It managed to fill my room with low-frequency energy during moments of action or suspense. One particularly aggressive bass moment was the opening of the portal which was accompanied by a room-shaking rumble; the R-121SW was giving its all, and it was enough to vibrate my ceiling tiles. Again, I don’t think a single R-1212SW would suffice for a dedicated home theater, but for any normal family room or bedroom, I do think users will be very happy with the sound it can make. It added a lot of weight to the sound mix for “The Void,” a movie that really benefits from strong bass reproduction.

gimpy posts on January 21, 2023 12:57
FYI, for anyone interested in this sub, Crutchfield has it on sale right now.
Teetertotter? posts on January 19, 2023 15:45
I have had their R-100SW{10"] for 3 years, in my 10 X 12 room. It has been a stellar subwoofer and have the gain turned down, as do not like a whole lot of base, but just enough. At low AVR volume, the base still comes through loud and clear for all movies. Thank you for your review.
shadyJ posts on January 17, 2023 04:07
gimpy, post: 1587369, member: 99846
shadyJ, thx for this review. I just bought this sub on Black Friday (Thanksgiving) at my local BB store at a very good price. It replaced an older DIY sub that I built several years ago (a Dayton 15 inch woofer in a sealed 20" square box) with a 250 watt (I think) amplifier. Any way, I don't think my sub had been working the last couple of years (this was confirmed when I hooked the Klipsch up and it started rattling the house).

I have a mixture of a 5.1 speaker setup and was wondering what you had your gain set on the back of the sub? I initially set it halfway. That is when it really rattled the house making the wife complain about it. I have run audessey a few times since and have gotten the gain at —7.5 readout on my Denon avr. So, just curious what your gain was set at.

When I ran an spl meter, I was getting quite a bit lower dB readings than the 75.(in the 60's). Would you suggest using the audessey settings, or running the test tones using my spl meter and raising the gain/dB levels?
I would appreciate any answers you could/would give me.
Markers on the sub's volume dial are almost arbitrary and don't usually mean anything specific, unless you have a sub that has a gain tied to some reference point like THX. I don't remember what I had the gain set at. If I were you, I would just use Audyssey to set the levels initially, and then adjust the gain from there to where ever you think it sounds the best. The bass level is a matter of personal preference, so there is no right answer here unless you are just going after a level-matched setting with your speakers for the most accurate sound.
gimpy posts on January 16, 2023 23:44
shadyJ, thx for this review. I just bought this sub on Black Friday (Thanksgiving) at my local BB store at a very good price. It replaced an older DIY sub that I built several years ago (a Dayton 15 inch woofer in a sealed 20" square box) with a 250 watt (I think) amplifier. Any way, I don't think my sub had been working the last couple of years (this was confirmed when I hooked the Klipsch up and it started rattling the house).

I have a mixture of a 5.1 speaker setup and was wondering what you had your gain set on the back of the sub? I initially set it halfway. That is when it really rattled the house making the wife complain about it. I have run audessey a few times since and have gotten the gain at —7.5 readout on my Denon avr. So, just curious what your gain was set at.

When I ran an spl meter, I was getting quite a bit lower dB readings than the 75.(in the 60's). Would you suggest using the audessey settings, or running the test tones using my spl meter and raising the gain/dB levels?
I would appreciate any answers you could/would give me.
XaVierDK posts on January 14, 2023 01:37
It's always great to see more budget-oriented options under review. Both because they're what most of us will end up buying anyway, but especially because it's a great eye-opener for people that good sound isn't necessarily prohibitively expensive, and it's a category where more interesting compromises are made to ensure value and performance targets match.
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About the author:

James Larson is Audioholics' primary loudspeaker and subwoofer reviewer on account of his deep knowledge of loudspeaker functioning and performance and also his overall enthusiasm toward moving the state of audio science forward.

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