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Monoprice SW-15 15in 600 watt Subwoofer Review

by December 30, 2023
Monoprice SW-15 Subwoofer

Monoprice SW-15 Subwoofer

  • Product Name: SW-15 Subwoofer
  • Manufacturer: Monoprice
  • Performance Rating: StarStarStarStarStar
  • Value Rating: StarStarStarStarStar
  • Review Date: December 30, 2023 00:35
  • MSRP: $ 300 (includes shipping!)
  • Buy Now
  • Frequency Response:: 30 ~ 150 Hz (‑10dB)
  • Woofer: 15" reinforced paper cone
  • Speaker Type: Bass reflex with down‑firing port
  • Amplifier Power (RMS / Peak): 600 watts @ THD < 0.5% / 800 watts
  • Variable Low‑pass Filter: 40 ~ 150 Hz @18dB/octave
  • Variable Phase Control: 0° or 180°
  • Inputs: Stereo line level and speaker level
  • Dimensions: 18.1" x 21.0" x 22.7" (460 x 533 x 577 mm)
  • Weight: 66.1 lbs. (30.0 kg)

Pros

  • Gigantic output
  • Good extension for a low-cost sub
  • Not terrible looking for a large sub
  • Inexpensive

Cons

  • Upper-frequency extension limited to 80Hz
  • Heavy distortion when pushed very hard

 

A 15" $300 Powered Subwoofer - How Good Could It Be?

Throughout this year, we have looked at a number of lower-cost subs in the $500 and below range. One often discussed low-cost sub that slipped through our net was the Monoprice SW-15. After many reader requests for a review of the SW-15, we asked Monoprice to send us one to see how it would fare, and that brings us to today’s review. The SW-15 is very affordable at $300 (including shipping), and its spec sheet claims to have a 600-watt RMS amplifier, although I find that figure hard to believe. Most halfway-decent 600-watt amplifiers cost considerably more than the SW-15 itself, especially in plate amp form. Unless that number is massively fudged, Monoprice would have to be selling these things at an enormous loss, and I doubt that is the case. Nonetheless, the most important attribute of this product is going to be performance rather than a number on a spec sheet, no matter how inflated. What will make the SW-15 a success is how it stands out in its price class rather than the specs, because shoppers in this price class are looking for a good value above all. So then let’s dive into the SW-15 to see if it meets that criteria…

Monoprice SW-15 Subwoofer Packing and Appearance

The SW-15 arrived double-boxed. Inside, there were some thick polyethylene corner pieces glued to an additional cardboard sheet. The sub itself was wrapped in a plastic cover to protect against moisture. Overall, this is an impressive level of packing given the cost of the sub.

SW15 grille2  SW15

The SW-15 is not a luxury item and doesn’t pretend to be one.

Once unpacked, we are met with a pretty typical subwoofer, albeit it is on the somewhat large side. It is a black oblong box like so many other subs. The extended horizontal edges are rounded which does help to soften the appearance. The finish is a textured vinyl like we see on many other budget speakers. It doesn’t look bad, and it is resistant to scuffs and fingerprints. The grille covers the entirety of the front baffle, and it is just black fabric draped over a shaped frame. With the grille on, the SW-15 looks fairly blank: a nearly featureless black box. Without the grill, we get to see the driver cone, and that gives the sub a lot more character. At a glance, the cone almost looks like carbon fiber, but a closer inspection reveals that it is a simulated threaded texture, not an actual woven material. The driver has a beefy surround, and the frame edge is mostly covered by a rubbery gasket piece. The cone is not recessed much into the enclosure and the surround does stick out a bit. The sub floats a couple of inches above the ground on some plastic cone feet. The SW-15 is not a luxury item and doesn’t pretend to be one. Those who are shopping for subs in this price range probably won’t be bothered by its rather plain appearance. However, it doesn’t look awful, and the grille would help it disappear in many rooms.

