MonAcoustic SuperMon Mini Bookshelf Speaker Review

I knew very little about Mon Acoustic except that they were a high-end loudspeaker manufacturer based out of Korea, so I was a bit surprised when Audioholics editor-in-chief Gene DellaSala asked if I wanted to review a pair of their speakers. With enclosures made from aluminum, these are not your typical loudspeakers; to be honest, they are not quite like anything I have dealt with before. The metal cabinet is only one of the unusual design characteristics of their speakers, and there are a host of others that we will cover in this review of the SuperMon Mini. The Mini, as its name indicates, is a small loudspeaker designed for small rooms or desktop systems. At $2k per pair, they are geared toward those interested in luxury products and want to get the most out of a small space. They are manufactured and hand-assembled entirely in Korea. With an all-aluminum cabinet, the luxury aspect is certainly there, but what about the other elements that comprise a loudspeaker? That is what we will be examining in today’s review.

Packing and Appearance

The SuperMon Mini speakers arrived in a heavy-duty cardboard box. The speakers were fitted in some pockets of a soft polyurethane foam bedding. Most speakers ship in stiffer polyethylene foam packing, but that is to hold the speakers in place since normal hollow wood enclosures can not endure being thrown around as much as these metal cabinets. The goal of Mon Acoustic’s packing is more geared toward protecting the speakers from scuffs and scratches rather than protecting the cabinet from jolts and shock since these aluminum enclosures are far more solid than normal speakers and that isn’t as much of a concern.

 

Once unpacked, we are presented with some very upscale speakers that have a glistening aluminum body. The speakers that I was sent have a lilac-colored front baffle that gives them some flair, whereas an uncolored metal baffle might be a bit too business-like for some people’s tastes. Side panels have an undyed metallic luster, and there are some machined stripes on the sides. Custom colors can be ordered for an additional cost. There are many different colors available, and customers should get in contact with Mon Acoustics to order their desired color. These speakers have a stylized industrial look that would fit in nicely with modernist interior decor. They do not come with grilles, but there would be little point in buying a speaker with such a high-class metal exterior only to hide it behind some boring fabric. The front baffle has a shallow beveling at the top for a slightly sleeker look. I would imagine this shaping is aesthetically important since the wholly flat front baffle might be a bit blunt looking. Longitudinal edges have a rounding to help soften the appearance. An AMT tweeter is sunk into a deep waveguide that has a steep inward beveling, and the silvery woofer is sunk into the front baffle with a 90-degree beveling. The quality of the milling is excellent throughout. A Mon badge is printed in the lower part of the AMT plate. Screw heads are tastefully hidden by some magnets that make it look like the speaker was bolted together with flat head rivets that are flush with the front baffle. That is a beautiful attention to detail which is befitting the cost of these speakers. Model labeling and serial number are laser-etched on the rear. The SuperMon Minis look like they would serve well as a business executive’s desktop system. The aesthetics can not be faulted; these speakers look terrific.

Design Analysis

The SuperMon Mini is an unusual loudspeaker not just in enclosure composition but in the overall design. The base description is that it is a 2.5-way small bookshelf speaker with a number of unusual design choices. The obvious departure from the speaker design norm is the use of aluminum as cabinet construction material, so we will start our design analysis there before getting into the other unseen divergences from typical design practices. Aluminum is a great material to use as a loudspeaker enclosure when weight is not a consideration. It is very dense and so will make for an inert and resonance-free enclosure, and it is highly corrosion and heat resistant, especially the grade 6061 alloy used by Mon Acoustics. Furthermore, aluminum is also a great material for heat transfer, so the aluminum enclosure can also serve as a heatsink to disperse thermal buildup from the driver motors, and that should help dynamic range a bit by reducing thermal compression. The front baffle is 0.7” thick, the rear plate is 0.6” thick, and the side panels are 0.3” thick. There is also windowpane bracing around the midsection which is a part of the aluminum extruded main structure instead of being an additional welded piece. There is a spot-welded frame to hold the inner woofer which would add to the rigidity of the cabinet.

