Custom Art FIBAE 4

General Information


FIBAE 4 comes as natural continuation of Custom Art’s lineup, merging qualities of FIBAE 2 and 3 into unique sounding IEM. Top Firing Drivers provide improved frequency extension compared to traditional Balanced Armature drivers with a spout resulting in immensely detailed sound.
  • Single low, Single full-range, single proprietary high, single proprietary super high
  • Sensitivity : 115dB @1kHz @0.1V
  • Distorsion : Low % THD
  • Impedance 8.1 Ohm @1kHz (+-0.95 Ohm 10Hz-20kHz)
  • Frequency range : 10Hz-21000Hz (+-20dB into IEC 60318-4 coupler)
We tuned FIBAE 4 to be fun sounding IEM with warm and smooth signature. It offers excellent sub-bass depth and punch, detailed and natural midrange finished with extremely detailed, but never harsh highs. It combines big headroom, high resolution and expansive sound stage. FIBAE 4 is a perfect tool for guitarists, bassists and drummers for stage monitoring.

Latest reviews


500+ Head-Fier
Pros: Smooth and detailed presentation, material and build quality, amazing design, fun and engaging sound, powerful bass,
Cons: simple package, lack of energy on trebles,
Before reviewing, let me share technical aspects and package details.
And also, I would like to thanks to Piotr for this great opportunity.




Single low, Single full-range, single proprietary high, single proprietary super high

Top Firing Balanced Armature Drivers

Flat Impedance technology

115dB @1kHz @0.1V

Low % THD

8.1 Ohm @1kHz (+-0.95 Ohm 10Hz-20kHz)

10Hz-21000Hz (+-20dB into IEC 60318-4 coupler)

Custom or Universal fit



Package Details:

– Carton box

– Peli 1010 case

– Zipper case

– Wax pick tool

– Drying pellet

– Warranty card

– Ear tips in 4 sizes (universal fit only)


Test Equipment:

Lotoo Paw Gold Diana

Astell & Kern AK120

Opus #1


Emotiva Big Ego


Package, Design;

Fibae 4 comes with a black box that is the same as their other products. Inside of the box, there is Pelican 1010 case and mini zipper soft carrying case with tips and cleaning tools. I’ve always been a big fan of Pelican 1010 case to store my gears, and probably I have more than 10 Peli1010 case at home. Package is not fancy and unboxing experience is not so impressive like some brands, but everything you need is in to the box.

If I have to choose only one company that has the most beautiful earphone design, I would pick the Custom Art. They make the amazing beautiful earphone; you should check them on their Instagram page. They did a fantastic job with my Fibae 4 which is the cutest, sweetest, prettiest earphone that I have ever had. It looks like a candy and I feel like I’m going to get a delicious taste if I eat it. I am hundred percent sure that all the babies want to eat it when they see. Build quality is fantastic as expected, no flow, no defect, nothing, it is beautifully made. 2 pin socket feels super solid, and it is so tight. I had a hard time to took it of the stock cable. Stock cable looks great and it is better than most of the stock cables but the only thing that I don’t like is its memory wire. Unfortunately, I don’t like memory wire and I never find good fit on it. F4 (Fibae4) doesn’t have a big shell, on the contrary it is fairly small. Its rounded edges and ergonomic design make it super comfy. I’ve used it many hours and I haven’t felt any pain or discomfort issues at all. I believe no one would complain about its comfort.



Normally, when I listen to earphone for the first time, I could understand how is the sound signature in first minutes, but with Fibae 4, it took longer than I thought and I couldn’t make any judgements. I decided to burn in like 50 hours than try to get used to its sound, and it started to give some result. The indecisions of the beginning that I faced are disappeared and I fall in love the Fibae 4’s sound. Fibae 4 sound is typical V shape, with powerful bass which hits like Thor’s hammer and relaxed smooth trebles with laid back, detailed mids. Overall sound is tad of dark but don’t let this mislead you, all the details and nuances in the music are there and easy to hear. The high frequencies are not in front of the other frequencies and are generally creamy and smooth. Mids are leaned backwards but it provides good amount of detail. Bass is the locomotive frequency of the Fibae 4. Extremely strong and deeper which dominates the overall presentation. One thing that I quite like about the bass, its articulated and natural presentation. Bass is not dry and dull tonality in despite of balanced armature drivers, on the contrary it has a very natural and organic presentation.

