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Background
A current university student on a limited budget here. Subsequently, I don't have nearly as many frame of references as others have (but I do check out the nearby audio store and try out the common open headphones!) I'm not a super enthusiast (yet?) about audio, but music means a lot to me. My files are either lossless/uncompressed from Bandcamp or wherever I can get the source version from. I get some of the basics of high fidelity audio such as sound signatures, presence range, etc. but I'm definitely not a sound engineer. Music is subjective - hence, don't expect a superlative impartiality of sound explanations from me!
From reading countless comparisons and reviews across the wide internet, I ended up with the choice of three in-ear monitors that I believe matches my sound preference: neutral (negotiable, the upcoming aspects are not) with the greatest emphasis on clarity and spaciousness. The three IEMs I had rounded down to after an extensive multi-language search were the Etymotic ER4SR ($349, single balanced armature, known to be the benchmark of IEMs for a good reason), the Audeze iSine 10 ($399, planar magnetic IEM) and the much, much lesser known FLC 8S ($350, 1 dynamic driver + 2 balanced armatures hybrid). Though I haven't tried all three (the perks of living in Oceania... this is not one of them), both the ER4SR and iSine 10 had quirks that became problems for me: the former for deep insertion and fit (I bike as a primary means of transport and the ER4SR would stick out against my goggles; anything but foam tips are not comfortable enough for me to listen for long periods of time) and the latter for having no isolation, supporting Apple devices only while having an off-tone, massive peak between the 1-2 kHz range (the cipher cable they later developed to address this does not match my needs for an IEM). Being a university student studying full-time, I did not have the opportunity or money to splash around to try all these excellent and critically acclaimed in-ear monitors. This was a - very - luxury purchase I have made for myself, and I had absolutely no room for regretting a purchase. Ultimately, after reading many reviews of the FLC 8S, all the goods and bads (one saying that the iSine 10 was so much better (ehh no) than the FLC 8S - in hindsight, that person probably didn't tune their FLC 8S very well) I decided on purchasing the FLC 8S knowing that it would be the least regrettable purchase decision out of the three considering its advertised flexibility of 36 different tuning configurations. And so I brought these on sale for ~US $300 from Lend Me Ur Ears (great customer service, by the way) and eagerly awaited and withheld myself from excitement to try them at the right time and place of mind.
Disclaimer?
I brought the FLC 8S with my own money and felt the need (without anyone's suggestion) to share my experiences with these high fidelity in-ear monitors.
Misleading first impressions
TD;LR
If you experience sibilance and/or hiss with the FLC 8S, throw away the stock silicone tips and use memory foam tips with a good seal in your ear.
So I prepared mentally and physically to listen for the first time. After hearing so many amazing reviews about this IEM, I was completely ready to be blown away. Putting on the smallest silicone tips (so I could get the deepest and clearest fit into my ear), I set down for the revelation of awesomeness.
I was blown away by how horrible the stock tips with Grey/Grey/Gold was and how sibilant they sounded.
Literally, I played a track with NO vocals and I heard hissing (which disappeared when I pause the track; not present in any other IEM I have, so I'm 100% sure it's not equipment) coming from the treble. Changed to another track. Still hissing. A vocal track. The vocals sounded like a ROBOT trying to mimic a snake rattle. They weren't even pronouncing 'S' sounds! Everything was hissing and sibilant so badly, I thought of returning the IEM for repair 10 minutes after I opened the box. They sounded worse than broken. But then I had a revelation of my own. I was going to change to foam tips anyway, but it struck me that the smallest stock silicone tips was the issue (I might miss the "best treble extension" stated by FLC... but with that sound. No. Not at all).
So I changed the tips to Comply TX400 (smallest size, the one with the waxguard filter). It was as if an entirely new experience of the FLC 8S opened up to me. And they did. They stopped sounding sibilant and broken. Literally, all the hissing disappeared from any of my tracks. No exaggeration, it was completely gone. And its not like any other variable could have caused it either, the hissing was so bad that I removed the stock tips after ~2 minutes of rapid-fire listening of many of my tracks. Suddenly, they sounded natural, incredible and normal (the incredible part is helped a lot by the TX400, great pairing to balance the sound of the FLC 8S) like what you would've expect from any non run-overed high-end IEM.
As such, I recommend that you take hold of all the stock silicone tips that came with the FLC 8S,
and throw them away.
(At least don't use them and look for alternatives, ESPECIALLY IF you are hearing unnatural tin robot sounds/sharp edges with them).
Second (unabridged) thoughts on the stock silicone tips
After seeing others praise the stock tips, I decided to give them another try. This time I used the medium size and made sure to get the best seal as I could (doesn't help that these do not adjust to the shape of your ear canal like the complys - felt like it could uncomfortably pop out of my ears at any moment). Tried with the track that I heard unlistenably terrible hissing and sibilance (Krys Talk - Fly Away <Mendum Remix>) and the awful hissing was mostly not there any more. Still, the treble stands out too much and reduces the amazing coherency and timbre of the FLC 8S. Sibilance ("WEU'LL SSHAYSSZEEEE") was still there. On other tracks, the brilliant no nozzle filters configuration started to sound shouty, unnatural and off-tone with the medium stock silicone tips. I did hear marginally more treble detail with the silicone tips, but I'm not sure if you'd really want to hear that with this IEM given that its midrange clarity is absolutely transcendental. I don't think the "most treble extension" silicone tips is a good combination if you want natural clarity from these IEMs. Also they diminish the FLC 8S's awesome detailed subbass and midbass (regardless of your filter configuration) by a lot. This is from someone who doesn't even like bass - it's as if the stock tips absorb the subbass impact or something. Compared to the complys, the stock tips made the sound somewhat tinny and far too bright - it lacks the fullness and wholeness that the comply gives with the IEM. Swapped back to the Comply TX400, and all became right with the world. The coherency, naturalness and clarity of the FLC 8S with the Comply TX400 is just incredible - a match made in audio heaven.
TD;LR stock tips changed from discard/10 to 3/10 listenable with proper fit and improving bass response through red thumbstack. Stock tips has poor bass response, making the IEM sound tinny. Small Comply TX400 (medium and large sizes causes recessed mids and muddies everything up) with good ear seal reveals the capability of the IEM's tremulous subbass while evening out the sound on top of making it feel like its not even on your ear - highly recommended. With it, I can not imagine a better pairing in terms of naturalness and effortless music. If you think that the FLC 8S is too bright or sibilant, then you owe it to yourself to try them with the small Comply TX400 - an incredibly even and harmonious tone awaits you with this pairing.
Quirks
The FLC 8S comes with an earguide hook that you can place on the cables. At first, I struggled for a good 10 minutes to even put the thing on until I realized that the ear hooks actually had "L" and "R" imprinted on them. Trying to put it on the first few times was rather discordant, but now that I know how to properly put them on it only takes me about ~5 seconds (make sure that the ear hooks cover the entire part of the cable; put the ear hook over your ear first, then guide the IEMs into your ear). The ear hooks were very soft and comfortable for me, most of the time I forget that it's (along with the super lightweight IEM) even hanging on my ear (if not for the incredible sound that these produce, that is).
The braided pure copper cable produces a lot of cable noise and should be replaced if you are intending to breathe and/or allow your heart to beat while listening to the FLC 8S. Well, its not actually that bad, but given that the IEM is designed to fit over-ear and yet still produces any microphonics at all (just from moving your head slightly, but the cable noise from this can be unnoticeable by increasing the volume), it definitely is a weakness to consider. I wear my IEMs with the cable over my back so that I never touch the cables and it stays more stable while moving (and also reduced microphonics to zero in my other cable-noisy IEM), but the FLC 8S cable still produced very little-but-still-there microphonics when I did this. For most people, the microphonics will be gone once you increase the volume, but if not, you should strongly consider setting aside the stock cable and seek an alternative, (non-cheap because the FLC 8S deserves great cables!) non-microphonic cable especially if you plan to move around a lot with this IEM. Newer FLC 8S comes with a revised pure copper cable (its more deep teal in color) with a proper non-cheap looking cinch and without the memory wire. I don't notice any stiffness and discomfort with this cable, I was able to sleep listening to the IEMs and the cable got out of the way without ricocheting and hitting me in the face like the other stiff cables I've tried, so I'd say the stock cable, sans microphonics, is actually quite nice.
They are also 1.2m long (for both the 7N pure copper stock cable and the 6N pure silver upgrade cable), which considering that includes the over-ear design may be too short for some. Understandably, these styles of cables are rather expensive (just look at how much Ultimate Ears sells their pure silver cable for... I'll let you guess. Over 60% the price of the FLC 8S... yikes) so I wouldn't consider it a flaw as you can use your own cables either way.
The socket is TF10 and is 0.74mm, so cables apart from FLC's own pure silver upgrade cable could potentially make the earpiece socket larger and slightly loose. They actually advise not changing cables often for the IEM's longevity, so these quirks should definitely be taken into an account if upgrading the cable is to be an attractive option for you.
I'm trying to blow holes at the FLC 8S's possible weaknesses at this point. Aside from the tiny thumbstack and cylinder filters making it potentially difficult to change on the go (I sort of got used to it and can change more often without the filters going and flying everywhere... I think. After getting used to the changing (grip the thumbstacks securely with your fingernails, push down from an angle opposite to the nozzle), it only takes me ~8 seconds assuming that I gripped the parts properly so that it doesn't fly off. Besides, considering how small these IEMs are it's really a given physical limitation) there really isn't much else you could criticise about the FLC 8S. Especially the sound. You can't make a tuneable IEM without being at least very good in all parts of the audio spectrum after all - and for that, they have done super well. I hadn't realised until now that 'You're Not Alone' by CMA actually had cymbals behind the empowering bass. It sits far behind it and is a bit subtle. With sibilance I probably would've just thought that the bass was distorted (its not, the artist's tracks are amazing and well-balanced) because I wouldn't have been able to distinguish between the overpowering bass and the subtle treble. I have no problems doing that with this IEM! The FLC 8S does a superb job of covering the general flaws of IEMs, and I think its very unlikely that its physical aspects would cause issues for anyone. I wouldn't even consider their custom shelled version because the universal one already fits so well for me. But that is an option if one finds the FLC 8S to not fit as well (not likely from what I can tell out of the countless impressions I've read, which is a very, very good thing for a universal IEM).
Impressions Update!
(The review of the FLC 8S continues down below!)
75 Ohm Impedance Adapter
Neutron - Crossfeed | Surround Sound
By now I have tried many things on my quest to bring out the best possible sound from the >magnificent< FLC 8S. I have used the 75 Ohm Impedance Adapter for a while now, and while it does reduce listening fatigue at higher volumes, the added length makes it cumbersome to use when you're out and about. So I have been moving levers around in Neutron's Crossfeed and Surround Sound DSP settings and found that, with the right configuration, these can have the effect of reducing listening fatigue overall while also increasing soundstage depth (for Crossfeed) or soundstage width (for Surround Sound) significantly. The sound improvements are far greater than even the praises I put out for the impedance adapter, I don't think I could accurately describe the experience in words. It's an entirely new dimension of sound (maybe literally with Surround Sound) that I have never experienced in any headphone or IEM - ever, and the FLC 8S's superb technicalities and tuning ability have allowed me to hear and discover this new galaxy of sound better than any other sound producing equipment I have tried.
Descriptions of the perception of where the sound comes from may vary based on your setup, the ear tips that you use, ear tip insert depth, and your configuration. Oh, and your own ears, too.
These are the greatest and most significant improvements in sound I have heard thus far.
Crossfeed
Music flows serenely in the background, allowing you to be focused and immersed in other tasks. Improves soundstage depth with the side-effect of lowering the volume and pushing the music back noticeably, making music very easy to listen to.
