Klipsch Reference R-121SW 12" Ported Subwoofer Review

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…

Appearance

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.

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.

The 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

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.

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. 

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.

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.

Klipsch Reference R-121SW Subwoofer Measurements & Conclusion

Testing on the Klipsch R-121SW was conducted with the microphone facing the woofer at a 1-meter distance with measurements scaled back to a 2-meter distance by subtracting 6dB. The temperature was recorded at 59F degrees with 70% humidity. The subwoofer’s gain was set to maximum, phase was set to zero, and the low pass filters were set to bypass.

The above graph shows the measured frequency responses for the R-121SW subwoofer. This response was produced by measuring the rear of the sub at 1 meter and the front of the sub at 1 meter and then averaging the two responses. A single measurement of either side doesn’t wholly capture the amplitude response of this unit. This is not quite the ruler-flat response that we see on more expensive subwoofers, but then this is not a tremendously expensive item. But those who are worried that it is not ruler-flat shouldn’t be; typical room acoustics pretty much make low-frequency ruler-flat responses a moot point since room modes will mangle the response anyway hence the need for equalization even for the most linear subwoofers. The response here centers around a broad peak at about 53Hz and has a gradual rolloff below that point down to the port tuning frequency. Below that point, the roll-off becomes steeper like we would expect to see from a traditional ported response. At about 16Hz and above, the response resembles that of a sealed sub. It looks to me like the port is more being used to reduce distortion and protect the woofer rather than giving the low-end of the response a big boost like in other ported subwoofers. The shallow low-end response should lend itself to pressure vessel gain which shores up the lower frequencies in an in-room response. Pressure vessel gain can give a very significant boost, especially in small to medium-sized rooms. This sub isn’t really made for large rooms, so this type of response is a good trade-off. This sub has a relatively low tuning for its size, but I guessed that we would see such a low tuning frequency by looking at the dimensions of the port. The upper-frequency extension is ok and we do get usable bass all the way up to 200Hz for those who want to use crossover frequencies higher than the standard 80Hz.

The above CEA-2010 measurements are short-term bursts that show the subwoofer’s clean peak SPL before heavy distortion sets in. Our measurements have been referenced to 2-meter RMS, which is 9dB down from the standard requirement for the measurements to be shown at 1-meter peak. However most publicly available CEA-2010 measurements are shown at 2-meter RMS, so we followed that convention. What we see here is a healthy and respectable set of measurements for a small ported 12”. I was surprised the R-121SW could net a passing measurement at 16Hz, but it did, although just barely. The burst output trends generally follow the base frequency response with most output hovering between 50-80Hz with a gradual rolling off above and below that range. While the mid-bass region is about what I would expect, this sub has more lower frequency oomph than I would have expected with 93dB burst output at 20Hz and 95.4dB at 25. That does show that the deep bass that I heard when watching “MoonFall” was not just my imagination. The above measurement set technically would get this sub our Bassaholic’s ‘Small’ Size Room Rating, but since it only misses the 31.5dB threshold by 1dB, and since it is highly protected from being overdriven, I am going to give it a ‘Medium’ size rating, meaning it should be sufficient for a room of 1,500 to 3,000 cubic feet. While it’s not a THX Reference-level barn burner, I think most people would be pretty happy with its output in a medium-sized room. For information on how the room ratings are determined, please read our article “Bassaholic Subwoofer Room Size Rating Protocol”.

Testing for long-term output compression was done by first conducting a 20-second sweep tone where 50Hz hit 90 dB with the subwoofer 1 meter from the microphone (graph has been scaled to 2 meters for easy comparison with our other review measurements). We then conduct further 20-second sweeps by raising the gain by 5dB until no more output could be wrung out of the subwoofer. These tests show us the long-term continuous headroom that the R-121SW is capable of. Eagle-eyed readers will note that the nominal response shapes in this graph do not match that of the base frequency response that we posted above, and that is because this is taken at 1 meter from the woofer only, and this does lose quite a bit of port contribution to the output. There is a bit more deep bass headroom from the R-121SW than what is shown here, and what is missing would mostly be between the range of 13hz to 28Hz. Pulling the microphone back from the sub further would have yielded a response with more port contribution, but it would also have raised the noise floor of the testing conditions, and since this sub doesn’t have a huge amount of headroom, we opted for a lower noise floor.

With some deep bass headroom missing from this graph, I don’t want to offer too much commentary in that region since it would be speculative. What I can say is that the R-121SW has a healthy amount of mid-bass, surpassing 105dB from 45Hz to nearly 80Hz. That isn’t bad at all, and this little ported 12” can throw a nice jab. Compression doesn’t really alter the response shape until the last few dB, so this sub should mostly retain the same tonality from low drive levels to high drive levels.

