Custom Art FIBAE 5

The wild, fun loving kid that likes to party!

PROS: Fun, energetic and engaging signature, sub-bass rumble, well executed bass oriented tuning with sizzly and airy treble, very good staging performance with a very wide and open soundstage, good micro-detail retrieval and layering, Knowles filters included to reduce the bass shelf by 2.5dB.

CONS: Mid-treble sizzly boosts need time to adapt, treble sensitive might have an issue with the same, shells are slightly on the large side for Custom Art IEMs.

About Custom Art.

Custom Art was founded in May 2012 in Warsaw by Piotr Granicki, a long-time reviewer of portable audio equipment, Head-Fi member and DIYer. The natural step forward for him was to create his own series of earphones. The company’s foremost philosophy is to deliver the best products possible at the most affordable pricing and delivering this kind of quality requires Custom Art to be excellent at service and sound. As one of the few companies in the world offering custom in-ear monitors in silicone instead of regular acrylic, Custom Art takes advantage of silicone and its soft comfort to allow monitors to be worn for longer periods.

In 2015, the company entered the acrylic CIEM market with the Ei.3, the world’s first 3-way, 3-driver CIEM priced below $300. In August 2015 Custom Art introduced FIBAE technology. The name stands for Flat Impedance Balanced Armature Earphone and is world’s first, revolutionary IEM design providing flat impedance and phase, which solves one of the oldest problem in the audio industry – dependence on output impedance of sound source for correct earphone output. IEMs equipped with FIBAE technology will always perform best from any audio source. First two models (single driver FIBAE 1 and dual-driver FIBAE 2) were released in April 2017.

Official Website – FIBAE 5 UIEM (€999)  | FIBAE 5 CIEM (Starts from €1100)

Custom Art FIBAE 5 Solo 3

Technical Specifications.

  • Tri-brid: Dynamic, Balanced Armature & Planar Magnetic Drivers
  • Single 10mm Dynamic Driver Sub-Low, Dual BA Mid, Single Planar High, Single Planar Super High
  • Flat Impedance technology
  • Pressure Optimizing Design
  • 3D-printed waveguide
  • Sensitivity -109 dB @1kHz @0.1V
  • Impedance – 10 Ohm @1kHz (+-2 Ohm 10Hz-20kHz)
  • Frequency Range – 10Hz-21000Hz (+-10dB into IEC 60318-4 coupler)

Included in the box. 

  • Ear tips – SML silicone single flange, 1 double flange
  • Cleaning brush
  • Warranty card
  • Zipper case
  • Drying pellet

Custom Art F7U Case

Build Quality, Fit and Comfort.

F5 shells are slightly bigger in size and have a fatter nozzle, which results in a slightly different fit compared to F7U and F7. For me the fit is still fairly snug and the shells do sit flush with the outer ear but the shells don’t go too deep into the canal as much as the F7U and F7 shells did because of their smaller size.

Custom Art FIBAE 5 Solo 2

Cable – F5 comes with a non-branded SPC cable. It is soft and supple, doesn’t tangle up, is light with very little downward pull and enables for a very comfortable wearing experience. All in all, no complaints here.

FIBAE (Flat Impedance) Tech.

Custom Art’s FIBAE flat impedance technology is highly welcome breakthrough tech that is extremely useful without you even knowing that you need it. Since low impedance IEMs can act quirky and sound absolutely wrong when plugged into sources with high output impedance (hint – Andromeda), it is not only great for audiophiles who like using a multitude of sources to listen to music but even more useful for musicians who have to plug their IEMs into an even more variety of unpredictable gear depending on availability and situation, especially when you need to plug IEMs into extremely unpredictable vintage gear with ‘who knows what’ output impedance. FIBAE tech makes sure that the source’s output impedance won’t affect the sound signature of the IEM, whatever source/device you plug it into.

Drivability – FIBAE 5 has a very low 10Ω impedance and fairly high sensitivity of 109dB. It can be driven via any device, no problem!

Sounds Analysis.

Custom Art FIBAE 5 (Filter IN vs OUT)

Graphs are measured using an IEC60318-4 (IEC711) setup. You can compare all the graphs on my IEM Graph Database here – Animagus Squiglink.

Summary – F5 has a fun, energetic, strong W-shaped leaning V-shaped signature with boosted bass, fairly forward upper-midrange and sizzle, sparkle and air added on top. It has a boisterous, unapologetic tuning that goes for a huge sound presentation that adds boom, energy and excitement to even the most boring mixes. This is not a reference set; it’s highly coloured but with the kind of colouring that doesn’t stray too far into wonky territory and makes for an experience that you can’t ignore. It’s like standing and listening to the band in a big, very lively arena with fairly good acoustics and tonal character. It’s also the kind of IEM that you can listen to at louder than average volumes for some fun, without it coming across too warm or too harsh. It does have its caveats and we shall go into them in detail in the analysis below.

Filters to reduce bass shelf – Custom Art include a set of Knowles impedance filters that you can install in the shell to reduce the bass shelf by around 2.5dB, as you can see in the graph above. I actually prefer F5 with the filters installed. The filters only reduce the bass shelf and do not affect the rest of the FR regions, which is perfect!

