1Custom FX

1Custom FX Review

Our review of the 1Custom FX is a new entry-level single dynamic driver universal in-ear monitor exclusively sold through Jaben. It is priced at $99.

Disclaimer: This was sent to us as a sample for our honest opinion. Headfonics is an independent website with no affiliate links or services. We thank Jaben for this opportunity.

To read up on more 1custom products we have featured on Headfonics you can click here.

Note, this review follows our latest scoring guidelines which you can read up on here.

1Custom FX
1Custom FX
There are a few amazing 'bang for the buck' IEMs in the sub-$100 range and if you’re considering upgrading or getting into one, the 1Custom FX is a great addition to that list of consideration.
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Reader's Score

Following the release of the new flagship 1Custom XR, the company has released a new entry-level single-driver monitor, the 1Custom FX. This is different from the last year’s entry-level 1Custom Jr, in terms of price, features, and drivers.

No DIP switches can be found on the FX like the previous flagship XR we recently reviewed. Instead, it goes back with the basics, 1 dynamic driver, a smaller shell, and of course, at a lower price of $99.  

Tech Highlights

In terms of specification, they are sparse at best. The only information that can be found about the 1Custom FX is that they are equipped with a single 32Ω rated dynamic driver. Unlike past 1Custom models, the FX doesn’t have the DIP switches that allow for sound signature customization.

1Custom FX


Compared to the Jr and XR, the FX’s shell is significantly smaller, perhaps due to the elimination of the DIP switches. It still has a simple glossy finish with a subtle deep ruby red, almost black faceplate. The same minimalistic subtle gold logo of 1Custom is still there.

Despite the change in shell, it is still evident that an ergonomic fit was kept in mind. Subtle curves across the body are there. 1Custom retains the small vents, which are used to reduce ear fatigue, at the bottom of the cable socket. These are nothing out of the ordinary, but still, very wonderfully done.

1Custom FX

Comfort & Isolation

The 1Custom FX shells are lightweight. Due to their simplistic design, these are comfortable to wear, even for long periods. They fit well and are pretty seamless when worn.

Nozzle depth has a comfortable length. They are not inserted deeply, but instead, they are just right, which I very much like. In terms of isolation, I would have to say they are just average. The stock tips are normal black dome-shaped single-flanged ear tips. Emergency notifications can pass through with ease.

1Custom FX

Stock Cable

The only information about the 1Custom FX cable is that it’s an SPC cable. Visually, it is identical to the XR’s cable, housed in a matte black color. It is relatively thin, with a 4-core braided cable with a comfortable length.

It is terminated with an MMCX and has a 3.5mm L plug. The cable is light and easy to wear. No excessive microphonics were heard when moving around. The wire sits comfortably at the back of the ears, with the right amount of memory retention.

1Custom FX

Packaging & Accessories

The 1Custom FX model came in an ordinary-looking box, similar to the previous 1Custom IEMs covered. Inside the magnetic flap are foam inserts that make sure the items are safely transported. The overall package includes the FX monitors, cable, carry cases, and 2 extra tips.

The carry case is a sturdy black plastic clamshell box, with a clasp that locks the items into place. It is identical with the previous 1Custom models, nothing different. Inside are 2 thin foam inserts, one above and one below. The space is just enough to carry the 1Custom FX and cable comfortably.

1Custom FX

Sound Impressions


The bass on the FX is adequate in amount, it has a strong presence without bleeding into the mids. It is actually impressive how 1Custom has managed to add in an enjoyable amount of bass while still maintaining a clear midrange. The bass is not over-pronounced, it just sits beside the midrange, with comfortable levels of presence.

It also throws a tight and low punch, with a fast attack and adequate decay for a dynamic driver. Low rumbles in each thump are heard in the sub-bass regions. The mid-bass is well textured with a good definition and without excessive blooms. Good control is more evident in fast bass-heavy tracks.