Surround Sound
Vocals span the space around your head, creating a large area of perception for audio. The sound is not perceived close to you or has the left speaker/right speaker obvious sound location pinpointing, which also makes it comfortable to listen to like crossfeed. Surround sound demands more of your attention naturally due to the expanded soundstage width.
The differences that crossfeed and surround sound makes are just too significant to put into words. If you are interested in improving soundstage depth (crossfeed, surround sound to a lesser extent) or soundstage width (surround sound), try them out. It just has to be heard to comprehend the massive differences that they make to the sound.
The Pure Silver (Single Crystal) Upgrade Cable
Let me preface by saying that the stock 7N pure copper cable (minus the microphonics) is already very good. Either the stock or the pure silver upgrade cable will offer great sound without issues (0.74 mm pins). The 99.9999% (this is expensive stuff) pure silver upgrade cable comes with memory wire which I can adjust to stop the cables from touching the back of my neck (compared to the ear hooks, which points the cable inwards slightly due to its shape). It also allows a more secure fit on your ear in case you're doing gymnastics or something with these IEMs. The cable is the same length, still with microphonics (though somewhat reduced maybe? but with more shape retention), so don't expect much of a difference in those areas. The upgrade cable does have 400D Kevlar at the core though, so it'd probably stop a bullet before failing out (the price would be mainly due to the single crystal silver they used - its not cheap). Any improvements in sound quality made beyond upgrading the actual IEM itself is not as large (unless your source files are really bad), hence divisive and subjective (we sure know that on this forum!), and depending on your setup and circumstances, the differences might be massive, it might be slight, or there might not be any perceivable difference at all. With that said, I'll try to describe the differences (and improvements) I hear when swapping from the stock pure copper cable to the pure silver upgrade cable deliberately and exactly. First, lets get some things out of the way first.
The difference between copper and silver is that silver transmit electrical signals ~5% better than copper. You can look it up and see why people even bother with expensive silver in high end equipment!
But would you really notice that 5% (real-world estimated, not likely to transfer exactly to listening experience) difference? Theoretically, it might improve sound performance (again, theoretically). But how would you be able to measure that? A cable shouldn't be changing the sound frequency (unless its very bad or is intentionally designed to do so) and an artificial model can only do so much to imitate the millions of different variables creating different overall experiences to the sound that makes audio fidelity perception inherently subjective. I can't speak for everyone, but since the audio-focused FLC released these cables (at a small sum of $100 dollars), I felt that these might actually make some differences (though I am not inclined to think so), or that they should if they bothered to make it given they said that they worked so hard on perfecting the 7N copper stock cable. So, now I got the pure silver upgrade cable (the FLC 8S really impressed me!), this is what I have noticed after listening with the stock pure copper cable then swapping immediately to the pure silver upgrade cable with my setup:
- In Phillip G. Anderson's 'Winter', the subbass of the orchestral drums are tighter and more refined. The bass not only has more impact like you would expect from boosting subbass and midbass - the impact is clearer, as in the specific repercussions could be felt (I also felt this with the stock cable but the pure silver upgrade cable does this rumble effect more cleanly and distinctively). The echoes of the drums seem to extend slightly longer, making everything sound more natural.
- In the soundtrack 'What Becomes Of Us' from Final Fantasy Type-0, the female and male choirs sounded somewhat fuller (not in terms of soundstage depth or anything, but rather the opposite of 'thin' sound), I could hear the background layers of vocals a bit better.
- Hammock's 'Ten Thousand Years Won't Save Your Life' sounds fuller and overall more whole. The violins are more intimate and impactful.
- The piano in DJ Okawari's 'Flower Dance' and 'Luv Letter' sounds like they have more presence (not thin or forwarded - the instruments sound more balanced and is comfortably in their respective places), sounding more natural and slightly more real compared to the stock cable.
- The wall of treble in Porter Robinson's 'Sea Of Voices' sounds somewhat more powerful with a higher sense of density.
The improvements isn't just better resolved bass, though that would be the first thing most would notice when not listening analytically. In all of my tracks (even in ones that doesn't boost the bass very much), the bass rumble sounds and feels more detailed - there is more of it when the music presents bass (though still completely silent when it doesn't). Secondary layers of vocals sound more pronounced compared to the stock cable, though I do not notice an increase in treble quantity (which is a good thing as the FLC 8S already has a lot of treble). This makes the FLC 8S feel more powerful, not in a typical bass boosted sort of way, but in terms of offering a more realistic presentation of music. I can definitely see and hear why they call it an 'upgrade cable' for the FLC 8S.
A year after - Impressions update
My initial impressions were too modest. The silver upgrade cable is AMAZING with the sound it enables for the FLC 8S! The newer cables don't seem to have any audible microphonics at all, the cinch is now the same as the stock copper cable (i.e. no longer a cheap looking plastic tube, instead something sturdy and easy to use). No more memory wire that's shown in the impedance adapter picture above, but I've never found the lack of to be an issue (even while cycling) if I wear the cables over my back with the cinch up to the back of my head. And the sound. Everything is somehow even more clear, including the subbass (20 - 40 Hz) and lowbass (40 - 80 Hz) precision and naturalness that I've mentioned previously. I can hear the vocalists' breaths at the beginning of every sentence more easily compared to the stock copper cable, yet it still does not sound fatiguing. The entire frequency spectrum is just rendered better. That ~5% difference in conductivity between copper and silver is absolutely being utilized here (not to mention the expensive 6N 99.9999% silver purity), and if you're familiar with how the FLC 8S braided single crystal copper and silver cable sounds, I would go as far as to say that the differences will present itself to you.
For example, I have several music files that primarily uses the 19 kHz region at certain parts of the track (which the spectrogram shows it being as loud as the bass region; it manifests as faint light note scribbling/wind sound), on the stock copper cable it was audible and kind of there, but with the pure silver cable it was - easily - noticeable and effortlessly presented. Upper frequencies 16k to 20 kHz reminds me somewhat of the Shure KSE1500 (that I've demoed twice, pretty much unparalleled detail in mids and treble but Balanced Armature-ish bass with little to no decay compared to the stunning natural subbass of the FLC 8S's dynamic driver) with the silver upgrade cable, it's just super glorious. Treble sounds more accurate, but not harsh, and the subbass - I can feel the gentle but powerful and clean rumble of the subbass and lowbass in my chest and even down to my stomach if I turn the volume up high in certain tracks (like Nero's 'Promises') with the red thumbstack! Listen to the beginning of Max Richter's 'November' and you can FEEL the precise and clean rumbles with the red thumbstack filter (but it doesn't affect the clarity of the mids at all! Hybrid IEMs huzzah!) I've just mentioned how incredible the FLC 8S's subbass is with the silver upgrade cable, red thumbstack and easy-to-get-a-complete-seal small comply TX400, right? Listening to the combination as I'm writing this, I felt the need to say it again. I've heard top-of-the-line headphones like the Stax SR-009S and the Sennheiser HD820 and they do not compete with the FLC 8S IEM in subbass quality and naturalness at all. If you're looking for an upgrade to the FLC 8S, buy the silver upgrade cable (or if you're uber rich, import the ~2k USD clockwork gear tuning 135 sound combinations FLC Celeste from Hong Kong). I'll resolutely assert that there is no better universal and tunable high fidelity sound than this at the now ~300 USD price range after trying the stock copper for a while then switching back to the silver upgrade cable!
But, of course, this is my subjective perceptions of the improvements I've noticed. While I can definitely pinpoint the more defined subbass and lowbass (Phillip G. Anderson's 'Winter' is a very good example of this, as well as Torsti Spoof's 'Faith'), someone else with different audio equipment, music tastes and several thousand other things may notice something else entirely or nothing different at all. It's all subjective approximation either way. Some people might not be able to distinguish a pair of Beats over the Sennheiser HE 1 in a blind test, and that's okay too. What experience that person perceives and prefers is what matters. For me, the pure silver upgrade cable offers a nice improvement to the sound of the FLC 8S, and with that I'd say it's worth using over more convenient custom cables. After all, I brought the FLC 8S for its incredible sound; if you listen to music through IEMs a lot like me and you enjoy the FLC 8S's tuning capabilities and sound, it might be worth getting if price is not a factor - the pure silver upgrade cable presents a sound that is slightly more real and more complete in all types of music.
Subjectivity to consider
Sound quality is influenced by an astronomical number of factors - the genre of music you like the most (which generally determines the sound signature/IEM you would prefer), the shape of your ear canal, the sources of your music (smartphone versus dedicated amplifier, file quality), the list goes on. All these things could have the potential to affect sound quality drastically (again, dependent on your circumstances) as I've demonstrated with the smallest stock silicone tips and small Comply TX400 in my first impressions of the IEM, so your experiences can and probably will vary to mine. I am from a perspective that clarity and spaciousness above all else matters for high-end headphones, and with that said I am rather aversive to bass and its tendency to make tracks feel like a nightclub party (have used a bass reducer equalizer ever since I've started to listen music more attentively, which I now longer do with the FLC 8S because it is no longer needed - the clarity and balance is incredible). Of course, treble standing out is not a good thing (usually destroys the timbre and harmony of the music) so its a very delicate balance for me in the sound that I prefer. The FLC 8S allows me to achieve this balance and change the sound based on what I feel like listening to (upbeat EDM for biking, Ambient for relaxing/studying) which to me makes it understatedly unique compared to every other IEM on the market. Of course there will be more technically proficient IEMs out there (the electrostatic Shure KSE1500 for example), but the FLC 8S's versatility and comfort to my ear makes it the best use-everyday high fidelity IEM I could imagine. Because everyone will invariably have different experiences and perceptions to audio, I would like to speak from my standpoint, particularly the configuration which have led me to praise the FLC 8S so much. You should get a chance to hear these configurations first before modifying your expectations (for better or worse) of this IEM.
Small size Comply TX400 memory foam with waxguard
Comfortable and removed all sense of sibilance I heard from my first impression of the FLC 8S. For those who believe that the FLC 8S is on the bright side for an IEM, these will very likely change that perception in offering a more balanced and customizable sound.
What have blown me away:
Grey | Grey | No Filter
Immensely coherent and harmonious sound with stunning resolution, forwardness and clarity of the midrange.
Red | Clear | No Filter
Detailed energetic bass response with great clarity. Midbass recessed, but potentially offers a wider space of sound.
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The Sound|s| of the FLC 8S
Filters - Thumbstack [Subbass] | Cylinder [Midbass] | Nozzle [Midrange and Treble]
Colors, most to least respectively:
Thumbstacks
Red
Black
Clear
Cylinders
Black
Grey
Clear
Nozzles
Green - Most treble
Black - Medium mids, second most treble
Gold - Most mids
Blue - Deletes treble and reduces midrange
(I will be calling the black thumbstack filter grey for coherency and color-coordination).
There is actually a lot more to know and discover about the FLC 8S beyond the claimed 36 configurations design. Changing one filter affects the rest of the frequency response and thus the sound. For example, using a clear clear black configuration will push the frequency peak of the black nozzle filters slightly from ~1.3 kHz to somewhere closer to 2 kHz (check out the graph measurements at innerfidelity for a comparison) compared to any other bass filters combination. This means that changing just one filter can have a larger than expected effect on the entire audio spectrum, particularly the midbass cylinder filters which determines how much airflow goes into the IEM. Basically, the FLC 8S can be VERY complex and advanced if you choose to go the advanced tinkering route (someone in this forum added an acoustic dampening cloth to their cylinder filter - the frequency response changes were rather interesting!). On a particular track that I found had too much treble coming from one side, I literally removed the cylinder filter with my hands from that side, WHILE listening to the IEM, and found that side suddenly becoming more coherent! It should be noted that the general issue of disjointed sound found in other hybrid IEMs is nonexistent with the FLC 8S. The combinations of drivers are exceedingly technically well-tuned that they overlap and blend in sound, creating a natural sounding hybrid IEM that doesn't sound off-balanced, being just as whole and pleasing as single-driver type style IEMs (maybe even moreso with the brilliantly clear, wide midrange of no nozzle filters i.e. what the IEM is wholly capable of in terms of 'soundfullness'). Now, I'm not advocating for mismatching the volume and frequency response of the IEM, but it shows the deep potential and customizability of the FLC 8S. I don't think I would be exaggerating in saying that these are perhaps the most customizable IEMs ever released (at least for the time being... new technology are so limited and expensive!)
Since I don't have frequency response graphs to show (the other reviews have already done an excellent job on this), I'll just (not word for word) quote FLC's founder Forrest Wei on precisely what the filters do.
"Without the ULF plug [Thumbstack], the earphone will be like an earbud; you could wear it to run.
Without the LF plug [Cylinder], the midbass is about 2 dB higher.
Without the nozzle, the mids will be higher around 2K Hz - vocal is more forward, the treble will lessen at around 4~5K Hz, sibilance will be less, but the treble would not be so solid and bright."
You could probably get it from his explanation on what the functions of the filters are. The purpose of the filters is to control how much specific sound frequencies are dissipated from the IEM before reaching the nozzle and into your ear. What this means is that there are actually even more (!!!) ways to tune the sound than the stated 36 configurations if you get creative with the no filter combinations.
No Thumbstack filter
This covers the area where the dynamic driver rests. It removes (maybe all) low-end subbass from the IEM and make it sound as if they sit outside your ear, even with a perfect seal. From what I've noticed, this makes energetic EDM tracks or anything reliant on bass sound bad as if the entire low-end frequencies are missing. This may be a good thing on some poorly mastered tracks or orchestral music, but for cohesiveness of sound, using at least the clear thumbstack filter for reduced bass (instead of removing bass entirely) would be recommended for most styles of music.
No Cylinder filter
This covers the area where the dynamic driver and two balanced armature drivers are situated. According to Forrest Wei, this option is the most bassy option of all, offering 2 dB more bass than the max bass filter (black cylinder). This is accurate in my experience, as the moment I remove this filter while listening I was greeted with bass energy that wasn't there before. Using no filters here provides more airflow for the dynamic driver, and in increasing midbass controls the presence of the higher end frequencies. Having no filter here at all noticeably reduced the clarity of orchestral tracks, particularly the piano where it became harder to discern the particular notes as you increase the midbass. To reiterate: removing the cylinder filter and using none will actually increase bass presence and energy. The clear filter here gives the dynamic driver the least amount of air (aside from taping over the port completely) for the bass, so you can tune subbass and midbass separately which makes the various interactions with the filters rather interesting - you could come up with some unexpected results by changing this filter in combination with the others!
No Nozzle filter
This is the final filter before the sound reaches your ear, and arguably its removal makes the FLC 8S shine. Using no nozzle filters as FLC founder Forrest Wei says will make vocals sound forward while simultaneously reducing the treble around 5 kHz (which according to the presence range definition you can find in the forums, would make instruments 'more distant and transparent'. I interpreted this as greater clarity and spaciousness on the FLC 8S). With no nozzle filters, the IEM becomes somewhat mid-centric, which would sound unusual if not for the FLC 8S's excellent technical capability. With no nozzle filters in place I was able to pick out minute details that was not present or less noticeable with the black, blue or even gold filters (the green filter was only partially equal with music that extensively utilise/mainly focused on the high ranges above 6 kHz). The sound could actually be characterised as an enhanced gold filter experience. Detail resolution expanded when I took off the gold filters and put the Comply TX400 on in its place. While the default configuration of Grey/Grey/Gold filters was great and supremely harmonious, using no nozzle filters made me felt moved - by the sound, and I found myself involuntarily moving to the rhythm with a smile on my face. No nozzle filters definitely deserves to be heard (can't say the same for no thumbstack filters). It makes the midrange sibilance-free and clear with impressive imaging and a great sense of expansiveness.
I can't say much about the thumbstack and cylinder bass filters as the preferable tuning of these are highly dependent on the music you listen to. Increasing any parts of the bass should eliminate any sibilance (with Comply foam tips plus waxguard) that you might hear on even the most awkwardly mastered tracks. I will say that the subbass of the FLC 8S (with red thumbstack filters) goes very deep. Compared to a V-shaped IEM with more midbass, in the track 'Winter' by Phillip Anderson, the drum parts were seismic (if you have a complete seal with foam tips) and I could feel the specific repercussions of the drum's echoes. With the more midbass V-shaped IEM using the same foam tips, I was not able to feel the same effect, it didn't really came close to reproducing the detailed and powerful subbass of the FLC 8S. With red thumbstack, its pretty strong in the subbass department for sure. Midbass is quality in terms of being detailed, though there isn't as much quantity as there is compared to the subbass (I might not be holistic with this, my last IEM essentially attacks you with midbass) so you might not feel the midbass of the FLC 8S as much as you would feel its subbass. As others have said, low mids are not affected by the tuning components as far as I could hear (i.e. it didn't increase with the configurations I've tried, I guess its an intentional tuning to make the IEM sound more detailed and spacious?) so instruments like violins might be detailed, but not feel as full compared to a midbass elevated IEM (this was with my equipment, I have heard that this aspect improves with dedicated amplifiers so try that out if you have it!). Though I regard the sounds of the no nozzle filters configuration to be the signature highlight of the FLC 8S, the nozzle filters give flavors of sound that could better suit and enhance the music you listen to. Your primary choice of nozzle filter would thus likely be dependent on the frequency ranges that your music tend to produce and emphasise.
Blue Nozzle
Matches | Dark, enclosed, bass-heavy
Listening casually, focusing on other things.
I tested these out with the stock medium silicone tips (offers the most treble extension according to FLC).
| Destroys treble response and reduces the midrange considerably, but offers more bass rumble and presence. Good for having music sit in the background. |
Coming directly from no nozzle filter with the TX400 tips, the blue nozzle sounded immensely muffled in comparison. It sounded so bad initially that I relegated the blue nozzle from the blue container to one of the plastic accessory bags (where I'll likely not touch it ever again). The blue nozzle mimicked the sound of my 5+ years old Apple EarPods quite well (enclosed, filtered, though with incomparably better detail retrieval obviously) so there's that going for it. That sounds way too harsh, because it is (don't actually compare the Apple earbuds to the FLC 8S - the differences exist in parallel dimensions separated by infinity) - its intended to show the MASSIVE difference between the audio clarity of no nozzle filter and the blue nozzle. And I would assume that you're looking at the FLC 8S for its stunning brillance and tendency to make you react passionately to the music. It probably wouldn't be found with the blue nozzle.
With that said, after listening to various tracks for an extended period of time and getting mentally used to the sound, I did notice that they offer more bass and thump. If you manage to get used to the sound of the blue nozzle, then it will still sound good regardless as the technical prowess and tuning of the FLC 8S is phenomenal. The blue nozzle could be regarded as offering a more lounging friendly sound - if you don't focus and listen attentively, they might be good for relaxed listening or just having music sitting in the background while you do something else (might not work if you have a good seal increasing the sense of bass/going for isolation in loud environments). Though after listening with no nozzle filters, I can't imagine why anyone would want to use the blue nozzles, they don't exactly play to the FLC 8S's strengths. Regardless, its a nice option to have if you want to just relax without feeling moved by the sound of the FLC 8S at the best parts of a song.
For listening closely and for intending to use these as the primary filter though - if your music selection consists of something along the line of 60% bass, 30% mids and 10% treble (in every song you listen to), then the blue nozzle might sound good in enhancing the bass feel at the expense of everything else. Whether that would be worth it to you, well, you'll just have to try it and find out.
Who knows, you might enjoy feeling the music more than you do listening to it. If that's the case, the blue nozzle might be of use to you.
Green Nozzle
Matches | Airy, not vocal-oriented, clarity necessitated
Listening to the nimbility and gracefulness of orchestra.
| Quick and precise treble imaging. High amounts of detail at the high ends, amazing for piano. May produce very noticeable sibilance in vocal tracks depending on the bass filter combination used. |
With my previous bass-heavy V-shaped IEM (Degauss Labs Noir), orchestral tracks or anything that emphasises the piano sounded... not good. The boomy midbass contoured and muffled everything, reducing the ability to distinguish the notes of the piano, so everything sounded very muddy and 'samey' as far as orchestral tracks go. Experiencing the green nozzles of the FLC 8S have opened a new door for me in music. A good benchmark for audio clarity of piano would be the track 'Blink' by James Maloney. The piano here is VERY quick and absolutely demands precision and clarity in the higher ranges or else the presentation would be very bad. With a V-shaped sound signature, the piano sounded like a mushed blur. Absolutely no detail could be distinguished because it was so blurry. With the FLC 8S's Clear/Clear/Green combination, I could distinguish every piano note and realized that the piano was actually linearly moving up and down in notes rapidly - and I could hear all of those notes without extensive focus. That is the clarity that these nozzles offer. When I changed the clear cylinder midbass filter to the grey one, it became more difficult to discern the individual notes. So if I were to use the green nozzle, I would definitely only stick to the clear cylinder filter to make sure that the treble isn't reduced from the more open port. Any subbass filter should be fine here for the most part - I didn't notice those directly affecting the clarity of the piano as much as the midbass filters.
A downside of these filters however is the added sibilance and unnaturalness added to vocal tracks. Vocals started to sound like they came out of a cymbals sound mixer instead of an actual human being. 'Chase' in the track Fly Away by Krys Talk/Mendum (the track where I noticed the horrendous sibilance in my inital impression) becomes 'shayse' with the green nozzle. And this was with the small Comply TX400 with waxguard, which is known to reduce and harmonise the treble. I can't imagine how bad the sibilance would be with any other tips (actually, I can - refer to my initial impressions with the unnatural silicone treble blaster-err I mean stock silicone tips).
I also noticed that everything had less sound decay in general, because the treble would just move from one note to another quickly without really letting it fade away naturally (like the sounds coming from the dynamic driver, which sounded more natural). As such, this nozzle is definitely not 'main-use'-able unless your music selection consists mostly of vocaless tracks. Would the green nozzle be worth keeping around for changing? Again, that is up to you and whether you like treble or not. The green nozzle filters does not destroy the spaciousness of the music like the blue filter does (actually it could be seen as enhancing it slightly), but it does destroy any sense of naturalness if your music is particularly vocal heavy. All in all, the green nozzle filter is a nice option for those looking to enhance their piano listening experience. It has the potential to make orchestral imaging astonishingly wonderful.
Gold Nozzle
Matches | Smooth, intimate, sibilant recordings
The fullness of vocals.
Referred by many as 'liquid vocals', the gold nozzle pushes the emphasis towards the ~2 kHz range while reducing treble noticeably around 8 kHz (resulting in it eliminating sibilance really well). It helps with the finish of the vocals, making them sound more 'complete' in a sense. The tradeoff is that there can be a lesser sense of space because the vocal is closer to you (though imaging and soundstage is excellent like the other non-blue nozzles), but it's definitely not as enclosed as the blue nozzle.
This nozzle can help with tonality and naturalness for some because it smoothens out the sound while bringing vocals to the center stage. It offers a slightly more natural decay of sound compared to the black nozzle for example at the expense of treble details. Treble is definitely pushed back with the gold nozzle, so that is something to take into consideration. You won't feel like being surrounded by clouds with this nozzle, but rather you'd feel like you're comfortably on the ground, at the front seat of a live performance. The gold nozzle sets out what it aims to do really well, and should work well with all styles of vocal music.
