In-Ear Fidelity

BLON BL-03: Unboxing


I don’t even know where to start with BLON, but it seems that they are now a company that needs no introduction. The BL-03 is their newest golden goose, often compared to established models like the Moondrop KXXS or the Tanchjim Oxygen despite its price.

I’ll take this opportunity to clown on BLON’s name, which stands for “Belief, Letmusicburn, Oppoty, Nevergiveup”.

Oh China. Never change.

Product page:

MSRP: $39

The BL03 was kindly provided by Linsoul.


My unboxing posts are pretty much the only times I’ll ever talk about build quality, accessories and the like. I’m not really the person to ask about these things as I don’t really care about them that much.

Accessories: cloth case and tips.

Cable: 4-wire round braid, generic plastic sheathing that feels like a cheap PlasticsOne cable. Pretty bad texturing and doesn’t feel particularly good.

Connection: extruded 2-pin, almost like classic UE. It’s a weird connection by today’s standards but is relatively secure. 

Regular 2-pin cables still work with the BL-03, but it will be in a flush configuration when done so.

Build: metal build. Self-explanatory.

Fit: the shape of the shell is as if they tacked on a nozzle onto an earbud shell. The fit is horrible and is absolutely a dealbreaker for my ears. It takes a lot of time and careful adjustment to get a good seal on these, and even when that is achieved it does not stay put for long when I do activities with these on.

I need to stress this again: the BL-03’s fit is by far its biggest problem and this should be your biggest concern when considering to buy one.

Isolation: ranges from “average” to “bad” depending on the kind of fit you have. Not very consistent since the seal you get is also inconsistent at times.


Here’s a quick one-off section in top of the usual “initial impressions” section for reasons stated in the “measurements” section.

Q: Does this use the same driver as the Tanchjim Oxygen and/or the Moondrop KXXS?
A: I do not have the exact details. Anything is possible, but I’ll want to see a proper teardown before I (and you too!) make any conclusions.

Q: Was the BL-03 tuned by the same guy who tuned the Oxygen?
A: Refer above. I don’t know and I haven’t seen concrete evidence that proves that statement, so I won’t comment.

Q: Is this a “mini Oxygen”?
A: For the units I received (addressed below), no. It’s too different tonally.

Q: Can this compete with established top-of-the-line dynamic driver IEMs?
A: In my honest opinion, no. Don’t get me wrong; this is a very well-tuned IEM and an absolute steal for its price if you’re willing to overlook its drawbacks (highlighted above). Don’t expect this to be A or even S tier.

Q: But <insert reviewer here> said–
A: Whoever it is, we are not the same person and we will have different opinions on things. Live with it.

That said, there might be an issue with my units specifically…


First thing you’ll realise is that my BL-03 seems to measure differently to others. Audiofool, Prime Audio, Antdroid and Klaus Eulenbach‘s measurements all seem to have one thing in common that mine doesn’t: that linear response between 400Hz and 1kHz that represents a well-tuned sub-bass focus, while mine sounds like a somewhat generic V-shaped DD IEM.

I have contacted Linsoul for a second unit to confirm any unit variance. The measurements of this second unit is shown below:

Obviously I’m not expecting perfect unit matching from a $30 IEM, but both units I received do not exhibit the linear 400Hz-1kHz response that everyone else seems to be getting. Whatever the reason may be the concern still remains the same: the BL03 you purchased may not have the same response as these reviewer’s units. At any case, I will be reviewing the first BL-03 unit I received since it has less channel matching issues.