The midrange is more forward than the bass and treble. It is comfortably tuned such that vocals do not sound shouty. In fact, the distance is just right such that mids are not recessed while maintaining a good overall tuning.

There is a good balance between the lower and upper midrange when further evaluating technicalities. Male and female vocals sound very natural during duets and solos. The midrange sounds rich and clear, with neither bloom nor veil. It is in fact smooth and well balanced.

Instruments are also well replicated. Instruments such as piano, trumpets, flutes, and violins sound rich and accurate, represented with the natural textures which differentiate them from each other. Although, if I were to nitpick, the acoustic guitars felt a bit rounded on some tracks, instead of hearing an expected somehow sharp strum.


The treble is tuned to be more laid back than the bass and midrange. It is tuned comfortably without peaks or harshness on upper frequencies.

Hi-hats are less pronounced, which is positioned to be a bit behind the vocals. Even with a relaxed tuning, the treble is still heard clearly with plenty of perceived treble extension. Cymbals still sound lively, although a bit lacking in shimmer and airiness.

Overall, the treble complemented the overall tuning of the 1Custom FX. It is tuned quite well such that the midrange is emphasized while still maintaining a clean and crisp treble.


The soundstage of the 1Custom FX is above average. It does feel generously spacious for its price range. Although, I find it to be only to be a bit better with other IEMs at the same price point. Imaging is also above average on the FX. Instruments are spread apart, with a good multidirectional replication.

1Custom FX



With an impedance of 32Ω, the FX is not difficult to drive. Smartphones are enough in powering up the FX at decent volumes.

Although, playing the 1Custom FX with dedicated audio players such as the Hidizs AP80 PRO-X and HiBy R3 Pro enhances its dynamics, imaging, and soundstage. There was no unwanted noise observed on both DAPs, instead, an overall improvement in sound is noticed.


The 1Custom FX is a flexible monitor since there are no noticeable dips in the frequency spectrum. The pairings would deeply depend on user preference in terms of sound signatures. I find both the Hidizs AP80 PRO-X and Hiby R3 Pro Saber to be good pairings with the 1Custom FX. Both DAPs reveal both technical details and fun synergies with the 1Custom FX.

For users who prefer a more elevated treble, the Hiby R3 Pro Saber would be a good match with the 1Custom FX. The R3 Pro Saber pushes a bit more treble, while still maintaining a good punchy low.

Users that are more sensitive to treble would find the Hidizs AP80 PRO-X to be a better pair with the FX. The AP80 PRO-X enhances the midrange timbre, with an adequate boost to the lower frequencies, making it a fun and enjoyable pairing.

Jaben 1Custom Junior

Select Comparisons

1Custom Jr



The 1Custom Junior is a hybrid universal IEM featuring a single dynamic driver and 2 balanced armatures. The Junior is 1Custom’s past year’s entry-level hybrid monitor while the FX is this year’s entry-level offering with a single dynamic driver. The JR has DIP switch settings that let users customize their sound signature while the FX doesn’t.


The JR and XR shells are similar in material but different in design. They both have the black glossy shell with the main difference of the JR having a 2 DIP switch setting that adds bulk in the monitor’s internal. The FX is compact in form, without the DIP switches. Both have vents below the cable sockets.

Another difference is its faceplate. JRs have a plain black faceplate while the FX has a deep ruby red translucent covering, adding character to the monitor.

Both IEMs have an MMCX termination. The cable on the JR is noticeably thicker with a 16-core vs FX’s 4 core SPC. Both monitors have a 3.5mm termination, JR with a straight jack and the FX with an L jack.


The following comparison will be done using JR’s DIP Switches on Standard Mode. Compared to the 1Custom Jr, the 1Custom FX has more elevated lows. The quantity of both sub and mid-bass are more generous on the FX, but hardly noticeable.  

Both have a good bass tuning such that there is no bloom heard in the upper frequencies. The bass is very clean and well-controlled. Although both have a slightly longer decay, which amplifies bass presence.