In sacrificing some airyness (treble) for a smooth tonality, I can definitely see a lot of people enjoying this nozzle filter.
Black Nozzle
Matches | Neutral, most music, forwarded instruments
No particular emphasis on anything. Easeful reference balancing.
This nozzle is quite neat (literally). According to innerfidelity measurements, they roughly emphasise the ~1.3 kHz and ~9 kHz ranges, so they could help with providing a fuller sound at higher ranges (for reference, the green nozzle filters also emphasise these ranges). Actually, comparing the black nozzle and green nozzle frequency response graphs, you could say that the black nozzle filter is the more balanced version of the green nozzle. It is the filter with the second most amount of treble (roughly ~4 dB higher than gold nozzle it looks like) and as such you might notice slight sibilance on a few tracks (increasing midbass helps alleviate this). It can work very well for those looking for a more linear extension and sound. I can't really say much else about this nozzle however, because nothing really stands out in my tracks to me using this. Is that a good or a bad thing? You decide.
Grey | Grey | None
Matches | Everything
Clarity and reference sound comes to life.
This, to me is the absolute highlight of the FLC 8S's coherent tuning and preeminent midrange. To reiterate on what no nozzle does: "without the nozzle, the mids will be higher around 2K Hz - vocal is more forward, the treble will lessen at around 4~5K Hz". From my listening, some definitions and playing around with a music editing tool and increasing/decreasing those specific ranges, I've found that this gives the most spacious, yet complete sound of all the nozzles. Listening to 'Times Like These' by The Eden Project, the vocals are paramount, spacious and effortlessly clear while the entire track emanated energy that made me feel the need to move along with it. I hadn't realised that the chorus had more than one vocal sound (there's another layer of vocals, who could've guessed with that clear singing!) before listening to it with the FLC 8S. Likewise, the awesome 'Wake Up' sung by the same person sounds incredibly passionate with this configuration - I could hear them breathing in lows and highs (I could differentiate how they breathed for each word they spoke with the no nozzle filter) without any sense of sibilance. It really, really is amazing how clear these are. With experiences like these on a constant basis across all of my music, I knew immediately from early listening that these were absolutely worth the price point (and I would say even more! The pure silver upgrade cable is an option...) - these sound coherent on every genre that I listen to, from classical/orchestral or ambient (which tends to sound blurry and congested when there is too much bass and little midrange - the FLC 8S is revelatory for me here!) to EDM (tune the FLC 8S to lift the bass and hear the pumping adrenaline beat!). These genres of music could not be further apart in terms of sound signature and emphasis - EDM needing midbass and midrange while Ambient needing midrange, treble and reduced bass. With the right sound tuning of the FLC 8S, such as this one (you might find others depending on your equipment!), both sounds amazing without the need for an equalizer or anything similar (unlike the other IEMs I've listened to. Equalizer can't make those excessively exaggerated peaks found in non-neutral, boosted IEMs sound good, believe me I've tried). Using lossless files, this IEM is incredible in evoking the more subtle details of well-mastered tracks. What is yet amazing is that you can still improve the already awe-inspiring sound with some advanced tinkering and better amplifier combos (+ impedance adapter) as well as using an equalizer (though absolutely not needed!). The FLC 8S sounds amazing at low volumes, and even better with a good impedance adapter and source at higher volumes! Still hearing some treble standing out? Remove the cylinder midbass filter from the right ear piece of the FLC 8S and feel the music even more!
"Clarity" and "legendary variety of sound"
I previously used the Degauss Labs Noir, a V-shaped hybrid (1 dynamic driver & 1 balanced armature) IEM with a midbass boost. I'll compare the Noir with the FLC 8S back and forth to describe what I mean by clarity and effortlessness, at least from the perspective of a non-super enthusiast. The Noir is by all means a good IEM, excellent for its goal of sounding energetic and impactful, but I do not even doubt for a second in saying that the FLC 8S offers (much) (but-I-wouldn't-say-that-the-Noirs-are-bad) greater clarity and detail retrieval - it's immensely obvious because the less pronounced details stand out and make an impression on you. For example, with the track Quasar by Michael FK you can hear subtle, multiple layers of airy voices throughout the entire track, effortlessly presented with the FLC 8S at medium volume while I have to increase the volume to loud to even hear the layered voices on the Noir. While this is partially due to the characteristic of the Noir in having a V-shaped sound signature with bass boost (the combination generally reduces the ability to pick up subtle details due to a recessed midrange), reducing the bass with an equaliser did not make hearing the details easier. You have to squint and listen closely to hear the details, and even at ear-destroying volumes the Noir does not resolve all the details that FLC 8S does so effortlessly. Swapping back and forth between the IEMs there are so many echoes and sounds that I have never heard before when quickly changing to the FLC 8S, such as the echoes of the speech found in Moonlight by Rameses B. Effortlessness also improves other aspects such as airyness - the airy treble in Porter Robinson's Sea Of Voices is so awesome, easy to listen to and clear! By 'detail' I mean the character of the sound, so for example while the Noir produces much more bass, the bass is just "bass" and sounds like what you'd typically expect. The FLC 8S is able to produce the same amount of bass at a greater level of detail, allowing you to discover new things each time you listen, which makes re-listening to your music fun and exciting. The nuances of tracks presents itself to me clearly and distinctively and does not need me to critically listen so that I may hear them.
Want to be mind-blown even further? Listen to
Red | Clear | None
and feel the clarity of sound!
It sounds absurd, but I actually feel moved listening to the FLC 8S even without the energetic tuning due to the sheer clarity and detail presented that I have never noticed before. Put simply, the music feels more 'alive' despite not presenting that exciting V-shaped sound that is highly popular among IEMs currently. It's an incredible hallmark of high fidelity audio that makes pursuing music truly rewarding, and the FLC 8S offers this astronomical leap more seen in $1000+ headphones at a $350 price point. It's astonishing what FLC have accomplished as a new company with the 8S - they didn't just make an amazing in-ear monitor that surpasses the typical downfalls and flaws, they made one that could potentially sound like 5 distinct IEMs (and potentially much more if you're crafty) for the price of one, with its own breathtakingly beautiful midrange character. The FLC 8S doesn't just stand out, it shines with the face of a thousand suns, and should be the premier headphone recommendation for those looking to take a flexible and unregrettable step into higher fidelity sound. For some, it could be their last pick for the foreseeable future of driver-based headphones, and in which case I can definitely see why. The FLC 8S is the most versatile headphone out there right now, and its clarity, resolution and uniqueness could be appreciated for decades to come.
Background
A current university student on a limited budget here. Subsequently, I don't have nearly as many frame of references as others have (but I do check out the nearby audio store and try out the common open headphones!) I'm not a super enthusiast (yet?) about audio, but music means a lot to me. My files are either lossless/uncompressed from Bandcamp or wherever I can get the source version from. I get some of the basics of high fidelity audio such as sound signatures, presence range, etc. but I'm definitely not a sound engineer. Music is subjective - hence, don't expect a superlative impartiality of sound explanations from me!
From reading countless comparisons and reviews across the wide internet, I ended up with the choice of three in-ear monitors that I believe matches my sound preference: neutral (negotiable, the upcoming aspects are not) with the greatest emphasis on clarity and spaciousness. The three IEMs I had rounded down to after an extensive multi-language search were the Etymotic ER4SR ($349, single balanced armature, known to be the benchmark of IEMs for a good reason), the Audeze iSine 10 ($399, planar magnetic IEM) and the much, much lesser known FLC 8S ($350, 1 dynamic driver + 2 balanced armatures hybrid). Though I haven't tried all three (the perks of living in Oceania... this is not one of them), both the ER4SR and iSine 10 had quirks that became problems for me: the former for deep insertion and fit (I bike as a primary means of transport and the ER4SR would stick out against my goggles; anything but foam tips are not comfortable enough for me to listen for long periods of time) and the latter for having no isolation, supporting Apple devices only while having an off-tone, massive peak between the 1-2 kHz range (the cipher cable they later developed to address this does not match my needs for an IEM). Being a university student studying full-time, I did not have the opportunity or money to splash around to try all these excellent and critically acclaimed in-ear monitors. This was a - very - luxury purchase I have made for myself, and I had absolutely no room for regretting a purchase. Ultimately, after reading many reviews of the FLC 8S, all the goods and bads (one saying that the iSine 10 was so much better (ehh no) than the FLC 8S - in hindsight, that person probably didn't tune their FLC 8S very well) I decided on purchasing the FLC 8S knowing that it would be the least regrettable purchase decision out of the three considering its advertised flexibility of 36 different tuning configurations. And so I brought these on sale for ~US $300 from Lend Me Ur Ears (great customer service, by the way) and eagerly awaited and withheld myself from excitement to try them at the right time and place of mind.
Disclaimer?
I brought the FLC 8S with my own money and felt the need (without anyone's suggestion) to share my experiences with these high fidelity in-ear monitors.
Misleading first impressions
TD;LR
If you experience sibilance and/or hiss with the FLC 8S, throw away the stock silicone tips and use memory foam tips with a good seal in your ear.
So I prepared mentally and physically to listen for the first time. After hearing so many amazing reviews about this IEM, I was completely ready to be blown away. Putting on the smallest silicone tips (so I could get the deepest and clearest fit into my ear), I set down for the revelation of awesomeness.
I was blown away by how horrible the stock tips with Grey/Grey/Gold was and how sibilant they sounded.
Literally, I played a track with NO vocals and I heard hissing (which disappeared when I pause the track; not present in any other IEM I have, so I'm 100% sure it's not equipment) coming from the treble. Changed to another track. Still hissing. A vocal track. The vocals sounded like a ROBOT trying to mimic a snake rattle. They weren't even pronouncing 'S' sounds! Everything was hissing and sibilant so badly, I thought of returning the IEM for repair 10 minutes after I opened the box. They sounded worse than broken. But then I had a revelation of my own. I was going to change to foam tips anyway, but it struck me that the smallest stock silicone tips was the issue (I might miss the "best treble extension" stated by FLC... but with that sound. No. Not at all).
So I changed the tips to Comply TX400 (smallest size, the one with the waxguard filter). It was as if an entirely new experience of the FLC 8S opened up to me. And they did. They stopped sounding sibilant and broken. Literally, all the hissing disappeared from any of my tracks. No exaggeration, it was completely gone. And its not like any other variable could have caused it either, the hissing was so bad that I removed the stock tips after ~2 minutes of rapid-fire listening of many of my tracks. Suddenly, they sounded natural, incredible and normal (the incredible part is helped a lot by the TX400, great pairing to balance the sound of the FLC 8S) like what you would've expect from any non run-overed high-end IEM.
As such, I recommend that you take hold of all the stock silicone tips that came with the FLC 8S,
and throw them away.
(At least don't use them and look for alternatives, ESPECIALLY IF you are hearing unnatural tin robot sounds/sharp edges with them).