Monoprice SW-15 Subwoofer Design Analysis

As a very economical design, the SW-15 is a relatively simple subwoofer, but it does have a couple of unusual attributes worth highlighting. Let’s begin our discussion of the design by talking about the driver. It does use a 15” woofer, but that is measuring it from the edge of the frame, not the cone. Most, but not all, manufacturers rate their driver diameters the same way. The cone is reinforced paper that is coated in some kind of lamination, and it attaches to the frame with a 1 ¼” half-roll butyl foam surround. The frame is stamped steel with ridges to help increase stiffness. It attaches to a not-huge magnet measuring 6 ¼” diameter with a 1” thickness, but you can’t expect a massive magnet in a sub with a $300 price tag. Besides, the number that really counts is how much magnetic flux it delivers in the gap to the coil, and that number isn’t known to us. Venting is done through the pole piece, and the backplate is bumped out to permit higher excursions before bottoming out.

SW15 driver  SW15 driver motor3

The driver is ostensibly powered by a 600-watt RMS amplifier, but, as was said before, I find that number to be implausible. Amp controls are the bare necessities of a volume knob, a low-pass filter knob that goes from 40hz to 150Hz, an on/off switch, an auto-on power switch, and a 0-180 degree phase switch. Connectivity is implemented through left and right RCA inputs and speaker-level inputs. As a digression, I don’t know why so many low-cost subwoofers have speaker-level inputs. I would imagine that very few people use them. They were a lot more useful 25 to 30 years ago when lower-cost receivers weren’t guaranteed to have subwoofer outputs. Unless the cost to add speaker-level inputs is next to nothing, manufacturers ought to skip this feature.

SW15 amp panel   SW15 amp

The enclosure uses a ⅞” thick front baffle, and there are pieces of corner bracing at points in the corners. A thin layer of polyfill-type stuffing lines the interior panels. The feet are some tall plastic cylinders that give fingers plenty of clearance to safely place the sub by hand. The grille uses a thick MDF piece as a frame, and it attaches to the front baffle with some plastic pegs. If the grille is not going to be used, store it somewhere where it will be left alone, because I can see the plastic pegs getting easily broken off by knocking them across anything hard.

SW15 bottom panel   SW15 interior

The port is unusual; it takes a 90-degree turn within the cabinet. I think there would have been room for a straight port of its size, but, for whatever reason, this one has a right angle. It is a bottom-mounted port that extends 8” upwards within the cabinet and then extends another 6” after the angle. It has a 3 ¼” diameter and is flared on both ends. I would guess that a port with those dimensions should have a somewhat deep tuning frequency for this class of sub. I would also guess that a hard 90-degree turn wouldn’t be great for reducing port turbulence and that a more gradual bend would have been better in this respect. However, much of the turbulence this port can generate will likely be masked by its down-firing orientation.

There is not a whole lot else to talk about regarding the SW-15’s design. Its individual components are expectedly simple, and what really matters is how they all come together to produce sound. Let’s now hear it in action to see what it can do…

Monoprice SW-15 Subwoofer 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 Ellis 1802G custom bookshelf speakers.

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 always, I started my listening using the mighty pipe organ as a reference, and the recording I chose for this sub was “The Grand Organ of Salisbury Cathedral” which featured, you guessed it, the Grand Organ of the Salisbury Cathedral. This massive, world-renowned organ uses over 4,000 pipes, and the deepest tuned ones have a 32’ height which makes for a 16Hz fundamental resonance. I streamed this album on Qobuz, but it originally came with a 5.1-channel video recording of the performance on DVD from Priory Records. This performance, by organist David Halls, covers a wide range of compositions from many different composers and is intended to show off what the Salisbury Organ can do. It is not shy on low bass, and it will keep the sub busy throughout its runtime.

