Monoprice Monolith M15-S 15″ Sealed Subwoofer Review

Monoprice Monolith M15-S

By Jim Wilson

{picture courtesy of Monoprice}


Introduction

The subject of this review is the Monoprice Monolith M15-S subwoofer. Released just recently, the M15-S is a sealed model in the same family as the ported version that first appeared about 1 1/2 years ago. The M15-S measures 23.5″x17″x21″ (HWD) and weighs a little over 80 pounds. Motivating the front-firing 15″ driver is a Claridy 1000 watt RMS class D amplifier that’s capable of almost 2000 watts peak. Stated frequency response is 20-200Hz for THX mode, 16-200Hz when using Extended mode.

You can buy the M15-S directly from the Monoprice website for $1349.99. They do have an Amazon store as well, although the entire Monolith line doesn’t seem to be available there. Warranty is 5 years for the driver and amplifier. They also offer a 30 day in-home trial with a money back guarantee.


Unboxing

If I’m spending over $1300 for a subwoofer I expect it to be well protected on the journey from the manufacturer to my front door, and thankfully Monoprice feels the same way. Before you can play with your new toy you will have to free it from the outer box, which is of the double-wall thick variety. Once inside that you’ll encounter yet another box, which is also double-walled. Cut open the inner box and you’ll find custom molded 2″ medium density foam protecting the entire top and bottom of the sub. Remove the top portion and then take out the thick L shaped cardboard pieces which are strategically positioned to prevent any vertical loads from crushing the M15-S. Placed on each corner of the foam protectors are additional cardboard guards of the same thick material to defend against crushing there as well. Once you finally slide the subwoofer out of the inner box you still have to free it from the cloth bag that protects the finish (the grill is packed in its own cloth bag). Be sure to set aside a few minutes when you’re unpacking the M15-S because you’ll likely need it.

The only accessory is a power cord. No manual is included but a PDF is available from the Monoprice website. The manual covers 10″, 12″ and 15″ models for both the sealed and ported alignments. It goes over all the dials, knobs and settings along with the various connection options and even some placement suggestions. The specifications at the end of the manual reference each model as a 5 digit part number with no obvious way to correlate it to the subwoofer you own other than a connect-the-dots concept from the images and part numbers on the first page. I understanding the reason behind consolidating everything into a single manual but perhaps some consideration should be given to separating them by sealed and ported at least. From my perspective, a subwoofer in this price class should probably have more focused documentation.


Impressions

Until recently Monoprice was mostly known for very inexpensive products, and their house brand subwoofers were certainly no exception. A complete 5.1 home theater package consisting of both speakers and a subwoofer that cost a mere $200 are not uncommon for them, but in the recent past Monoprice has been expanding beyond those modest roots and have begun branching out into some competitive markets. To an extent Monoprice’s move ‘up market’ reminds me of the Genesis car brand, a Hyundai premium line launched in 2015. Hyundai, long known for somewhat generic entry level cars and SUV’s, wanted to extend their reach and offer vehicles to the more affluent so they created Genesis. When I first saw what Hyundai was attempting I thought “I wonder if this venture will succeed when their name is firmly associated to a bargain image”. Years before Toyota, Nissan and Honda had all done something similar but each of those established Japanese car manufacturers created new companies for their upscale ventures (Lexus, Infinity and Acura, respectively). Hyundai didn’t, they sold the first Genesis cars as Hyundai’s. Thus far that has proven to be an unwise choice as the Genesis line has done very little for them, despite the cars themselves being considered solid offerings for the price. Will Monoprice suffer that same fate? It appears they are straddling the line between both approaches; selling Monolith-branded speakers and subwoofers yet still clearly referring to them with the Monoprice name. Sometimes a reputation is a hard thing to overcome.