Second (unabridged) thoughts on the stock silicone tips
After seeing others praise the stock tips, I decided to give them another try. This time I used the medium size and made sure to get the best seal as I could (doesn't help that these do not adjust to the shape of your ear canal like the complys - felt like it could uncomfortably pop out of my ears at any moment). Tried with the track that I heard unlistenably terrible hissing and sibilance (Krys Talk - Fly Away <Mendum Remix>) and the awful hissing was mostly not there any more. Still, the treble stands out too much and reduces the amazing coherency and timbre of the FLC 8S. Sibilance ("WEU'LL SSHAYSSZEEEE") was still there. On other tracks, the brilliant no nozzle filters configuration started to sound shouty, unnatural and off-tone with the medium stock silicone tips. I did hear marginally more treble detail with the silicone tips, but I'm not sure if you'd really want to hear that with this IEM given that its midrange clarity is absolutely transcendental. I don't think the "most treble extension" silicone tips is a good combination if you want natural clarity from these IEMs. Also they diminish the FLC 8S's awesome detailed subbass and midbass (regardless of your filter configuration) by a lot. This is from someone who doesn't even like bass - it's as if the stock tips absorb the subbass impact or something. Compared to the complys, the stock tips made the sound somewhat tinny and far too bright - it lacks the fullness and wholeness that the comply gives with the IEM. Swapped back to the Comply TX400, and all became right with the world. The coherency, naturalness and clarity of the FLC 8S with the Comply TX400 is just incredible - a match made in audio heaven.
TD;LR stock tips changed from discard/10 to 3/10 listenable with proper fit and improving bass response through red thumbstack. Stock tips has poor bass response, making the IEM sound tinny. Small Comply TX400 (medium and large sizes causes recessed mids and muddies everything up) with good ear seal reveals the capability of the IEM's tremulous subbass while evening out the sound on top of making it feel like its not even on your ear - highly recommended. With it, I can not imagine a better pairing in terms of naturalness and effortless music. If you think that the FLC 8S is too bright or sibilant, then you owe it to yourself to try them with the small Comply TX400 - an incredibly even and harmonious tone awaits you with this pairing.
Quirks
The FLC 8S comes with an earguide hook that you can place on the cables. At first, I struggled for a good 10 minutes to even put the thing on until I realized that the ear hooks actually had "L" and "R" imprinted on them. Trying to put it on the first few times was rather discordant, but now that I know how to properly put them on it only takes me about ~5 seconds (make sure that the ear hooks cover the entire part of the cable; put the ear hook over your ear first, then guide the IEMs into your ear). The ear hooks were very soft and comfortable for me, most of the time I forget that it's (along with the super lightweight IEM) even hanging on my ear (if not for the incredible sound that these produce, that is).
The braided pure copper cable produces a lot of cable noise and should be replaced if you are intending to breathe and/or allow your heart to beat while listening to the FLC 8S. Well, its not actually that bad, but given that the IEM is designed to fit over-ear and yet still produces any microphonics at all (just from moving your head slightly, but the cable noise from this can be unnoticeable by increasing the volume), it definitely is a weakness to consider. I wear my IEMs with the cable over my back so that I never touch the cables and it stays more stable while moving (and also reduced microphonics to zero in my other cable-noisy IEM), but the FLC 8S cable still produced very little-but-still-there microphonics when I did this. For most people, the microphonics will be gone once you increase the volume, but if not, you should strongly consider setting aside the stock cable and seek an alternative, (non-cheap because the FLC 8S deserves great cables!) non-microphonic cable especially if you plan to move around a lot with this IEM. Newer FLC 8S comes with a revised pure copper cable (its more deep teal in color) with a proper non-cheap looking cinch and without the memory wire. I don't notice any stiffness and discomfort with this cable, I was able to sleep listening to the IEMs and the cable got out of the way without ricocheting and hitting me in the face like the other stiff cables I've tried, so I'd say the stock cable, sans microphonics, is actually quite nice.
They are also 1.2m long (for both the 7N pure copper stock cable and the 6N pure silver upgrade cable), which considering that includes the over-ear design may be too short for some. Understandably, these styles of cables are rather expensive (just look at how much Ultimate Ears sells their pure silver cable for... I'll let you guess. Over 60% the price of the FLC 8S... yikes) so I wouldn't consider it a flaw as you can use your own cables either way.
The socket is TF10 and is 0.74mm, so cables apart from FLC's own pure silver upgrade cable could potentially make the earpiece socket larger and slightly loose. They actually advise not changing cables often for the IEM's longevity, so these quirks should definitely be taken into an account if upgrading the cable is to be an attractive option for you.
I'm trying to blow holes at the FLC 8S's possible weaknesses at this point. Aside from the tiny thumbstack and cylinder filters making it potentially difficult to change on the go (I sort of got used to it and can change more often without the filters going and flying everywhere... I think. After getting used to the changing (grip the thumbstacks securely with your fingernails, push down from an angle opposite to the nozzle), it only takes me ~8 seconds assuming that I gripped the parts properly so that it doesn't fly off. Besides, considering how small these IEMs are it's really a given physical limitation) there really isn't much else you could criticise about the FLC 8S. Especially the sound. You can't make a tuneable IEM without being at least very good in all parts of the audio spectrum after all - and for that, they have done super well. I hadn't realised until now that 'You're Not Alone' by CMA actually had cymbals behind the empowering bass. It sits far behind it and is a bit subtle. With sibilance I probably would've just thought that the bass was distorted (its not, the artist's tracks are amazing and well-balanced) because I wouldn't have been able to distinguish between the overpowering bass and the subtle treble. I have no problems doing that with this IEM! The FLC 8S does a superb job of covering the general flaws of IEMs, and I think its very unlikely that its physical aspects would cause issues for anyone. I wouldn't even consider their custom shelled version because the universal one already fits so well for me. But that is an option if one finds the FLC 8S to not fit as well (not likely from what I can tell out of the countless impressions I've read, which is a very, very good thing for a universal IEM).
Impressions Update!
(The review of the FLC 8S continues down below!)
75 Ohm Impedance Adapter
By now, I have been listening to the FLC 8S (with small Comply TX400, no nozzle filters) for quite a while, and as such I have been accustomed to its wonderful sound. I had thought that the FLC 8S's strengths was its clarity at lower volumes. I felt that it sounded more whole when you didn't increase its volume to loud. I was also looking for ways to remove crackling sound/electronic distortion and noise when using sensitive IEMs at very high volumes (its a general characteristic of IEMs), but was skeptical of impedance adapters as they are known to change the frequency response (compared to something like an iFi iEMatch for example). I was concerned that the frequency response changes would affect the coherent tuning of the FLC 8S - let alone not knowing what the added power through the impedance adapter would do. I first tested my theory on a single dynamic driver 16 ohm IEM I had around but could not explain the subtle difference I heard there very well. Moving into trying something that isn't very well understood, I wondered if the risk would be worth it.
That was what I thought, until now.
Using a good impedance adapter, the FLC 8S suddenly sounded much more whole to me. The entire sound spectrum is more - defined - everything is even clearer than it was before (an aspect that was already superb without the impedance adapter), and more importantly, it sounds slightly more lifelike - as the sound is more harmoniously balanced (but not flat) at higher volumes. The sound is no longer fatiguing, shouty and somewhat harsh at high volumes, and I don't notice any loss of detail compared to without the adapter. Actually, there is much, much more detail to everything now. In previous tracks that I thought only had one or two layers of vocals, I can now distinguish 3 or more if the track has it. Additionally, I notice more natural decay to the sound of everything, hence the sound being more true to life. Is this unlocking the potential of FLC 8S? The never-ending discovery of the IEM's capabilities continues. If this incredible surpassing improvement can be had with a 15$ impedance adapter, it's hard to imagine what awe-inspiring sound would I be able to hear by improving my equipment. The FLC 8S surprises me on a constant basis - it's a ridiculous thing to say, I know - and I am rewarded by an empowering sound that makes high-fidelity audio worth pursing all the way.
You think I'd be exaggerating when I said that. But really, I'm not (at least what I'm hearing makes me think that way). With no nozzle filter, small Comply TX400 and a 75 Ohm impedance adapter, the FLC 8S creates a sound that's so magnificently clear, it absolutely deserves to be heard. It's important to note however that while the impedance adapter makes the entire sound spectrum more defined, it most notably increases treble resolution and quantity (or at the very least the perception of it). What this means is that it may sound excessively treble-heavy and artificial with the stock silicone tips. This is one of the reasons why I've emphasised the necessity of the small Comply TX400 in balancing the sound of the FLC 8S. The waxguard filter reduces the sibilance and hiss (i.e. the artificial sound) and keeps the sound balanced and cohesive (in actually providing bass response... *cough* stock silicone tips). The impedance adapter also stops the music from trying to overwhelm each other as if every frequency is vying for your attention. For example, in the track Titanium by David Guetta, the primary vocals before the chorus are backed up with two layers of secondary vocals that sing in the opposite tone to the first. Without the impedance adapter it was very difficult to hear the secondary layers as the primary vocals are very forward and loud, drowning out most of the secondary layers of vocals. With the impedance adapter, the secondary layers come out alive and clear and compliments the base vocals pristinely, thus making the sound more complete and dynamic as well as multi-dimensional thanks to the improved ability to hear echoes and more subtle details. Without the impedance adapter, I don't listen to any of my IEMs at a volume beyond medium-high (the distortion and electrical noise/crackling at very high volumes with sensitive IEMs obviously doesn't help with this. I just use Neutron's compressor to eliminate electrical noise/sound distortion from the source entirely. No iFi IEMatch needed!) I think the impedance adapter might be making the sound signature slightly more neutral, but I can't say for sure. Basically, the empowered everything due to the impedance adapter may cause the sound to be off depending on the ear tips that you use. Try it out with the Comply TX400 and you can get the clear treble without the terrible sibilance! Win-win!
I can hear even more details, even more easily (sounds like a broken record by now, I know, but really!), cymbal sounds now sound improved in resolution and distinguished from one another, which helps a lot with realism and the presentation of sound. This isn't just in the case of putting the green nozzles on and focusing primarily on the treble - its much better than that. Everything is more powerful, multidimensional and embodied at high volumes compared to without the impedance adapter at roughly the same volume range, listening by ear. Without the impedance adapter, I hear 6 to 8 layers in some music. With the impedance adapter, I hear 10+ (including the really subtle breathing and voice echoes!) With my midbass boosted IEM, the impedance adapter made the speech echoes of Rameses B's Moonlight much less blurry and more noticeable (FLC 8S without impedance adapter is completely clear here by comparison). Without the impedance adapter, I noticed things sounded less complete - as if there were gaps in the sounds of the piano and instruments, or that they were shallow and less whole at higher volumes (or that they were cancelling each other out). Using the impedance adapter have made it much easier, less fatiguing and more enjoyable to listen to any of my IEMs at higher volumes. Does this potentially suggest the scalability of the FLC 8S? I'll definitely try new audio stuff and find out!
But don't take my word for it. Try out a good 75 ohm impedance adapter with the FLC 8S and hear the (awesome) differences yourself!
That was what I thought, until now.
Using a good impedance adapter, the FLC 8S suddenly sounded much more whole to me. The entire sound spectrum is more - defined - everything is even clearer than it was before (an aspect that was already superb without the impedance adapter), and more importantly, it sounds slightly more lifelike - as the sound is more harmoniously balanced (but not flat) at higher volumes. The sound is no longer fatiguing, shouty and somewhat harsh at high volumes, and I don't notice any loss of detail compared to without the adapter. Actually, there is much, much more detail to everything now. In previous tracks that I thought only had one or two layers of vocals, I can now distinguish 3 or more if the track has it. Additionally, I notice more natural decay to the sound of everything, hence the sound being more true to life. Is this unlocking the potential of FLC 8S? The never-ending discovery of the IEM's capabilities continues. If this incredible surpassing improvement can be had with a 15$ impedance adapter, it's hard to imagine what awe-inspiring sound would I be able to hear by improving my equipment. The FLC 8S surprises me on a constant basis - it's a ridiculous thing to say, I know - and I am rewarded by an empowering sound that makes high-fidelity audio worth pursing all the way.