Most of the tracks on this album don’t hammer deep bass to rattle the listener’s teeth but rather serve the purpose of bass in most music, which is tying the harmony and rhythm together and adding weight to the sound. Toward this end, the SW-15 did a fine job. It was gentle when it needed to be but had no problems showing strength in the more intense passages. On sustained deep bass notes, it exhibited the undulating texture of the vibrating pipes nicely. The low-frequency decay of the reverb within the cathedral was also an audible detail not missed by the SW-15. It’s possible that the SW-15 missed some of the lowest bass notes in this recording, but, if so, I didn’t notice it. In my room, the SW-15 produced a strong response down to 30Hz before it lost much of its power. That kind of extension is sufficient to catch most of the bass in typical pipe organ recordings, but an organ like the one featured in this recording is capable of deeper bass than 30Hz. Hardcore pipe organ aficionados may want to save up for a subwoofer with lower extension, but, of course, that will cost significantly more. However, I am sure that casual pipe organ music enjoyers will like what the SW-15 has to offer.

Organ of Salisbury  Oppenheimer

I enjoyed revisiting the music of “Oppenheimer,” with the SW-15...

One recent orchestral work that uses a healthy amount of lower bass was the score for “Oppenheimer” by Ludwig Goransson. I rarely go out to cinemas anymore, but I made an exception for “Oppenheimer,” since it looked to be a rarity itself: a major Hollywood movie made for adults. Goransson worked with Christopher Nolan previously on the “Tenet” score, itself a good workout for subwoofers, and while Goransson doesn’t pile on the bass like Hans Zimmer’s collaborations with Nolan, he certainly doesn’t avoid it either. I thought that the score itself would be a good way to see what the SW-15 can do for orchestral bass.

Low frequencies don’t really kick in until track 2 where the thrumming of some bass violins was given a true sense of weight. They were the main source of low-frequency content for this album, but kettle drums and a full piano also gave the subwoofer something to chew on. The SW-15 had no problem bringing these instruments to life with the same pulsating urgency that I experienced when I originally saw “Oppenheimer” at an Imax theater. The SW-15 delivered a depth to these instruments that added a layer of realism to the sonic presentation. There was never a moment where I thought that the subwoofer was ever dynamically constrained. Again, there may have been some super-deep bass that was missing, but I never sensed content on this album that was beyond the extension of this sub. The SW-15 also had no trouble with the quick transients on some of the more rapid passages in this album. While laggy bass is very often an integration issue rather than a problem with the sub itself, a badly-tuned sub can add a lot of port output delay in audible bands - not a quality unheard of subwoofers in the SW-15’s price range. Thankfully, the SW-15 wasn’t smearing the bass or adding any time-domain ambiguity that I noticed. In fact, the whole presentation sounded shockingly good considering the cost of the sub. I enjoyed revisiting the music of “Oppenheimer,” and the SW-15 very much made a positive contribution to this experience. 

the SW-15 plunged these depths with ease and made my living room sound like a much larger space than it was.

The Cryo Chamber label has always been a reliable source of bass-heavy dark ambiance, and one of their newest releases is a humdinger in this respect. “Mechanical Gods” by Gdanian uses deep bass profusely to create an atmosphere of awe and menace. The music lives up to the track names such as “Darkest Cavern,” “Underground Complex,” and “Subterranean Winds.” Near-infrasonic bass appropriately suffuses these tracks, and although the music itself is calm in tempo, the bass energy in use is very active. Being ambient music, the bass here is textured and finely sculpted, and a low-fidelity subwoofer wouldn’t be up to the challenge of recreating this music precisely. I thought it would stand as a good test to see how the SW-15 would fare.

