Introduction
Since joining Head-Fi nearly 15 years ago back in 2004, like so many others I have spent countless hours researching and reading reviews of different audio hardware in what is easily one of my favorite corners of the internet. Head-Fi is unquestionably one of the best places to meet fellow audiophiles, and to discover and learn about new headphones. That’s a great thing, because there are a lot of headphones out there! The sheer number of headphones and IEMs that exist makes it that much more meaningful when we encounter one that stands out from the rest, and is capable of introducing us to something new that we’ve never heard before.
For many, the U18t is one of those standout products.
It is truly impressive just how much technological innovation and artistry there is in the IEM market right now and 64 Audio is clearly at the forefront of it all. It takes a hell of a lot of audacity to even attempt to shoehorn 18 drivers into a single monitor, and it makes me feel a little tingly just to know that there are manufactures out there who are passionate enough to try. But knowing is only half the battle. It’s hearing that really matters. 64 Audio is well aware of this, and their slogan, “Hear Everything” is fitting to mention during this review. When you listen to the U18t, it’s nearly impossible to hear anything less.
I am writing this review while in possession of a demo pair of U18t which I reached out to 64 Audio myself to acquire. I have also had the chance to spend a good amount of time with both the U12t and Trio thanks to the recent 64 Audio tour organized by @Barra. The U18t is my clear favorite in 64 Audio’s lineup that I have heard to date. (*I have heard the Fourte as well, but I have not spent a significant amount of time with it. The sound of the U18t/U12t/Trio have all captured my attention more, and those are the units that I have spent the most time with. I will therefore not be including the Fourte here.)
I will sprinkle in comparisons between the different 64 Audio models I have heard throughout this review. I will also draw some comparisons to my personal custom Noble K10s, a virtual sonic lighthouse around Head-Fi, that will hopefully serve as valuable reference point for many others exploring the delightfully crowded world of IEMs…what a great time to be an audiophile!
*64 Audio presently allows you to spend a few days with a demo set of any available universal model of your choice. 64 Audio will place a hold on your credit card for 50% of the value of the IEM during the time you have them. Once the IEM is returned safely to 64 Audio, the hold is lifted and your money returned. The only charge for the experience is a small shipping fee (~$30.)
M15 vs. M20
The U18t currently comes with two different sets of replaceable modules that change its sound signature dramatically. When I first saw them, I wondered how these little pieces could have such an impact, but it’s hearing that matters, right? I did indeed hear a difference and my preference tilts very strongly toward the M15 (vs. the M20) modules, and this review will focus primarily on impressions using the M15 modules. The determining factor for which modules you choose will come down to personal preference, the genre of music you are listening to, or the mood you are in. The bottom line is that having options is sweet, and it only takes about 30 seconds to swap out one set for the other.
M20 – More emphasis on bass – deeper, rounder sound with more focus on low/mid impact vs. texture. Less air and high-end extension.
M15 – Less emphasis on bass...but it’s still 8(!) BA drivers working in harmony to produce low-frequency nirvana. The U18t produces fantastic bass for a BA monitor, no question. There is never a time where you feel like the U18t is producing massive bass at the expense of texture and control; at all times with the M15 modules the U18t seems to be striving to present to you a sincerely balanced, detailed, spacious and coherent aural picture across an impressively wide frequency range.
In the case of the M15 modules, less is more...much more. The real reason for my preference of the M15 modules is due to the way they enhance the high-end extension and airiness of the U18t’s overall sound. To me, it’s the M15 signature that elevates the listening experience with the U18t to the monitor’s highest level.
Sound Impressions
I feel that there are five key characteristics of the U18t’s sound that work together to create one of the most detailed and exciting sounding IEMs on the market today. In order of the significance I feel they play in shaping the U18t’s overall unique sound, those traits are:
Soundstage (30%)
High End-Extension (Tia) (25%)
Bass Impact/Power/Texture (20%)
Transient Response (15%)
Nearly Flat “Reference” Tuning (10%)
Soundstage (30%) – I do not believe IEMs are currently capable of sounding as open and spacious as over the ear headphones. After all, our outer ears do a lot to help provide us with spatial cues. IEMs pump sound directly into the ear canal leaving the rest of our ears out of the listening equation. Due to this anatomical omission, my expectations for how “open” and “spacious” an IEM can sound are less grand than my expectations vs. a headphone. Regardless of what your expectations are for an IEM, the U18t is bound to impress with its staging prowess, and the ease with which it can recreate sounds seemingly originating from somewhere far off in the distance. I’m not sure how 64 Audio accomplished this, and it’s worth experiencing for yourself.
While the U12t presents a large and wonderful spacious sound, the soundstage of the U18t is even larger; just massive really, by IEM standards. The U18t’s extra clarity, airiness, and headroom provided by the additional BA drivers helps it to best the U12t, if only slightly, in stage size. The Trio also has a large sense of space, but its soundstage is a different shape. Where U12t/U18t place you in the middle of the sound, the Trio seems to push the sound out in front of you a bit, placing you “a few rows back” and presenting a sound that is more laid back, albeit still engaging. The K10 is far more intimate in its presentation, and it also conveys a sense of space and air around instruments, it’s just not as massive and airy as the stage presented by 64 Audio. It is nice to be able to choose between a more open or more intimate stage.