For about a year and a half Monoprice has been selling a ported version of the Monolith. Widely acclaimed for its performance, the new subwoofer line quickly gained fans and converts so it seems they dodged the Genesis bullet that time. Recently they released sealed versions of the Monolith which begs the question “can lightning strike twice”? History suggests not; the ported Monolith subwoofers were a substantial leap forward from anything Monoprice was selling, and typically a company does not make such a huge gain without luck factoring in heavily. Doing it twice then is highly unlikely. Or maybe these folks sweat the details and it’s less about luck and more about execution. Perhaps due diligence and hard work are how they attain results. Something fairly easy to overlook on their website gave me a glimpse of the answer.

Proudly displayed is a THX Ultra certification. What that means is the M15-S has successfully passed a battery of stringent tests that gauge output, accuracy and distortion. The Ultra designation means it’s able to achieve those results in a 3000 ft^3 room, not a small space by most measures. I can understand why the ported 15″ version was able to fulfill the THX Ultra requirements, but for a sealed subwoofer with a single 15″ driver to achieve those results is quite an accomplishment. Few manufacturers submit their subwoofers for THX certification however, so there are those who dismiss its relevance, but I applaud Monoprice for going the extra mile. To me it says they aren’t afraid of the scrutiny and are willing to have an independent organization verify their products. That has to stand for something.

One thing I noticed instantly after unboxing the Monolith M15-S is it looks a bit different, and you know how I like the unconventional. Let’s start with the cabinet dimensions; it’s tall and deep but not very wide, asymmetrical in some respects. Where the horizontal and vertical side panels converge there are 45 degree junctions so it’s not merely a simple box or cube shape. Finished in a black ash PVC it has a rather unique yet commanding appearance; you know it’s there but it’s not obtrusive.

The grill breaks from convention as well. It’s held in place with 6 pins instead of the typical 4. In reality those 6 pins are stand-offs that suspend the grill 1″ from the front panel, making it appear to float off of the cabinet (Monoprice actually refers to it as a ‘floating grill’). At first that seemed a bit strange, but quickly I came to appreciate it. On the test unit the top 2 pins didn’t fully seat and pushed the grill outward just a smidgen. Visually you couldn’t tell – and it never rattled no matter how high I pushed the volume – so it’s likely more of an anomaly than anything else. The grill frame is made from 1″ painted MDF and proved to be very sturdy. Monoprice affixed a silver company logo centered along the bottom that artfully breaks up the black-on-black appearance.

{picture courtesy of Monoprice}

Visually I like what they’ve done here; in spite of the M15-S being on the large side, relative to its competition, this subwoofer blended into my decor seamlessly. How something looks and its dimensions are important of course, but when push-comes-to-shove the driver and amplifier are where you want a manufacturer to have spent the majority of their time and effort. Monoprice has that covered.

The driver uses a black painted cast aluminum frame with 6 massive spokes. Add to that a triple-stack Y35 ceramic magnet structure that weighs 216 ounces – an impressive 13.5 pounds – and you have the makings of a beast. The cone is a composite made from layers of long fiber pulp and fiberglass to create a lightweight yet rigid material. Monoprice uses a large half-roll surround made from NBR (Nitrile Butadiene Rubber), a copolymer renown for strength, elasticity and ability to withstand a wide range of temperatures. The driver is rated to 50mm (2″) of linear mechanical travel. I can’t verify if it is capable of moving that much but I can tell you I had the grill off on more than one occasion just to watch it in action and the thing has quite a bit of travel.

The amplifier Monoprice uses for the Monolith M15-S is huge, taking up 3/4th’s of the back panel.

{picture courtesy of Monoprice}

It’s mounted flush to the enclosure and uses no heat fins. All of the adjustments are neatly arranged in a horizontal line across the very top. Everything is logically organized and laid out well. There are dials for Crossover, Phase and Level (gain/volume) along with toggle switches that control the Crossover type, Power setting and EQ mode. The crossover dial has clearly marked delineations for 40Hz, 50Hz, 60Hz, 70Hz, 80Hz, 90Hz, 140Hz and even 160Hz. Phase shows 0°, 90° and 180° with dots (but no numbers) at 45° and 135°. The Level control is equally clear showing -20dB, -18dB, -12dB, -6dB, 0dB, +6dB and +15dB. There’s an additional position for THX which is used in conjunction with the EQ and Crossover toggle switches when they’re also set for THX. The power switch does what you expect it would, with settings for either auto/standby or always on.