“Mechanical Gods” opens with a rumbling sound that almost sounds like a lava flow, and the deep frequency texture of the grinding rock noises was not lost as an ill-defined smear on the SW-15. The following track used a deep drone along with a near infrasonic beat that underlaid a verbal report of the unfortunate plight of the “exo-planetary sanctuary” of Kepler 16-49-C and its inhabitants’ enslavement to their AI overlords. The SW-15 helped to realize the atmosphere and scope that the artist was trying to convey with effortless assurance. Further tracks used deeply tuned percussion that sounded like giant taiko drums, and the thunder of these instruments was effortlessly rendered by the subwoofer. Other tracks use low-pitched reverberations to evoke massive underground spaces, and the SW-15 plunged these depths with ease and made my living room sound like a much larger space than it was. A subwoofer with lower extension might have brought out some of the deeper frequency sounds on this album, but such a sub would have cost much more than the SW-15, and the 30Hz extension is certainly catching the vast majority of bass in this music. Listening to “Mechanical Gods” on the SW-15 was an enjoyable dive into a dark and fantastical psycho-acoustic space, and the SW-15 helped to actualize this musical landscape into a living, breathing environment.

Mechanical Gods  Evaluate Me

For something that hits bass in a more flagrant manner, I listened to Gyrofield’s “Evaluate Me,” a six-track self-released EP. Gyrofield’s unique brand of drum’n’bass music keeps much of the hard bass yet has meticulous and twisted sound designs along with unusual percussive rhythms and a strong sense of melody. I have quickly become a fan of Gyrofield after discovering her music a couple of years ago and have devoured her limited yet high-quality discography. Naturally, music like this can be quite the test of stamina for subwoofers at high enough drive levels, so I set out to see what the SW-15 could do when pushed hard.

The SW-15 delivered the low-frequencies in “Evaluate Me” with a brawny presentation. Beats had chest-punching thump, and basslines had a palpable pulsating sensation. The drop in track 3, “Kaede,” filled my room with a thick, clean bassline and had a positively club-like sound. Track 4 had an unusual, squelchy low-frequency sound which was given a tactile buzz in my seat by the SW-15. The staccato bass in the last half of track 5 had rapid attack and decays, and the SW-15 gave each rest a clean break, and I didn’t notice any overhang or lag that would have diminished the effect. The final track, “R.F.D.,” was undoubtedly the centerpiece, and its wildly fluctuating low-frequency sounds were nicely delineated by the SW-15. I decided to see how well the sub could keep its composure at max volume, so I turned its volume knob all the way up. At maximum volume, the SW-15 was able to pack a massive punch, although it did add a slightly buzzy aspect to the sound which was harmonic distortion. It wasn’t the dominant aspect of the sound, but it did alter the tonality of the bass. It probably would have been much more obvious at deep frequencies, but I doubt that much of the bass in this music went below 40Hz. Backing off the volume just a little bit did return the sound to clean yet powerful bass. The bottom line here is that buyers looking for an inexpensive killer sub for electronic music have a great choice in the SW-15. 

Movie Watching

One movie that looked like an amusing excursion that should have some moments of heavy bass was 2022’s “Violent Night.” This comedic action film stars David Harbour as Santa Claus who gets caught in an armed robbery at a house where he is delivering gifts on Christmas Eve. It then turns into a “Die Hard” setup where Santa must free the family under siege and defeat the bad guys. I had not yet seen “Violent Night,” but this film looked to be especially violent and derives its comedy from the blood that is shed by our children’s fable character.

“Violent Night” certainly lived up to its name, and I am happy to report that the SW-15 helped it in that respect. Much of the action scenes were given an added brutality thanks to the subwoofer’s support. Outside of the initial home invasion, much of the action scenes were of Santa battling the heavily armed intruders. Gunfire and explosions were given a meaty thump by the SW-15, but its time to shine was when Santa used his favorite weapon, a sledgehammer. Each strike with the sledgehammer landed with a bass-heavy blow, and the SW-15 nearly let you feel its bone-breaking power. The SW-15 also helped to enhance the impact of some bowling ball impacts in a grisly “Home Alone” style booby trap. Another fun moment for bass frequencies was all the mayhem in the snowmobile chase, a funny nod to “Die Hard 2.” Indeed, much of cinema would be improved by borrowing liberally from “Die Hard 2.” “Violent Night” is a simple movie, so there isn’t much else to say about the SW-15’s performance in it, except to say that it contributed nicely to the overall experience.

