DISCLAIMER: SLT Technologies (Kumitate Lab’s Indonesian distributor) loaned me these universal demos in exchange for my honest opinion. I will send the units back following the review. I am not personally affiliated with the companies in any way, nor do I receive any monetary rewards for a positive evaluation. I’d like to thank SLT Technologies and Kumitate Lab for their kindness and support. The review is as follows.

Kumitate Lab is a Japanese custom in-ear manufacturer run by the immensely passionate Mr. Ryosuke Ito; a well-renowned pioneer in the DIY space. Much like Piotr Granicki of Custom Art or Joseph Mou of Jomo Audio, Ito-san is a massive enthusiast who decided to take pen to paper (by the way, he still sporadically posts experimental designs – like his 24-driver Thanatos – and tutorials on his blog; truly one of a kind). Kumitate Lab has since grown to become one of Japan’s most acclaimed CIEM brands, and currently boast some of the most beautiful in-ears throughout the market. Today, we’ll be looking at the all-new NEXT 5 line-up: the 3-driver Corona, 4-driver Meteo and 4-driver Sirius.

Build and Accessories

Despite Ito-san’s humble beginnings in the DIY realm, I can safely say Kumitate Lab is near – if not at – the pinnacle of build and cosmetic design. A simple glance at their web gallery or their 44-page design booklet reveals an immense passion (and specificity) the likes of which I have never seen. Summarily recounting all the info available in that booklet would be too big a task, so here’s a link to see it for yourselves (be warned; it is in Japanese). From a variety of carbon fibres, woods, metal finishes, mirror finishes, gold perimeter inlays and – their specialty – Raiden faceplates (which use Urushi lacquer to essentially turn your in-ear monitors into glowing Japanese tapestry), the possibilities are endless.

Photo courtesy of Kumitate Lab

Now although the demo units I was provided aren’t as stylish necessarily, they’re still great examples of Kumitate Lab’s craftsmanship. This is particularly visible in the two transparent monitors. They’re crystal clear with no unevenness in shell thickness or lustre, and they’re completely bubble free as well – glistening in the sunlight. Even the translucent Meteo is evenly coloured throughout, with no transparent or opaque patches to be found. My only minor gripe would be the soluble paper they use for the text inlays (i.e. SIRIUSNEXT 5CORONA, etc.). In my macro shots, you can clearly see the rectangular outline surrounding the text, especially on the transparent faceplates. But really, it’s a nitpick at best.

Finally, Kumitate Lab added both MMCX and 2-pin connectors to all three IEMs. I think this is an incredibly smart feature to include in your demos for maximum comptability, and they even offer it for the final CIEM version – albeit it at a decently sizeable charge. Regardless, this is an idea I’d love to see other companies replicate; as an option at least.

Page 2: Kumitate Lab Corona
Page 3: Kumitate Lab Meteo
Page 4: Kumitate Lab Sirius
Page 5: Verdict

Kumitate Lab Corona

Technical Specifications

  • Driver count: Three balanced-armature drivers
  • Impedance: N/A
  • Sensitivity: N/A
  • Key feature(s) (if any): N/A
  • Available form factor(s): Custom acrylic IEM
  • Price: 70,000 円
  • Website: www.kumitatelab.com

Sound Impressions

Starting off with the Corona feels a tad awkward because – ironically – it’s the most unique of the three monitors. As we’ll explore later, the Meteo and Sirius both emit a spacious, open and airy sound aided by a tightly controlled mid-bass and peaks along 7 and 12kHz. Conversely, the Corona is an intimate piece tailor-made for vocal reproduction. Most of its frequency response serves the midrange, where its buttery, warm and organic tone rekindles vague recollections of the Warbler Audio Prelude and Earsonics EM10. It outputs a similarly modest soundstage (though one deeper and wider than the former) and maintains a similar sense of coherence as well. Notes come through not by sheer clarity, but through balance and linearity – no one range overtaking another, so the instruments within exist in harmony.