You think I'd be exaggerating when I said that. But really, I'm not (at least what I'm hearing makes me think that way). With no nozzle filter, small Comply TX400 and a 75 Ohm impedance adapter, the FLC 8S creates a sound that's so magnificently clear, it absolutely deserves to be heard. It's important to note however that while the impedance adapter makes the entire sound spectrum more defined, it most notably increases treble resolution and quantity (or at the very least the perception of it). What this means is that it may sound excessively treble-heavy and artificial with the stock silicone tips. This is one of the reasons why I've emphasised the necessity of the small Comply TX400 in balancing the sound of the FLC 8S. The waxguard filter reduces the sibilance and hiss (i.e. the artificial sound) and keeps the sound balanced and cohesive (in actually providing bass response... *cough* stock silicone tips). The impedance adapter also stops the music from trying to overwhelm each other as if every frequency is vying for your attention. For example, in the track Titanium by David Guetta, the primary vocals before the chorus are backed up with two layers of secondary vocals that sing in the opposite tone to the first. Without the impedance adapter it was very difficult to hear the secondary layers as the primary vocals are very forward and loud, drowning out most of the secondary layers of vocals. With the impedance adapter, the secondary layers come out alive and clear and compliments the base vocals pristinely, thus making the sound more complete and dynamic as well as multi-dimensional thanks to the improved ability to hear echoes and more subtle details. Without the impedance adapter, I don't listen to any of my IEMs at a volume beyond medium-high (the distortion and electrical noise/crackling at very high volumes with sensitive IEMs obviously doesn't help with this. I just use Neutron's compressor to eliminate electrical noise/sound distortion from the source entirely. No iFi IEMatch needed!) I think the impedance adapter might be making the sound signature slightly more neutral, but I can't say for sure. Basically, the empowered everything due to the impedance adapter may cause the sound to be off depending on the ear tips that you use. Try it out with the Comply TX400 and you can get the clear treble without the terrible sibilance! Win-win!
I can hear even more details, even more easily (sounds like a broken record by now, I know, but really!), cymbal sounds now sound improved in resolution and distinguished from one another, which helps a lot with realism and the presentation of sound. This isn't just in the case of putting the green nozzles on and focusing primarily on the treble - its much better than that. Everything is more powerful, multidimensional and embodied at high volumes compared to without the impedance adapter at roughly the same volume range, listening by ear. Without the impedance adapter, I hear 6 to 8 layers in some music. With the impedance adapter, I hear 10+ (including the really subtle breathing and voice echoes!) With my midbass boosted IEM, the impedance adapter made the speech echoes of Rameses B's Moonlight much less blurry and more noticeable (FLC 8S without impedance adapter is completely clear here by comparison). Without the impedance adapter, I noticed things sounded less complete - as if there were gaps in the sounds of the piano and instruments, or that they were shallow and less whole at higher volumes (or that they were cancelling each other out). Using the impedance adapter have made it much easier, less fatiguing and more enjoyable to listen to any of my IEMs at higher volumes. Does this potentially suggest the scalability of the FLC 8S? I'll definitely try new audio stuff and find out!
But don't take my word for it. Try out a good 75 ohm impedance adapter with the FLC 8S and hear the (awesome) differences yourself!
Neutron - Crossfeed | Surround Sound
By now I have tried many things on my quest to bring out the best possible sound from the >magnificent< FLC 8S. I have used the 75 Ohm Impedance Adapter for a while now, and while it does reduce listening fatigue at higher volumes, the added length makes it cumbersome to use when you're out and about. So I have been moving levers around in Neutron's Crossfeed and Surround Sound DSP settings and found that, with the right configuration, these can have the effect of reducing listening fatigue overall while also increasing soundstage depth (for Crossfeed) or soundstage width (for Surround Sound) significantly. The sound improvements are far greater than even the praises I put out for the impedance adapter, I don't think I could accurately describe the experience in words. It's an entirely new dimension of sound (maybe literally with Surround Sound) that I have never experienced in any headphone or IEM - ever, and the FLC 8S's superb technicalities and tuning ability have allowed me to hear and discover this new galaxy of sound better than any other sound producing equipment I have tried.
Descriptions of the perception of where the sound comes from may vary based on your setup, the ear tips that you use, ear tip insert depth, and your configuration. Oh, and your own ears, too.
These are the greatest and most significant improvements in sound I have heard thus far.
Crossfeed
Music flows serenely in the background, allowing you to be focused and immersed in other tasks. Improves soundstage depth with the side-effect of lowering the volume and pushing the music back noticeably, making music very easy to listen to.
Idle listening to help with focus and flow.
Effect Parameters
Filter, Hz - 250
Level, dB - 0.01
Works with any filter combination and in combination with the impedance adapter.
Moves perceived origin of sound from the area around your mouth to the area in front of you. Depth of sound can be much more easily discerned. Sound no longer has the obvious piercing-like effect of coming from the left or right speakers exclusively in binaural tracks or any type of music.
For the best 'listening to music lightly in the background' experience possible, I use Clear - Clear - None + Comply TX400 as well as sometimes turning on the parametric equalizer with BW 1.00 -3 dB reductions between 20 to 250 Hz. This achieves the most unintrusive, freeform sound I've ever heard.
Effect Parameters
Filter, Hz - 250
Level, dB - 0.01
Works with any filter combination and in combination with the impedance adapter.
Moves perceived origin of sound from the area around your mouth to the area in front of you. Depth of sound can be much more easily discerned. Sound no longer has the obvious piercing-like effect of coming from the left or right speakers exclusively in binaural tracks or any type of music.
For the best 'listening to music lightly in the background' experience possible, I use Clear - Clear - None + Comply TX400 as well as sometimes turning on the parametric equalizer with BW 1.00 -3 dB reductions between 20 to 250 Hz. This achieves the most unintrusive, freeform sound I've ever heard.
Surround Sound
Vocals span the space around your head, creating a large area of perception for audio. The sound is not perceived close to you or has the left speaker/right speaker obvious sound location pinpointing, which also makes it comfortable to listen to like crossfeed. Surround sound demands more of your attention naturally due to the expanded soundstage width.
This effect is incredible with some music, particularly vocal or choir, but would probably sound veiled and warped with other, less vocal focused music.
Listen to 'What Becomes Of Us' by Takeharu Ishimoto for an extraordinary demonstration of what surround sound can do to music.
Effect Parameters
Filter: Low-pass, Frequency (Hz) - 800
Filter: High-pass, Frequency (Hz) - 16000
Attenuation, dB - 5.00. Increase if music sounds warped.
Delay, Time - 20.00
Surround sound might not work well with certain genres of music and some filter combinations.
For example, with orchestral music without a vocal focus, it tends to move the perception of the sound from the left and right speakers to slightly behind your head, which does not work very well. Electronic music may sound off with surround sound on, but with the configuration that I use (Clear - Clear - None + Comply TX400, silver upgrade cable) I get used to the sound quickly and keep it on for its massive benefits in tracks containing vocals - unless I want to listen to music in the background, where I would switch to crossfeed.
With the 75 Ohm Impedance Adapter, Red - Clear - None + Comply TX400, it makes music sounds astronomically powerful, balanced, astonishingly spacious, detailed and clear in all types of music.
75 Ohm Impedance Adapter, Clear - Clear - None + Comply TX400 and silver upgrade cable (plus the reduced bass equalizer I have mentioned in the crossfeed segment, but that's just my personal aversion of bass) makes for an enjoyable analytical or close listening of music.
Moves perceived origin of sound from the area around your mouth to the area surrounding you or to the space of your mind. Position of sound is much more precise. Details of music reveal themselves distinctively to you. Music is no longer being perceived as being produced by the speakers - it instead originates from the space around your head in a way that's impossible to describe. Neutron's surround sound is the most beautiful rendition of music I have ever heard.
Listen to 'What Becomes Of Us' by Takeharu Ishimoto for an extraordinary demonstration of what surround sound can do to music.
Effect Parameters
Filter: Low-pass, Frequency (Hz) - 800
Filter: High-pass, Frequency (Hz) - 16000
Attenuation, dB - 5.00. Increase if music sounds warped.
Delay, Time - 20.00
Surround sound might not work well with certain genres of music and some filter combinations.
For example, with orchestral music without a vocal focus, it tends to move the perception of the sound from the left and right speakers to slightly behind your head, which does not work very well. Electronic music may sound off with surround sound on, but with the configuration that I use (Clear - Clear - None + Comply TX400, silver upgrade cable) I get used to the sound quickly and keep it on for its massive benefits in tracks containing vocals - unless I want to listen to music in the background, where I would switch to crossfeed.
With the 75 Ohm Impedance Adapter, Red - Clear - None + Comply TX400, it makes music sounds astronomically powerful, balanced, astonishingly spacious, detailed and clear in all types of music.
75 Ohm Impedance Adapter, Clear - Clear - None + Comply TX400 and silver upgrade cable (plus the reduced bass equalizer I have mentioned in the crossfeed segment, but that's just my personal aversion of bass) makes for an enjoyable analytical or close listening of music.
Moves perceived origin of sound from the area around your mouth to the area surrounding you or to the space of your mind. Position of sound is much more precise. Details of music reveal themselves distinctively to you. Music is no longer being perceived as being produced by the speakers - it instead originates from the space around your head in a way that's impossible to describe. Neutron's surround sound is the most beautiful rendition of music I have ever heard.
Surround sound can cause music with high peaks in the midrange to crackle/be affected by electrical noise, or cause ringing in your ear due to hearing sensitivity or aliasing from using many DSP effects on a 44.1/48 kHz audio file. Neutron's compressor with the following settings can be used to eliminate crackling/clipping/ringing and other sound distortions like it (regardless of whether you use surround sound or not):
Ratio, N:1 | 2.00
Threshold, dB | -65.00
Knee, % | 100.00
Attack, Time (msec) | 0.00 (I had to set it this way so that Neutron doesn't cause loud audio popping when you pause/begin to play a track)
Release, Time (msec) | 60.00. This setting depends on the music, though anywhere between 10 to 200 should not affect music negatively from what I've listened and tested.
Output Gain, dB | 0.00. Might want to decrease if you still hear crackling/electrical noise alongside the music.
Look-ahead, Time (msec) | 0.00 (Set to 0 for the same reasons as attack, audio popping during pause/begin play from what I've tested)
Window (RMS), Time (msec) | 1.00
Limiter | Off
A compressor makes loud parts quieter, which can make it appear to flatten the audio (bass would be reduced to the same audio sound level as the midrange, whereas it's usually ~20 dB louder). It also reduces the volume massively with the settings I use to eliminate all sound distortion when using surround sound/higher volumes, so a good amplifier or a powerful audio source will be needed to use it at audible and enjoyable volumes. I don't really use the impedance adapter alongside the compressor with my setup, as even at the maximum volume (which would pretty much blow out eardrums if used without the compressor) it does not get loud at all. The compressor processes the audio and reduces the volume before it's actually sent to your DAC.
With how the compressor changes the audio spectrum, the maximum bass configuration
Red | None | None
could potentially sound more balanced, as bass is reduced by a lot with the compressor on.
If you don't particularly like bass, using the configuration of Clear | Clear | None and this surround sound setting may sound better in tandem with the compressor:
Filter: Low-pass, Frequency (Hz) - 800
Filter: High-pass, Frequency (Hz) - 5500. To focus on the midrange, as it is also particularly reduced by the compressor. But it really depends on your own ears and preference (higher values = more airy, less depth). Can cause sibilance if you extend the high-pass above this value, in which case you'll need to counterract it with equalizer to reduce frequencies 4k - 20 kHz depending on your preferences (if you still want the wide soundstage without the possible sibilance caused by attenuation extending to 16 kHz)
Attenuation, dB - 3.30. No need to worry about distortion/clipping with the compressor enabled, so feel free to lower the value as far as you'd like. Lower values (greater effect) are amazing for vocal focused tracks, but bad for music that already sounds very wide such as orchestral (though it can sound good using Red | None | None, as the bass balances out the midrange focus of surround sound).