Violent Night mortal engines

The SW-15 reproduced the Earth-shaking rumble of the immense machines with an authoritative fervor.

Another movie that promised a lot of deep bass was 2018’s “Mortal Engines.” This film, based on a young adult book series, takes place in future future-devastated Earth where gigantic mobile cities on treads consume smaller towns. The plot concerns an outcast boy from the lower tiers of a mobile London. He meets with a rebellious fugitive young girl who is a part of a group trying to stop the roving, predatory cities from wreaking destruction. While the plot looks like boilerplate young adult fare, a big-budget film about gigantic moving cities should have a ton of deep bass, so I set out to see how the SW-15 could handle this peculiar setting.

The first thing that we hear as the movie starts is deep thumps as the Earth in the familiar “Universal Pictures” scroll gets wrecked by nukes, a sound that the SW-15 forcefully reproduces. We are then greeted by the city of London on massive tank treads chasing a smaller wheeled city and eventually ‘consuming’ it, a ludicrous sight that had me laughing out loud. However, it was a bass fest that gave the SW-15 a workout but nothing it couldn’t handle. The SW-15 reproduced the Earth-shaking rumble of the immense machines with an authoritative fervor. The movie had a nearly ceaseless pacing of action, so the subwoofer was never left without something to do. There were all manner of gigantic mobile craft, and all of them were recreated with a lively roar. Accompanying the action was Tom Holkenborg’s monumental orchestral score, a fitting match to the monumental setting, and the SW-15 gave the score the same robust treatment that it reproduced with the effects sounds. While I could complain about the plausibility of the movie’s setting, I can’t complain about the SW-15’s performance during any of it, certainly not for the pricing. It produced a pretty tremendous sound for not a tremendous cost.

Monoprice SW-15 Subwoofer Measurements

 

SW15 outdoor testing

Testing on the SW-15 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 67F degrees with 85% humidity. The subwoofer’s gain was set to maximum, phase was set to zero, and the low pass filters were set to maximum.

SW15 Frequency Response 

The rapid fall-off above 80Hz puts this sub at a bit of a disadvantage.

The above graph shows the measured frequency responses for the Monoprice SW-15 subwoofer. The most obvious aspect is that this sub has a relatively small bandwidth. Users might think that I mistakenly measured the SW-15 with the low-pass filter set to 80Hz, but this is not the case. I might characterize the +/-3dB window of this sub to be about 33Hz to 81Hz. I was a bit surprised about the SW-15’s lack of upper-frequency extension, but it gets the job done for most people who will be using an 80Hz crossover frequency to the sub. The port tuning frequency looks to be around the low 30 Hz range, and, like myself, I think room gain will shore the in-room response up to 30Hz but not much below that point.

The rapid fall-off above 80Hz puts this sub at a bit of a disadvantage. That means that the SW-15 isn’t really suitable for crossover frequencies above 80Hz. It’s NOT a subwoofer I would use with small bookshelf speakers that usually need a higher crossover frequency in order not to have a gap in the mid-bass response. However, those with full-sized bookshelf speakers as well as tower speakers should be fine. This lack of upper-frequency extension also works against multi-sub setups where placement can address acoustic problems above 80Hz.

SW15 CEA2010 table

Monoprice SW-15 CEA 2010 2-meter RMS

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.

The measured burst numbers for a $300 subwoofer are absolutely superb. I measured this sub on two separate occasions just to make sure the first measurement set was not a fluke or a mistake, but it measured similarly in both sessions. In sheer output, the SW-15 blows away all of the $500 subs that we rounded up recently. The only sub that isn’t outperformed at every single frequency is the BIC PL-300 which maintains a lead only around its adjustable port tune frequencies at 16 to 20Hz. That is pretty nuts considering the SW-15 is significantly cheaper than any of them and in many cases doubles their output. 