At the very bottom of the amp, also neatly grouped in a horizontal line, are the inputs. There are dual unbalanced (RCA) connectors, one each for LFE and line in. Next to those are a pair of balanced (XLR) connectors, one for input and the other a pass-thru so you can presumably daisy chain multiple M15-S subwoofers. I spied another connector labeled Service Port. It’s a 20 pin male positioned toward the top of the amp. The owner’s manual doesn’t mention it, so I’m uncertain as to its purpose, but my guess would be that Monoprice uses it for diagnostics and troubleshooting (think OBD-II port, but for a subwoofer rather than your vehicle). It’s possible it can be used to update the firmware as well, but that’s purely speculation on my part.

Setting the Level, Crossover and EQ switch to THX makes the M15-S perform within THX certified parameters. The output and extension are changed in this configuration and for those who want the least amount of distortion it’s the way to go. You’ll find later in the article that I did try THX and Extended mode back-to-back and noticed a difference so you should experiment to determine the best setting for you. The auto on/standby functionality is pretty reliable and almost always worked the way I would like it to have. According to the documentation the M15-S requires a full 30 minutes of no input before it goes to sleep and that seemed to be the case for the most part. On occasion it did drift off while I was watching sports programming, which at this time of year means mostly car and motorcycle racing. Admittedly those programs are primarily commentator banter, and contain little in the way of frequencies a subwoofer is likely to be called upon for, so the occasional lapse in concentration is not unexpected. The M15-S wakes up quickly with just the slightest ‘click’ when aroused from slumber. Interestingly, the volume required for that to happen was higher than the volume necessary to prevent it from having a siesta in the first place.

Monoprice goes the extra mile by using HDF (High Density Fiberboard) instead of MDF (Medium Density Fiberboard) which is what you typically find used for subwoofers. The enclosure has 1″ thick walls with a 2″ thick front panel. There is a full perimeter window brace in the middle that adds further structural integrity. The interior walls are lined with foam sheets of damping material.

{picture courtesy of Monoprice}

When you consider the size of the cabinet and driver weight the Monolith M15-S is not as heavy as I thought it might be. The knuckle rap test on both the horizontal and vertical panels was fine, but I half expected a more dead/muted sound. Construction quality was first rate with not a single issue to be noted. Similar to the grill, with 2 extra pins, the M15-S has 6 feet instead of the proverbial 4 you find on most other subwoofers. Somebody at Monoprice was apparently paying attention to the details.


Listening

Is this thing a ported sub? More than once I found myself asking that question. Sometimes it sounded like it might be. Typically a sealed subwoofer has a more subdued approach, being less conspicuous than its ported brethren. The Monoprice M15-S occasionally blurred the distinction between sealed and ported, growling at me like it was angry one minute and then hanging back the next. A bit schizophrenic. That’s a compliment though as I’m not a big fan of in-your-face subwoofers, I prefer a more subtle approach to low frequency. That doesn’t mean I’m OK with weak subs, only that I gravitate toward refinement over noise.

Another thing I like about the Monoprice M15-S is how it acts when it has nothing left to give. The sub is not afraid to play loud – it almost seems to enjoy the extra volume – yet it steadfastly refused to go beyond what it was designed to do. No matter how hard I hammered the M15-S it simply would not make a bad sound. Monoprice programed their limiters to perfection, eking out all the performance they could while still protecting the driver from damage. That may sound easy to do but I can assure you it’s not.

Part of the impressive capabilities are likely due to the physical size of the enclosure; cabinet volume has a lot to do with acoustic performance, and unlike some of their contemporaries Monoprice has not shied away from large cabinets for their Monolith series of subwoofers. While they ultimately may not win many WAF (Wife Acceptance Factor) battles the company is probably not too concerned about it. Interestingly, because of the narrow profile the depth and height of the M15-S isn’t as obvious as you may think. An optical illusion perhaps, but it didn’t stand out as much as I initially assumed it might. Visually anyway, when it was time to make a ruckus the M15-S became conspicuous. Best of both worlds? I’ll take that 10 times out of 10.