The Corona’s low-end resembles a slight downward slope. There’s ample mid-bass content for impact and punch, while the sub-bass emphasis provides admirable gusto and great rhythm. Although okay extension limits it from becoming a true all-rounder down low, it still rumbles effectively with heavier tracks like Eminem’s The Ringer. And, with recordings where the bass is better balanced against the rest of the mix, that visceral-ness takes a step back and becomes favourably less apparent. The mid-bass sits in-line with the midrange, but a lower-treble peak renders the presentation as a whole less rich and full than the Prelude, for example. Additionally, enough energy exists between the mid-bass and lower-midrange to give vocals proper heft and body. I would’ve loved to hear a touch more extension to further boost the Corona’s dynamic range, but as it is, it’s a very proper fit to its signature: Punchy, organic and clear.

The midrange is where the Corona takes centre stage; presenting natural, vibrant and engaging instruments – both clear and warm in tone. It benefits from the monitor’s uniquely linear upper-treble (relative to its bigger brothers) and achieves an emotionally resonant timbre. Though unlike the Prelude, it employs a 7kHz peak for airy and crisp articulation. This gives the Corona a more open, transparent response without much compromise in tone or melodiousness. The Prelude may be more analog and life-like, but the latter is comparatively more exciting, musical and clean. Midrange notes take up a large majority of the stage, with a lift centred around 2-3kHz bolstering its size. But, excellent linearity from 1kHz on gives the presentation a sense of completion; coherent from the chesty fundamental, to the vibrant tone, to the articulate release. Despite its slight compromise in technical performance, the Corona has my favourite midrange of the three: Sufficiently clean, seductively intimate, and organic and refined all at the same time.

Again, the Corona employs a 7kHz peak for air, which renders its lower-treble neutral-leaning. However, as we’ll soon see with the Meteo and Sirius, this emphasis is seamlessly integrated into the frequency response; linear, buttery smooth and teemed in headroom. It gives instruments great clarity whilst remaining sufficiently natural. This is the Corona’s last peak before it rolls off around 10kHz. This shows admirable extension, but it is the weakest of the three. As a result, its stage is more intimate and its imaging isn’t as precise. But, it does play into the in-ear’s romantic response, and it’s an admirable performer in terms of separation. Instruments are well-organised horizontally, with enough space to thoroughly fill the head. Finally, speed is great – imbuing snare drums and cymbals with impact. All in all, the Corona’s treble fittingly concludes its signature; natural, smooth and unintrusive, yet dynamic and engaging all the same.

General Recommendations

The Corona’s midrange-first mentality makes it a strong performer with vocals and instruments alike. But, its clever treble and punchy bass extend its versatility beyond similarly-targeted IEMs; putting its proverbial feet on both worlds. As a result, if the following three aspects describe your ideal custom IEM, the Corona should definitely be on your radar.

Sweet, intimate and well-resolved vocals: The Corona’s balanced, well-structured and vibrant midrange makes it a shoo-in for genres like jazz, singer-songwriter, R&B and simpler pop productions. Vocalists like Jason Mraz, Tori Kelly, Alicia Keys and Emeli Sandé immediately come to mind, while contraltos like Laura Fygi and Diana Krall absolutely shine as well. This is a presentation ideal if you want an intimate, you-are-the-mic experience – resolved, layered and emotionally resonant. But, the Corona’s admirable extension allows sufficient headroom, so the stage never gets claustrophobic.

A natural tone with clarity and refinement: Once again, the Corona’s specialty is its lightly warm tone that emphasises the melodiousness of the midrange – seductive, sultry and oh-so-easy to listen to. Vocals are delivered with a meaty timbre, but a 7kHz peak adds cleanliness and refinement there as well. Instruments won’t sound overtly honky or ill-defined. They carry with them a clear leading edge, so contrast between the images and the black background is moderately high. This will prevent vocalists like Diana Krall from sounding overtly chesty or deep, and allow her natural raspiness to add some colour to the presentation. For vocal enthusiasts, this can be considered the best of both worlds.

