BLON BL-03 Review

Flavor of the Year

Kazi Mahbub
Nov 8, 2019 · 8 min read

Did someone say Flavor-of-the-month? Well, the BLON BL-03 has been the FOTM for a few months running, so maybe, just maybe, there’s a gem in the hiding.

The BL-03 uses a Carbon (nanotube?) driver, and is one of the cheapest, if not the cheapest IEM to use such tech inside the housings. The first CNT driver IEM that I recall was Dunu Falcon C, and that thing had a price-tag of over $200. The “trickle-down-effect” has done its wonders indeed and so we have a strictly budget IEM that aims to take a shot at the big boys.

(Note: the ratings given will be subjective to the price tier. Definitely the expectations from a $15 IEM won’t be the same as a $150 one, and that’s the approach taken while assigning scores. I bought the IEMs with my own funds, still, Disclaimer)

Sources used: LG G7, Questyle QP1R, Yulong DAART Canary, VE Odyssey, Apple USB-C to 3.5mm dongle, iPhone SE

Build: The BL-03’s housings are made of “Kirsite” alloy, which apparently is a variant of Zinc alloy. Irrespective of the metal used, they feel really solid in hand, and there is no roughness around the seams. The mirrored finish does not attract fingerprints or smudges easily, which is a plus. My biggest complaint would be the protruding 2-pin connector, where using 3rd-party cables will put unnecessary strain on the connectors and this might be a potential point of failure in the long run.

Some cryptic messages on the box.

Accessories: The accessory set is pretty complete in terms of the amount of stuff you get: 6 pairs of eartips, a 2-pin cable and a carry-pouch. However, the tips are practically useless as they are shaped in an oblong manner, thus not getting a good seal. Moreover, the cable is really tangly and worst of all — that memory wire is absolutely atrocious. Buy a separate cable to make life easier (you can find cheap ones under $10 on AliExpress). That leaves the only usable thing that you get with the box — the carrying pouch. Sigh.

Comfort: The Achilles’ Heel of these IEMs would be how awkward their fit is. In fact, it is one of the most fit/eartip-dependent IEM I’ve come across in quite a while. Just changing from Final E-type tips to Spinfits bring about drastic changes. The nozzle size is the culprit here as it’s too short and thus the IEMs often dangle about. The only way to get a good seal is to use double/triple-flange tips, or using Final E-type/Spinfit tips that bend into your ear-canal. I’ve personally used Spinfit CP-500 tips throughout the course of this review. Another thing to note would be the driver-flex as these IEM exhibit that phenomenon quite often.

Now, on to the sound:

Lows: The bass response on BL-03 depends on the type of tips used and how deep an insertion you’re going for. For the usual shallow-insertion, the bass is neither overpowering nor lacking in any sense. It mostly gives you a faint sub-bass kick and that’s about it. Bass decay is faster than the usual dynamic-driver IEMs, which gives a pacy “rhythm” to every song you play that has a punchy bass-line. On Fort Minor’s Where’d You Go, the heavy baseline never overshadows the mids, nor does the bass distort in high SPL (volume).
It won’t be enough for bass-heads, but it’s quality bass indeed.

Mids: Vocals are slightly accentuated, with high-pitched vocals being given more emphasis than lower-pitched/baritone ones. The comparatively leaner sounding male vocals might be the only point of contention with BL-03’s midrange as the rest of it is just sublime. Acoustic guitars and string instruments have a very natural attack and decay, with mostly spot-on tonality and timbre. I find that acoustic guitars/piano tend to sound a bit brighter than reference, but it’s nothing too noticeable unless you’re A/B-ing and it’s mostly a matter of taste. Micro-detail retrieval is where it will fall short, but that’s the only time when you’ll realize that you’re listening to a budget device. Instrument separation is excellent.
All in all — some great mid-range performance here, and not just “for-the-price”.

Treble: Treble is neither on-your-face, nor is it veiled. Balanced — the word that best describes it. There is enough emphasis around the presence (5/6KHz) region to keep things exciting, while the 8–10KHz region is tuned down even further with some peak around 13KHz or so to introduce more air into the treble. This makes cymbals sound more distant than reference, and the initial cymbal hits are less exciting than they should be. It’s just nitpicking at this point though, as BL-03’s treble performance is more than adequate, if not outright great.

Soundstage: Soundstage width and depth is above-average, while the height is just about average. Nothing to write home about here.