I remember when I first heard the U18t back at Canjam NYC earlier this year. I was listening to Mura Masa’s I Miss You at the 64 Audio table and was amazed by both the large sense of space and deep and powerful bass. A major benefit of an IEM that can produce sounds that appear to come from outside your head, is the ability to create a sense of atmosphere. I find this tremendously enhances electronic music, especially songs that are heavily layered with complex, lush sound effects. When sound seems to come from off in the distance, it also appears less fatiguing (though, this is likely just psychological as the sound is still originating in your ears, of course.) There is also a level of excitement created as you’re constantly wondering where the next sound you hear will come from.
High End Extension (Tia) (25%) – 64 Audio’s Tia driver has stirred up a lot of excitement, and for good reason. It sounds fantastic. While some people have said that they are sure Tia is “the future,” I’m less concerned with tomorrow and happy that we can all enjoy listening to Tia right now. 64 Audio’s engineers have clearly been coming up with and building some seriously awesome tech into their products. The Tia driver is surely one of the company’s most significant recent achievements.
The theory behind the Tia driver is that with the help of some fancy engineering, certain resonance and interference commonly associated with closed BA drivers and piping sound through tubes can be removed, and a clearer and cleaner sound can be achieved. It would be interesting to speak to an audio engineer to learn more about this, but for now I’ll just trust my ears and say that the high-end presentation on the U18t is one of the best I’ve ever heard in an IEM. The U12t also benefits from the Tia driver, however there is a level of detail and extension up top that is far more pronounced on the U18t. The Trio also has the Tia driver, but the highs are rounder and less extended. Again, the Trio seems to be aimed at delivering a more laid back presentation. Whatever your sound signature preference is, 64 Audio has you covered.
The K10 does not match the high-end extension of the Tia driver, but the Noble highs are still quite satisfying and do not appear to be lacking much detail at all. A direct A-B comparison between the K10 and U18t/U12t does reveal the additional extension disparity more clearly, but the K10 still sounds great. It’s just tuned for an ultra non-fatiguing and smooth sound up top, and there are plenty of times where that may be what you’re looking for.
One instance when the Tia driver really impressed me was when I was listening to Tom Misch’s Tiny Desk Concert. Tiny Desk is a YouTube series put out by NPR and it’s an absolutely awesome mix of amazing artists, ranging from Tyler the Creator to Yo-Yo Ma. But it’s the format of the performances that makes them special: very intimate gatherings of the artists and a small crowd in what appears to be a library-like(?!) setting. The audio is very well-recorded, and each one I’ve watched has made me feel like I’ve had the chance to become better-acquainted with the artist.
At the very beginning of the Tom Misch Tiny Desk concert, right around 27 seconds you can easily hear Misch take a breath before he begins singing. However, a second earlier there’s another sound either his mouth or nose makes just before he takes the breath. I had never noticed it listening with my K10s, but on all of the Tia-equipped 64 Audio IEMs, I could hear it. It was most pronounced on the U18t/U12t, a little less so on the Trio. But hearing this kind of detail reveals just how well the Tia driver handles and conveys subtle details in the high frequencies.
Additionally, listening to orchestras with the Tia driver is a real treat. Violins sound marvelous on the U18t, and the monitor easily showcases one of, if not the best string presentations I’ve ever heard on an IEM. There is a bit less excitement present on the U12t. The Trio, with its slightly darker more laid back tuning gives up some of the sharpness from the U18t/U12t in exchange for a rounder, slightly more subdued sound.
While the K10 cannot match the high-end extension of the Tia driver, (and while we’re on the subject of violins,) it’s worth mentioning that the K10 does have a wonderfully warm timber and tonality that makes violins sound incredibly life-like. This is one trick the K10 has up its bore, and one of the reasons why the K10 can still hang with some of the newest and best IEMs on the market, like the U18t.
Bass Impact, Power, and Texture (20%) – Just thinking about the fact that 64 Audio put 8 BA drivers dedicated to pumping out glorious low frequencies in the U18t is kind of crazy. High-quality, deep, controlled, and textured bass is probably one of the most universally-lacking sonic traits in the world of average consumer-level audio. Boomy, distorted, bleeding into midrange, powerless…now, imagine the exact opposite of all of that and you’ll have a good idea what to expect with the bass on 64 Audio’s newest IEMs. Even then, you may still be surprised by the combination of impact, power, texture, and sustained rumbling capabilities of the bass when you hear it for yourself.
Many people fell in love with the original A12 because of its MOAR bass capabilities. Since the original A12, 64 Audio has been busy fine-tuning that bass. The bass on the U18t is probably the most versatile presentation of bass I’ve ever heard in an IEM. In an interview with The Headphone List, Vitaliy Belonozhko, 64 Audio’s founder and lead designer explained the logic behind shoving 8 BA bass drivers in the U18t: “The smaller the driver the faster it sounds. Because of their small size it takes 8 of them to achieve the low distortion, sensitivity and headroom that we desired.”