The internal construction wouldn’t be bad if these speakers of this size were made from some composite wood, but using aluminum with that thickness makes them positively boulder-like. On top of that, there is a fair amount of open-cell foam used as acoustic that lines the enclosure walls as well as the port. Anyone worried about panel resonances at all can breathe easily with the SuperMon Mini since this enclosure will be totally inert and vibration free. 

Some readers will see that 2.5-way design description and wonder where the other woofer is, since 2.5-way designs use multiple woofers, but only one woofer is visible on the Mini. This is where the term ‘isobaric’ comes in. Isobaric derives from Greek and means the quality of having equal pressure. For an isobaric loudspeaker design, the equal pressure refers to an air mass suspended in a chamber that is sandwiched by two active drivers which are moving in phase. So the Mini’s other driver is hidden and is mounted behind the exposed woofer at a halfway-deep point in the enclosure, and the two drivers enclose a sealed pocket of air between them. The reason to use this design is to get deeper bass from a small cabinet. The effect of having a pocket of air with unchanging pressure between two drivers is that the system retains a lower resonant frequency in a smaller cabinet by doubling the moving mass yet halving the compliance. It is like using one driver with a heavier moving assembly but a larger and softer suspension; it will have a low resonant frequency although at the cost of efficiency. The efficiency cost is minimized with an isobaric system since it halves the impedance and sensitivity.

Mon Acoustic’s take on an isobaric system is a bit different since the rear woofer has a low-pass filter and is only generating bass frequencies. That technically means that the air pocket between the woofers is not strictly static, because the excursion from the outer woofer is not matched by the inner woofer. But the volume of air needed to be moved to produce bass is much greater than higher frequencies, so the air pocket is largely being pushed around in a uniform manner due to the low frequencies for the most part, and the principle still holds. 

 

Using an isobaric system makes a lot of sense when metal is used as a cabinet material. Mass and weight add up very fast as the enclosure grows larger. Indeed, even though the Mini’s are quite small, they still weigh 11.5 lbs. each which is what I might expect of a well-built bookshelf speaker of twice their size. What is more, the outer woofer on the Mini is being tasked with playing up to treble frequencies, so a heavy driver wouldn’t have been an option since it could not serve as a wideband driver. The weight needed for a single driver to hit a lower resonant frequency in a small enclosure would have prohibited the ability to produce the midrange or treble frequencies that the engineer wanted.

The internal driver of the SuperMon Mini loads a port, and the port uses an elliptically shaped tube instead of a straight cylinder. Research by JBL and Bose has shown that similar-shaped ports will produce less turbulence than simple cylinders with some flaring on the ends. The port used by Mon Acoustics is a step up from the usual cylinder. The port is roughly 3” deep with a 1 ¾” diameter, and with dimensions like that, it is bound to have a somewhat high tuning frequency.

The crossover between the woofer and the tweeter is quite high at 6.8kHz. That means the tweeter is relegated to producing high treble only, and the vast majority of sound from the Mini will be coming from the woofer. With such a wide frequency band, a special wide-range driver is needed, because even though the woofer diameter is small at 4”, most 4” drivers would run into break-up modes by 6.8kHz. Break-up modes are the behavior that the cone starts to exhibit when it is moving so fast that it can no longer hold its shape. Larger cones will bend and flex at very high-frequency movement, and the frequency at which these break-up modes set in decreases as the size of the cone increases. The woofers used are 4” wide-range MarkAudio drivers. MarkAudio specializes in wide-range drivers that can maintain good performance out to high frequencies, so Mon Acoustics picked a good driver brand for this task.

One reason for giving the woofer such a wide-frequency range is that there will be no problems associated with a crossover circuit anywhere near the most important frequency bands. Most harmonic spectra from common musical instruments as well as human speech and singing are very low in amplitude by 7kHz. That means that the vast majority of the sound from these sources will be reproduced by the Mini’s woofer and not the tweeter. The advantage of this design decision is that there will be no phase rotation right in the middle of this important frequency range. Most 2-way or 2.5-way speakers have their crossover frequency somewhere between 2kHz to 3kHz, which is right in the middle of the spectrum of many human voices as well as acoustic instruments. The problem with that is, even if the crossover circuit is perfectly executed so that the frequency response exhibits no sign of the crossover point, there will still be phase rotation around the high and low pass filters used to create the crossover. While it was previously thought that phase distortion was not a major audible problem unless it was extreme, there has been some research in the last few years that suggests these types of phase artifacts can degrade speech intelligibility. In other words, the SuperMon Mini should have excellent speech intelligibility due to the absence of a crossover circuit in a common speech frequency spectrum.