Euphony and musicality without congestion: Despite the Corona’s more organic response, it remains relatively free of warm air permeating its stage and causing what hi-fi enthusiasts tend to call a veil. Although the aforementioned group may still find the Corona lacking in crispness due to its linear upper-treble, it still manages to conjure sufficient space between its images; creating an admirable sense of separation. Its 7kHz peak is crucial in making sure compromises like these are as minimal as possible, so the Corona can maintain its naturalness whilst being relatively versatile too.

The downside to the Corona’s midrange emphasis is its lack of dynamic contrast. For those whose playlists expand much further beyond vocal-reliant tracks, here are aspects the Corona won’t deliver – especially relative to its bigger brothers.

Pristine cleanliness and bounds of treble sparkle: The Corona has a decidedly linear upper-treble, which contributes to its organic tone and realistic timbre. However, this’ll be to the chagrin of those looking for bell-like clarity and crispness. The Corona is certainly smoother than some would like, so if you’re used to the energy of IEMs like the 64Audio A18t or the Campfire Audio Andromeda – and you’re not willing to compromise that slightly for tone – then look elsewhere.

A gutsy, impactful bass: Although the Corona’s low-end has decent physicality and tone, okay extension limits it from achieving greater guttural-ness, texture and dynamic range. Rhythm sections and percussion won’t ever feel empty, anaemic or dull, but it’s worth keeping in mind if you place more emphasis on the low-end than average.

Utmost stage expansion and clinical imaging: The Corona may have admirable air for the signature it’s going for, but it’s certainly the weakest of the three in that regard. If your preferences lie closer towards an operatic, theatrical presentation rather than a more romantic, lush and intimate one, then you’d be better off looking at the Sirius or Meteo.

Kumitate Lab Meteo

Technical Specifications

  • Driver count: Four balanced-armature drivers
  • Impedance: N/A
  • Sensitivity: N/A
  • Key feature(s) (if any): N/A
  • Available form factor(s): Custom acrylic IEM
  • Price: 90,000 円
  • Website: www.kumitatelab.com

Sound Impressions

The Meteo has an addictively dynamic response; lively, engaging and – most crucially – smooth. It’s highly reminiscent of Lime Ears’ Aether and Model X. Both create contrast through a light v-shape, but maintain present, airy and vibrant upper-midranges. The Meteo outputs a stunningly vast stage, conjuring clear images within a sphere-like setting. Its spatial achievements are unprecedented in its price range, including clearly-defined diagonals (10 and 2′ o clock, which often sound smeared in lesser in-ears), strong holography and high resolution along the x-axis. Furthermore, despite its significantly accentuated bass, the Meteo showcases outstanding control. It outputs minimal warmth and focuses all energy on impact. As a result, the monitor maintains a clean stage with gobs of air and headroom to spare.

The Meteo’s slams are hybrid-esque, fuelling its presentation with a satisfyingly visceral sub-bass. There’s a clear scoop between the mid- and upper-bass – so it’s more felt than heard – but it’s no detriment to impact whatsoever. Although it lacks the authentic thump of a dynamic driver, the nimbleness it maintains ensures the bass is never overwhelming – neither overtly forceful nor sluggish in decay, yet fun and musical at all times. Tone is not its strongest suit, as it sacrifices accuracy for dynamic energy. But, it still plays well with jazz, where upright basses benefit from rumble and authority. Bass notes are also neither particularly full nor dense, as thumps more closely resemble waves surrounding the perimeter of the soundscape; almost out of head as they rush into the rhythm. But to its advantage, it keeps centre stage vacant for the midrange to fill – playing its role as fun machine with little compromise in cleanliness and finesse.