Delay, Time - 20.00
If you hear ringing from piano sounds, using Oversampling (under Audio Hardware) and setting it to at least 8x (Neutron will oversample to the highest sample rate your DAC will accept) should significantly reduce it or eliminate it entirely. This is because using DSP effects can cause sound artifacts without enough frequency headroom to filter out distortions. I heard piano and midrange ringing at high (not just super high) volumes on the Shure KSE1500, a full-range electrostat which has its own dedicated amp and internal DAC that resamples everything to 24 bit/96 kHz. Similar story with other high-end headphones and IEMs I've tried, ringing most noticeably from the low mid sounds (250 to 800 Hz mostly, sometimes even up to 2 or 4 kHz), so I know that this is a problem on the digital side and not with the hardware. I'm guessing this would be caused by sound aliasing, and with oversampling combined with dither plus noise shaping, it will mostly be moved far above 20 kHz (made possible by the extra headroom from oversampling) and as a result becoming not noticeable, or at least not nearly as distracting.
With the compressor and surround sound on, voices may sound somewhat dry and artificial due to the changes in the sound balance. Setting surround sound to the parameters above should significantly reduce that, and increasing the bass through using red thumbstack and/or no cylinder filter should make it completely nonexistent. If you want to test out attenuation to find a value you like, the orchestral track 'Reverie' by James Everingham (it's available in WAV/AIFF format over at Bandcamp) might be good to use as a bass/midrange cohesion test, as it is already mastered to be very wide and as a result does not sound particularly good with surround sound on. Regardless, I'd say that surround sound is important to have on when using the compressor, as the volume of the midrange is reduced considerably and may sound recessed/dull/not very loud with surround sound off. The compressor setting I use to eliminate all sound distortion reduces the volume by something like 70 dB (probably more based on what the spectrogram is showing me), so increasing the volume to an enjoyable volume might not be an option depending on the power of your source (you could increase the compressor's output gain, but that might bring in electrical noise/crackling/clipping depending on your setup). Personally, I always keep the compressor on now, as I don't hear any electrical noise or ringing anymore thanks to it (piano music with high peaks like DJ Okawari's Luv Letter was practically unlistenable with surround sound on and the compressor off, as it clipped/crackled and caused ringing at every single note). After all, I'm listening to music - not testing the technical specifications of the THD/DNR/SNR or anything!
-- Note: take care when using the compressor and adjusting its settings. As you'll need to increase the volume level while using the compressor, the volume differences with the compressor on or off will be enormous. You really don't want to disable the compressor while you are playing music at a higher volume than you are used to (the volume that you usually use without the compressor turned on), as that will revert volume levels back to normal, which is of course not a good thing if you have set the volume way higher than usual in order to use the compressor. It's also a good idea to be vigilant when adjusting the Threshold, Window (RMS) and Output Gain, as those changes the volume output. If you are using something like a smartphone, be warned that any sound going to your headphone not coming from Neutron will not be altered by the compressor, and will play at the volume you have set. This can make using the compressor not viable if you are expecting to be interrupted from listening to music often by other apps, or you are using Neutron to play music in the background while you use other apps that also transmit sound to your headphones; basically anything not from the music player itself, unless you are willing to silence/specifically reduce the volume of all other sounds in their respective settings as well as your ringtone (ones that play through the speakers are fine). High volume will still be high volume (outside of the music you are playing through Neutron's compressor), so do keep that in mind if something like this could be a possible situation for you.
Ratio, N:1 | 2.00
Threshold, dB | -65.00
Knee, % | 100.00
Attack, Time (msec) | 0.00 (I had to set it this way so that Neutron doesn't cause loud audio popping when you pause/begin to play a track)
Release, Time (msec) | 60.00. This setting depends on the music, though anywhere between 10 to 200 should not affect music negatively from what I've listened and tested.
Output Gain, dB | 0.00. Might want to decrease if you still hear crackling/electrical noise alongside the music.
Look-ahead, Time (msec) | 0.00 (Set to 0 for the same reasons as attack, audio popping during pause/begin play from what I've tested)
Window (RMS), Time (msec) | 1.00
Limiter | Off
A compressor makes loud parts quieter, which can make it appear to flatten the audio (bass would be reduced to the same audio sound level as the midrange, whereas it's usually ~20 dB louder). It also reduces the volume massively with the settings I use to eliminate all sound distortion when using surround sound/higher volumes, so a good amplifier or a powerful audio source will be needed to use it at audible and enjoyable volumes. I don't really use the impedance adapter alongside the compressor with my setup, as even at the maximum volume (which would pretty much blow out eardrums if used without the compressor) it does not get loud at all. The compressor processes the audio and reduces the volume before it's actually sent to your DAC.
With how the compressor changes the audio spectrum, the maximum bass configuration
Red | None | None
could potentially sound more balanced, as bass is reduced by a lot with the compressor on.
If you don't particularly like bass, using the configuration of Clear | Clear | None and this surround sound setting may sound better in tandem with the compressor:
Filter: Low-pass, Frequency (Hz) - 800
Filter: High-pass, Frequency (Hz) - 5500. To focus on the midrange, as it is also particularly reduced by the compressor. But it really depends on your own ears and preference (higher values = more airy, less depth). Can cause sibilance if you extend the high-pass above this value, in which case you'll need to counterract it with equalizer to reduce frequencies 4k - 20 kHz depending on your preferences (if you still want the wide soundstage without the possible sibilance caused by attenuation extending to 16 kHz)
Attenuation, dB - 3.30. No need to worry about distortion/clipping with the compressor enabled, so feel free to lower the value as far as you'd like. Lower values (greater effect) are amazing for vocal focused tracks, but bad for music that already sounds very wide such as orchestral (though it can sound good using Red | None | None, as the bass balances out the midrange focus of surround sound).
Delay, Time - 20.00
If you hear ringing from piano sounds, using Oversampling (under Audio Hardware) and setting it to at least 8x (Neutron will oversample to the highest sample rate your DAC will accept) should significantly reduce it or eliminate it entirely. This is because using DSP effects can cause sound artifacts without enough frequency headroom to filter out distortions. I heard piano and midrange ringing at high (not just super high) volumes on the Shure KSE1500, a full-range electrostat which has its own dedicated amp and internal DAC that resamples everything to 24 bit/96 kHz. Similar story with other high-end headphones and IEMs I've tried, ringing most noticeably from the low mid sounds (250 to 800 Hz mostly, sometimes even up to 2 or 4 kHz), so I know that this is a problem on the digital side and not with the hardware. I'm guessing this would be caused by sound aliasing, and with oversampling combined with dither plus noise shaping, it will mostly be moved far above 20 kHz (made possible by the extra headroom from oversampling) and as a result becoming not noticeable, or at least not nearly as distracting.
With the compressor and surround sound on, voices may sound somewhat dry and artificial due to the changes in the sound balance. Setting surround sound to the parameters above should significantly reduce that, and increasing the bass through using red thumbstack and/or no cylinder filter should make it completely nonexistent. If you want to test out attenuation to find a value you like, the orchestral track 'Reverie' by James Everingham (it's available in WAV/AIFF format over at Bandcamp) might be good to use as a bass/midrange cohesion test, as it is already mastered to be very wide and as a result does not sound particularly good with surround sound on. Regardless, I'd say that surround sound is important to have on when using the compressor, as the volume of the midrange is reduced considerably and may sound recessed/dull/not very loud with surround sound off. The compressor setting I use to eliminate all sound distortion reduces the volume by something like 70 dB (probably more based on what the spectrogram is showing me), so increasing the volume to an enjoyable volume might not be an option depending on the power of your source (you could increase the compressor's output gain, but that might bring in electrical noise/crackling/clipping depending on your setup). Personally, I always keep the compressor on now, as I don't hear any electrical noise or ringing anymore thanks to it (piano music with high peaks like DJ Okawari's Luv Letter was practically unlistenable with surround sound on and the compressor off, as it clipped/crackled and caused ringing at every single note). After all, I'm listening to music - not testing the technical specifications of the THD/DNR/SNR or anything!
-- Note: take care when using the compressor and adjusting its settings. As you'll need to increase the volume level while using the compressor, the volume differences with the compressor on or off will be enormous. You really don't want to disable the compressor while you are playing music at a higher volume than you are used to (the volume that you usually use without the compressor turned on), as that will revert volume levels back to normal, which is of course not a good thing if you have set the volume way higher than usual in order to use the compressor. It's also a good idea to be vigilant when adjusting the Threshold, Window (RMS) and Output Gain, as those changes the volume output. If you are using something like a smartphone, be warned that any sound going to your headphone not coming from Neutron will not be altered by the compressor, and will play at the volume you have set. This can make using the compressor not viable if you are expecting to be interrupted from listening to music often by other apps, or you are using Neutron to play music in the background while you use other apps that also transmit sound to your headphones; basically anything not from the music player itself, unless you are willing to silence/specifically reduce the volume of all other sounds in their respective settings as well as your ringtone (ones that play through the speakers are fine). High volume will still be high volume (outside of the music you are playing through Neutron's compressor), so do keep that in mind if something like this could be a possible situation for you.
The differences that crossfeed and surround sound makes are just too significant to put into words. If you are interested in improving soundstage depth (crossfeed, surround sound to a lesser extent) or soundstage width (surround sound), try them out. It just has to be heard to comprehend the massive differences that they make to the sound.
The Pure Silver (Single Crystal) Upgrade Cable
Let me preface by saying that the stock 7N pure copper cable (minus the microphonics) is already very good. Either the stock or the pure silver upgrade cable will offer great sound without issues (0.74 mm pins). The 99.9999% (this is expensive stuff) pure silver upgrade cable comes with memory wire which I can adjust to stop the cables from touching the back of my neck (compared to the ear hooks, which points the cable inwards slightly due to its shape). It also allows a more secure fit on your ear in case you're doing gymnastics or something with these IEMs. The cable is the same length, still with microphonics (though somewhat reduced maybe? but with more shape retention), so don't expect much of a difference in those areas. The upgrade cable does have 400D Kevlar at the core though, so it'd probably stop a bullet before failing out (the price would be mainly due to the single crystal silver they used - its not cheap). Any improvements in sound quality made beyond upgrading the actual IEM itself is not as large (unless your source files are really bad), hence divisive and subjective (we sure know that on this forum!), and depending on your setup and circumstances, the differences might be massive, it might be slight, or there might not be any perceivable difference at all. With that said, I'll try to describe the differences (and improvements) I hear when swapping from the stock pure copper cable to the pure silver upgrade cable deliberately and exactly. First, lets get some things out of the way first.
The difference between copper and silver is that silver transmit electrical signals ~5% better than copper. You can look it up and see why people even bother with expensive silver in high end equipment!