 

The crossover itself uses some very heavy-duty components such as Mundorf large film capacitors, air-core inductors, and massive resistors. The robustness of these components is very likely overkill, but it’s better to have it and not need it than to need it and not have it. These are all very low-tolerance components, and given their size and build, the capacitors should hold a stable capacitance value for a very long time to come instead of drifting in value like a ceramic capacitor. These large film capacitors are much less affected by heavy use, so they won’t get hot and change their value from thermal effects.  

While the Mini is a small speaker, it is using some pretty beefy five-way binding posts. When I asked Mon Acoustics how much power the Mini’s could handle, they advised 30 watts from tube amps, 100-200 watts from class AB, and 150+ watts from class D. Over 100 watts seems like a lot for such a small speaker, but the isobaric woofer system plus an AMT tweeter should be able to take a lot more power than a typical small speaker.

The Mini’s tweeter is a small AMT tweeter. It is crossed over at such a high frequency that it almost functions more as a supertweeter than a normal tweeter. The tweeter is sunk into a steep waveguide that has been milled into the front baffle. This waveguide looks like it is serving a contrary function to the 4” woofer. The woofer is bound to have wide dispersion out to a high frequency, whereas the waveguide on the tweeter looks like it would significantly restrict dispersion. That could set the drivers up for a directivity mismatch, but we will get a look at its nature in the measurements section of this review. Another potential problem with the waveguide is it could create a hefty amount of diffraction. In narrow waveguides like this, diffraction is caused when sound from the transducer diaphragm experiences a lot of reflection off the inner sides of the waveguide. These reflections can interfere with the direct sound of the tweeter diaphragm and cause comb-filtering patterns in the response or other types of phase distortions. This could be exacerbated by the use of a small AMT tweeter that would naturally have a very wide dispersion, so it is throwing a lot of acoustic energy off to the sides. On the surface, a waveguide of this shape would seem to be suboptimal for this loudspeaker design, but it’s possible that it was necessitated by manufacturing practices where a wide, shallow waveguide would have been much more difficult to execute in milling aluminum. And with such a high crossover frequency to the tweeter, I wouldn’t expect the suboptimal waveguide shape to turn into a major audible problem since it isn’t touching midrange frequencies at all. 

Zooming out, we have a small speaker with an excessive build quality that is trying to get some bass out of a small enclosure through an isobaric driver arrangement while relying on a wide-band driver to carry most of the sound to avoid any crossover circuit issues. Mon Acoustics have pulled some clever engineering moves to pull this all together, but let’s see what it all sounds like in practice…

Listening Sessions

Most of my listening with the SuperMon Minis was done in an office room with the speakers placed about three feet in front of me on an office desktop with some desktop speaker stands to angle them at my listening position. It is not the ideal space for speakers, but it is an intended environment for the Minis that many users will use. This being the case, I decided to evaluate them in the conditions that they will probably be used in by most owners. The Minis are intended to be placed near a back wall (Mon Acoustics recommend 6-7 inches of distance from the back wall) to properly load port output. The receiver used was a Denon 4311CI AVR with a PC as the source. No equalization was used, and no subwoofers were used unless stated otherwise.

Music Listening

A very nicely performed and recorded album that I recently discovered is Christina Vane’s “Make Myself Me Again.” This is a bluesy country album that was released in early 2022 that has a personal sound unlike so much other country music that is mixed to sound like arena rock music. Vane’s vocals are the star of this show, but she is a skilled slide guitar player as well, and this album is a great showcase for her guitar chops. She is backed by a bevy of other talented instrumentalists in the country and bluegrass scene, and we hear accompaniment by fiddles, harmonicas, banjos, bass guitar, acoustic guitar, and percussion. The album as a whole is an intelligent and engaging listen, and it deserves attention from more than just country music fans. I streamed this album in Qobuz at a 24-bit/96kHz resolution.

