In-Ear Fidelity

Lime Ears Model X: Two-faced


The Model X is Lime Ear’s quad driver model that was first released back in late 2017. As with most other boutique-style companies, the Model X was offered only in custom and universals only existed as demo units for distributors and sellers. I myself have tried the Model X demos before and have ranked them at A- a few months ago. Now, Lime Ears is offering the Model X in universal shells commercially and have provided me with a unit for a full review.

Lime Ears Model X Universal

The Signature

The most defining feature of the Model X has to be its switch system. Now yes, what was once a feature exclusive to kilobuck IEMs has now been gaining relevancy on the IEM stage in recent years, with many cheap chifi models now sporting switches. However, most switches seem to be rather specific with their changes with most opting for rather focused frequency boosts, most popular being boosting the bass. Lime Ears takes a rather unique (for now at least) direction with their Model X switch, changing the overall signature of the IEM quite drastically.

On what I dub “neutral mode” (switches down), the Model X is… well, neutral. A little like the UERM in a way with some extra upper midrange, so it’s what I’d personally define has slightly coloured due to the small tilt in tonality towards the higher frequencies. More or less completely flat from the bass to the lower mids so it fulfills the classic textbook definition of sterility and being “reference” in that regard.

Turning up the switches to what I dub as “warm mode”, the Model X could be an entirely different IEM and I’d be none the wiser. There is a wide band boost in the lower frequencies as well as a slightly reduction in the upper mids and treble, which balances out the tonality nicely. Even in this mode though, it’s not that warm and still less warm than something like the Massdrop Plus. Lime Ears intends for the “bass boost” switch to be used for low volume listeners per the equal loudness contour, though objectively speaking it’s not quite accurate since they’ll require a much higher sub-bass increase than what is tuned in. But let’s just throw the textbook out the window for now.

The Bad

To be absolutely clear, the Model X is a very capable all-rounder (moreso with its dual signatures) and so these aren’t hard flaws, more like shortcomings that any potential buyer should be aware of.

For one thing, the treble tilt can get a little hot. It’s not quite screaming in your face demanding damping, but it gets fatiguing for sensitive people like me who can appreciate a rolloff. That said, it’s just emphasised but not splashy, so it retains definition and control despite its brightness. I can see the Model X being a “makes you wince” kind of sound for many people but at least it has the resolution and definition to justify the use of foam.

Bass is another issue but it’s pretty much a guaranteed talking point on the “The Bad” section of my reviews if it’s a pure BA IEM. I do have my biases and I’m not afraid to talk about them; the Model X’s low end doesn’t hold a candle to any of my hybrid or DD IEMs and so sounds limp and inarticulate in comparison. That said, even in the realm of BA IEMs the Model X also doesn’t have particularly good “BA bass”. It still fails to convey the authority and darkness of a bass drum in an orchestral piece or the proper rumble of a deep synth note. Of course you can still hear the notes, but my usual criticisms of BA bass apply here, no escaping that.The characteristics of the bass itself don’t change much between modes, with only the overall volume getting louder or softer depending on the switch position.

Additionally, there’s a hint of that crunchy, plasticky aftertone that’s a sign of the good ol’ BA timbre. Thankfully it’s not too obvious and I’ve definitely heard worse, but that is something to look out for if you’re sensitive to that kind of phenomenon. Rather common in these kinds of reference-style BA IEMs so given the amount of it I’m hearing, I’m willing to close one eye.

The Good

Let’s shift the fluff out of the way; the Model X is very good bordering on exceptional. What I feel is its strongest point is the way that both modes are tuned. I’ve let no less than ten people have a go at the Model X and there was almost a 50/50 split between those who prefer it in “neutral mode” versus those who prefer it in “warm mode”. Small sample size but it’s hard to argue that the Model X can offer something to almost everybody. As I’ve said before: “neutral to warm in a pinch”, though it is to be noted that the Model X is capable of both proper neutral as well as proper warmth, nothing half-baked with either.

That being said, tuning is nothing if not backed up by technical proficiency, especially in the kilobuck realm. But obviously I’ve avoided talking about technicalities in “The Bad” section for a reason here. The Model X scores high marks across the board, nailing resolution, definition, tonal balance and attack speed and achieving passing grades for timbre and decay naturalness. There is virtually no smearing of notes even on the warm mode, remaining clean and defined even on my busiest metal tracks. Furthermore, there is almost no sacrifice in technicalities when going neutral to warm mode, a nice surprise given the amount of monitors I’ve listened to that fall apart with just a small emphasis in the lower midrange.

Neutral mode tends to bias percussions and plucked strings more, though the bias shrinks on warm mode. Depending on your tracks and genres, there isn’t an emphasis of one instrument type over the other and the tone is well presented, perhaps one of the best in my recent pool of review units.


Proper tuning, proper technicalities, proper use of a switch. Not much to say, the all-rounders are always the hardest to praise.

Perhaps I’ll get some flak for doing this only after getting a review unit, but my reputation will survive. Lime Ears deserves this.

Grade Adjustment: A- A

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