The Meteo resumes its vibrancy through its brazenly energetic midrange. There’s a clear emphasis on the upper-mids, but there’s enough lower- and centre- content for vocals to sound sufficiently dense and seamlessly coherent. Linearity with the bass is wonderfully preserved, as they move like a solid, singular unit. It won’t necessarily win points for organicity or emotional resonance, but – like the Aether and Model X – it plays its instruments like a well-made action movie: fun, light and fast, yet smooth, charismatic and endlessly entertaining. Following a rise around 2-3kHz for added sweetness and presence (esp. with strings and female vocals), the Meteo employs a 7kHz peak for openness, air and crisp articulation. Cymbals and snare drums pop and crackle to satisfying effect, yet remain smooth. It’s very forgiving and neutral in tone, with great coherence to keep its zingy, airy cleanliness in check. It’s not necessarily the most rounded, but it’s as exhilarating as it is easy to listen to – a wonderful blend of smooth delivery and effortless detail.

A key player in the Meteo’s sense of excitement is its bright, articulate treble. In addition to the 7kHz peak, a 12kHz rise gives it energy and body, whilst avoiding areas of sibilance. But because the top-end is placed slightly further back in the mix, the Meteo maintains excellent refinement and prevents any brittleness. Again drawing comparisons to Lime Ears’ IEMs, the two peaks feel seamlessly integrated into the treble for an extremely cohesive presentation. Though, the Meteo certainly has the crisper edge and more clear-cut separation. The stage itself has a slightly bright ambience – so it isn’t completely transparent – but it images and organises with great precision. Each element remains in its allocated space, with some of the best left-right separation I’ve heard for the price. So despite the Meteo’s constant dynamism, it never feels claustrophobic. Instead, it excels in air, definition and discipline – open, crisp and deliciously smooth.

General Recommendations

The Meteo’s loud, large-and-in-charge presentation makes it addictively fun to listen to – constantly lively and unwaveringly smooth. But, its achievements in stage expansion, tonal balance and spatial precision make it a technically-strong piece as well. These are categories which take most advantage of the Meteo’s energetic signature:

A bombastic, impactful and fun signature with sufficient density and realism: The Meteo’s w-shaped response makes it most ideal for energetic genres of music like EDM, pop, acid jazz, rap and rock. These categories of music utilise the Meteo’s impactful bass and crisp treble to summon gobs of energy, rhythm and musicality. But, the Meteo’s midrange is well- structured, such that its versatility extends to calmer genres as well. This is what makes it a true all-rounder.

Tonal adaptability and zero sibilance: The Meteo’s avoidance of problematic areas – such as the lower-mids (which can get too full and congested) and treble (prone to stridence in select areas) – make it versatile in track quality as well. It’ll sound smooth, exciting and tonally balanced no matter what you throw at it. So, it’s definitely worth considering – if your tastes are more eclectic – as a budget alternative to similarly-versatile in-ears like the Lime Ears Aether and Model X.

Outstanding balance between dynamic energy, headroom and imaging precision: Creating an in-ear that sounds spacious and energetic at the same time is an extremely difficult task. Emphasising the former usually creates a sound that’s laid-back and sometimes alienating/unengaging, while the latter usually leads to an overtly crowded stage. Fortunately, the Meteo balances both with little compromise to tone, musicality or imaging precision, due to its well-extended treble and expertly-controlled bass. If you want a three-dimensional stereo image packed with energy, the Meteo is it.

Despite my love for the Meteo and its deft balancing act, there are elements that it simply wasn’t built to entertain. If you’re in the market for a CIEM with the following characteristics, the Meteo shouldn’t be at the top of your list:

A calm, laid-back response: The Meteo has a decidedly dynamic signature. So, if you’re looking for a richer, fuller and more relaxed IEM to lounge with, the Corona is something you should consider above the Sirius or Meteo.

Full, intimate and holographic vocals: One of the Meteo’s key elements is its holographic, three-dimensional stage. However, that depth unfortunately doesn’t extend to its vocal presentation. The Meteo’s dynamism inherently needs a neutral lower-midrange, so its instruments are more articulative and hard-edged than they are harmonically rich. The Meteo’s vocals are smooth and bodied; they simply don’t have the intimacy required for that you-are-the-mic sensation.

