Earphone Review

FiR Audio Frontier Series (XE6, KR5, NE4) Introduction and Comparison.

Design.

Frontier Series introduces three models, each with a unique name and a number corresponding to total drivers.  Xenon 6 (XE6, $3,899) uses 6 drivers: 10mm kinetic DD bass, 1x open BA bass, 2x open BA mids, 1x open BA high w/sound reflector, 1x EST ultra high, and has 28ohm impedance.  Krypton 5 (KR5, $2,999) uses 5 drivers: 10mm kinetic DD bass, 1x open BA bass, 2x open BA mids, 1x open BA high w/sound reflector, and has 22ohm impedance.  Neon 4 (NE4, $2,299) uses 4 drivers: 10mm kinetic DD bass, 1x open BA bass, 1x open BA mids, 1x open BA high w/sound reflector, and has 22ohm impedance.

Regardless of a driver config, the exterior dimensions of these IEMs are the same, only varying in the shell material/finish and faceplate design.  Top of the line XE6 features a machined stainless-steel shell (14g each) with gold plating exterior and sapphire glass faceplate over carbon fiber with infused gold flakes.  The next one, KR5, has an aluminum shell (8g) with a shiny chrome-like plating and a sapphire glass faceplate over carbon fiber with a granite-like pattern.  NE4 also has aluminum shell (6g) with a similar chrome looking plating, sapphire glass faceplate, and unique granite-looking faceplate pattern.  Obviously, SS shell will be the heaviest, and the difference in weight between KR5 and NE4 is probably due to additional BA driver.  Each universal pair has infamous “bunny ears” artwork on the right side and either XE6, KR5, or NE4 logo on the left side.

firaudio-frontier-series-14

But one thing will remain common between all Universal and Custom Frontier series models, the main feature of the design, the Kinetic bass.  It refers to 10mm Dynamic Driver that is open and ported under a mesh cover while facing outside through the back of the shell.  By design, it offers a hybrid conduction system, allowing you to hear the low frequencies in two ways.  One is through air-conduction of the sound hitting your eardrums via the nozzle, and the other one is by means of bone-conduction from the back of the driver transmitting directly to the ear cartilage through the bones in your head, converting to kinetic energy as it reaches the inner ear (cochlea).  That is what this Kinetic Bass is about, a hybrid conduction where you can both hear and feel the bass.

One thing I did notice, while the driver size is the same, the actual Kinetic driver opening of XE6 is bigger than KR5/NE4, which probably explains XE6 having a more elevated bass impact relative to KR5/NE4.

firaudio-frontier-series-16

Also, every IEM will have Atom (air transferring open module) pressure relief system which reduces ear fatigue during extended listening and at higher volume by venting pressures that build up in a sealed ear canal.  As it was already mentioned, UIEMs use small screw-size Atom XS modules, while CIEMs with removable module option use a regular size Atom X.  XS does require a tool to remove it.  Not going to deny it, it’s a finicky process where you have to be very careful not loose XS module, thus make sure to use a well-lit area and a flat surface.  Furthermore, as you screw the module in, there is no hard stop, it will continue turning once inside, which is OK and expected.  Per FiR Audio, “The thread on the module is only to help back the module out when removing, there is no thread in the receiving pipe.  You can simply press the module in on insertion gently until it stops, no spinning required.  This feature uses what we call a soft thread.  It can’t strip so no worries on that.”

Frontier Series IEMs come with a set of 3 Atom XS/X pairs:

  • + Isolation 16dB: gold
  • N Isolation 15dB: silver
  • – Isolation 14dB: black

Frontier Series also features FiR Audio Open Acoustic system which is part of the tubeless driver design.  The low and mid BA drivers are open with no sound tubes, radiating directly into the sound chamber, referred to as Sound Reactor which uses natural acoustics instead of dampeners and filters for the shaping of the sound before it reaches your ear canal.  The high BA driver, also open, is located inside the nozzle (canal stem) and uses a Sound Reflector instead of Reactor, to direct high frequencies into the ear canal.  Basically, everything is tubeless and all sounds get mixed together naturally while directed to your earcanal.

Another unique feature of Frontier Series is Rigid Technology which improves the reliability and durability of the design, and even allows you to “service” IEM thanks to its modular components which you can replace yourself instead of sending it back to manufacturer.  The universal 2pin shell socket is part of this rigid modular design which you can replace if you ever run into a problem.  Also, you will find a snap screen at the tip of the nozzle which can be replaced by removing a spring ring that holds it securely in place.  And when it comes to CIEMs, the 3D printed shells are 20% thicker than average for a better protection of the internal components.