Custom Art FIBAE 5 + Filter (Instructions)

Let’s dig in deeper…

Bass – Bass duties are handled by a 10mm Dynamic Driver. The 14dB of bass shelf has the bass rumbling really nice and strong but without coming in the way of other things – which is how boosted bass should be done. I actually prefer the bass presentation with the Knowles filters installed, which result in an 11.5dB bass shelf. Overall, F5 can do punch as well as rumble when the song demands but it isn’t the upfront in your face kind of bass and remains in control. Don’t get me wrong, F5 sure is a bass boosted IEM but doesn’t really go into bass head ‘only bass everywhere’ territory because the north of neutral boosted planar treble makes sure that the bass doesn’t overpower the presentation and the overall signature remains super crisp, clear and sparkly. Bass transients are quick but I would’ve liked slightly better separation in the centre image. The bass has the tendency to come across as extra sub-woofery, slightly smudging the centre image in the process. This is mostly a nitpick, but a valid nitpick nonetheless.

Midrange – The midrange is done quite tastefully for a W-shaped leaning V-shaped signature, without taking it too far away from accurate tonality and timbre of instruments. F5 has fuller lower-midrange than neutral in the 250-700Hz region, which adds in warmth and extra body to the instruments. I would’ve liked if this region was flatter as it can lead to a bit of veil when listening to songs at lower volumes, but it sounds fine at normal to loud volumes. It has 6-7dB of pinna gain, which brings the vocals and instruments fairly forward in the presentation but the dip around 4kHz takes it away from absolute accurate upper-midrange tonality and the amount of pinna gain I personally like. It majorly results in the instruments not being as strongly defined as they are in IEMs like Custom Art’s own F7U and original F7 as well as Moondrop S8 and Softears RSV. It comes across more V-shaped compared to F7U and the original F7 because of the dip in the 2k-4kHz range which pulls the instruments slightly back in the soundstage compared to the other two.

Treble –  F5’s planar treble is neutral warm in lower-treble, boosted above neutral in 9-14kHz mid-treble and neutral-airy post 15kHz that extends very well till 20kHz. For me the boosted mid-treble was noticeably sizzly for the first 4-5 songs or so, but I adapted to it quite quickly mainly because the treble peaks are in the 10k-15kHz sizzle range and not in the dangerous lower-treble’s 5k-10kHz region – where boosting above neutral can result in intrusive sharp attack and sibilance. Initially the cymbals will sound sizzly but that settles as your ears adapt to the planar treble. The treble timbre isn’t the most natural; it’s tuned to sound coloured and adds extra sparkle and sizzle to songs, which can result in addition of thin and sizzly timbre in case of songs that already have sparkly treble mixed in. I’d caution the overly treble sensitive to be wary of this as I can see them having an issue with it. But if you’re a fan of W and V shaped signatures, you’ll probably dig the sparkle and sizzle quite a lot. IMO, the mid-treble sizzle is like a double edged sword – it needs a small adaptation period for sure but is also necessary to balance out the big bass boost and turn F5 into a fun W-shaped leaning V-shaped IEM than an outright bass head IEM. Post that, what I really like and appreciate is F5 having good air post 15kHz, which a lot of IEMs in its price segment don’t execute as nicely. After more than a month of listening to it, F5 mostly sounds warm-ish with some extra sizzle and air on top, that greatly adds to the perception of a nice wide and open soundstage as well as clarity and micro-detail retrieval.

Technical Performance – F5 has a HUGE soundstage for an IEM, which sounds quite wide, deep, open and airy and is in fact class leading for its price segment. It falls a bit short in instrument definition compared to its older brother F7U, majorly because of the dipped 2-4kHz region, but is no slouch and actually performs quite well when placed in its own price segment competition. The boosted planar treble greatly helps with micro-detail retrieval and perception of clarity and resolution. It has very good left to right separation, with good space between the boundaries, but does not have a very strongly defined centre image – which I majorly attribute to the combination of boosted bass, dipped 2-4kHz and boosted 200-400Hz regions.

Custom Art FIBAE 5 + Shanling M6 Ultra


Custom Art FIBAE 7 Unlimited.

Custom Art FIBAE 5 vs F7 Unlimited

F7U is more a reference tuned set whereas F5 is much more V-shaped in comparison. F5 almost has an 8dB bigger bass shelf than F7U without the filter in and a 5.5dB bigger boost with the filter in. F7U comes across more maturely and neutrally balanced with a 6dB bass shelf whereas F5 is a set for bass lovers and fans of V-shaped tuning. F5 also has very slightly fuller lower-midrange in the 250-700Hz region, which results in instruments having slightly more lower-end warmth in comparison. F7U is more neutral in lower-midrange as well as with its upper-midrange pinna gain, which results in more accurate tonality and timbre of instruments. F5 on the other hand has a dip in the 2-4kHz range which results in instruments not sounding as forward as they are in F7U. Post that, F7U’s treble focuses on lower-treble accuracy and north of neutral airy upper-treble whereas F5 does the opposite, with warmer lower-treble, very sparkly and sizzly mid-treble and fairly neutral and airy upper-treble. Both have good treble extension till 20kHz. Both IEMs have class leading open and wide soundstage presentations but F7U has stronger defined left & right boundaries ‘coz of proper pinna gain, which results in a more forward upper-midrange presentation. F5’s boundaries on the other hand are not as well defined, which could result in perception of the boundaries being slightly wider just because the hard panned instruments don’t sound as well defined as in the F7U. When it comes to technical performance, both have very good detail retrieval but it is the F7U that has stronger instrument definition and resolution, better left to right separation and imaging, especially the well separated centre imaging of instruments. Don’t get me wrong, F5 is no slouch and is excellent for its price range, but it does fall behind F7U, which is why F7U is the more expensive flagship of the brand.

