FiR Audio Krypton 5 (KR5)
1 10mm Kinetic DD, 1 open BA bass, 2 open BA mids, 1 open BA with sound reflector highs.
22 ohm impedance, sensitivity n/a, 20Hz - 20kHz FR response
Thank you to Andrew at MusicTeck for the opportunity to receive a modest discount on this pair in exchange for an honest review. And for his excellent customer service over the years.
I am NOT a career or professional reviewer, just an audio enthusiast who enjoys having music in my life on a daily basis.
Therefore this review will reflect my personal sound preferences.
I’m not entirely familiar with the FiR audio story, but I know the two brothers have a connection with 64 Audio, and these Frontier Series IEM certainly share 64 audio DNA.
Kinetic Bass is a hybrid bone conduction method of delivering bass presence. The backs of the Dynamic Drivers are vented toward the inner ear to, in theory at least, enhance bass via bone conduction.
I have experience with bone conduction IEMs so I assumed good inner contact would be desirable and I sized my Sedna Earfit Standard tips accordingly to allow for a deeper insertion depth.
ATOM XS vent modules allow the IEM to vent pressure from inside the ear canal to eliminate pressure build up and reduce listener fatigue.
They also alter the sound signature and allow for some degree of personal tuning preference.
The KR 5 comes with 3 ATOM XS modules.
Gold, Silver, and Black.
GOLD: Plus +1 dB isolation (16 dB)
I found the Gold module to have the strongest bass presence. Mids have good presence and detail, vocals are warm and natural. Highs are clear, detailed and airy. However, for me the bass tends to overwhelm the sound signature somewhat, it pushes the mids back, and attenuates the detail retrieval of mids and highs a bit.
SILVER: Neutral isolation (15 dB)
Sub bass is more managed and stays in place, overall bass presence remains strong, but is less overwhelming. Mids come forward nicely, vocals very natural, and mids and highs detail improves.
BLACK: Minus -1 dB isolation (14 dB)
Bass presence remains strong but I felt sub bass becomes slightly muffled. Mids come further forward but loose some weight and also loose some natural tonality in vocals. Highs are very clear, micro detail retrieval is best of the three modules.
I’m not going to sugar coat it. I don’t like the design of these modules, they are small, and very finicky to work with. I have dropped them a few times and crawled around looking for them on the floor twice.
If I don’t outright loose one of these next time I swap them, I’m buying a lottery ticket.
I chose Silver ATOM module as best for my listening preference.
Equipment:
- FiR Audio Frontier Series KR5 with 60 plus hours. Silver ATOM XS module.
- A&K SP2000T on solid state (OP) amp mode.
- Stock cable 4.4mm balanced termination.
- Sedna Earfit Standard ear tips. (Stock tips didn’t work for me)
Tracks:
varied selection of tracks from my playlists played from SD card. FLAC 44 through 192 and DSD to 22.4 (512)
My mainstay are Blues, Rock, Jazz, Country, Classical.
I also streamed Apple lossless for electronic, R&B, Death Metal, etc. to get a well rounded experience of how well this IEM handles a variety of genres.
Bass is very good on KR5. Sub bass is thick, rich, well defined and has the ability to extend really low when called on. With the silver atom module installed it stays managed and in its place. Mid bass is quick and agile, it has excellent punch and slam when called on.
Mids are clear and detailed with just enough mid bass carry over to provide a warm and natural tonality. They present nicely forward, but not in your face.
Vocals are clear, natural, and accurate on both male and female vocals. They present forward and blend well with mids instruments.
Highs are crisp, clear, and detailed. They have very good air but never sibilant or harsh. Micro detail retrieval is good, but I have heard better.
Soundstage is excellent. Width is between the ears, even slightly outside the head. Height is well above average, good air gives it height, and sub bass extension pulls it low. Listening to Gunna - Pushin P track I perceived the sub bass down around my neck area. Depth is good, the forward mids and vocals provide good front to rear layering. Separation and imaging is also very good. Soundstage is open and I never noticed any congestion, individual instrument placement is accurate and easy to target.
** Note I found Gold ATOM module to have the least open soundstage, Black module the best. But all are good, we are talking degrees of separation.
Summary:
I wasn’t thrilled with KR5 out of the box, it sounded bloated and incoherent to me. However some hours of aging the IEMs and some lengthy listening sessions have me convinced. These are a very good IEM and IMHO, deserving of flagship designation.
The Kinetic bass concept seems to work. I pick up on the “feeling” the bass as well as hearing it that is synonymous with traditional bone conduction drivers.
Build quality is excellent, fit is comfortable for me. Shells are not overly large by todays hybrid standards, they are on the thicker side though.
The ability to personalize the tuning via the modules is nice, however as mentioned earlier the tiny size and design is a bit of a pain, at least for gnarled hands they are.
The included 4.4mm balanced cable is a plus for me, as I’m a balanced convert. The cable is decent, reasonably supple with good ear hooks (not memory wire) that support the IEM well.
Comparisons:
FR5 vs Fourte.
There is some shared DNA here.
Fourte single DD and 3 BA up against KR5 Kinetic DD, and 4 BA.
Bass on KR5 is stronger and sub bass more prevalent. I like good bass presentation, but I’m open to variation and it’s more about how it fits with the overall sound signature.
Bass on Fourte has less definition between sub and mid bass, but it can still pull low and punch when called upon.
Mids are clearer and more detailed on Fourte, KR5 is warmer and carry’s more weight.
Vocals are more forward on KR5, both IEM present vocals quite natural and accurate.
Highs are more airy and better micro detail retrieval on Fourte. Both are clear and detailed.
Soundstage; Fourte does have a unique “openness” to the middle of the soundstage that individual instruments/vocalists move in and out of depending on how tracks are recorded. Some people like this, some don’t, but it does provide one of the most unique and expansive soundstages I’ve heard to date on an IEM.
FR5 vs U18s
Ok, completely different IEM here. All BA vs Hybrid, but retail pricing is the same.
Bass on U18s is very similar to Fourte, so bass comparison with KR5 is virtually the same. KR5 has a stronger overall bass presence and better sub/mid bass definition.
U18s has better detail retrieval in the mids than KR5. U18s mids are more forward than Fourte, similar to KR5. KR5 is again warmer and weightier in the mids.
Highs are crisper with better micro detail retrieval on U18s.
Sounstage is similar between these two, very good width, depth, height, KR5 has slightly more overall height, or vertical depth if you prefer, due to sub bass extension. Imaging separation and layering are also very good on both. Imaging on U18s has a slight edge due to additional detail retrieval.
KR5 Kinetic Bass Driver vs EVO W9 and Bone Conduction Drivers.
This is a cage match.
Both are impressive.
EVO is smoother richer bass that pulls down as low as FR5, but it also expands out wider than FR5.
FR5 however has tighter punch and slam and more definition between sub and mid bass.
Bass on EVO fills (bleeds) the soundstage more (compared to FR5 with silver atom module, more similar to the gold atom module) but the mids and highs rise above the bass effortlessly and it works.
Mids and highs are more detailed on FR5, but both have very good mids and highs.
Vocals are warmer on EVO, both IEM present vocals nicely forward, natural and accurate.
), but I have not yet been tempted to switch stock cable yet.
, I experimented and found this to be a pleasant tweak in certain cases:
