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FLC Technology FLC8 IEM


The FLC8 earphone from FLC Technology is a truly unique earphone because the FLC8 comes with the ability to adjust its sound signature. You might think, “Sure, but so do the Shure SE846 and AKG K3003″, but what makes the FLC8 so different is that you can tune the sub-bass, bass, and mids / treble all separately so you can create a fairly neutral / flat sound, or a v-shaped sound, or a warm and bassy sound – whatever you want. It’s pretty clever! At a price of around $350 USD, the FLC8s have the potential to really compete with the bigger players in the market if they’ve pulled off the whole tuning thing effectively…


  • Drivers:  8.6 mm dynamic + 2 x balanced armature
  • Impedance:  11 Ohms
  • Sensitivity:  93 dB/mW
  • Frequency response: 20-20,000Hz
  • Cable: 1.3m detachable (2-pin standard) with 3.5mm stereo jack

Many of the hybrid IEMs I’ve tried have offered beguiling sound quality in many ways, but have been undermined by harsh treble or peaky sound. The FLC8 offered a chance to try a hybrid where I could potentially pull back that treble if I didn’t like the tuning straight from the factory. With 3 different filters across 3 different frequency bands, the chances of creating the perfect sound seemed high. I was keen to try them to find out.

This review will be a little different to many of my others because there’s some time pressure caused by the fact that these are tour IEMs and, as I’ll explain shortly, I have received these a fair way through the tour which often impacts things like presentation, accessories and the like.

Design & Accessories

FLC8-1376The FLC8s I’m reviewing are courtesy of a Head-Fi tour organised by DJScope (thanks very much for the opportunity!) so I didn’t see exactly what came in the original packaging, and much of it is slightly scattered now (including some lost filters), but from what I can gather, the FLC8s come with a range of silicone tips, a cable, a screw-top metal carry case, a key-ring filter holder and tweezers to remove and insert the filters. Oh, there’s also an IEM cleaning tool included.


The stock cable for the FLC8 is absolutely dreadful! Thankfully they’ve updated the cable with the FLC8S, a new, updated version that I believe sounds exactly the same but is better built and come with a better cable.

The issue with the stock cable is entirely ergonomic. The cable looks and feels fine, but the cinch on it is unmovable and it’s way too close to the earphones themselves so you’re forced to wear the FLC8s with the cable behind your head – not a comfortable option for commuting and working at a desk. It’s more a configuration for stage performers where the earphones are connected to a wireless receiver on a belt pack that doesn’t require the listener to access it. For desk / portable use, having the cable go behind the head and then have to wrap back to the front is very uncomfortable so I’m glad they’ve fixed that design.

Design / Build Quality

The design and build of the FLC8 is very good. They’re quite small and light so they’re very comfortable to wear and they seem to have held up well to the tour which is as good a test as any for an earphone. There are slight signs of cracking where the nozzle exits the housing of one of the earphones – perhaps from someone over-tightening the mid / treble filter, but it’s very minor and seems to be at no risk of cracking completely so much as just showing signs of stress.

The housings are finished in an attractive dark metallic blue that almost looks black and the finish is stylish, but understated so they won’t attract attention or look “blingy” if that’s important to you.

Sound Quality

Because the FLC8s are tunable, it’s a bit tricky to discuss their sound signature so instead I’m going to discuss the quality of each frequency range within its tunable limits.

Sub Bass

FLC8-1375The sub-bass of the FLC8s is tunable via a small, mushroom-shaped plug on the inside of the housing. The sub-bass adjustments make a significant difference to the FLC8’s ability to present a deep rumbling sensation and with the red (maximum) filters, the FLC8s offer a top-notch sub-bass performance. If that’s not your cup of tea you can always install the clear (minimum) filters to create a leaner sound that will let you focus more on the mids and treble. Personally, I find the sub-bass so well controlled that the red filters are a great choice and really help the FLC8 to sound dynamic and musical.


While you might have expected the tuning options to be bass, mids and treble, the second option with the FLC8 filters is actually for the bass. This filter is a small rubber cylinder that inserts on the front side of the housing and alters the mid-bass from the FLC8.

With the clear (minimum) filter in the bass port, the sound becomes quite lean and thin with the upper bass / lower mid-range losing its sense of body and weight. The quality of the sound is still excellent, but it’s not to my taste. Thankfully, both the (middle) grey and (maximum) black filters beef up the bass to extremely enjoyable levels and maintain the excellent quality of the sound.

While I thoroughly enjoy bass and quite like the sound of the FLC8s with the maximum bass filter, I think the best balance in the sound is achieved with the middle, grey filter – particularly when already using the max (red) sub-bass filter. With this combination, the FLC8s offer great extension and presence in the bass without getting slow or loose in the bass. With the black bass filters I think the FLC8s are just beginning to border on slow / bloated bass even though it’s still very good overall.

