Bellos Audio Lineup – X4, X3 and X2

Utilitarian, unique and effective is the name of the game!

PROS: Warm, musical, easy to listen signatures, very good timbre, easy shallow comfortable fitting CIEM and UIEM shells, very nice no-BS easy feeling monitors for live use, customisability of fit with different ear tips, easy on the ears for long listening sessions, nice metal hockey puck case that holds all ear tips and has your name inscribed on it.

CONS: not for people who like deep insertion depth CIEMs, lack of variety in signatures between the 3 IEMs in the lineup, no reference grade options for audio engineers/absolute tonal accuracy lovers, minimal customisation options, basic accessories and unboxing experience.

The product was provided to me free of charge for review purposes in exchange for my honest opinion.

About Bellos Audio.

Bellos Audio is FiR Audio’s sister brand started by Vlad and Bogdan Belonozhko, who over 20 years of combined experience in designing and manufacturing personal and professional audio products. Bellos Audio was started as a response to the challenges that the brothers saw in the pro-audio industry. Leaning on their experience and background they were able to distill the challenges to find the core underlying issues that needed to be addressed. Their latest offerings are the X-Series Custom In-Ear Monitors with In-Air Canal technology. It’s a CIEM that is a CIEM but more like a hybrid between CIEM and UIEM where you can customise the in ear canal fit using the different sized ear tips. Also engineered are industry leading technologies such as ATOM Venting, Rigid RCX Connector, comfortable 3D Printed Shells, a Removable Faceplate design for quick and efficient repairs and a 2 Year Warranty – all at an affordable price.

Official Website – Bellos Audio

Technical Specifications.

Bellos Audio X4.

Driver Specs – 1 DD + 3 BA (1 Ultra-high | 1 High | 1 Mid/Low | 1 Dynamic 6mm Low)
Frequency Response: 20Hz – 20kHz
Impedance: 16Ω at 1kHz
Sensitivity: 116 dB/mW
Crossover: Integrated 4-Way Crossover
Isolation: -17dB (internal ATOM)
2 Year Warranty (CIEM + Cable)

Bellos Audio X3.

Drivers – 1 Dynamic Driver + 2 BA (1 High | 1 Mid/Low | 1 Dynamic 6mm Low)
Frequency Response: 20Hz – 18kHz
Impedance: 17Ω at 1kHz
Sensitivity: 116 dB/mW
Crossover: Integrated 3-Way Crossover
Isolation: -17dB (internal ATOM)
2 Year Warranty (CIEM + Cable)

Bellos Audio X2.

2 Balanced Armature drivers
Frequency Response: 20Hz – 18kHz
Impedance: 41Ω at 1kHz
Sensitivity: 114 dB/mW
Crossover: Integrated 2-Way Crossover
Isolation: -17dB (internal ATOM)
2 Year Warranty (CIEM + Cable)

Technology in Bellos In-Ear Monitors.

In-Air Canal Technology.

If you’ve ever used Custom IEMs before, you know that they are not always comfortable because with any jaw movement or facial expressions ear canals change shape and as a result, the CIEMs lose seal and feel uncomfortable in the ear. Bellos Audio have developed the In-Air Canal technology – a proprietary design that enables a full seal at the aperture (the entrance) of the ear canal and giving the user the tweakability of snugness of fit by using the different ear tips supplied with the CIEMs. This helps give all the benefits of CIEMs with out the drawbacks. Read more.

ATOM Venting Technology.

ATOM is a pressure relief system that vents air pressures that build up in a sealed ear canal. Expanding the soundstage and greatly reducing listener fatigue so you can hear more and listen longer. You no longer feel like you’re disconnected from your environment.

3D Printed Matte Finish Shell.

Using our patented 3D Printing technology we design the Custom In-Ear Monitors inside a 3D software with nanometer precision. The parts are printed and efficiently assembled by hand. Shortly after, the matte finish is applied to the CIEM shell to provide a very comfortable and organic fit with a “grippy” consistent seal.

RCX Cable & Connector.

One of the most common points of failure is the cable. Bellos’ proprietary RCX Cable changes this and is the only cable connection specifically made for Custom In-Ear Monitors. It is rated for 5,000 connections without fail and comes with their standard 2 Year CIEM warranty.

Removable Faceplates.

A revolution in Custom In-Ear Monitor design. A conventional Custom IEM needs to be cut open to be repaired. Our design features a faceplate that is attached with alloy steel screws and allows us to quickly and efficiently repair Custom In-Ear Monitors.