From the start of the album, it was apparent that the Minis imaged superbly. Vane’s voice as well as her slide guitar took dead center stage between these speakers, even placed back on a desktop. Instruments had their positions nicely defined as well. As an example, on track 3, “River Roll,” it was easy to hear the banjo’s placement on Vane’s far left and a fiddle just to her right. Lazy mixing would just place everything in the center, but the sound engineer for “Make Myself Me Again” decided to spread the performers across the soundstage more, and the Mini’s reflected that quite nicely. Since the speakers were positioned at a somewhat lower height, the performance did sound slightly lower in altitude than my ears, but I don’t think any speaker could image differently when the speaker is lower than the listener. This is easily solvable by getting desktop speaker stands to elevate the speakers to my ear height, but the slightly lowered soundstage didn’t bother me enough to go out and get new desktop speaker stands. The Minis articulated Vane’s voice with precision, and the instruments were rendered with detail as well. The crunchiness of the distorted guitar on “Little Black Cloud” was vividly reproduced, and the Minis gave it a thick, crisp sound. 

The Mini’s had bass, and the bass guitar properly underpinned the music here. A nice demonstration of that occurs in the track “Old Enough.” To be sure, we are talking about mid-bass. Most of what a bass guitar produces lies in the mid-bass region. There is no consensus on what frequency range exactly constitutes mid-bass, but I am just going to offer an off-the-cuff definition of 70Hz to 160Hz, with maybe 160Hz to 380Hz being upper-bass. I would say that bass in general is sound that covers the fundamental frequencies of music and speech and also has a physical dimension to it that just isn’t there at higher frequencies. That tactile quality seems to be gone by 400Hz, at least for me. But however you want to subdivide bass ranges, I doubt anyone would argue that the Minis weren’t able to bring enough bass to make these tunes enjoyable. Larger speakers would certainly have given more muscle to the lower bass guitar notes and bass drums, but those sounds were present enough from the Mini’s that the music didn’t sound thin.

 

I was deeply impressed with the early music vocal ensemble Graindelavoix’s rendition of Josquin Desprez’s works, so I looked through their back releases to hear their other performances. One that caught my attention was “Messe de Nostre Dame” by Guillaume de Machaut. Machaut is one of the leading European composers and poets of the 14th century, and “Messe de Nostre Dame” (“Mass of Our Lady”) holds a place as one of the towering achievements of medieval music. The influence that this mass has had on subsequent sacred music cannot be overstated. Graindelavoix gives it an extravagant treatment, and the celebrated early music record label Glossa provides an exquisite production that makes this album a major event for fans of medieval music.   

Again, the first aspect of the sound from the Minis was how well they could image in a desktop environment. While the harmony of the singers was excellent, they weren’t mixed to blend in together as an indistinguishable choral mass but rather as an assembly of individual voices. The positions of the individual singers were readily apparent in the soundstage projected by the Minis. The timbral character of each of the singers came through as well thanks to the elocution of the Minis. This helped me differentiate each of the tenors and baritones as well as hear that there was one bass whose voice was so deep he might well have been a basso profundo. Graindelavoix’s voices were beautifully presented by the Minis. They sounded natural and full. The acoustic environment of the recording was also translated well, and even though I was listening in a near-field setting, I could still hear what it was like to have a front-row seat at St. Augustine’s Church in Antwerp where this album was recorded. I am not sure how similar this performance is to the originals done in Guillaume de Machaut’s time, but I found this music to be surprisingly complex and emotionally vibrant, especially for a 14th-century mass. It’s a long way from gothic chants of earlier sacred music, and I found myself captivated for the entire 72-minute running time. The SuperMon Mini’s proved to be a terrific tool to facilitate this experience.

It is not surprising that the avant-garde American composer Michael Gordon and famed San Franciscan string quartet Kronos Quartet had been friends for many years since each of these eclectic artists has been pushing the boundaries of instrumental music for decades. I was therefore not at all surprised to find an album of the Kronos Quartet’s performances of Gordon’s compositions, but even so, I was intrigued, because there was no way this music could be boring. “Michael Gordon: Clouded Yellow” features three pieces of music commissioned over the years as collaborations between Gordon and the Kronos Quartet. Obviously, this music is going to be a long way from the sedate Baroque classical music that comprises so many chamber music releases, but I wondered how far out in the left field would it go? This is something that speakers like the SuperMon Minis should excel at, so I queued up the album on Qobuz to give it a spin. 

Again, the soundstage projected by the Minis was striking considering that I was using them as desktop speakers. However, while the violins didn’t sound bad, there was a nasal quality to them that I attributed to acoustic reflections off the desktop. I moved them from some desktop speaker stands that merely angled the speakers upward without raising them very much to the top of some tower speakers that were flanking the desk. In this placement, they were much more out in the open, and so that nasal quality was gone. There was still some slight heaviness in the sound that I blamed on the acoustics, but later, after having measured the speaker, I saw in the measurements that there was a mid-bass bump that did give the lower notes a bit more thickness. It wasn’t severe, but it did add some coloration to the sound of this particular album. The Mini’s lent the violins and viola a vibrance and dynamism that belied the small speaker size; on the latter half of the second track, “Potassium,” the repetitive sharp bowing created a tremolo effect that sounded like the instruments were going to leap out of the speakers. The Minis also managed to effect some very otherworldly imaging on some sampled children’s voices in “The Sad Park, Part 1,” where a reverberant child’s voice was stretched over time and wandered back and forth in the soundstage. Much of the music played by the Kronos Quartets was dissonant, and, layered on top of the twisted sampling, summed up to an uncanny and surreal effect. This was challenging music for sure, and the Minis gave it all the queasy energy that was no doubt intended by the artists involved.

  

Moving on to a non-acoustic recording, I listened to an electronic music album titled “Don’t Forget Me” by w o s u 命 from the subgenre of Dreampunk. Dreampunk is heavily influenced by Blade Runner and future-set anime, but it isn’t merely a generic cyberpunk soundtrack. Rather, it is emotionally charged and evokes a sense of melancholy and anxiety about the social isolation of urban life. It is largely produced by synthesizers, samplers, and drum machines, and I wanted to hear what the Minis could do with a wholly artificial sound rather than a sound that is engineered to seem natural.

For this album, I brought the speakers into my home theater room as an experiment to see how they would handle use as a typical hi-fi loudspeaker. I also gave them a subwoofer with a 110Hz crossover frequency to give those 4” woofers a break since there was some significant bass in this music, and they didn’t have as much of an advantage in boundary reinforcement or near-field listening to shore up the low end. Needless to say, they sounded much more open and had a greater sense of space. The extra bass provided by the subwoofer was also a marked improvement and lent them an authority that they didn’t possess on their own (not that anyone should expect a loudspeaker with a 4” woofer to have subwoofer level bass). The Minis offered a wide and enveloping sound that is very much a goal of this music. The soundstage seemed to extend well beyond the width of the speaker positions. The sweeping synths and reverb-drenched percussion washed over the breadth of the soundstage and created a soundscape that I could get lost in. The transition from a three-foot listening distance to an eight-foot distance did not perturb the Minis, and they still had enough dynamic range to deliver enough loudness to give “Don’t Forget Me” some verve, although the inclusion of the sub really assisted in that respect. There is no doubt that these speakers had their dynamic limits, but I listened to this album at the same level as I would any other speaker, and I was happy with how loud they could get. In retrospect, perhaps I shouldn’t have been surprised at how good the Minis sounded in my home theater given that they managed to pull off a decent sound in a very compromised desktop setting, but they did, and I quite enjoyed listening to this atmospheric electronic music with these speakers. 

Movie Watching

One movie that had been lingering on my watch list for a while was “State of Play,” a 2008 political thriller starring Russel Crowe and Ben Affleck. This movie is about a rising-star congressman whose research assistant is found murdered. A journalist that is an old friend of the congressman runs into a web of conspiracy when he proceeds to investigate the murder. This movie looked like a typical big-budget thriller with much of the plot being dialogue-driven rather than action-scene-driven, and I thought that would be a good test of the Mini’s ability to reproduce standard-issue Hollywood fare. I decided to avoid something with an extremely wide dynamic range with lots of deep bass since there is no point in throwing a lot of deep bass at a speaker that is not geared to handle that, but it should be capable of catching most of the sound mix in a talky thriller such as “State of Play.”