Warm, vintage and analog bass tones: The Meteo prioritises bass impact over tone – once again – to complement its dynamic signature. As a result, it’s a bass more felt than heard. If you’re someone who relishes in warmer low-end textures reminiscent of analog tube gear, the Meteo won’t provide the euphony you’re after. Its control, impact and authority are all high, but in its efforts to provide a clean stage, it does compromise in that aspect of the low-end.

Kumitate Lab Sirius

Technical Specifications

  • Driver count: Four balanced-armature drivers
  • Impedance: N/A
  • Sensitivity: N/A
  • Key feature(s) (if any): N/A
  • Available form factor(s): Custom acrylic IEM
  • Price: 90,000 円
  • Website: www.kumitatelab.com

Sound Impressions

The Sirius has a clear-cut focus on cleanliness and clarity. Although its smoothness and linearity harkens back to the Meteo, it differs from it in proportion and priority. The Sirius has a much lighter bass and a more present treble. So, it’s noticeably brighter and a touch thinner as well. Strong linearity prevents instruments from ever sounding metallic or insubstantial, but it’s still a signature that even marginal bassheads will find inadequate. Nevertheless, its response makes it a natural achiever in imaging and separation. It takes the Meteo’s already-outstanding size and adds height, so images feel further out of head. Note compactness and speed also create a more defined sense of geography. Warm and rhythmic it is not, but it resumes Kumitate Lab’s masterclass in spatial resolution at (relatively) modest prices.

The Sirius has an upper-bass-emphasised low-end with little in the way of sub-bass rumble and mid-bass warmth. As a result, it’s a response that’ll come across as light, calm and nonchalant. However, it’s technical performance should not be ignored. Despite its reservation, extension is excellent. So, bass hits always cut through with palpable definition in spite of its minimality. Strong linearity also ensures a rounded bass; neither hollow nor wispy. This comes paired with a natural tone, which gives the low-end admirable realism. The treble emphasis does colour it a tad bright in the end, but only by a slight margin. Once again, nimbleness and control score very high. This complements the bass’s density with detail retrieval and layering. It’s a shame, though, when this becomes something you have to look for, rather than sit back and enjoy. At the end of the day, the Sirius’s bass gets many things right. I simply wish there was more of it.

This reservedness in the bass directly affects the Sirius’ vocal presentation. Instruments are clean, crisp and brighter in tone. Thankfully, crucial lifts along 1-3kHz give notes enough density to avoid sounding metallic, incoherent or hollow. But, the Sirius’ laid-back low-end leave voices in dire need of warmth and body. Baritones like Michael Bublé and Rick Astley lose much of their gusto (gravitas) and the attitude they bring with it. On the other hand, raspier vocalists like Laura Fygi and Rod Stewart end up sounding throaty and hoarse; their rasps overtaking the lower fundamentals. But despite these tonal shortcomings, Kumitate Lab deserve massive credit in technical performance. Once again, layering, imaging precision and separation are some of the strongest I’ve heard at this price point. There’s a real sense of depth that sounds earned (rather than artificially recessed) and unwavering smoothness in every track it tackles. All in all, the Sirius has a midrange that’s clean, spacious and technically sound, even if its tonal balance could use some work.

With the Sirius, Kumitate Lab continues to impress when it comes to tuning treble. The 4-driver’s top-end is wonderfully crisp and airy, yet smooth and refined. Similar to the Meteo, it employs peaks along 7 and 12kHz – as well as a 6kHz dip – but the treble region as a whole is further elevated here. This gives the stage a more open ambience, but it brightens the monitor’s background and contributes to the tonal shortcomings we discussed earlier. Nevertheless, it’s a wonderfully clean treble with massive headroom that never ceases to remain smooth. This is particularly gorgeous when listening to cymbal crashes and ride bells – every ring, crash and sizzle rendered with crystalline clarity and air. But, the linearity with which it does so prevents any amount of harshness, tizzy-ness or fatigue. Simply put, it’s a top-end that balances cleanliness and refinement like it’s child’s play. It’s neither warm nor thick enough to be considered fully natural, but it solidifies Kumitate Lab as a benchmark with one of my favourite treble tunings since Lime Ears.