Interestingly, this testing has proved to me that the FLC8s are not able to be tuned to extremes. Sure with the maximum sub-bass and bass filters, they’re bassier than some earphones, the FLC8s never approach the bass levels of the dedicated, bass-oriented IEMs out there. They manage to still sound mostly balanced and that’s great I think – you can’t ruin them, just tune them.

Mids & Treble

The final filter affects both mids and treble in one go. Rather than 3 filters, there are 4 provided at this level – probably because it’s altering two frequency ranges.

With the green filter (medium mids, max treble) the sound tilts towards something reminiscent of all those other hybrids I’ve tried – a little sharp and a little fragile in the treble. It’s not quite harsh or sibilant, but there’s too much treble to be able to sound balanced and the mids start to sound artificial and a bit canned. The good news is you don’t have to listen to that – just change the filter.

Of course, treble heads might love the sound from that filter so it’ll suit some people, just not me. While we’re on that point, the quality of the treble remains excellent which is a very good sound. It would be very easy for a tunable to IEM to get a bit out of control at the extremes, but across all of the tunable frequencies, the quality remains excellent with all different filters and it’s just the balance of the sound that you’re effecting with the filters.

Moving to the gold (max mids, medium treble) filter shows a significant shift in the sound and really highlights the vocals and instruments. For those who love a mid-centric sound, but still want optimal clarity, this configuration is brilliant. To my ears, the sound with this filter can be a little edgy at times and I find it hard to fully relax into the music – moreso than I did with the green filter, but the sound is still excellent and it might just be a personal taste and personal sensitivity thing.

Jumping to the other end of the scale, the blue (minimum treble) filter creates a very smooth, rolled-off experience which is great for those who are sensitive to treble, but it might result in too smooth a sound for some people. I find the sound enjoyable, but I can’t describe it as completely engaging. For me, the final filter, described as gun blue (dark grey / gun-metal) is the optimal choice with a nice balance of mid-range and treble clarity and smoothness. With the other filters, the FLC8s always sound good, but with the gun-metal filters, the mid-range and treble is really special, delivering a perfect balance of clarity, sparkle and energy.

Staging & Imaging

Staging and imaging are a direct result of the interplay between every frequency produced by an earphone, but particularly the upper mids and treble. For that reason, the FLC8s can be highly variable in their imaging and staging, but when you get the right combination of filters (for me that’s the max sub-bass, medium bass, and medium mids / treble) the staging and imaging is outstanding. The image is sharply focussed and well-defined with great separation and the stage, while not particularly large, is spacious enough to never feel cramped.

It’s impressive how cohesive and coherent the sound from the FLC8s is – they’re right up there with the best in-ears I’ve heard which is an achievement when combining a dynamic driver with two balanced armatures and then throwing them into a fully tunable housing!

FLC8 vs Noble Kaiser 10

The Noble K10s are still my reference for truly brilliant sound quality mixed with loads of musicality. I thought it might be interesting to tune the FLC8s similarly to the K10s and then put them head-to-head – $350 upstart vs $1650 flagship.

FLC8-1373My tuning choice for the comparison is the one I mentioned above – max sub-bass, medium bass and medium treble / mids. On their own, the FLC8s with this setup sound like a flagship quality – crisp, clean sound with body and weight where it matters. I could listen to them all day with a big grin on my face, but how do they stack up against the best (in my experience)?

Switching to the Kaiser 10s reveals instantly why they’re top of the audio pile, but it’s not a run-away victory. Actually, what it shows is that the FLC8 provides 80-90% of the Kaiser 10’s performance at about 20% of the price! Where the K10s show their superiority is that they provide slightly better bass presence and punch without losing control. For the FLC8s to achieve the same kind of bass impact you’d have to install the maximum bass filter, but that results in some bloat and slowness in the bass whereas the K10s are nimble and detailed in their bass delivery even while delivering a full-bodied experience.

The other area of advantage for the K10s is the epic layering of the mid-range sounds that they can provide. While the FLC8s are very, very good, the K10s are simply sublime and it’s no shame to be defeated by a behemoth like the K10s – the FLC8s were punching well above their weight in this comparison and they fared incredibly well. In fact, I’d say the FLC8s are comfortably one of the absolute best-performing IEMs I’ve heard for less than $1000. The fact that you can also tune them to your tastes is a huge bonus!


Looking for a great universal IEM that suits your personal tastes in signature? You have to try out the FLC8. Apart from its astounding ability to be adjusted to taste, the flat-out performance from this compact hybrid IEM is simply excellent. You’ll be very hard-pressed to find a better value offering on the market, particularly with the new FLC8S model packing a better cable and better build quality. Don’t be fooled into thinking they’re a giant-killer, but do be confident in spending $350 of your hard-earned cash knowing that you’re going to get every cent’s worth of value and plenty of fun tuning the FLC8s to suit your exact tastes!