  • The fit issues of the BL03 are made even worse by the fact that it’s actually a damn good sounding IEM, especially for $40. It’s not a giant killer but I can call it a $100-$200 killer purely sound-wise.
  • These are not Harman. For one, the bass is tuned with an early rise and for the another, the upper midrange doesn’t shout like the other Harman-tuned IEMs do. It’s a much more subdued presentation and closer to my own neutral target curve.
  • Bass is merely okay, rather generic bassy-chifi style stuff. I can see these being even better with reduced midbass response, but again you’re just as likely to receive a unit that responds similar to mine as you would a unit that has that linear 400Hz-1kHz response.
  • Technicalities-wise, they do not live up to the usual kilobuck stuff in A-tier and above. I feel like Captain Obvious stating this, but with expectations so high I feel like I have the responsibility to tamper them down to realistic levels.
  • Overall, a great sounding IEM with atrocious fit. I have to keep reiterating this as yes, it is that bad. Most people (read again, most) will not achieve a satisfactory fit with these IEMs.

In case you haven’t seen it yet, I’m going on hiatus till mid-November. Just squeezing in some quick small articles in the little downtimes that I have.

As usual, thank you to my loyal Patrons and to my big money boys:


15 thoughts on “BLON BL-03: Unboxing”

    1. Yes it is the midrange but the 400 to 1K area follows the midbass so any drastic dips or peaks in the midbass will have an effect on the lower midrange.

  1. Hello,so,let me talk about my experience with the blon bl-03 and the tricks hacks i did to transform this strange iem in a fantastic almost high end one.First,i have chance that horrible cable,(for 10 bucks you can find a great value cable) second,i use a 2.5 balanced jack,the difference in quality toward the 3.5 is huge…then,thrown away the ear tips out of the box and replace them with kz starline upside down hacked.magically you will have tips with longer fit (they look like a comply tips)before puting the tip,i cut a small ring of a tip that i applied before putting the tips,this will make it more longer…. at last but not at least i cover the small vent on the iem with a small sticker..this will increase the bass….after this ”hack” i have a AMAZING INCREDIBLE FABULOUS SOUND,AND A PERFECT GREAT FIT….hope this can help.cheers.skrotum.

    1. I did the same thing, except the Bass mod. Very satisfied, since I really like the tuning. The only thing I think could be better is the a little bit lose bass-response.

  2. Just received my pair in the mail today. I was expecting to need to use my spinfit tips to get a good fit but I guess I won the luck of the draw for fitment on these. They fit absolutely perfectly in my ears with the stock tips even. These sound great, nothing bad to say about them.

    1. To add on, to my ears it seems like the unit I received is indeed closer to the other measurements rather than yours. I got lucky again I guess.

      1. same, the biggest stock tip works, almost as good as my foam tips. I can use them for hours without pain. Will get e1da 9038s soon for a much better portable experience.

  3. When I got these, I completely agreed that it was probably the most uncomfortable IEM that I had ever tried, to the point that it was useless for a normal use. Took me quite a time even to find out a way just how to place them in my ears! Not to mention that there was no sealing at all. Well, just replacing the tips by the stock big ones (I received the grey ones) and removing the guides in the cable and then putting the R shell in the L cable and vice versa and wearing them hanging up-down instead of over the ear, a hell transformed into a helluva of comfort, fitting to my ears and with a perfect seal. And as pointed out in the review, it is a damn good sounding IEM!

    In my experience, there’s no need of further purchases. For the tips I did some roll tip, i.e. mh755 big tips, final audio tips, KZs and other similar, and I could not find any differences with the stock grey big ones or these were even better, maybe a placebo but at the end of the day these were the ones I left and I’m using. Regarding the cable, I removed the guides using a pin and the nails and removing chunks with a scissors, it sounds like more work than it really is, it is not difficult at all. With the guides removed I think the cable is not bad at all, maybe a bit prone to tangling but when it comes to comfort, I have no complains and I actually like how it looks like

    Hope this helps to enjoy this IEM!

  4. Would it be possible to drop a grade, based in SQ only, not taking into account the fit?

    After using them for a month, wearing them hanging up-down with the changes in the cable that I mentioned, not only they’re not uncomfortable, they’re damn comfortable! I feel even guilty for being so lucky, lol

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