The above graphs show the corresponding total harmonic distortion to the long-term output graphs. Essentially, they depict how linear the subwoofer remains for the corresponding drive level seen in the long-term sweeps. The quantity being measured is how much of the subwoofer’s output is distortion and is shown here as a percentage. The results seen here are good for the class and pricing. Distortion stays below 10% above 45Hz even at the maximum drive level. In other words, this subwoofer has fairly clean mid-bass output even if you push it hard. At the highest drive level, meaning the last few dB that the R-121SW can produce, distortion does rise in the low end below 40Hz, but unless you push this sub to its absolute limit, it stays very well composed and largely keeps at or below 10% THD. The bass here is unexpectedly clean for a subwoofer of this size and pricing. In my outdoor testing for this sub, I noted that it was highly restricted from producing any kind of heavy distortion. It’s difficult to get this sub to make a bad noise; the rise below 40Hz is mostly comprised of the least audible distortion products and while they can be heard, they are not terribly jarring or dissonant. The driver doesn’t lose its composure, so the R-121SW is on a tight leash and cannot be over-driven.

The above graphs depict measurements of the constituent harmonics from the long-term output sweeps and are what the total harmonic distortion measurements are composed of for the 2nd and 3rd harmonics. These individual harmonics can give us a clue as to what might be the cause of some quirk or non-linearity. We are only showing the 2nd and 3rd here because they more or less reflect the higher even-order and odd-order behaviors, although higher-order harmonics tend to be much further down as a percentage of distortion compared to the second and third.

Here we can see that most of the distortion products of the R-121SW are even-order. The advantage to this is that even-order is less audible or objectionable than odd-order distortion products. The disadvantage is that it means that only one side of the driver’s motion or the signal waveform is being constricted or affected. And that means that there was probably an opportunity to iron out whatever was causing the distortion for more undistorted output. In the case of the R-121SW, I would guess that much of the even-order distortion is caused by induction effects. Induction occurs when the charged voice coil’s motion in the magnetic field creates a counter-current, but the problem is that the counter-current creates an opposing magnetic field that diminishes the initial, desired field. Induction tends to be a source of even-order distortion as well as a peakish frequency response as we see in the R-121SW. Many drivers use short-circuiting rings (often just called ‘shorting rings’) in the motor structure to address this, but it is more expensive to implement shorting rings, and I am not surprised that Klipsch decided to do without them in this lower-cost model. Shorting rings aren’t really needed for the distortion exhibited here since it is mostly at very low levels and also is of a more benign type. The rise in second-order distortion below 40Hz at the maximum drive level isn’t coming from induction but is more likely due to the moving assembly running into motor or suspension travel limits, so the inclusion of shorting rings wouldn’t help in that area. However, shorting rings would help to flatten the frequency response and increase upper-frequency sensitivity, so there are still real improvements that can be had by using them.

Group delay is the measurement of how much time it takes for individual frequency bands of an input signal to be produced by the speaker. It can indicate that some frequency components are developing slower than others or are taking longer to decay. It is generally thought that 1.5 sound cycles are needed for group delay to be audible at bass frequencies, although there is an argument that group delay should remain under 20ms to be completely unnoticeable, but that is likely meant for mid and upper bass frequencies.

I have included both port side and cone side measurements since I think that just posting the cone side measurements doesn’t fairly account for all of the group delay that the R-121SW is producing. In general, group delay here is fairly low, so there isn’t enough to worry about either way. With the exception of a pipe resonance at around 150Hz (which is unlikely to manifest into anything audible when using the standard 80Hz crossover frequency), group delay doesn’t surpass 1 cycle at any frequency. Normally, ported subs have a 1 cycle spike at the port tuning frequency where the port resonance lags behind the woofer output, but that isn’t seen here. One reason might be that the port seems underdamped compared to the rest of the response meaning that its output simply is not on the same level as that of the cone output, and likewise its contribution to group delay would also not be as great. Also, Klipsch could have implemented some kind of phase compensation in the DSP to keep group delay in line with that of the woofer’s output- we have seen that strategy employed by some other ported subwoofers such as Monoprice’s Monolith subs. The group delay from the R-121SW is above average, and its time-domain behavior is quite good.