Modular Drivers.

The CIEM shell is designed to accept a pre-assembled driver package which is tested in advance to ensure it meets all specifications. Modular drivers are designed to be installed and removed without having to damage and destroy the CIEM shell.

What comes in the box?

The whole packaging, carry case and accessories are minimalistic but very well executed for the utilitarian purpose they are designed for and serve. The best thing I loved is how all the ear tips and cleaning brush are integrated into the carry case so that you don’t have to carry them in a separate pouch. They basically designed for everything to go inside the carry case and that is just wonderfully executed for touring musicians and engineers but even for people using them as EDC portable setups.

CIEM/UIEM
Carry Case with your name inscribed on it.
Ear tips
Cleaning brush

Ordering, Build Quality, Fit and Comfort.

You can simply place an order for the model you like by filling the minimalistic form shown below. It’s extremely easy, absolutely no-BS. You can send them physical ear impressions or scanned STL files for them to use.

After reading all the Bellos tech and marketing material, I’m sure the first question anyone will have is what’s so special about these CIEMs amongst the sea of CIEM brands who all claim their tech to be revolutionary and ground breaking?

Well, here’re are the key points that differentiate Bellos Audio CIEMs from the others –

A hybrid CIEM meets UIEM fit where the outer ear – concha part of the shell is a CIEM built to one’s ear shape while the ear canal insertion is sliced off to make a tiny nozzle that accepts Bellos Audio ear tips, which you can swap out to customise the snugness of fit as well as insertion depth using the different sizes of supplied ear tips. Quite a few 3rd party ear tips are able to hold on to the tiny nozzle too which greatly increases tweak-ability to one’s preferences.
A completely modular CIEM design where every part is screwed in or designed in such a way that can be quickly changed if any repairs are required.
The whole driver assembly is pre-assembled and modular, which allows quick repairs if a driver conks off.
High quality looking 3D printed matte shells of limited stock colour options greatly shorten build times to just 5 days compared to several week build times of other brands. These are utilitarian and not luxury-artistic CIEMs. So you can’t customise them except for choose between 3 colours but can receive them in 1/4th the average delivery time of CIEMs, without one needing to be an A-list star for that kinda treatment.

I received one X4 CIEM while all the models, X4, X3 and X2 as UIEMs so that I get to test their proprietary CIEM fit, sound performance of all models as well as the differences between CIEM vs UIEM (comparison in the latter part of the 2nd page of this article).

The shells have a minimalistic matte design which works quite well if you ask me. It is simple and yet classy. I anyway am biased as I have a soft corner for matte black. They look quite nice, be it used casually for EDC or for live performance on stage. In fact quite a few A-listers in the industry actually go for such minimalistic designs even when they have the option to customise them to the moon and back, including the ones offered by Bellos Brothers other big company – FiR Audio. The build quality on these is very good and the modular design is spectacularly executed with all the screws that enable the modular design being cohesively placed and nicely recessed for one to not even feel them when you run your fingertips above them, let alone notice them in the design prominently.

When it comes to their proprietary fit, even though I as a musician and audio engineer like my CIEMs to have deeper insertion depth for absolute snugness and noise isolation, I was quite impressed and enamoured with the easy feeling Bellos fit. These IEMs have a shallower feeling fit and then leave it to the choice of ear tips to customise the snugness and insertion depth. But even with the longest ear tips that can be used with that tiny nozzle, none of them go as deep as the 2nd bend in the canal like the deeper fitting CIEMs do. So, it’s a shallower fit which actually feels very easy on the ears. On top of that, the ATOM venting system is also greatly effective in equalising ear pressure and keeping ears free from any pressure build up, while giving very decent levels of noise isolation.

Cable – I’m so thankful to see that the stock cable isn’t that cheap Plastics One cable, which a lot of the brands in the west like to cheap out on in their lower range IEMs. This is still no premium UP-OCC cable and is more utilitarian than premium or luxurious – quite robust, something that can survive a good beating and demands of live performances. I preferred to go with 2-pin connectors just so that I could try out my massive collection of aftermarket premium cables with the IEMs, which are all mostly 2-pins but the RCX connectors are better for durability and rough & tough use. So if you’re the one who’d want something more durable, stick to the stock RCX connectors. 2-pins aren’t bad but RCX are better.

Page 2 – Sound Analysis, Technical Performance, CIEM vs UIEM and IEM suggestions for musicians.
Page 3 – Comparisons of X4, X3 and X2 with several competing IEMs and Conclusion.