Fibae 4 has smooth, relaxed trebles that never harsh or sharp. It puts pretty enough space to separate the instruments and support to soundstage wideness in a good way. Although its dark presentation, it’s energetic yet detailed. It’s laid back but it never fails to show its ability to bring details. You may not clearly hear the details in the very first listening, but when you get used to it, you will notice that all the details and resolution hidden in the upper frequencies are actually there. Upper trebles missing some extension and dynamism but it makes easy to listen for long hours. This reminds me the Um Pro30 some way. But I would like to tell that some people might want more quantity, so this might not be a good option for treble-head people. Generally, trebles play well, but not as remarkable as bass or mid frequencies.

Bass frequencies might be the star of the show, but there is another hidden gem on F4 which is the mid frequencies. It is laid back and step up behind of the overall sound but it has fantastic details and pattern of the sound that produces. Layering an imagining are also great on mid frequencies. Stringed instruments are not dry and it has natural timbre. Mid bass doesn’t give any stress and it plays airy and clean. Vocals and instruments’ location are easy to distinguishable. While listening to Above & Beyond, it creates an incredible atmosphere like in the club and all the sounds spread out to the stage and vocals can be heard clearly without narrowing the soundstage. I fall in love its mids tuning with every vocal Trance track that I listened. As a result, Fibae 4 became my latest favorite EDM genres earphone. Smooth and mellow presentation doesn’t give any fatigue and although its dark sound never become muddy, ever.

Who said that balanced armature driver doesn’t have punchy bass like dynamic driver? Well, Fibae 4 will destroy those thoughts right away when you hear it. It has a huge bass that rumble of your bones and puts a big smile on your face then it pushes you to open another bassy tracks to listen it over and over and over again. Bass is super enjoyable to listen and there is a plenty of power on low frequencies and it reminds itself with every song that you listen. If I remember correctly, talking about more bass quantity than SE846. Although the bass is quite high in quantity, it does not tend to spread out or dominate the entire sound frequency, but it has some minor bleeding in to the mids that don’t bother me at all. The bass doesn’t dazzle in speed, but it still offers pretty good speed in this regard.

he soundstage is quite wide and simplifies to listen instrument and positioning. Air between instruments are great. The depth provides a good amount of space and help to improve layering an imagining. Background is not pitch black but it is pretty clean.


Cable Rolling:

Effect Audio Origin:

Origin is limited budget series of the Effect Audio cables’ and I got 2 set of them when they released. To be honest, Origin doesn’t make any drastic change on Fibae 4 and its sounds almost similar with the stock cable. Bass is punchy, deep and mids are laid back. Tonality is almost same, but Origin adds some extra brightness on overall sound. The only change that I noticed is on the highs. Highs are slightly clearer and more prominent than the stock cable. Soundstage remain same or I didn’t notice any change. Overall, improvements are mostly nuance and there are no big differences between stock cable and Origin. After comparing stock cable with the Origin, I come to conclusion that stock cable is really great in terms of sound.


Rhapsodio SGD2.98 MK2:

SGD2.98 MK2 is gold plated silver cable from Rhapsodio Audio and its overall signature is warm, lush and smooth. When I try with the F4 I just realized in very few second that it won’t be a good match. F4 sound is already smooth, extra warm sauce make it dark and almost muddy in this sense. The main improvement on the bass frequencies, it hits more, goes deeper and at the same time it loses its control and bleed in to mids. Only positive improvement on the soundstage, it adds more width and depth make it more holographic. Overall, it is not good match with F4 for my personal taste.


Effect Audio Ares:

Ares is the well-known cable on the community and it deserves its good reputation. Due to its budget friendly price, it is the most popular product of the Effect Audio lines as well. F4 and Ares are not the best pair but still they have good synergy. As expected from a copper cable, bass quantity is slightly increased and feels more controlled and tighter. Mids are slightly forward and thicker than the stock cable. Trebles are same in quantity but presentation is cleaner and clearer. Soundstage is better on both width and depth and also there is more air than the stock cable. Ares matches good with F4 but still it’s not what I looking for.