The midrange of both monitors is quite contrasting. Right off the bat, JR has a more articulate midrange. Vocal and instruments are more textured, wherein vocal huskiness is easily noticed compared to the FX.

The FX does however have a more natural and warmer midrange. On certain tracks, its tonality sounds warmer, velvety, and inviting, wherein the JRs are colder and distant but more detailed.  

With the treble region, the JR has a better treble extension. The JR has the sparkle, which is a significant edge compared to the FX. The more elevated treble on the Jr materializes with more splashy cymbal crashes and more airy highs.

The Jr does perform better than the FX in terms of the soundstage. It is wider, with more headspace than the FX. Do note that the FX never felt cramped, in fact, it is actually quite spacious. The Jr is just a little above FX’s price range, which makes this difference understandable.

The imaging of both monitors is fairly accurate. It is multi-directional with enough gaps in between, utterly impressive for its price range.

Moondrop Aria

Moondrop Aria



The Moondrop Aria features a 10mm LCP diaphragm and the lightweight Japanese-made Daikoku CCAW voice coil dynamic driver. Similarly, the 1Custom FX is equipped with a single dynamic driver.


In terms of design, the two have what I would define as subtle differences. Both monitors are black in color. The Aria has a matte-black finish looking like truffles in an expensive box of chocolates. The FX on the other hand has a glossy black finish with a subtle deep dark ruby red faceplate.

Both IEMs have an ear-hook design, with the Aria having a 2-pin 0.78 termination and the FX having an MMCX termination. Visually, the cable on the FX is better, with a neat matte-black uniform braiding. The Aria has a woven fabric insulator which frankly looks grim.

It is also good to note that the cable on the 1Custom is less tangle-prone, unlike the cable found on the Aria. The cable on the Aria is a mess when not taken care of properly. Both cables are terminated with a 3.5mm L-shaped plug.

The two monitors wear comfortably over long periods. The FX does however have a noticeably better fit than the Aria. I also liked the smaller form factor compared to the Aria.


Both the 1Custom FX and Moondrop Aria have a fun and enjoyable bass, wherein both have a deep and tight rumble on the sub-bass and a detailed and controlled mid-bass. Although, the lows are more generous on the 1Custom compared to the Moondrop Aria.

In terms of bass control, the Aria has a faster attack and decay compared to the FX. There is a bit of delay on 1Custom’s decay, which results in a prolonged bass presence.

The midrange is where the FX shines compared to the Aria. FX’s mids are significantly more forward than Aria’s. FX also does well with its even midrange region, compared to Aria’s uneven presentation. Male and Female vocals are thicker and more articulate with the FX, and the same goes with instruments in the lower midrange.

However, Aria has a more pronounced treble. The FX’s treble has a laid-back tuning which is very contrasting to Aria’s more aggressive highs. Aria’s treble is energetic and has a crisp presentation.

It also has an airy feel on the upper frequencies that can’t be found on the FX. However, Aria’s aggressive treble tuning does come with a price, and that is sharpness during cymbal crashes in certain tracks. 

Soundstage and Imaging on both monitors are very similar, without the advantage of one on the other. They are both above average, with good width and depth, enough to provide enough headspace and proper imaging. The sound on both monitors is multi-directional, with an accurate presentation.

1Custom FX

Our Verdict

1Custom is a relative newcomer that has made a name for itself in creating customizable monitors sold through Jaben in Singapore. This time around, they ditched the customizable aspect and made what seems to be a competitive entry-level single dynamic driver priced at the sub-$100 price range.

Despite the change in design, 1Custom has delivered a simple, durable, and fun monitor. There are a few fantastic ‘bang for buck’ IEMs in the sub-$100 range and if you’re considering upgrading or getting into one, the 1Custom FX is a great addition to that list of consideration.

1Custom FX Specifications

  • Driver: 1 Dynamic
  • Impedance: 32Ω
  • Cable: SPC
  • Termination: 3.5mm Stereo


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