“State of Play” turned out to be a perfectly serviceable political thriller, if not a particularly memorable one, but it was engaging while it lasted, and the SuperMon Minis helped to make it an enjoyable experience. Dialogue was always crystal clear and intelligible, and the snappy patter and shorthand of the veteran newsroom crew were never difficult to follow. Alex Heffe’s orchestral score was given a detailed and vibrant accounting. The orchestral strings that coincided with shocking plot revelations had an unexpected amount of punch considering the size of the speakers. Once again, imaging was stellar, and speakers adroitly tracked the voices to the actors’ on-screen positions. The Minis can’t duplicate the larger-than-life sound of an Imax theater, and no speaker of its size ever could, but it can deliver a satisfying sound for something that doesn’t depend on epic action scenes to be watchable. It exceeded what I would have expected from a pair of small desktop speakers. 

 

For something that puts a bit more emphasis on sound effects and especially spatial effects, I watched “Malevolent,” a 2018 supernatural thriller that I hadn’t seen before. “Malevolent” is about a team of con artists that pretend to be exorcists and are hired to go into ostensibly haunted houses and rid them of their ghostly presence. They stage ghost cleansing rituals with hidden trickery to bilk homeowners, and since the homes are never actually haunted, it is a scam with little blowback. Everything goes well until they are hired to cleanse a home that is actually haunted. The plot of cynical, non-believing ghost hunters who unwittingly encounter a real haunting with dire consequences has been done a lot over the past decade (thanks to the success of the film “Grave Encounters”), but I still watch these movies because I love that “Oh s**t” moment when the fraudsters realize they have run into the real thing. Since so much of the action in these types of movies is relayed off-screen as sound, I do think they make a good test of how well a two-channel system can reproduce a movie soundstage that puts heavy emphasis on sound effects imaging. 

For this film, I had set the speakers up in my home theater and used a subwoofer, so the Minis were alleviated of a congested desktop setting but now had to power a home theater room, albeit with the help of a subwoofer. “Malevolent” was not filled to the brim with jumpscare ‘boo’ moments, but it did have its share of creepiness, and a lively sound mix was instrumental to its success. The location of the haunting turned out to be a mansion that served as a foster home where a dozen orphans were murdered 15 years before, so the sound mix featured lots of disembodied giggling and whispers as they taunt our team of fraudulent spiritualists. The Minis reproduced these off-screen sound effects with eerie realism. The score by Al Hardiman abetted the tense atmosphere, and it was intensely expressed by the Minis. As with “State of Play,” character dialogue was always totally intelligible. Even though the movie took place in a murky old mansion, the sound mix as reproduced by the Minis gave clarity to the events, so I was never left unsure of what was occurring. Another factor that might have contributed to that is that I realized about an hour into the movie’s running time that I had seen it before when it was first released. It wasn’t a bad movie, but I suppose it didn’t leave much of an impression upon my first viewing, especially when it took me so long to recognize it. Nonetheless, I enjoyed my unintentional second viewing of “Malevolent.” With reasonable expectations of what small speakers can do, my viewing experience proved that the Minis can be used as speakers for movie content very nicely.

Mon Acoustic SuperMon Mini Measurements & Conclusion

The SuperMon Minis are not typical stand-mount hi-fi loudspeakers. They are desktop/small space loudspeakers intended to be placed in a quarter-space acoustic environment. Therefore, the usual suite of measurements that we post is not really suited for evaluating them. Instead, we will post a few graphs that do demonstrate some of their idiosyncrasies as a guide to help users in optimally setting them up.

 

The above polar map graphs use color to portray amplitude, and this allows the use of a purely angle/frequency axis perspective. The advantage of these graphs is they can let us see broader trends in the speaker’s behavior more easily. For more information about the meaning of these graphs, we again refer the reader to Understanding Loudspeaker Review Measurements Part II. 

In the above graph of the horizontal dispersion, the most stand-out aspect is how much the tweeter’s frequency band is restricted compared to the woofer. This is about what I expected when looking at the speaker’s design: wide dispersion from the woofer and narrow dispersion from the tweeter. The narrow waveguide on the tweeter is really constricting the tweeter’s dispersion, so users will want to be within a 30-degree horizontal angle of the tweeter. Listening within that angle isn’t likely to be a problem in a desktop situation.