ItsFit Fusion.

Custom Art FIBAE 5 vs ItsFit Fusion

Fusion has 1DD + 2BA +1 Magnetostatic driver and it too is a fun tuned, W-shaped leaning V-shaped IEM like the F5. Both have DDs for bass but F5 has much more bass quantity, resulting in more rumble and punch than Fusion. Fusion has a very slightly warm tinge to its lower-midrange but still sounds a bit leaner than F5. Both have a forward upper-midrange with a dippy-boosty character but Fusion comes across as the one with stronger instrument definition because its boosted peaks have slightly more gain. Fusion has much brighter lower-treble, where F5 is warmer, but then F5 has more north of neutral boosting in the mid-treble, where Fusion’s is slightly lower. As a result, Fusion comes across brighter because of its lower-treble boosting and F5 more sparkly and sizzly because of its mid-treble boosting. F5 has more air up top. Coming to technical performance, Fusion has slightly stronger instrument definition than F5. F5 has a more open and wide soundstage whereas Fusion’s is cleaner with better left to right separation. Both have very good micro-detail retrieval but F5 edges the Fusion by a bit and also comes across having better layering and resolution.

Softears RSV.

Custom Art FIBAE 5 vs Softears RSV

Softears RSV has 5BAs and is a more neutral-warm reference tuned IEM. It may seem like F5 has a way bigger bass shelf and would have much more bass quantity as a result. But that’s not really the case because F5’s boosted planar treble also adds in a lot of brightness to balance the bass, while the RSV is much warmer in the treble region in comparison. As a result, F5 comes across having more sub-bass rumble and RSV having more mid-bass punch. For the same reason, it is the RSV that also comes across having slightly fuller lower-midrange and fuller instrument body. RSV has a more traditional pinna gain peak, which results in it having more accurate instrument timbre tonality. RSV is warmer in treble and F5 comes across brighter, sizzlier as well airier, with better treble extension up top. When it comes to technical performance, there is no competition and F5 is outright superior in every aspect – be it soundstage, micro-detail retrieval, resolution or left to right separation. Where RSV excels is instrument tonality, timbre and definition.


As I stated in my opening tagline, FIBAE 5 is the wild, fun loving kid that likes to party hard! Its unapologetic W-shaped leaning V-shaped energetic and exciting tuning will have most people engaged and lost in the music, obsessing over its excellent staging capabilities, tiny nuances in the songs as well as the sweet low end rumble. The treble sensitive might take issue with the mid-treble boosts but I personally got used to them fairly quickly and it now mostly sounds warm with some sparkle and sizzle sprinkled up top. It’s not a reference neutral set but the good thing is that it is a fun sounding IEM without moving the sound too far away from accurate tonality of instruments. With it excelling in most areas of technical performance for its price, and with an exciting and energetic signature that breathes life into even the most boring songs and mixes – all make FIBAE 5 quite an easy IEM to recommend. Do give it a shot if you get the chance!

Gear used for testing and review.

  • DAPs – Shanling M6 Ultra | iBasso DX240 | Lotoo PAW6000
  • Laptop – Apple Macbook Pro 15″
  • Phone – OnePlus 7 Pro

Artists I like and listen to.

  • Rock – Foo Fighters, Linkin Park, Switchfoot, Imagine Dragons, Daughtry, Green Day, MuteMath, X Ambassadors, Dave Matthews Band, Vertical Horizon, Our Lady Peace, Lifehouse, Fall Out Boy, Breaking Benjamin, Muse, ACDC, Audioslave, Rage Against the Machine, Biffy Clyro, I Am Giant, Normandie, Paramore, Slash & Guns N Roses, 3 Doors Down.
  • Pop Rock – John Mayer, Coldplay, Paul McCartney, James Bay, Hunter Hayes, Niall Horan, Keith Urban, The Bros Landreth, Bryan Adams.
  • Progressive Rock/Metal – Porcupine Tree/Steven Wilson, Karnivool, Tool, Dead Letter Circus, Periphery, Lamb of God.
  • Pop/Soft Rock – Ed Sheeran, Adele, Taylor Swift, OneRepublic, The Script, Gavin James, Magic Man, Maroon 5, Bruno Mars, Charlie Puth, Dua Lipa, The Weeknd, Oasis, Panic! At the Disco, TwentyOne Pilots.
  • EDM – Chainsmokers, Zedd.

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