Custom Art FIBAE 4 – Fun, Fidelity, Finesse



Custom Art’s FIBAE 4 is a fast-paced, spacey and impactful-sounding earphone. Perhaps Piotr’s most v-shaped entry to date, the in-ear thrives on energy. The low-end provides a bold, gutsy and almost subterranean foundation, undercut by the top-end’s swift, articulate cuts. And, the midrange humbly bridges the gap. However, while monitors of this type usually cause fatigue to set in much quicker than usual, the FIBAE 4 largely avoids this downfall. This is achieved through rapid decay. Images come-and-go with great immediacy, so the listener is never bombarded with noise during listening.

Now, there is a less desirable aspect to this speed. If you’re one to enjoy lots of wispy, euphonic warmth permeating throughout your soundscapes to bind instruments together, the FIBAE 4 won’t provide that. The images this monitor renders are almost their own little islands scattered throughout the soundscape, rather than one big, unified, wall of sound. Obviously, where this benefits the FIBAE 4 is in separation. Detail retrieval and layering is the FIBAE 4’s strong suit. A clean stable background and precise imaging also make for a tactile and convincing surround sound experience. Again, it’s a refined, smooth, fast-paced sound with bounds of air and space, founded by a dense, bold low-end below.


The low-end is the FIBAE 4’s engine. It’s impact-driven, dense and generously-bodied. There seems to be a rise towards 100Hz that bolsters kick drums forward – one of the FIBAE 4’s highlight instruments. Whether listening to or performing with them, kick drums always cut through the mix very clearly. Personally, I find that feature wonderful when I’m having to learn a new kick pattern from a busily-arranged track. And, it works wonderfully with genres like prog-rock and metal as well, where double pedals are abundant. Past that 100Hz mark though, they low-end dips, especially toward the low-mids. This is what steers the FIBAE 4’s bass towards a quick and open timbre, rather than a warm, euphonic or wet one.

This dip allows the low-end to have tons of concentrated impact with minimal bleed. The FIBAE 4’s stage remains clean as a result. In fact, clean can also be used to described the low-end notes themselves. Kick drums and bass guitar come through with tons of clarity and textural data. It isn’t this blubbery mess that trades in resolution for volume. Rather, it achieves both through clever tuning and raw extension. I also admire Piotr’s decision to keep sub-bass relatively linear. It’s what gives the bass headroom, and allows the natural textures of the track to come through without any artificial rumble. All in all, it’s a response with the right blend of bigness, clarity and warmth to sit well with a plethora of genres.


The midrange is where airy and open come in. Instruments are given tons of space – both from each other and from the listener – as they’re positioned neutrally in the stage. One thing the FIBAE 4 never is is in your face; stuffy. Whether or not that’s a good thing will ultimately depend on your tastes. Technically, a low-mid dip encourages definition. Images are well-defined, compact and tight, so there’s always air around them. This allows clarity to always be apparent even in the busiest of arrangements. Transitioning from there is a rise around 1-2kHz, where the majority of the FIBAE 4’s midrange energy is focused. This gives instruments a solid body, so despite the neutral positioning, they never lose their integrity.

In the upper-midrange lies the FIBAE 4’s most audible colouration: A 3-4kHz dip. It’s what pulls the instruments back for a more reserved, open profile. As mentioned, they more so resemble tiny islands scattered throughout the soundscape; modest in note size and in projection. This ensures the soundscape is never saturated with loud instruments fighting for attention. But, at the same time, I find it has the adverse effect of limiting dynamic range. Midrange instruments have a tendency of lacking impact and punch. This is especially true of brass sections, like those on Snarky Puppy’s Chonks. The drama from those horns projecting boldly in your face is diminished. But, at the end of the day, when you consider the bigger picture, it is a compromise necessary for the FIBAE 4’s v-shape to work, and one that others may enjoy regardless.