Positional Tip: An easy way to know if you are too far off-axis is if you cannot see all of the lettering in the word ‘MON’ printed on the tweeter plate, you are not going to be hit with much of the tweeter’s output.

The above graph is a polar map of the Mini’s vertical dispersion. The tweeter is the axial reference point, and positive degrees are angles above the tweeter with negative degrees being angles below the tweeter. The tweeter’s band above 5kHz produces an unusual result. The narrow waveguide is causing some complex diffraction and reflection patterns. The angles at which there aren’t any nulls occurring are ten degrees above and below the tweeter, so that is where users should ideally aim the speaker to hit the ears on the vertical axis. However, even if those exact angles cannot be managed, this type of interference pattern, called comb-filtering, isn’t tremendously audible. In my own listening, changes in height did produce a change in the sound, but unless the height differences were dramatic, such as standing up versus sitting down, the effect on the sound was not huge. One of the reasons that this disordered dispersion pattern is not easily audible is that these effects are restricted to treble frequencies where human hearing isn’t the most sensitive. The entire midrange band is very consistent on both the vertical and horizontal axis. Moreover, the type of acoustic reflections this pattern can produce can average out at the point of the listener’s ears, so the dips created by this response can be shored up by reflections from near vertical surfaces, i.e., the desktop. Nonetheless, there is room to optimize the sound by adjusting the vertical angle. If the treble seems a bit soft, simply angle the speaker up or down by a few degrees.

 

The above graph shows the SuperMon Mini’s low-frequency response that I captured using groundplane measurements (where the speaker and microphone are on the ground in a wide-open area). The most prominent feature is a bump at the port-tuning frequency of about 150Hz. This is probably what I heard as some thickness of the strings during my listening to the Kronos Quartet album. A lot of small speakers go for this type of voicing in order to make it sound bigger than it actually is, but it does color the sound, and I would prefer a more neutral response in that range. Curiously, the slope below that point rolls off at 12dB/octave slope, which is not normal for a ported enclosure. Usually ported loudspeakers roll off at a much steeper 24dB/octave slope below port tuning. I could only guess this is some kind of byproduct of the isobaric design since both woofers surround a sealed compartment. This is, however, not an unwelcome attribute, since it will do more to promote room gain which will shore up the low end thereby giving the user deeper bass extension than a typical ported roll-off.  Nonetheless, I wouldn’t expect much deep bass from this speaker, and the addition of a subwoofer did significantly improve the sound in my own listening. I would encourage a higher crossover frequency over the standard 80Hz as well for those who do choose to use a subwoofer with these speakers. Few speakers of this size will deliver much deep bass at all. The ones that do have a very limited dynamic range and can reach their limits very quickly. That is the trade-off that has to be made in a small loudspeaker; you can have dynamic range or low extension but not both. 

 

The above graph shows the electrical behavior of the SuperMon Mini. Mon Acoustics specs this as a 4-ohm speaker, and that is correct. The impedance and phase take on an unusual shape relative to other speakers, and I would attribute that to the isobaric design. The impedance minima dips down to just under 3 ohms and occurs around the crossover frequency between 5kHz and 6kHz. It is accompanied by a steep phase angle, and that can be a tough load for amplifiers. It is only alleviated by the fact that this low impedance and steep phase range starts at 4kHz which is just above the all-important midrange that is so heavily used by so many recordings. The other good news is that in a desktop environment, it’s not likely to get cranked super loud, so most amplifiers that are paired with this speaker aren’t going to be driven to the bleeding edge. All the same, I would not try to drive these speakers with a cheap, low-powered chip amp, not that anyone spending $2k on a speaker set is going to power them with a $75 amplifier.

I measured the sensitivity of the Minis to be 86.1dB for 1 meter at 2.83v. While that is a tad under Mon Acoustic’s listed sensitivity spec, this is actually a bit more sensitive than I would have guessed given the design. For a small speaker, 86.1dB is quite good. These speakers won’t need a powerful amp to get loud, especially for their intended application.

