Review - Kefine Delci

Review - Blon BL03 (sub 50€)

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Also available on YouTube in Spanish: Acho Reviews YouTube

The Blon BL-03 are by no means a recent release, at least at the speed that Chinese IEMs are released. However, they seemed to get a lot of praise (maybe too much) so after not purchasing any IEMs since the ZS10 Pro (or was it the ZSN Pro?), I decided to give them a try and see what the hype was about.

I purchased them a couple of months ago but due to the Covid issues, they went around in circles for a while, with me even cancelling the order at least twice but they still showed up in the end, and to be honest I am glad they did so that I could form my own opinion.

I purchased the version with a microphone as it was actually cheaper than the version without and after checking them out online, I had already come to the conclusion that I would be changing the cable anyway. The connectors used are 2 pin 0.78mm so I swapped it out for a balanced cable from NiceHCK.

The shell of these IEMs is made completely of metal, however, they are not heavy, weighing in at around 8g per side.

The finish seems to be well done and gives them an impression of costing more than they actually do (they cost 30€ here on Amazon).

Normally, I will only use foam tips on the majority of my IEMs barring a few exceptions. This is due to personal comfort and I am willing to sacrifice whatever I may lose due to the foam in exchange for the comfort. I actually found them quite comfortable with silicone tips although I did have to mess around to get the left side to seal properly but once I swapped over to foam tips, these issues disappeared.

I have read many people that find find the BL03 uncomfortable, due to the short insertion, in my case I must say that I do not have this problem. In fact, I find them to be very comfortable, probably one of the most comfortable IEMs I have tried to date.

Their sound is slightly V shaped, well, it is actually sort of between a V and an L, which I guess is a signature that appeals to more people interested in IEMs at this price.

The bass is very present, although not excessive in my opinion, but it does have issues that I will mention in a moment.

The mids, although slightly recessed, in their higher part resolve pretty well.

As for treble, again, it is there but doesn't present too much sibilance, at least in the majority of songs.

To give a brief recap on what I found while listening to these, I will break it down into music
categories rather than specific songs, as I found that they remained very similar while playing songs of the same type.


Let me start by saying that I am not much of an EDM listener, however, when I first tried the BL03 it inspired me to listen to some EDM.

The majority of songs were from a few years ago (2015-2018) and I couldn’t give you names as I just put a random list on Tidal and let it play.

With this genre, I found the Blon to defend themselves pretty well, with very present bass, without being excessive, and good clarity in the treble. I think that the sound signature of these IEMs works well for this type of music, although some songs that were more vocal centric did show up the recess in the mids.


This is a genre that I listened to a lot until 5 or 6 years ago. I have a few albums that I like to use to test headphones and speakers, being “2001” by Dr.Dre and “All Eyez on Me” by Tupac.

The first album, 2001 by Dr.Dre, I started listening to without really noticing any issues but the longer I listened the more I started to feel that the bass and lower mids were colliding and creating a sensation of being congested and even dirty sounding. When not paying much attention they were acceptable but as soon as I focused on the music, the whole of the lower mids seemed to get more and more congested.

Moving on to the All Eyez on Me album by Tupac, I noticed the exact same issue as with the Dre album. Again, the lower mids seemed to suffer from a bleed from the bass, but on top of that, the whole lower mid range just sounded congested and lacking clarity.


Moving on, I am a great lover of acoustic music, mainly while I work. I am referring to songs that are mainly based on spanish guitars, acoustic guitars, vocals (mainly female) etc.

Here I didn’t notice the issues I found with Hip Hop. I think that due to the separation of instruments and the songs not being as busy, it did not congest the lower mids as much.

In fact, the sound of guitars, acoustic bass etc. is very pleasant. I wouldn’t say that they have perfect timbre but the stringed instruments sounded very real and full of life.

Sometimes songs that have a larger amount of instruments, particularly when piano is involved, the lower mids can again feel congested but nowhere near to the extreme as I found with the hip hop albums I mentioned.

Voices are clear and natural sounding, at least to my ears, and I actually enjoyed listening to acoustic music on the BL03 while working. They are by no means perfect for this genre but I needed to focus on the music of songs I have heard many times in order to pick the faults.

Modern pop…

Due to their V shaped signature, ok, L shape, without being overpowering, I am sure that many will love these for modern pop, and I must say that I am quite happy with them myself.

I think these adapt quite well to modern pop although I find that they do much better with female vocals than male vocals, especially deep male vocals, mainly due to the congestion in the lower mids that I have already mentioned.


On the graph you can clearly see the V shaped signature that the BL03 have and how the bass is elevated. To be honest, the graph shows the bass to be more exaggerated than it really is, at least to my ears.

If we compare them to the ZS10 Pro, an IEM that I have listened to a lot and holds its own pretty well (especially with a little EQ), we can see even more the elevated bass that the Blon has.

*These measurements are taken on my own sistem that is in no way calibrated to match the systems of any other person. My measurements must not be compared to any other measurements taken on any other system and are only presented as a guide to compare between different IEMs I have measured. For more info on how I do my measurements, you can visit this link:


For me they are a very comfortable IEM, although I know I am a minority.
The imaging is pretty acceptable although soundstage is not the widest, but it is difficult to find a good soundstage in IEMs in this price range.

The timbre is good, particularly on stringed acoustic instruments, although I did find the Cajon and similar percussion instruments to sound a little off at times. This is noticeable on songs like “La Luna” by Ottmar Lieback and Luna Negra, where the space between instruments and their placing is good but the timbre of the cajon can sometimes seem a little strange.

With songs that have a lot of movement in the bass and lower mids, the congestion in these frequencies presents itself again and again. It is very noticeable in songs like “Black Muse” by Prince.

On simpler songs, where these frequencies are not saturated, they respond quite well and I don’t feel that it is an excess of bass or even the bleed that causes it, I think that it is there lack of speed for resolving the different instruments that share that same sonic space.

The majority of my time listening to the Blon BL03 has been with the Shanling M2X (balanced) and a few hours on the JDS Labs Atom for analyzing purposes. I did, however, run them from the Loxjie P20 (fed by the SU-8) and really enjoyed them as background music while working. Admittedly, I wasn’t really focusing on the music but I had them for periods of 4 and 5 hours without complaints (mainly acoustic music).

I think that for the 30€ they cost me, they are certainly worth it. They have their issues but they also have their strong points and luckily one of them is with one of my preferred genres.

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