In-Ear Fidelity

Tanchjim Oxygen Review: Over the Moon


For non-audio opinions, please refer to my unboxing post.

There are always a few companies that come to mind when you think “Harman-tuned”. Maybe it’s AKG, perhaps even Samsung. Though it’s more than likely that you’d think of the one company that has the “Harman DD IEM” market cornered: Moondrop.

Tanchjim is not a brand that got the traction Moondrop had, often only coming up in conversations as an alternative rather than its own solid recommendation. And it’s pretty easy to see why; where the Kanas Pro came in at a retail price of $180 and the subsequent KXXS at $190, Tanchjim’s direct answer to the two was was… basically in a separate price bracket.

Does Tanchjim truly deserve to be forever under Moondrop’s shadow? Can the Oxygen meet expectations and beat its cheaper, more popular counterparts?

Product page:

MSRP: $270

Driver configuration: single DD

This Oxygen was kindly provided by Linsoul.


This section is meant for those who have not learnt how to interpret the graphs that I create.

The main characteristic of the Oxygen’s frequency response is its pinna gain from 2k to 6kHz, which is pretty in line with Hammershoi & Moller’s Diffuse Field target though is closer to Etymotic’s more conservative interpretation of DF. Bass response is very significantly boosted relative to these targets.

The Oxygen, for whatever reason, is most compared with the Harman Target which represents Harman’s interpretation of DF along with a preference-derived boost in the bass frequencies. In accordance to Harman, the Oxygen has too much midbass (200Hz-ish), too little sub-bass (<100Hz) and too little upper midrange (>3kHz). A sentiment I 100% do not agree with subjectively, but if you’re one who religiously follows the target then this is something to take note of.

The “crinacle Neutral Target” is a target curve in which I perceive neutrality. It can essentially be described as an even more conservative interpretation of DF, moreso than Etymotic’s target.

Relative to my own neutral target, the Oxygen has a sub-bass focus (kind of), slightly suppressed lower mids in combination with boosted upper mids. Treble seems more-or-less in line with everything else and is neither emphasised nor recessed.

A common comparison point would be Moondrop’s own KXXS, an update to their popular Kanas Pro model. Apart from mild differences such as a small increase in sub-bass response in the the KXXS as well as the Oxygen’s slightly smoother transition from 4kHz to 8kHz, on paper the two can be considered as basically identical.

Comparisons courtesy of the Graph Comparison Tool



Technically “Harman-neutral” as it follows the Diffuse Field upper-midrange emphasis somewhat with a boosted bass response, though not to the level of “true Harman”. Subjectively, the Oxygens sound slightly upper-mid forward with a mildly pronounced sub-bass emphasis to me, though it wouldn’t be a stretch to call it “neutral” either.


I don’t think that there’s anything outright bad on the Oxygen, so I’ll list down some things that you may not like with its signature.

The common critique of the “DF bump” still exists; you get a very pronounced emphasis of upper harmonics that make instruments sound more forward and possibly more intense. Note weight may be an issue if you want something rich or heavy; the Oxygen is on the leaner side and prioritises a more snappy transient response over a more “lush and smooth” experience.

Fit seems to be an issue with many ears as the lower area of the shell hangs down and comes into contact with the ear notch and the tragus, resulting in a less secure and shallow fit. It is not a problem for me, but with the number of reports I’m reading around the internet I think it’s a good idea to at least reinforce this potential non-audio dealbreaker to you.

THE Good

I have heard many IEMs that claim to have (or is famous for) a Harman-style tuning. I’m not a particularly big fan of the target myself; the bass boost is a little weird and pinna gain is way too intense for personal enjoyment. Moondrop’s own Kanas Pro, KXXS, Blessing and A8 are examples of this tuning philosophy and, while I may appreciate them as “good IEMs”, they aren’t exactly on my rotation list for personal use.

Despite this, there is something about the Oxygen that speaks to me more on a personal level than the theoretically-identical KXXS. Is it the lesser bass response? Is it the more even upper-midrange tonality? The KXXS sounds a little more “fuzzy” to me, perhaps a little warmer; overall it’s just a smidgen less clean. The Kanas Pro isn’t even in the comparison here, I wasn’t a fan from the start and the KXXS represents a clear upgrade over it.

The Oxygen’s imaging is surprisingly competent; while not completely awe-inducing it is absolutely better than most IEMs I’ve tried. Enough to get the rare tag of “above average” from me, at least. Resolution is fine, it’s no Etymotic but it digs below surface-level detailing fairly well, and does so with well-defined notes that are less smoothed over and more textured.

I’ve said that the Oxygen is one of the best Harman-style DDs I’ve heard so far and that statement still holds true after my usual critical listening sessions. Yes, the tonality is a little too upper-mid focused for my own tastes, but I’ve never really thought about the Oxygen as “fatiguing” despite this criticism. It’s a well-balanced set that doesn’t go overboard in any frequency range even if it may get a little liberal at certain points; the bass is cleanly boosted with zero smearing, bleed or anything resulting from a “dirty emphasis” or bad transients, and the treble (arguably the hardest frequency range to get right) simply exists as a cohesive part of the frequency response as a whole, neither dulled nor overly-sharp.


The Oxygen is one of those IEMs that is hard to gush over because it’s something that can be simply described as “it’s good”. It’s technically competent, it’s well-tuned and would fit most people’s sonic preferences to some extent.

The obvious question would be how it stacks with the KXXS and Kanas Pro as there is an obvious price hierarchy here, and in this specific case I’d say that price reflects performance. Though on that note, the concept of “value” is still too subjective for me to determine for you. Absolutely need that $80 discount? The KXXS is still a very respectable performer in its price bracket. Willing to go all the way for the better sound? I’d argue that the Oxygen would be the better IEM overall.

Grade: B+

Thank you to all of my patrons for your continued support. Unfortunately the Oxygen will not be going onto the giveaway roster; it will remain as a reference IEM for future reviews.

And of course, my shoutouts to my very special big-money boys:


3 thoughts on “Tanchjim Oxygen Review: Over the Moon”

  1. Hi Crin, could you comment on the advantage of picking the moondrop blessing over this set???

    Im looking for something that has splendid air/breath in female vocals.
    I remember enjoying details coming from the flc8s, just wondering if the other two Im considering can provide very detailed vocals.

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