Imaging: Imaging, on the other hand, is exemplary. Yosi Horikawa’s Crossing is a good song to test out imaging performance, and here the BL-03 just shines. The motorcycle going from left to the right, the ambient noises that pop up every now and then throughout the whole track — everything is in the right place. Tool’s Chocolate Chip Trip is another song where you can point out the general direction of every single drum hit.

Bang-for-buck: Outstanding, in one word.

The short nozzle is the biggest negative

Source and Amping: BL-03 sounds good outta everything, or at least out of most decent sources. It sounded as it should out of both iPhone SE and LG G7. Obviously plugging into a good external amp makes everything sound better, but it’s a complete overkill for such a budget device. If you have a good DAP, however, that will bring the best out of these, just that it’s not necessary and more of a luxury.

Select Comparisons

vs TinAudio T2: Tin T2 is perhaps the most well-known chi-fi IEM at under $50, and for very good reasons. It sounded unlike anything under $50 in the chi-fi realm back in the day. Pitted against the BL-03, it holds its grounds when it comes to sheer details, and I would say that T2 out-resolves the BL-03 in terms of sheer details retrieval. However, the bass response is far superior on the BL-03, and the mid-range tuning is more “mature”. The treble is also more even-handed on the BLONs, without the often annoying peaks of the T2. Soundstage is wider on T2 while BL-03 has better imaging. Build quality is about the same while T2 is slightly more comfortable. Both have terrible cables and stock tips, so it’s mostly a home-run for the BLONs.

vs KZ ZSX: KZ ZSX has more treble detail and bass quantity, but BL-03 has far better bass quality and treble tuning. Midrange is where KZ ZSX falls apart, just like every other KZ IEM before it (and probably in the foreseeable future). It just sounds completely off in terms of tonality. Moreover, there is the infamous “BA Timbre” that’s on full display here. Comfort and soundstage width goes to KZ’s way for once, but it’s handily beaten in terms of overall sound quality.

vs Fiio FH1: The only worthwhile IEM Fiio has ever released was the good ol’ EX1, but even that was made by Dunu. Well, that was a completely irrelevant rant so let’s get back on course. FH1 only has better build and cable/accessories. It doesn’t even register as a competition elsewhere. Sorry guys, but this thing is overpriced beyond belief and now is getting handily beaten by IEMs that cost ~70% lower.

vs Sennheiser IE40 Pro: Now this is more like it! IE40 Pro is one of the best IEMs you can buy under $150. Compared to the BLONs, it has more accentuated mid-bass while the sub-bass extends even deeper. Vocals are slightly better on the IE40, esp male vocals. Cymbals also hit harder and has more authority in the mix.
Rest of it is pretty much back and forth though, with imaging being about par on both and the IE40 having a wider soundstage at the cost of having the vocals sound more distant.
The best part about this comparison though is that if you prefer a mid-forward signature, the BL-03 would surely be the one you’d pick after a blind audition, provided you can get a good fit (an area where the Sennheiser absolutely shines). Overall, the IE40 is the better IEM if you consider every single facet, but the BL-03 is the better buy due to the off-the-charts price-to-performance ratio.


BLON BL-03 has officially changed the status-quo of budget IEMs, at least for me. It absolutely shames some of the popular IEMs with a much higher price-tag, and it does it all in such an unassuming manner that it boggles your mind. Why can’t Fiio do something like this with far more resource at their disposal? What can’t KZ still figure out something an obscure company has managed to do with aplomb?

The poor eartips/cables, and the short nozzles that further compound the awkward-at-best fit aside, this thing aces everything else. This is not a flavor-of-the-month, rather a flavor-of-the-year.

Moondrop Crescent, before its discontinuation, was my singular recommendation if you were looking for an IEM under $50. I don’t know how long the BL-03 will survive, but it’s on sale as of today, so grab a pair while you can. Don’t forget to get a pair of SpinFits/double-flange eartips though (mandatory), while getting some decent cable (I’m using this one) will help in the long run.

The BLON BL-03 demands a recommendation of the highest order, and that’s what it’s gonna get. I wait with bated breath to see what BLON comes up with as a successor.


You can buy it from here (non-affiliated link), or look around for deals.

Test tracks (as YouTube playlist, often updated):

Kazi Mahbub

Written by

Currently studying MS in Informatics. Tad too picky when it comes to audio. Occasional film-buff. Budding cook.

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