Movies

How to Train Your Dragon

Historically animated movies have some of the best soundtracks, and How to Train Your Dragon is no exception. HTTYD is set in the time of Vikings and is about a small village of people who inhabit the island of Berk. They’re besieged by dragons who steal their food and torch buildings, so naturally this makes them public enemy number one. The clan’s leader, Stoick the Vast, has vowed to eliminate the threat. Unbeknownst to him is his very own son, a klutzy kid named Hiccup, has gone and befriended one of the aerial flamethrowers who he names Toothless. Naturally that leads to all kinds of drama and intrigue as Hiccup tries to keep it a secret from his father. Everything comes to a head when Stoick decides to meet the threat head on and confront the dragons so they can end the problem once and for all.

Scene 15 is where things get interesting. The Vikings sail to the dragon’s home where they are deeply ensconced in a mountain. In order to get at the enemy the Vikings have to blast it open. They begin their assault with catapults, hurling large boulders that crash into the mountainside. The M15-S immediately let me know it was ready to play; the rumble from the catapult launch and the impact of the boulders was formidable yet clear. That part is fairly challenging, but what happens next forced the Monolith to give me all it had. And “all it had” proved to be a lot.

When the Vikings finally crack open the mountain hundreds of smaller dragons escape and fly off into the distance. Thinking the battle has been won they begin to relax. Bad idea as the dragon they need to concern themselves with – the aptly named Red Death – awakens and launches itself out of the mountain to confront the men. At the volume I typically use when doing these evaluations it’s scenes like this that tend to highlight any deficiencies. Monoprice has clearly done their homework because there were no weaknesses detected. Quite the contrary actually, the Monolith M15-S treated me to a rousing performance on some difficult material by being both impactful and articulate.

Red Death is massive, half the size of the mountain itself. In order to portray that immensity you need a subwoofer with stones, and the M15-S has them. Red Deaths every footstep hit with a resounding thud, including the essential floor vibrations necessary to make the scene believable. At one point it takes to the sky in order to battle Hiccup and Toothless. Every wing flap from the massive beast caused the driver to pulsate widely, yet at no time did it lose composure. Their dogfight culminates when Red Death plunges into the ground, an effect reportedly so deep it has fundamental tones in the single digits (less than 10Hz). While the Monolith wasn’t quite able to handle that part of the soundtrack, it didn’t trip all over itself trying to do something it wasn’t designed for. The M15-S went as far as it safely could and then reined itself in. For me, that’s perfect.

TRON: Legacy

THX Ultra certification should mean a subwoofer is able to handle difficult material at volume without sounding as though it’s drowning. Since TRON: Legacy has a soundtrack that can be pretty obnoxious at times this is one of the first movies that came to mind. I plan on not only being very critical of the overall sound quality but also the magnitude of… oh who am I kidding, I’m going to crank it as loud as I can. Let’s test those limiters again and see what that certification gets us, shall we?

Released almost a decade ago, TRON: Legacy is still an audio and visual tour de force. Set in a parallel universe the TRON world is a video game come to life, and like some examples of the genre there is a lot of violence. Battles usually mean good subwoofer tests however, and this movie is no exception. Kevin Flynn (Jeff Bridges), the inventor of the TRON game, gets trapped inside his own creation by his digital doppelganger CLU (Codified Likeness Utility). Sam Flynn (Garrett Hedlund) inadvertently joins him years later when he stumbles upon a computer console buried in the basement of his father’s video game arcade. This is where I started the evaluation in earnest.

While innocently typing commands into the computer Sam unintentionally keys in a sequence that transports him from the here-and-now into the world of TRON. Almost immediately he gets picked up by a patrol that just happens by as he runs out of the corresponding arcade inside this alternate reality. His sentence for being a ‘stray’ is to fight at the Games, a death match between programs. As Kevin steps into the floating arena the EDM music created a pulsating sound that reverberated throughout my room. It was strong yet not objectionable, which is just how I like it. Equally impressive were the disc wars that ensued. As the battle raged the intensity of the soundtrack escalates, yet despite being pummeled the M15-S never sounded annoyed, never became unpleasant.

Sam survives the Games only to be confronted by CLU himself and forced to participate in a Lightcycle battle. Fireworks herald the beginning of the confrontation and they produced a very satisfying vibration that rippled through my chair as they exploded. I consider this few seconds of the scene to be critical when evaluating a subwoofer. With all the other noises going on during this part the kick from a good sub really emphasizes the pyrotechnics. The M15-S did a very solid job of making sure you knew those fireworks were exploding, the embodiment of controlled aggression.

Given the difficult nature of the TRON: Legacy soundtrack this was one of the few times I ran back-to-back tests using the THX and Extended mode. THX actually did seem a bit clearer, although a little less potent. Extended mode lost some clarity but the extra punch was evident. Not night-and-day obvious, but different enough to suggest the settings Monoprice programmed into the two modes do have some variations. FWIW, I settled on Extended because… well, I like deep bass too after all.

Black Hawk Down

I honestly didn’t want to use this movie as it’s been featured in 3 reviews during the past 5 years, but for whatever reason I kept picking it up as I was rummaging through my collection looking for difficult material. Perhaps it was purely selfish of me – maybe I just wanted to watch it because I like the movie – but whatever my rational it always seemed near at hand. I typically consider something like that to be an omen so I ultimately decided to go with the flow. Besides, I can test the Monolith limiters one final time. Can you say “Irene”? Yea, you knew that was coming.

Released in 2001 – can you believe it’s been 18 years already? – Black Hawk Down is a stylized recreation of a real world conflict. During the early 1990’s a ruthless warlord named Mohammed Farrah Aidid was responsible for the massacre of several hundred thousand people in Somalia. The United States reasoned it was high time this man met his maker so they sent in some of the most elite members from our Special Forces; Army Rangers and Delta Force. Things don’t go according to plan unfortunately and the teams quickly find themselves in the battle of their life, or should I say for their life.

I like the way this movie slowly builds, allowing the characters and story to form naturally; it walks, then jogs and finally runs. Once the action does start it barely lets up, and of course that change of pace is heralded by the famous (infamous?) Irene scene. This section of the movie was perhaps the most obvious example of the Monolith limiters, but more on that later. Once the call to action goes out – “All units Irene. I say again, Irene” – the sound engineers upped their game.

It starts with the rotor blades from the choppers hovering overhead, something the M15-S seemed to enjoy; they were not only potent but very clear. Things quickly switch to the base as US forces board ground and air transports. During a scene like this you want the various elements to differentiate themselves, to create a layered sound and emphasize the individual facets similar to what you might experience from the real world event. It was here that the limiters made themselves most known.

I went over this section of the movie several times, increasing the volume on each pass. From an initial setting I would call medium the M15-S shined, providing all the detail and bass anyone could expect. It was both rich and precise, and I loved every minute of it. Replaying the scene and upping the volume a bit showed those same qualities, albeit with more output. Going beyond high and approaching stupidly loud the M15-S started to apply the brakes, backing off and refusing to lose its cool. The speakers I was using while evaluating this subwoofer have limits beyond what my ears can handle so I figured it was time to do a little experiment.

I grabbed a handful of the most punishing bassfest movies I own and subsequently repeated the same process I had used with Black Hawk Down; find a particularly brutal scene, start at a medium level and replay it several times increasing the volume with each pass. I’ll be darned if the Monolith M15-S didn’t behave the exact same each time. It would go from good, to great to done without ever making a bad sound. That’s exactly what I want from my subwoofer; give me everything you have then gracefully, and without drama, simply stop getting louder. Excellent job Monoprice, excellent job.