Bassaholic LargeSo why even consider other subs in this price range? One reason might be that those other subs keep their drivers on a shorter leash in terms of distortion. Yes, you can drive the SW-15 to huge output levels, but it does change tonality as distortion starts to creep in. That happens to most subwoofers, but the SW-15 is more subject to this effect than others. This can be seen in the THD percentage numbers as well as the harmonic limits. In the table above, the harmonic limit column has items in it at all frequencies except three. This means that the SW-15 could be pushed to surpass the distortion threshold for the stated harmonics for the CEA-2010 burst tests. These are pretty generous thresholds, so that means that the SW-15 can be pushed to produce a lot of distortion. However, these levels of distortion occur when the sub is pushed very hard. At nominal levels, it stays well-behaved, and those nominal levels are still relatively high. In other words, if we back down on the gain by 6dB from these levels, we are roughly at the maximum output level of the other subs, but now the SW-15 is much better behaved. So, in the end, you have a lot more headroom with the SW-15 but you have the potential for a lot more distorted output if you drive it hard.

This burst test data places the Monoprice SW-15 in Audioholics’ Bassaholic ‘Large’ Room Rating, meaning it should be able to handle a room of 3,000 cubic feet. For information on how the room ratings are determined, please read our article “Bassaholic Subwoofer Room Size Rating Protocol”. It is crazy to see a $300 subwoofer has snagged our large room rating!

SW15 CEA2010 table

The SW-15s mid-bass punch is unrivaled by anything close to its price point.

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 subwoofer is capable of.

The SW-15’s gobsmacking level of output is carried to continuous tones as well as short-term tones. This is a ton of SPL and, in sheer level, is what would be expected from much more expensive subs. It should be noted that the SW-15 becomes more nonlinear at the highest output level, and it wasn’t terribly linear to begin with. The ‘peakishness’ of the response looks like a product of inductance, and a sub of this pricing isn’t likely to employ the usual methods of fighting inductance such as shorting rings or copper caps which add significantly to the manufacturing cost. Nonetheless, it holds its nominal response shape nicely out to 100dB, which is very good considering its price. Its mid-bass punch is unrivaled by anything close to its price point.

SW15 CEA2010 table

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.

At nominal levels around 90dB, the SW-15 produces fairly clean bass. In this graph, it looks like distortion increases in the low-end as the drive level increases, but what is happening is that the noise floor of the testing environment is relatively high compared to the output of the sub at deep frequencies, so much of what is being reported as distortion at the 88dB and 94dB sweeps around 20Hz is just background noise. That being said, while this sub has huge output, it doesn’t have far-reaching extension, and if you do push it hard, it will run into distortion as can be seen in the higher-level sweeps. Distortion in mid-bass never becomes severe and doesn’t surpass 10% THD at any drive level. In deeper bass, the SW-15 can be pushed into higher levels of distortion, but it doesn’t really fly off the handle until just above 20Hz at maximum output.

SW15 2nd order harmonics

SW15 3rd order harmonics

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.

We can see in the above graphs that the main driver of distortion for the SW-15 is even-order harmonics until we get to the highest drive levels. That reinforces my previous guess from the peakish response that inductance is likely somewhat high in this driver. Inductance tends to inhibit one way of the driver’s travel and tends to rise at a steady rate with the drive level which is what we see here. This is not surprising in a $300 subwoofer. As we said before, addressing this issue is costly. Furthermore, inductance can actually contribute to output within a narrow range, and the SW-15 is probably using it to produce its tremendous output.

SW15 group delay 

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.

The SW-15 does pretty well in this test, even without considering the cost. While it does surpass our strictest 20ms criteria at around 35Hz, it does stay under 1 cycle down to 20Hz. Its lack of group delay above 80Hz is likely due to its rolled-off output in that range. The high delay below 20Hz is not anything to worry about since this sub doesn’t have much output at all in that range. In my listening, I didn’t notice anything amiss in the time domain such as laggy kick drums.