Conclusion

Before bringing this review to a close, we will briefly go over the strengths and weaknesses of the product under evaluation, and, as usual, we will start with weaknesses. In my opinion, the Klipsch R-121SW doesn’t have any particular weaknesses. That isn’t to say it is perfect, but rather it doesn’t fall way short in any particular respect. It is a well-rounded and competent sub. I might complain about the lack of features, but buyers probably shouldn’t expect anything too fancy at its price point. If it did sport any advanced feature, that would come at the expense of some other aspect of the sub to maintain the same price point, and that isn’t a worthwhile trade-off for what it is trying to be. The chief weakness of this product doesn’t really lie in the product itself but rather in its MSRP. We will get back to that after we address its strengths.

While the R-121SW doesn’t have any real weaknesses, it doesn’t have any aspect that makes it outstanding either. It does have a few attributes that are above average, however. First of all, the electronic limiter does a great job of keeping the driver out of trouble. This sub is bulletproof and cannot be over-driven. If you like to blast your equipment hard or if you want it protected from those who will blast it hard, the R-121SW will survive that kind of abuse, at least for a little while. Of course, it’s not a good idea to blast it hard all the time, and that kind of use surely would lead to a premature failure, but if you have a moment of lapsed judgment and decide to see how loud it can get, the R-121SW will not self-destruct. 

Another strength of the R-121SW is that it does dig a bit deeper in frequency than what would be expected of a sub of its size and pricing. The trade-off is that it doesn’t get tremendously loud, but that can be compensated for by purchasing multiple units. You can always increase dynamic range by buying more subwoofers, but you cannot increase low-frequency extension by adding more of the same sub. I am guessing that most people will be purchasing this subwoofer for home theater applications, and in that respect, the exchange of dynamic range for deep bass was a wise one.

In addition to its better-than-normal extension, the R-121SW also has very good time domain performance. This sub isn’t slow or sloppy. Many ‘big box’ store brands such as Klipsch take flack for somehow not having ‘tight’ bass, but that just isn’t the case with the R-121SW. This can be seen in the group delay measurements, and it was what I heard in my own listening. This sub can sound good if any care is taken in its calibration. I would love to see what would happen in a blind test between this ‘big box’ store brand sub and any of the pricey hi-fi brands. I think the outcome of that comparison would be surprising. 

Another strength of the R-121SW is its size. This is the smallest ported 12” subwoofer that I can recall seeing. There is a sacrifice that must be made to achieve its size, and that is dynamic range. This goes back to an axiom in loudspeaker design, ‘Hoffman’s Iron Law’ which roughly states that there will always be a trade-off between small size, wide dynamic range, and low-frequency extension. Physics dictates that an increase in one of those elements necessitates a reduction in one or both of the others. The R-121SW balances all three aspects pretty well, but it does go in more for small size and low extension than it does for dynamic range. It’s not a tiny sub, but I think many household members will not be too bothered by its size. 

The R-121SW doesn’t do anything wrong, but it is up against some stiff competition at its MSRP. Its problem is that there are subs that we recently reviewed that can match or exceed its performance for under $500, namely the RSL Speedwoofer 10S MKII and the BIC Acoustech PL-300. What complicates this is that the R-121SW frequently goes on sale for much less than $500, and when it does, that makes it a serious option in that price range. At the time of this writing, the R-121SW was on sale for $359, and that pricing has to make it the best bang for the buck in subwoofage at the moment. But at its $599 MSRP, it is a tough sell. If you happen to need a sub that isn’t large and has respectable deep bass extension with very good time-domain performance as well as bullet-proof protection from large signal abuse, it would still be extremely competitive, but if you prioritize deeper bass or wider dynamic range, you can get a sub with most of the R-121SW’s strengths for significantly less than its MSRP.  Of course if you're a Klipsch fan building an entire modestly priced Klipsch speaker system, the R-121SW would compliment it nicely.

The Score Card

The scoring below is based on each piece of equipment doing the duty it is designed for. The numbers are weighed heavily with respect to the individual cost of each unit, thus giving a rating roughly equal to:

Performance × Price Factor/Value = Rating

Audioholics.com note: The ratings indicated below are based on subjective listening and objective testing of the product in question. The rating scale is based on performance/value ratio. If you notice better performing products in future reviews that have lower numbers in certain areas, be aware that the value factor is most likely the culprit. Other Audioholics reviewers may rate products solely based on performance, and each reviewer has his/her own system for ratings.

Audioholics Rating Scale

• — Excellent
• — Very Good
• — Good
• — Fair
• — Poor

Metric	Rating
Bass Extension
Bass Accuracy
Build Quality
Fit and Finish
Ergonomics & Usability
Features
Dynamic Range
Performance
Value