What you generally find at this point in my reviews is a line that begins with “After all the testing had concluded I checked the amp to see how hot it had gotten”, and this time will be no exception. Sort of. I did check the amp for heat at the end of the movie tests, but what’s different is how long the testing portion was. Because I went a little nuts trying to trip up the limiters I eventually spent the better part of 2 hours torturing the M15-S so when I reached around back to see how warm the plate was I half expected to be pulling my hand away pretty quickly. Nope. While it wasn’t cold to the touch, it wasn’t hot either. I could easily lay my palm on it and hold it there without issue. I’m beginning to like this subwoofer. Perhaps I shouldn’t say that just yet, not until I hear what it can do with music.


Music

As you’re all painfully aware by now, I am a music junkie. No matter what a subwoofer can do with movie soundtracks if it doesn’t delight me when it comes to music than yours truly is not a happy camper. Guess what I’ve been doing almost the entire time I was writing this article? Did you answer “listening to music”? If so then I would reply “why yes, I have been”. I’m not quite prepared to call the Monolith M15-S “musical” – a designation I bestow on very few subwoofers – but I can tell you it certainly held its own here.

Because it had proven very capable thus far I decided to do the opposite of what I had done with movies, namely mix things up. I’ll bet you’re surprised. No, I’ll bet you aren’t. With movies I opted for torture, but when it came to music I changed my approach. There will obviously be some deep material, but there’s also lightning fast passages and even a what-the-heck song. The qualities that make a subwoofer proficient with music are not necessarily the same qualities that make it excel with music, at least not the type of music I favor. Since I’m already pounding the M15-S though perhaps I’ll start with something merciless and work my way up to (down to?) the easier stuff.

Bottom Dweller, Dub King 

The Dub King – aka AVS forum editor Mark Henninger – produces his own electronic music. Mr. Henninger has no governor and appears to deliberately create songs with zero concern for what they can do to your subwoofer. He’s remorseless; some of his stuff shows no quarter so naturally I’m drawn to them. I wouldn’t be surprised if I’ve used his creations in half a dozen reviews already, so why stop now?

In a recently posted article Mark used Throbberizer and So Low Project to test a system he was evaluating so I’ll avoid those. Some of his other offerings I’m familiar with are Halloweener, Dub Kingdom Come, Dead Serious and Funkenspelunkin. Given I’m yet again going to test the Monoprice limiters – while simultaneously gauging detail and precision when I push this thing to the brink – I opted to go with a song called Bottom Dweller. If Mark is reading this he’s likely nodding his head and saying something along the lines of “yea, good choice”.

When he created this song I wonder if there was a moment of compunction because he includes a disclaimer about how it may cause damage to your system (and not once, but twice you hear a synthesized voice give a warning). Pay heed or risk the consequences. Of course I didn’t do that. The first assault to your senses doesn’t come until roughly the 1:40 mark, at which point you understand the reason behind his public service announcement. Somewhere around the 1:55 mark it gets even more challenging, or it should have been anyway, but the Monolith seemed nonplussed. Remember earlier when I said “is this thing a ported sub”? Insert that question again here. It basically laughed off my attempt to find a weakness; I have never heard a 15″ sealed subwoofer do what the M15-S was able to do with this punishing material. Wanna have some fun? Buy this subwoofer, download Bottom Dweller, remove the grill, crank it up and sit back and watch how far that driver moves. Except for the ‘buy’ part that’s exactly what I did. Deep bass, prodigious output and poise is a hard combination to beat.

The Shattered Fortress, Dream Theater

There’s probably never been a band quite like Dream Theater. Their songs were totally unique, routinely putting half a dozen rhythms in a single 15 minute number. Sometimes it seemed like this group didn’t have any structure whatsoever, it was as though they just started jamming and recorded whatever happened. On occasion their songs lacked cohesion in my opinion – switching to something completely different without warning – but when they got it right boy did they get it right. I can’t even begin to imagine how hard it was to play these songs live.

The three longest term members of the band were John Petrucci, John Myung and Mike Portnoy. Not coincidentally, they were the founding trio. The story is they met at Berklee College in Massachusetts. I think Petrucci and Myung have been with the band for their entire 35+ years of existence. Drummer Portnoy, perhaps the most famous of them, left about 10 years ago. He’s the primary reason I chose a Dream Theater song for this article. Mike reminds me of Neal Peart of Rush, a person who was born with something the rest of us didn’t get. He has abilities that can’t be taught, you either have those skills or you don’t. Sometimes it seems as though he’s attacking his instrument and that’s beneficial when doing a subwoofer evaluation. Since it’s the same mentality I happen to have for this review I figured a DT song has to be part of the list.