The fit.

For the reference, relative to FiR Audio M-series and 64 Audio IEMs, the faceplate size/profile is smaller, but shells itself are deeper.

Frontier series universal shells do sit comfortably inside my ears, but they also stick out a little more.

Page 3 – Sound analysis and Conclusion.

Pages: Page 1, Page 2, Page 3

17 thoughts on “FiR Audio Frontier Series (XE6, KR5, NE4) Introduction and Comparison.”

  1. Out of these 3 FiR Audio IEMs, which one do you prefer? To me, it would be the KR5 w/ Silver Atom XS because it seems to be the least colored IEM.

    Like

    Reply

    1. Quite a few people mentioned to me that since they want less colored, more transparent tuning, KR5 would be the way to go, as an upgrade to M5. I prefer XE6 because it offers something different to complement the rest of the IEMs I have and use daily, but some might find it on a warmer and a smoother side of their preference.

      Liked by 1 person

      Reply

  5. Hi!!
    The Tool to change the Atom XS modules doesn’t came with the original package.
    Because of this i can’t change the modules of my Kr5…and i can’t find the correct tool to do it…
    Can you share some Amazon link of this tool?

    Like

    Reply

    1. Did you ask the retailer where you bought it from? Mine review set didn’t come with one either, so, as I mentioned in the review, I used 0.9mm hex driver. Search for it on amazon or ebay.

      Like

      Reply

  6. I’ve been in the hobby for a while and own: ier z1r, u12t, kse1200, lcd i4, ie900, a8000. I’m currently pondering over these fir iems as they seem very different to the norm type of tuning. Would you consider the xenon6 as being worth a shot or would I be better off with something like the Odin?

    Like

    Reply

    1. Based on iems you already have, btw, great collection!, I would suggest to get something new to complement the sound sig of others. So, look into XE6 since it will be more unique. Happy New Year!

      Like

      Reply

  7. Hey, you missed out on the better sound by not getting the red modules for review.
    I tried all three (4,5,6) and pretty much agree here with impressions, but found the more balanced Kr5 to also have a very slight metalic “S” sometimes in its trebles, and didn’t sound like the others (4&6) which had a more similar tonality.
    Anyways, using the red module (sold separately on website) really elevated the neon 4, with a balance and spacious sound. You can detect detail retrieval now on par with the kr5, and, to me, is like best of both ths others now. It clearly has a bit more low level resolve than my Mest2 & indigo. This now my main IEM, a real winner for me.

    Like

    Reply

    1. Yes, I love red module. But you gotta keep in mind, I had all 3 iems and reviewed it before they were announced or went on sale; they didn’t have red module at that time. Got red module for both uni and custom XE6 before it was announced as well, and absolutely loving it. Now, been using their new Radon 6 (RN6) for a few months and red module is also my favorite with those IEMs. The funny thing, RN6 was announced officially at CanJam NYC last weekend where Bogdan and Vlad unveiled it. When I was talking to them at the show, I suggested to try red module, and Vlad himself went wow. I think at the show, most of the people who tried RN6 preferred it with red module which makes the sound more expanded, more dynamic, and a lot less colored. XE6 is more about elevated bass, more low end weight, thicker lower mids. RN6, which is based on the same drivers but a different tuning, is all about transparency and accuracy which still retains the impact and the depth of the kinetic bass. They complement each other nicely!

      Like

      Reply

  9. hi Alex. Im your big fan.

    I used to really like Fourte because of its treble sound. Now that I’m using the kr5, I’m trying to find a nice treble sound similar to the Fourte on the kr5 using the Red Module, although I’ve noticed a significant improvement in Openness, airy and wider soundstage. But it seems that the mid is a bit forward and the treble, although more sparkling but lacks energy. Do you feel like that?And another annoying problem is the stock cable rolling. I replaced the fourte cable stock and it fits very comfortably, but the feeling is that the sound seems to be a bit thinner, the bass has slightly decreased in quantity. Can I get your opinion on this?

    Like

    Reply

    1. Typed a reply, but it disappeared 😦 I was suggesting to try either a different pair of eartips or go one size smaller to relax KR5 seal. Also, been a while since I heard Fourte. Maybe Ode to Laura cable will help here?

      Liked by 1 person

      Reply

Leave a comment