Conclusion

Before bringing this review to a close, I will briefly go over the strengths and weaknesses of the product under evaluation, and, as always, I will start with the weaknesses. While there is a lot to like about the SuperMon Mini, I do think there are a couple of aspects in which it could be improved. First, the response peak around the port tuning frequency could be toned down a tad. That voicing does make the Mini sound punchier but at the cost of a more natural sound. Most people would probably be fine with it and even prefer it, but I do think the overall sound of the Minis would be improved were that frequency band less elevated. Second, I would completely redo the waveguide on the tweeter. I would make it a lot shallower in order to simplify the tweeter’s dispersion and make it a lot less jumbled. To be fair, the speaker could be made to sound fine in actual practice without much fuss, but it is clear that waveguide design wasn’t something that Mon Acoustics was heavily invested in. The surprising thing about that there are many clever design decisions undertaken in the Mini as well as attention to detail, but somehow the opportunity for a better waveguide was overlooked. A more sophisticated waveguide will bring a more consistent sound over both vertical and horizontal planes. Mon Acoustics tell me that they are experimenting with new waveguide thicknesses, so future iterations of the Mini may well see improvements here. 

With those two complaints out of the way, I will now move on to the strengths of the SuperMon Minis. Firstly, the imaging was superb. I did most of my listening on a desktop system where I thought these would see most of their use by owners, and, as was mentioned before, a typical desktop environment is not an ideal acoustical space for a loudspeaker. Despite this disadvantaged placement, the Minis still managed to image very well and projected a superb soundstage. The tonality was fairly good; voices sounded lifelike, and music was always very clear and precise. Dialogue and lyric intelligibility were always top-notch. Something else I liked was that, despite the use of an AMT tweeter, the treble didn’t leap out to scorch my ears. Many manufacturers let their AMTs run a bit hot for some reason, but that wasn’t the case with the Minis. In fact, I would say these speakers are on the warmer side of sound voicing. If you aren’t a fan of aggressive treble, the Minis could have a very appealing sound to you. The dynamic range was fine and more than good enough for a desktop loudspeaker. Of course, users will have to keep their expectations in check; they don’t do deep bass, but that just isn’t realistically in reach of any speaker of this size.

  

Outside of their sound, the aesthetic of the speaker is very cool, and I think it will draw a lot of people in just by its looks. People who are going for a high-end desktop look are going to love the Mini, especially those in modernist office decor. They feel as solid as they look too; they have a solidity befitting of their pricing. They are a luxury item in every respect, and there are no shortcuts taken to cheapen the speaker. They are hand-assembled in Korea using Korean manufactured parts. Picking one up feels like holding a solid metal block. They may well have the highest build quality of any small speaker anywhere.

One aspect that their build quality leads to is longevity; these speakers could last a very, very long time. If cared for, the SuperMon Minis will last for many decades. They are a true heirloom product. The enclosure is obviously built to last, but there are other features of the design that leads to longevity. Firstly, AMT tweeters don’t have soft suspension components that can degrade over time, so they are not really susceptible to age-related degradation. In common crossover circuits, many types of capacitors can have their values drift over time, but not the giant metal film caps used in the Minis. Much like the enclosure and tweeter, the crossover circuit will not really age to any meaningful degree. The only components that are susceptible to age in the Minis are the rubber woofer surrounds. However, consider that only one side of either woofer is exposed to the environment due to the isobaric chamber, so it will only age half as quickly as a normal ported loudspeaker. If you want a beautiful speaker that will outlast you, the SuperMon Minis have the potential to do that. Furthermore, if you wanted to pass them down to someone else, they are not burdensome for many people to accommodate since they are quite small. The Mini’s durability and long life will probably be an advantage in terms of resale value as well in case owners ever wanted to sell them.

In the end, the SuperMon Mini largely accomplishes what it sets out to do, and I think that the vast majority of buyers will be very happy with what they receive. They are going after a niche market segment, but if you want a small but extremely high-end speaker, Mon Acoustic delivers here. Everyone that I showed it to were immediately impressed by its appearance and build quality, and they enjoyed the sound when I offered them a demo. They are pricey speakers, but if you want the best-built small speakers in the world, these would not easily be topped.  

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
Build Quality
Appearance
Treble Extension
Treble Smoothness
Midrange Accuracy
Bass Extension
Bass Accuracy
Imaging
Dynamic Range
Fit and Finish
Performance
Value