Monoprice SW-15 Subwoofer Conclusion

Before bringing this review to a close, I will briefly go over the strengths and weaknesses of the product under evaluation, and, as usual, I will begin with the weaknesses. Hammering the SW-15 for its weaknesses is a bit difficult because its pricing does shield it from a lot of normal criticisms. Indeed, for a $300 sub, we should be grateful for anything it does well. Nonetheless, we can state what it is and what it isn’t here. What it is not is a wide-band sub with a flat response. It drops off like a rock below 30Hz and above 80Hz and has a somewhat peakish response within that range. Not having a flat response isn’t a big deal for subs, since in-room acoustics will invariably mutilate the response anyway. However, not having upper-frequency extension does put limits on what kind of systems can be integrated. Buyers should make sure their speakers can reach down to 80Hz, and many small bookshelf speakers do not do that.

 SW15 hero6

Something else that I might consider a flaw, were this a much more expensive sub, is the very audible distortion that it will run into when played very hard. If you are looking for a sub that stays clean at any drive level, the SW-15 will not do that - but few subs anywhere close to its pricing would. On the other hand, it will cleanly reproduce sound at levels that other subs in its price range would struggle to touch. If it starts to distort the sound, just dial it back a bit and it will keep its cool. You can’t really complain much about a $300 sub that won’t playback 30Hz at 108dB and be clean as a whistle, since no other $300 sub can even get close to 108dB at 30Hz.

Monoprice badge2The build quality isn’t the highest, but it’s not at all bad for the pricing. The feature set is rudimentary, and, aside from the speaker-level connectivity, it doesn’t have anything beyond the bare minimum, which is fine for a subwoofer of its pricing. It only has a 1-year warranty, but again, this is not a luxury item that will be passed down from generation to generation. 1-year is pretty standard for consumer electronics, although a warranty extension for an additional fee would be a welcome option. It looks fairly plain, but anyone expecting a 15” subwoofer to be beautiful for $300 is out of their mind.

the Monoprice SW-15. It is a monster for the price.

So, yes, the Monoprice SW-15 is not perfect, but it is pretty darn good for a $300 sub. Let’s now list the stuff it does well, and its main strength is its astounding output capability. From 50Hz to 80Hz, it averages around 117dB. That is the only home audio sub that I know of that can accomplish that for under $1,000. The mid-bass punch is tremendous for the cost, and, as was said, nothing even close to its price range can touch that. Its deep bass is good for the price, but it doesn’t do much below 30Hz. Still, a 30Hz extension is not at all bad for $300. And its power at 30Hz still exceeds most subs that are double its cost. 

Apart from its sheer output, its clean playback at nominal drive levels is good. Until you push it hard, it produces very clean bass. And the nice thing about having so much headroom is that there is plenty of dynamic range in which to equalize it, so EQ boosts will not strain it (unless you boost it below 30Hz). Its time domain performance is also good. You would think that such a powerful yet cheap sub might sound quite boomy or sloppy, but that is not the case here. When set up correctly, it sounds very good.

I don’t know how Monoprice can afford to sell the SW-15 for only $300 and also include free shipping! I started this review by questioning the validity of its 600-watt amplifier spec. But its sheer output capability makes that claim plausible. It is not without its shortcomings, but its bang-for-the-buck is simply astonishing. The SW-15 is a beast. If you need a sub that hits hard for not a lot of money, and you can accept its size, you will not go wrong with the SW-15. It is a monster for the price.

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

  • StarStarStarStarStar — Excellent
  • StarStarStarStar — Very Good
  • StarStarStar — Good
  • StarStar — Fair
  • Star — Poor
MetricRating
Bass ExtensionStarStarStar
Bass AccuracyStarStarStar
Build QualityStarStarStar
Ergonomics & UsabilityStarStarStar
FeaturesStarStarStar
Dynamic RangeStarStarStarStarStar
Fit and FinishStarStarStar
PerformanceStarStarStarStarStar
ValueStarStarStarStarStar
About the author:
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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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