Custom Art FIBAE 4 – Smooth operator

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.


  • 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


  • A little more lower treble energy would have made the F4 even more fun

Price : 725€
Product page :


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 



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.

This review was originally published on :

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)

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