Penon Audio Leo:

Leo is a pure silver cable from Penon Audio, and this is the best cable on my hand to match with F4. Bright and open presentation of the Leo makes great soulmate with smooth and warm sounding Fibae 4. Bass stays in same quantity but it is much tighter and more controlled, and also slightly faster than the stock cable. Mids are more open and natural, and also the distance between vocals are slightly more forward. Trebles are clean and clear which Leo mostly touches on high frequencies. There are noticeably more sparkle o highs and details are more audible. Soundstage is more open and wider as expected and, instrument separation is much better. Overall Leo is great match with Fibae 4 which I am using it with F4 right now.




Fibae 4 vs Fibae 2:

Both F4 (Fibae 4) and F2 (Fibae 2) looks geourgeus looking IEM. F2’s space concept design is one of my favorite and anyone who sees loves at the first second. F4 design is completely different and its super sweet colorful design hard to dislike. There is no much to say about qualities and design, both earphones are top notch in this sense. F4 body is little bit fatter and more rounded shape while F2 is slightly slimmer and also its nozzle is little bit longer. Both are pretty comfortable and no issue with the fit. These are coming with exactly same type of box and only difference is the stock cable that F4 has. Sound wise, F4 is better in every technical aspect from F2 but that is all about personal preferences. F2 has more forward and upfront presentation, while F4 has more open and V shape like sound. Bass is more authoritative and powerful on F4. It hits harder and goes deeper. F2’s bass is more controlled, slightly faster and it takes powers on the mid bass. Both are definitely bassy earphones. Mids are more forward and centered on F2 while F4 is more laid back and distance. Due to its forward presentation, F2 has more melancholic and romantic presentation while F4 has typical V shape mids, but F4 is more detailed and better on resolution. When I start to compare side by side, I felt F2 has more in treble quantity but after some couple of tests I realized that F4 has slightly more in quantity. F2 has well extended, clear and detailed trebles. Both are good in quantity and quality. Soundstage is better on F4, wider and more open while F2 has limited soundstage and its forward mids has big role in here for sure. Both earphones are great in terms of sound, build and design. As I mentioned before, it is all about preferences.



Fibae 4 vs Nocturnal Atlantis:

Fibae 4 and Atlantis shares same number of drivers, but their presentations are completely different. Let’s talk about the design and build. Both earphones are beautifully designed. Material and build quality are top notch on both, no complaint here. Atlantis has golden space design while F4 has colourful dots. Sounds are totally different on both. Atlantis has more neutral reference like sound while F4 has more fun sound signature. Bass is much more in quantity on F4 and it goes deeper than the Atlantis. Atlantis has more linear and rolled off on bass when I compare to F4. Atlantis’ bass is faster and better on decay but F4 is punchier. Mids are more laid back and smooth on F4 while Atlantis has flatter and slightly forward. Trebles are more prominent and extended on Atlantis. Details and resolution are also slightly better. F4 is also detailed on trebles but Atlantis’ bright presentation makes it prominent and brings details more upfront. Stages are almost par and maybe Atlantis a bit of wider but hard to understand. Both earphones are great for specific genres. Fibae 4 shines with EDM, dance, pop, R&B while Atlantis better choice for Classical, jazz, country style genres.




Custom Art has a very special place in audio community and Piotr and his team create really amazing IEM in every new release. And, Fibae 4 has one of the amazing IEM that they made. Bass is so powerful yet detailed and mids are smooth as like hash brown and trebles are detailed and relaxed. Ergonomic shape of the body is great for long listening or outdoor. I don’t need to express of design, just as I said, check their Instagram page, they are building one of the best design IEM in the market. If you looking for a good IEM fantastic for EDM, Pop, R&B and also has an outstanding build quality and great comfort, I can highly recommend the Fibae 4.
Great review!! Thanks. I normally dislike such colorful housings, but one is really adorable :D.