Despite the v-shape descriptor I’ve been using throughout the review, the FIBAE 4 isn’t as egregiously contoured as the adjective may imply. This is especially true of the top-end. The FIBAE 4 possesses a clean, crystalline top-end with tons of air and detail, but it isn’t as sharp and crisp as one might probably expect from such a signature. This allows the FIBAE 4 to maintain a neutral tonal balance that errs too far neither in one direction nor the other. And, it also allows the FIBAE 4 to maintain coherence. Top-end transients are never too distant from the harmonics of the lows, so there’s a unified feel to the FIBAE 4 that’s become less common in the new hybrid era. It performs with precision and speed; no more, no less.

The top-end efficiently cuts without overdoing brightness or sharpness. Edges are refined, but never blunt or muffled. This comes from the top-end’s immediacy in both transient and decay. Notes appear out of thin air, then vanish just as quick. This is evidently showcased in David Benoit’s Cast Your Fate to the Wind, rife with extremely delicate hi-hat and ride cymbal work. All those tiny touches are rendered through the FIBAE 4 with stunning clarity, and a convincingly realistic timbre. The second part to that equation is the stable backdrop, courtesy of strong extension. Composure is something the FIBAE 4 is never short of, and the same can be said for left-right separation. Stereo spread is downright out-of-head with the right material, and thus completes a wonderful top-end response: Clean, smooth, precise and full of technique.

General Recommendations

The FIBAE 4’s lightly-contoured frequency response makes it an exciting, clean-sounding monitor ideal for a number of genres, as long as you enjoy lots of openness, clarity and air. Above all, though, here are three things it does very well:

Tight, clean and open-sounding instruments: The FIBAE 4’s airiness comes from its clean, well-defined instrument timbre. Images are crisp and well-outlined, which results in strong separation. And, great stereo spread places them all around you in convincing fashion. If you like light and fast instruments that don’t exude too much warmth, the FIBAE 4 is for you.

A guttural, full-bodied low-end with clarity: A great balance between heftiness and definition runs throughout the FIBAE 4’s lows. Although its inherent timbre is airy and clear, it carries tons of weight in its impact due to clever tuning and strong extension. This is especially ideal if you’re playing or monitoring kick drums, or you simply want them to pop in the mix.

Smooth, delicate yet crystalline highs: The same balance between finesse and cut exists in the FIBAE 4’s top-end. Notes cut through with airiness, refinement and clarity, yet they remain smooth and feathered in texture. These aren’t shrill, brittle highs that cut through the mix by force. Rather, they’re speedy, refined transients with a forgiving, effortless sense of air.

However, to achieve its effortless clarity, the FIBAE 4 certainly has its fair share of compromises. It’s not the wettest, warmest or most intimate in-ear monitor out there. Here are three attributes in which those colourations most lie:

Intimate-sounding, rich, warm mids: The FIBAE 4’s midrange is decidedly dominated by air. Instruments aren’t the most full-sounding, nor are they forwardly-positioned or intimate. They’re sat neutrally in order to emphasise spaciousness. So, if you prefer your instruments warmer, richer and more in-your-face, the FIBAE 4 may not be the ideal pick for you.

Impactful, dynamic upper-mids: This airy sensation is most prevalent in the upper-mids. If you’re a rock aficionado – or a concert go-er in general – instruments like electric guitars and horns won’t have that visceral, dramatic sense of impact. Rather, they’re slightly restrained to avoid saturating or congesting the image; limiting dynamic range as a side-effect.

Ultra-crisp and bright transients: The FIBAE 4 is only mildly v-shaped; particularly in the highs. The FIBAE 4’s top-end is crisp and articulate, but feathered and linear relative to the mids and lows as well. It’s a balanced presentation that may lie more towards the modest side to some, especially if you’re a treblehead looking for ultra-crisp, ultra-bright transients.

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About Author

Church-boy by day and audio-obsessee by night, Daniel Lesmana’s world revolves around the rhythms and melodies we lovingly call: Music. When he’s not behind a console mixing live for a congregation of thousands, engineering records in a studio environment, or making noise behind a drum set, you’ll find him on his laptop analysing audio gear with fervor and glee. Now a specialist in custom IEMs, cables and full-sized headphones, he’s looking to bring his unique sensibilities - as both an enthusiast and a professional - into the reviewer’s space; a place where no man has gone before.

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