From the bands Black Clouds & Silver Linings disc I went with The Shattered Fortress. Unless you have a taste for aggressive music don’t bother searching the interwebs for this one. If you’re a Dream Theater fan though this is definitely your type of song, a 12 minute blur of changes and impossible-to-do-live rhythms. That is precisely why I chose it. I won’t waste your time trying to put into words the flow of this song – because I can’t really explain it – but I will say this; the Monolith M15-S never missed a beat, no matter how out of control things got. And make no mistake, they get out of control on more than one occasion. Regardless of what Portnoy, Petrucci, Myung and company attempted to impose upon me the M15-S didn’t seem the least bit fazed. While to some that might seem like a lukewarm endorsement it’s anything but. If you can stomach high-energy songs like this try it on your system and see what it can do. The subwoofer I’m listening to now did an excellent job, thank you very much.

Hocus Pocus, Focus

Do you recall me mentioning a what-the-heck song? This is it. Hocus Pocus may actually be more of a what-the-#$%^ song for some. For a select few reading this there will be an “I remember that one!” moment, but the vast majority will be left scratching their head. I’m not certain there has ever been a rock song quite like Hocus Pocus. The best way to describe it is to say you take a heavy metal band, combine that with a guitar shredder and then mix in some… well, polka-esque music and you have this very unique song. Mull that over for awhile.

The Dutch band Focus was the epitome of a one hit wonder; Hocus Pocus was it for them, and even their one claim to fame was polarizing. For most people it’s considered that song; the one which gets stuck in their head, like it or not. For those of us who are a certain age it is undeniable. How many songs have an accordion, fuzzed guitars and yodeling? Yes, yodeling.

Released in the early 1970’s, Hocus Pocus garnered almost no airplay for the first few years. If you ever heard this song you’re probably not shocked as it seems unlikely to have any mass-market appeal. But funny things tend to happen when you create something as off the wall as Hocus Pocus; you may accidentally find an audience, and this song certainly did. Its quirky nature is not what made me choose it for this evaluation – OK, perhaps that’s partly the reason – it’s mostly due to how they recorded it. For a track fast approaching 50 years old Hocus Pocus has an unexpectedly good mix, replete with a lot of bottom end. Can you say subwoofer test?

So how did the Monolith comport itself with this ridiculous material? In a word, brilliantly. Although the rhythm section is fairly simple, the bass guitar and drums have a prominent role. If the bottom end is done poorly Hocus Pocus simply doesn’t work (assuming this peculiar song ever does work of course). But fear not because the M15-S never faltered. After almost 7 minutes of odd time signatures and unconventional changes this subwoofer only wanted me to play it again, so I did. More than once I might add, and at ever increasing volume each time. It seemed to be enjoying itself as much as I was. At the end of the day, can you really ask for anything more than that?


Conclusion

Earlier I questioned whether Monoprice could make lightning strike twice. Their Monolith ported subwoofers were an instant hit, able to stand toe-to-toe with the more established competition, but could they do the same thing with the sealed version? The answer is yes, they most certainly can. The Monoprice Monolith M15-S is a winner. It’s not the least expensive option, nor is it the smallest, but it certainly has what it takes to bring a smile to your face. It has a distinctive appearance, sounds really good and cannot be tripped up. In tennis terms that would be considered game, set and match. You’re gonna like the M15-S.

These measurements were taken using an Omnimic. The Monoprice Monolith M15-S was positioned in the center of my listening room with the microphone 1 foot from the drivers dust cap. The crossover was disabled, phase set for 0° and the level at 0dB. The AVR volume was slowly increased until the microphone started to clip, at which point it was backed down 1dB.

Frequency response: black line is THX mode while the blue line is Extended mode

Spectrogram: THX mode

Spectrogram: Extended mode


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