Reviewer at The Headphone List
Pros: Excellent clarity, separation and stage expansion
- Exceeding price-to-performance ratio
- A fun, v-shaped response executed with finesse
- Guttural, yet clean lows
- A richly detailed, yet silky smooth top-end
- Wonderful build and fit bolstered by 3D-printing
Cons: The midrange isn't the most intimate
- The upper-mids especially can be a tad compressed-sounding
- Isn't for those looking for extremely contoured v-shaped responses
- Packaging and accessories are rather simple
DISCLAIMER: Custom Art provided me with the FIBAE 4 in return for my honest opinion. I am not personally affiliated with the company in any way, nor do I receive any monetary rewards for a positive evaluation. I’d like to thank Custom Art for their kindness and support. The review is as follows.

Custom Art is one of the most eminent value-for-money CIEM brands today. Although many have gunned for the throne, a balance between constant invention and community dialog have made Custom Art the most impressive of them all to watch as they grew sonically, technologically, and aesthetically too. Their recent innovations in FIBAE technology and the Pressure Optimising Design have given birth to the FIBAE Black – one of the the best value in-ears I’ve heard period. And now, with top-firing balanced armatures comes the line-up’s fifth entry: The FIBAE 4 – gutsy, bold and a whole lot of fun.


Custom Art FIBAE 4
  • Driver count: Four balanced-armature drivers
  • Impedance: 8.1Ω @1kHz (+-0.95Ω 10Hz-20kHz)
  • Sensitivity: 115dB @1kHz @0.1V
  • Key feature(s) (if any): FIBAE technology, top-firing drivers
  • Available form factor(s): Custom and universal acrylic in-ear monitors
  • Price: €725
  • Website:

Build and Accessories

The FIBAE 4 comes in Custom Art’s signature shoebox, within which are two included cases: A Peli 1010 hard case and a smaller zipper case. Inside the former is the company’s customary Hi booklet, which acts as a quick-start guide, warranty card and certificate of authenticity all in one. There’s also a hand-written date-of-manufacture, which is a nice touch. And finally, below that are your custom IEMs attached to a Plastics One Hi-Res cable, along with a cleaning tool and desiccant.


It’s become a running gag through my numerous encounters with (Custom Art founder) Piotr Granicki on- and offline to contrast his forward-thinking in-ears with his stubbornly stagnant packaging. This plain, black box has been here since Custom Art’s conception in 2012. At this point in their career, I think a packaging revamp with more prominent branding, a classier aesthetic and a couple more accessories here-and-there is long overdue. At the end of the day, although it’s not ultra-crucial to the success of the in-ears, it would definitely make their already-accessible prices all the more sweet.


Thankfully, Custom Art have spared absolutely no expense where it counts. The monitors themselves are gorgeously designed, immaculately constructed and superbly fitting too. Although the shells aren’t 3D-printed per se, they do take advantage of Custom Art’s recent shift towards digital processing. The ear impressions are scanned and trimmed in the digital domain. Once the shape is finalised, it’s printed and turned into a cast for the traditional, hand-poured technique. So, you get the precision of digital processing with the transparency and pristine-ness of hand-poured, UV-cured acrylic.


Visually, the earpieces are exquisite. The faceplates are a hybrid between maple wood and blue acrylic resin, finished on top with a FIBAE IV logo I quickly put together on Photoshop. Below are clear shells flaunting those top-firing drivers as much as possible. As has always been the case for Custom Art, the in-ears are smoothly finished with zero seams, rough areas or dull spots. The colour-coded wiring for left and right are especially nice touches. Combined with the improved fit thank to Custom Art’s digital processing, my FIBAE 4’s are yet another home run on their fit-and-finish track and record.

FIBAE Technology

FIBAE is short for Flat Impedance Balanced Armature Earphone, and it has become Custom Art’s flagship innovation. First introduced with the FIBAE 1 and the FIBAE 2, what the technology ultimately aims to do is preserve the in-ear monitor’s tonal balance no matter the source it’s connected to. So essentially, whether you’re listening to a FIBAE monitor through your laptop or a dedicated DAP, the frequency response should remain the same. This is especially crucial if you plan to use these on mixing consoles, monitor mixers, etc., where the output impedances can vary wildly from one to the other.


However, that doesn’t mean you won’t hear any differences between said laptop and DAP either. Although FIBAE tech leaves the frequency response intact, the earphone will scale based on whatever data is fed to it. A more resolving DAC is capable of exhibiting superior stage expansion, background blackness, etc. So, although these in-ears won’t bridge the gap between capable and less capable sources, it will allow the user to judge those differences in a clearer manner. And, whatever source you choose to use at the end of the day, you’ll always be guaranteed the sound Custom Art intended.


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.

Select Comparisons

Custom Art FIBAE Black (€450)

The FIBAE Black is slightly warmer and denser-sounding than the FIBAE 4. Its instruments are unified by a very light whiff of warmth, while the FIBAE 4’s are more separated, airy and tight. Though, in midrange projection and vibrance, they are very, very similar. What then makes the FIBAE 4 the more energetic of the two is its sparklier treble. Presence along 5kHz and 8kHz give the FIBAE 4 a brighter, crisper edge. But, in terms of overall quantity, the FIBAE 4’s top-end isn’t too much greater than the Black’s. So, they can both be considered equally linear and realistic, despite lightly differing tonal hues.


Technically, the Black puts up a great fight. Its stage is wonderfully stable, well-defined and expansive. When it comes to background blackness, the Black does win out a hair. However, the FIBAE 4 has the edge in resolution and tactility. When you listen to hi-hats and ride cymbals, although they may be heard on the Black’s just as much as they are on the FIBAE 4, the latter’s reproduction sounds more tactile and corporeal. The Black loses a tad of integrity further up the range to the FIBAE 4. This is also because of the FIBAE 4’s more recessed lower-mids, which gives its notes more definition, clarity and contrast. This is what allows instruments like those to jump out at the listener more effectively, and boost realism.

Custom Art FIBAE 2 (€475)

Compared to its sibling, the FIBAE 2 is a more upfront-sounding monitor with a greater midrange emphasis. Images are larger in size and richer in timbre, assuming a more wall-of-sound presentation. However, this intimacy also comes from a significantly smaller soundstage. The FIBAE 4 expands far further, especially in terms of width. It also achieves stronger stereo spread with a more convincing surround sound sensation. Tonally, the FIBAE 4 is the cleaner-sounding of the two with tighter, faster, crisper and airier notes. It wins out by a sizeable margin in terms of resolution and transparency too.


The FIBAE 2’s lows are richer, darker and fuller than the FIBAE 4’s more concentrated hits. Nevertheless, the latter wins out in physicality and slam because of its superior extension. Texture more easily comes through as well. The same goes for the top-end. The FIBAE 2’s comes across more blunted. Although its top-end extension is fine for a dual-driver IEM, it simply can’t compete with the FIBAE 4’s. This is shown in the latter’s far cleaner, stabler and more transparent stage. If I were being honest, the FIBAE 4 beats out its younger sibling in just about every technical regard by a clear margin. If you own the FIBAE 2 and you crave leaps in cleanliness, resolution and imaging precision, the FIBAE 4 is a very strong option.

Custom Art FIBAE 3 (€525)

The FIBAE 3 is a closer competitor to the FIBAE 4 both tonally and technically. In terms of sheer size, the two aren’t far off. However, the FIBAE 4 has the more proportional stage. Its expansion in terms of width and depth are near-equal, resulting in a near-perfectly spherical sound field. The FIBAE 3 is noticeably wider than it is deep, which results in lead instruments that are more upfront and panned instruments that sound further away. This gives the FIBAE 4 the more believable surround sound experience; immersive and realistic. The FIBAE 3 meanwhile comes across a touch more flat.


In the lows, the FIBAE 4 is a touch meatier and more impactful. The FIBAE 3 perhaps has a hair more sub-bass content, but it really is splitting hairs as far as bass quantity is concerned. What is clear though, is that the FIBAE 4 is the victor in terms of bass extension, as the lows there possess a more realistic sense of slam. The FIBAE 3 possesses a more vibrant upper-midrange that gives it a touch more musicality than the FIBAE 4, while the latter’s more laid-back approach gives instruments more depth and air. The low-treble is the clearest discrepancy between the two. The FIBAE 3’s strong 5kHz dip will sound diffuse without proper adaptation, while the FIBAE 4’s is more tactile, coherent and realistic-sounding.


The FIBAE 4 is Custom Art’s most impressive technical effort yet: Clean, vast and precise in imaging. At the same time, it’s Piotr’s most cleverly-tuned piece as well, getting away with more guiltless colourations than my hands can count. From a hefty yet airy bass, to a smooth, feathered yet crystal clear treble, the FIBAE 4 pulls off its many balancing acts with great finesse. Admittedly, its upper-mids were less successful; slightly unexciting dynamically. But, besides that – and with the tech and asking price in mind – this in-ear is quite difficult to fault. With the FIBAE 4, Piotr has given us his interpretation of a mainstream sound, and – in true, time-tested Custom Art fashion – it’s as clever, unique, balanced and refined as ever.



Headphoneus Supremus
Pros: Very good sub and mid bass, with good textures and natural decay
Epitome of fun yet fatigue free tuning, with strong technical foundations
Very good soundstage, with good height and depth
Superb build, fit and isolation
Very good value for money, a top notch competitor at the price
Cons: A little more lower treble energy would have made the F4 even more fun
I have purchased and paid the full retail (but nice pre-sales) price for the FIBAE 4, this is not a sponsored review.

Review notes
This review is based on over a 100 hours listening to the FIBAE 4, with various sources : AAW Capri cable for iPhone, iFi Micro DSD Black Label amp and DX220 with both AMP1 mK2 and AMP9. As usual with FIBAE IEMs, the FIBAE 4 signature is consistent across sources. My preferred combo is DX220 with the NuTubes powered AMP9. I tried several cables but PW 1960 4 wires and PlusSound X series were my favorites

The FIBAE 4 in custom form comes with a solid black plain card box which contains a black Pelican 1010 hard case with a transparent lid itself containing a small blue pouch with a cleaning tool.

  • Single low, Single full-range, single proprietary high, single proprietary super high
  • Sensitivity : 115dB @1kHz @0.1V
  • Distorsion : Low % THD
  • Impedance 8.1 Ohm @1kHz (+-0.95 Ohm 10Hz-20kHz)
  • Frequency range : 10Hz-21000Hz (+-20dB into IEC 60318-4 coupler)

2019 will be Custom Art’s year for sure, as they pushed the envelope starting with the FIBAE Black release a very singular single BA with a Helmholtz resonator which also happened to be my first Custom Art IEM. The FIBAE 4 is another release this year and innovating as well with the first to include 4 BA top firing drivers. As stated on Custom Art’s website « Top Firing Drivers provide improved frequency extension compared to traditional Balanced Armature drivers with a spout resulting in immensely detailed sound».

I loved the FIBAE Black so much (which holds a unique place in my collection with its distinctive and intoxicating tuning) that I didn’t wait for reviews and enjoyed the preorder price making it a very attractive and refreshing proposition in a soaring prices market. No brainer.

The FIBAE4 tuning was quite appealing to my tastes as well : « We tuned FIBAE 4 to be fun sounding IEM with warm and smooth signature. It offers excellent sub-bass depth and punch, detailed and natural midrange finished with extremely detailed, but never harsh highs. It combines big headroom, high resolution and expansive sound stage. FIBAE 4 is a perfect tool for guitarists, bassists and drummers for stage monitoring. »

Does it hold its promises?
Let’s see !


Fit, Build and isolation
The FIBAE Black was the first Custom Art model introducing 3D shell printing and it also was one of the best fit I ever had with customs, no matter which price point. I was very confident that the fit would be perfect and it is indeed even better than the Black in the sense that it’s just slightly less tight while retaining a perfect seal. Isolation is better than my other custom because the seal is just a little bit tighter than my other customs (VE8, Phantom and EM64 which is based on the same digital impressions). Wearing a Custom Art IEM is a fatigue free experience for sure.

The build is simply perfect, and the FIBAE4 looks sturdy to withstand every day use.

I chose a full black shell (required for 3D printing) and stuck to black plate, plain if you will. There are benefits when commutting not to attract attention, although the brand is able to provide mouth watering art on their shells, and I think when I get the FIBAE7 I’ll pick something sexier :p


The FIBAE4 is a very dynamic IEM that manages to remain absolutely smooth across the range, thanks to a softer attack and a very nuanced presentation.

It is deeply grounded in bass with very good sub bass extension with good extension and beautiful textures, providing a lot of fun and great rhythm for a toe tapping experience. Interestingly Custom Art decided to keep the mids fairly neutral with good clarity and articulation, vocals are very natural and with good presence. Treble has very good extension providing welcome air with a very natural decay, probably a benefit of the top firing drivers.

Its signature grants the FIBAE4 a very good and balanced soundstage with good height and great depth, with very good layering. The overall sense is a highly coherent fun and smooth fatigue free signature. A fun tuning for sure but a mature and refined one too.

I expected the FIBAE4 to be a fun bass experience and it is indeed but without sacrificing technicalities. Typical of modern BA bass implementation, the FIBAE4 features big BA bass driver that is able to hold its own against good dynamic drivers, especially in terms of texture and - probably a benefit of its top firing driver - a very natural decay that offers a sense of realism that few BA can brag about.

Sub bass extension provides the oh so very pleasing hit of subs. The attack is on the softer side, providing kick without being fatiguing. It boast a lot of detail and never gets saturated. It’s somewhat reminiscent of how my former 64 Audio U12 portrayed bass, only the top firing driver is at work there instead of an ADEL module and is true of the whole bass range as well.

Mid bass has good presence but it manages to stay clean and controlled something IEMs in the same kind of tuning don’t always do so well. Again, it’s a mature tuning and an audiophile take on the fun well extended subs combined with great mid bass presence. It certainly does help the soundstage depth to have a more progressive decay.

The FIBAE4 mids is where all of its seriousness is revealed, for it’s very balanced and natural. I don’t find the FIBAE4 to be that warm despite the product page claim of warm and smooth. The warmth is inherited from its mid bass rather than its mids. Mid centric tracks will reveal the FIBAE4 to be quite accurate in terms of tone and timbre, and closer to neutral with just a touch of warmth to fall into the natural category.

The lower mids are lean and clean, with enough presence to grant its mids body but not enough to color them too much. Vocal presence is really good, male vocals do shine and female vocals are just a little sweeter than pure neutral which I don’t mind at all. Textures stand out and instruments are portrayed with a lot of realism.

Last but not least - given its signature this balances things nicely -the FIBAE4 have good upper mids presence which grants a very good level articulation and separation, while remaining buttery smooth. Bass and treble are what makes the FIBAE4 stand apart but its mids stay true to the Custom Art philosophy as smooth as can be while retaining very strong fundamentals and technicality. A real treat!

Despite the prominence of its bass, the FIBAE4 treble is key to its signature and with the support of two custom BA drivers. Good treble extension is definitely a factor in both soundstage providing welcome air and good resolution and a deceptive ability to retrieve the fine details. In this sense upper treble is really the highlight point of the FIBAE4 treble wise, and while it takes a step back to the bass it plays a very defining role in the signature. Lower treble is less prominent and I wouldn’t have minded a little extra energy there, but the benefit is an absolutely non fatiguing signature.


There is no mistaking a Custom Art IEM, and the FIBAE4 is definitely not breaking the common rule : it has this smoothness and musicality that is so characteristic of the CA house sound.

It would be tempting to categorize the FIBAE4 as a U shaped signature, but I never really dug the concept of V, U or L shaped as I find them too reductive and there is much more to an IEM signature than it’s frequency range distribution. While the bass and upper treble clearly are the foundation of the FIBAE4 signature, its mids have good vocal presence and instruments are not recessed either and it’s why I think it’s a good all rounder. On top of this, the softer attack and natural decay plays a key role to the sense of realism and naturalness of the FIBAE4.

If you’re looking for a fun IEM with sound technical foundations that you can listen to for hours at times without any fatigue, then the FIBAE4 is definitely a must own in a collection especially in its price bracket! If you’re looking for fun tuning with more bite and a snappier attack then there are a few mid range IEM that could suit you more like say Earsonics Velvet v2 or - more pricey - the Earsonics Purple or Campfire’s Atlas.

@jeffhawke Good point, I am a bit lazy on vacations there :p I’ll try to add some comparisons later, I don’t own many mid range IEMs but I’ll sure add a FIBAE Black comparison.
As a matter of fact, the Black is exactly the one I'm interested in comparing to the Fibae 4. I'm in the difficult and time consuming process of deciding which should be my first CIEM, and I'm sort of leaning towards the Black, but still very undecided.
Great review and pretty much shadows how I hear the Fibae 4.
Lush sound with the Ibasso DX220 and amp9


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