General Recommendations

The Sirius’s technical ability positions it as one of the best clarity-focused in-ear monitors in its price range today. If you’re in the market for a consistently smooth, neutral-bright IEM, these are what the Sirius can do for you:

Pristine, bell-like clarity with a sufficiently dense midrange: The Sirius has a top-heavy signature that drives its cleanliness and clarity. However, it does an admirable job structuring its midrange. Once again, its lean bass does leave instruments in need of warmth and harmonic richness, but the midrange remains surprisingly coherent nonetheless. If you don’t mind vocals sounding raspy – but not thinly wispy – if it means greater clarity, the Sirius is definitely worth considering.

A vast, open stage with excellent precision, layering and depth: The Sirius emphasises the Meteo’s strengths and structures an impressively vast stage – especially at its price point. Imaging precision and layering is reminiscent of in-ears almost twice the price, as its images boast excellent amounts of depth, width and height. The Sirius is a surefire contender for those looking for a grand, theatrical and operatic spatial presentation without losing engagement.

A bright-leaning – but smooth – timbre: Once again, the Sirius’s inherent tone makes it a shoo-in for fans of transducers like the venerable Sennheiser HD800. However, it pays its due diligence in avoiding sibilance just as deftly as its little brothers. It displays impressive tolerance for hotly-mastered tracks and maintains excellent headroom at all times.

Despite the Sirius’ technical achievements, its brighter tone and decidedly lean presentation limits its versatility quite a bit. If the traits of your ideal in-ear monitor are the ones below, the Sirius may not be the best fit for your needs:

Any amount of fullness from the bass: Proportionally speaking, the Sirius’ low-end gets the short straw. This is the main culprit behind its brighter timbre. Additionally, vocals end up sounding drier and raspier – articulative and detailed, but lacking harmonic richness and warmth. If a lush, laid-back signature is your cup of tea, the Sirius definitely won’t be.

A warm, natural tone: Once again, the Sirius’ treble emphasis gives it a clean image, as well as a brighter tone. Instruments may sound crystal clear and smooth, but they aren’t life-like in terms of timbre and hue. To those who prioritise an IEM’s tonal balance over sheer transparency and detail, the Sirius may prove too lean for your liking.

Dynamic energy and rhythm: The Sirius’ lean low-end also limits its dynamic range. Instruments like cymbals have impact, but there’s a missing sense of cadence when guitar riffs pop in, or in kick drum grooves, or in bass drops, etc. If you frequent genres like EDM or pop – or simply prefer a rock out presentation in general – the Meteo is a better candidate.

Verdict

Kumitate Lab’s NEXT 5 line-up carries three of the most exciting in-ear monitors in the mid-tier market today. Similar to brands like Custom Art or Advanced Acousticwerkes, they bring excellent innovation to an admirably accessible price tag – sacrificing neither build quality nor customer service along the way. Ito-san’s custom IEMs are some of the cleanest and most beautiful I’ve ever seen, and the universal demos I’ve been loaned echo that sentiment uproariously.

The trio carry their own unique signatures, only similar in how coherent, expansive and tonally lovable they are. The Corona joins the Empire Ears Phantom and the 64Audio A6t as one of my favourite pro-vocal IEMs, the Meteo has its sights set on the Lime Ears Model X as my go-to rock out customs, and the Sirius finds time as a monitoring piece both at home and behind the console. For years, many have considered Kumitate Lab an immensely underrated brand in the industry, but I think that ends today. The NEXT 5 is an outstanding prospect deserved of everyone’s consideration.

Photo courtesy of Kumitate Lab