Low distortion, sensitivity, and headroom…check, check, check. The U18t/U12t have impact, texture and power, and can both sustain rumbling better than any other IEM I’ve heard. The U12t undoubtedly has more bass quantity than the U18t, despite only having half the number of BA drivers dedicated to the deep stuff. The main difference is that on the U18t, there is an additional level of texture, refinement, and control. To be sure, bass on the U12t is still really damn good. In fact, there is no question that many people will prefer the slight low-end frequency bump in the tuning of the U12t over the U18t. Either way, you can’t go wrong.
The Trio, with its single dynamic driver, doesn’t quite have the same level of speed and refinement as its wholly-BA crafted siblings. But, if you’re a fan of DD bass you’ll likely appreciate the Trio’s presentation. The bass presentations on the U18t/U12t are just so damn good, that the comparative the lack of refinement of the bass on the Trio, at least to my ears, just isn’t quite as satisfying…really, this is just a case of personal preference and 64 Audio stepping on its own toes here!
Bass on the K10 is very, very good, and it’s still one of my favorites BA bass presentations in an IEM along with both the U18t/U12t. But the K10’s low-end is not quite as refined as the 8BA or 4BA bass on the U18t/U12t respectively. The K10 uses two large BA bass drivers, sort of the opposite strategy 64 Audio employed using a higher number of smaller drivers. One defining aspect of the K10’s sound signature is how generously the K10 spreads its bass and warmth across the overall sound. K10’s bass does at times seem more organic vs. the more digitally clean and precise sounding delivery of bass on the 64 Audio IEMs. These differences aside, bass presentation on any of these BA-driven monitors is extremely satisfying to me. One thing I’ve always loved about 64 Audio’s monitors is their ability to confidently produce sustained rumbling. I have yet to hear another IEM manufacturer do this better, and you can be sure that the U18t/U12t/Trio will all happy deliver aftershocks to your ears.
Transient Response (15%) – Transient response can succinctly be described as an auditory “slight of hand (ear?).” Now you hear it, now you don’t. In practice, it’s how quickly you can hear an initial burst of sound before it naturally decays. When you’re listening to a complex piano or violin solo, lots of notes are presented quickly. But, just as fast as those notes come, they also need to go. This is where terms like “lightning-fast” and “razor-sharp” often get thrown around to describe initial attack and subsequent decay. The U18t performs quite deftly here, better than any other IEM I’ve heard to date.
Good transient response isn’t something that I specifically look for in a headphone. It’s a sonic trait I imagine is most appreciated by an analytically-bent listener, and I generally prefer more musicality. That said, when you combine the U18t’s transient response, the airiness of the Tia highs, the deep textured and refined bass, and the large and airy soundstage, you end up with an IEM with such a uniquely detailed sound that the detail itself actually becomes exciting. You might even also be inclined to want to learn more about what you’re hearing. I was, and the fact that listening to the U18t inspired me to further research transient response, well, that says something doesn’t it?
Compared to the U12t and Trio, the U18t is definitely faster and more technically proficient in this regard, and it surely contributes to giving the U18t a slight edge in overall detail and clarity in direct back to back listening sessions. The K10 tilts much further in the direction of musicality, and that comes at the expense of some of the most minute details that the U18t effortlessly reproduces so well.
Nearly Flat “Reference” Tuning (10%) – The last defining aspect of the U18t’s sound signature is its near-flat “reference” tuning. Much like capable transient response, flat frequency response is something one would expect to see near the top of an analytical listener’s wish list. The U12t, Trio, and K10 all have bass that’s at least slightly bumped, ensuring a generally more fun sound. But, by now it should be clear just how dead serious the U18t is about its mission to serve as the de facto “reference” monitor in 64 Audio’s lineup. There is something refreshing about hearing all frequencies presented with equal volume and importance across the U18t’s impressive range. And it is undeniably satisfying in being presented with an ultra-refined, detailed, and balanced presentation of sound in this way.
Conclusion
These five aspects of the U18t’s sound are what I believe most define its overall signature. This is a monitor clearly in pursuit of the sonic ideals of “detail,” “balance,” and “neutrality” at every step. Yet, 64 Audio somehow manages to infuse a higher level of excitement into the U18t’s sound than I experienced with any other monitor in the lineup, despite the seemingly more “fun” tuning of the U12t/Trio.
And this brings me to what I believe is the biggest success of the U18t, and why it stands out amongst such a large field of IEMs: the U18t finds a way to straddle the line between possessing a sound that is both supremely analytical and extremely musical, and does so better than so many IEMs that have come before it. When I listen to the U18t I hear a monitor with some of the most detail and analytical prowess, and yet, the U18t also has one of most exciting and fun sound signatures I’ve heard to date in any IEM.
What a great time to be an audiophile, indeed.