But would you really notice that 5% (real-world estimated, not likely to transfer exactly to listening experience) difference? Theoretically, it might improve sound performance (again, theoretically). But how would you be able to measure that? A cable shouldn't be changing the sound frequency (unless its very bad or is intentionally designed to do so) and an artificial model can only do so much to imitate the millions of different variables creating different overall experiences to the sound that makes audio fidelity perception inherently subjective. I can't speak for everyone, but since the audio-focused FLC released these cables (at a small sum of $100 dollars), I felt that these might actually make some differences (though I am not inclined to think so), or that they should if they bothered to make it given they said that they worked so hard on perfecting the 7N copper stock cable. So, now I got the pure silver upgrade cable (the FLC 8S really impressed me!), this is what I have noticed after listening with the stock pure copper cable then swapping immediately to the pure silver upgrade cable with my setup:
LG V20, Sabre ES9218 32-bit DAC (B&O Play tuned, frequency response and other technical measurements by zerodecibel)
- Rooted - modified build.prop to play 16/24 bit files natively past Android resampling
- Modified mixer_paths_tasha.xml so that 'Normal audio device' mode functions the same as 'High impedance device' mode
Neutron Music Player
64-Bit Processing - On
Resampling - Audiophile
Dither - On > under Dither: Noise Shaping - On | I use Neutron's DSP effects; Neutron's developers have said that it can be beneficial in that circumstance, otherwise this option makes no discernible difference
Subsonic Filter - Off
Ultrasonic Filter - Off
Hardware Gain - On
Generic Driver - On
Settings under Generic Driver
- High-Res Codec (Direct PCM) - On
- Hi-Res Speaker - On
- Hi-Res Bluetooth - On
- Custom Format - On
Settings Under Custom Format
According to Neutron's developers:
- Format - None selected (selecting anything under this will cause frequency resampling, see the ADB datalog below)
- Frequency - None selected (not necessary with Follow Source Frequency turned on - no option should be selected under here like under format)
- Mode - DIRECT (set everything else under the mode setting to OFF)
Follow Source Frequency - On
Frequency - None selected (this causes resampling, leave it unselected and your audio files will play directly with the actual frequencies that they have. There's no option to select anything here with Follow Source Frequency turned on either way.)
If you are curious of what the other settings not listed here in Audio Hardware does, check out the ADB datalog below.
With these settings, Neutron will show your files' native sampling frequency as it is sent out to your DAC under Audio Hardware instead of showing 48000 for everything (which is indicative of Android mixer resampling the file before the audio data is sent to your DAC). Depending on the music you listen to (especially those using high frequencies), the Android resampling causes a very perceptible reduction in sound quality, assuming that you have good headphones that will present to you the ruined sample frequency that is. I recommend bypassing the resampling if you're using anything running with Android if you can. But if you are running Neutron with the AudioTrack driver enabled by the settings above (which doesn't resample everything to 48000 Hz and plays at your file's actual frequency or the maximum your device can handle) then you don't need root and this shouldn't be a problem. Neutron also supports a bunch of DAPs/DACs with each new update where they automatically configure the correct settings for you, if that's the case for your device just uninstall/reinstall (your settings will be the exact same if the NeutronMP folder isn't deleted) and the option to enable Hi-Res playback on your device should come up. Aside from that, these settings should work too!
FLC 8S configuration
Red | Clear | None + small Comply TX400
- Rooted - modified build.prop to play 16/24 bit files natively past Android resampling
- Modified mixer_paths_tasha.xml so that 'Normal audio device' mode functions the same as 'High impedance device' mode
Neutron Music Player
64-Bit Processing - On
Resampling - Audiophile
Dither - On > under Dither: Noise Shaping - On | I use Neutron's DSP effects; Neutron's developers have said that it can be beneficial in that circumstance, otherwise this option makes no discernible difference
Subsonic Filter - Off
Ultrasonic Filter - Off
Hardware Gain - On
Generic Driver - On
Settings under Generic Driver
- High-Res Codec (Direct PCM) - On
- Hi-Res Speaker - On
- Hi-Res Bluetooth - On
- Custom Format - On
Settings Under Custom Format
According to Neutron's developers:
- Format - None selected (selecting anything under this will cause frequency resampling, see the ADB datalog below)
- Frequency - None selected (not necessary with Follow Source Frequency turned on - no option should be selected under here like under format)
- Mode - DIRECT (set everything else under the mode setting to OFF)
Follow Source Frequency - On
Frequency - None selected (this causes resampling, leave it unselected and your audio files will play directly with the actual frequencies that they have. There's no option to select anything here with Follow Source Frequency turned on either way.)
If you are curious of what the other settings not listed here in Audio Hardware does, check out the ADB datalog below.
With these settings, Neutron will show your files' native sampling frequency as it is sent out to your DAC under Audio Hardware instead of showing 48000 for everything (which is indicative of Android mixer resampling the file before the audio data is sent to your DAC). Depending on the music you listen to (especially those using high frequencies), the Android resampling causes a very perceptible reduction in sound quality, assuming that you have good headphones that will present to you the ruined sample frequency that is. I recommend bypassing the resampling if you're using anything running with Android if you can. But if you are running Neutron with the AudioTrack driver enabled by the settings above (which doesn't resample everything to 48000 Hz and plays at your file's actual frequency or the maximum your device can handle) then you don't need root and this shouldn't be a problem. Neutron also supports a bunch of DAPs/DACs with each new update where they automatically configure the correct settings for you, if that's the case for your device just uninstall/reinstall (your settings will be the exact same if the NeutronMP folder isn't deleted) and the option to enable Hi-Res playback on your device should come up. Aside from that, these settings should work too!
FLC 8S configuration
Red | Clear | None + small Comply TX400
Neutron not configured:
16 bit/44.1 kHz audio file
Output thread 0xe9183380 type 0 (MIXER):
Thread name: AudioOut_15
I/O handle: 21
TID: 1390
Standby: no
Sample rate: 48000 Hz <------------- this is android messing things up
HAL frame count: 1920
HAL format: 0x1 (pcm16)
HAL buffer size: 7680 bytes
Channel count: 2
Channel mask: 0x00000003 (front-left, front-right)
Processing format: 0x1 (pcm16)
Processing frame size: 4 bytes
Pending config events: none
Output device: 0x8 (WIRED_HEADPHONE)
Input device: 0 (NONE)
Audio source: 0 (default)
Normal frame count: 1920
Last write occurred (msecs): 24
Total writes: 19256
Delayed writes: 0
Blocked in write: yes
Suspend count: 0
Sink buffer : 0xea14d000
Mixer buffer: 0xe989a000
Effect buffer: 0xea14f000
Fast track availMask=0xfe
Standby delay ns=3000000000
AudioStreamOut: 0xeaaa5a08 flags 0x8 (DEEP_BUFFER)
Thread throttle time (msecs): 280
AudioMixer tracks: 0x00000001
Master mono: off
FastMixer not initialized
Stream volumes in dB: 0:-10, 1:-36, 2:-53, 3:-37, 4:-36, 5:-36, 6:0, 7:-36, 8:-29, 9:-96, 10:0, 11:-33, 12:0, 13:0
Normal mixer raw underrun counters: partial=0 empty=0
1 Tracks of which 1 are active
Neutron correctly configured with the mentioned settings above:
24 bit/44.1 kHz audio file
Output thread 0xe9670000 type 1 (DIRECT):
Thread name: AudioOut_18D
I/O handle: 397
TID: 6141
Standby: no
Sample rate: 44100 Hz <-------------------- android sampling eliminated
HAL frame count: 1792
HAL format: 0x6 (pcm24)
HAL buffer size: 10752 bytes
Channel count: 2
Channel mask: 0x00000003 (front-left, front-right)
Processing format: 0x6 (pcm24)
Processing frame size: 6 bytes
Pending config events: none
Output device: 0x8 (WIRED_HEADPHONE)
Input device: 0 (NONE)
Audio source: 0 (default)
Normal frame count: 1792
Last write occurred (msecs): 18
Total writes: 1091
Delayed writes: 0
Blocked in write: yes
Suspend count: 0
Sink buffer : 0xe9668000
Mixer buffer: 0xe8d37000
Effect buffer: 0xe8d25c00
Fast track availMask=0xfe
Standby delay ns=1000000000
AudioStreamOut: 0xeaaa6e98 flags 0x2001 (DIRECT|0x2000)
Stream volumes in dB: 0:-10, 1:-36, 2:-53, 3:-37, 4:-36, 5:-36, 6:0, 7:-36, 8:-29, 9:-96, 10:0, 11:-33, 12:0, 13:0
Normal mixer raw underrun counters: partial=0 empty=0
1 Tracks of which 1 are active
24 bit/96 kHz audio file
Output thread 0xe9b6c000 type 1 (DIRECT):
Thread name: AudioOut_1AD
I/O handle: 429
TID: 8603
Standby: no
Sample rate: 96000 Hz <------------- no android resampling here
HAL frame count: 3840
HAL format: 0x6 (pcm24)
HAL buffer size: 23040 bytes
Channel count: 2
Channel mask: 0x00000003 (front-left, front-right)
Processing format: 0x6 (pcm24)
Processing frame size: 6 bytes
Pending config events: none
Output device: 0x8 (WIRED_HEADPHONE)
Input device: 0 (NONE)
Audio source: 0 (default)
Normal frame count: 3840
Last write occurred (msecs): 25
Total writes: 1214
Delayed writes: 0
Blocked in write: yes
Suspend count: 0
Sink buffer : 0xe8a8c000
Mixer buffer: 0xe8aab000
Effect buffer: 0xe9b60000
Fast track availMask=0xfe
Standby delay ns=1000000000
AudioStreamOut: 0xeaaa5a78 flags 0x2001 (DIRECT|0x2000)
Stream volumes in dB: 0:-10, 1:-36, 2:-53, 3:-37, 4:-36, 5:-36, 6:0, 7:-36, 8:-29, 9:-96, 10:0, 11:-33, 12:0, 13:0
Normal mixer raw underrun counters: partial=0 empty=0
1 Tracks of which 1 are active
Settings confirmed by Neutron's developers to prevent high fidelity output:
- DSP Effect (Device)
- 32-bit Output (IEE 754) | resamples the audio, confirmed in ADB logs
16 bit/44.1 kHz audio file
Output thread 0xe9183380 type 0 (MIXER):
Thread name: AudioOut_15
I/O handle: 21
TID: 1390
Standby: no
Sample rate: 48000 Hz
HAL frame count: 1920
HAL format: 0x1 (pcm16)
This is what the same audio file played looks like without 32-bit Output (IEE 754) being enabled
Output thread 0xe966e000 type 1 (DIRECT):
Thread name: AudioOut_23D
I/O handle: 573
TID: 12619
Standby: no
Sample rate: 44100 Hz
HAL frame count: 1792
HAL format: 0x6 (pcm24)
- Low latency | bypasses high fidelity output, does not work. It's for supporting older devices without Hi-Res capability.
- Selecting any of the format options under format in Generic Driver | resamples the audio, confirmed in ADB:
Output thread 0xe5803fc0 type 0 (MIXER):
Thread name: AudioOut_D
I/O handle: 13
TID: 1271
Standby: no
Sample rate: 48000 Hz
HAL frame count: 192
HAL format: 0x1 (pcm16)
No custom bit format selected under format:
Output thread 0xe5b32000 type 1 (DIRECT):
Thread name: AudioOut_8D
I/O handle: 141
TID: 10993
Standby: no
Sample rate: 44100 Hz
HAL frame count: 1792
HAL format: 0x6 (pcm24)
Neutron pads 16 bit files to 24 bit to avoid the resampling issue, which is much better than any resampling happening.
16 bit/44.1 kHz audio file
Output thread 0xe9183380 type 0 (MIXER):
Thread name: AudioOut_15
I/O handle: 21
TID: 1390
Standby: no
Sample rate: 48000 Hz <------------- this is android messing things up
HAL frame count: 1920
HAL format: 0x1 (pcm16)
HAL buffer size: 7680 bytes
Channel count: 2
Channel mask: 0x00000003 (front-left, front-right)
Processing format: 0x1 (pcm16)
Processing frame size: 4 bytes
Pending config events: none
Output device: 0x8 (WIRED_HEADPHONE)
Input device: 0 (NONE)
Audio source: 0 (default)
Normal frame count: 1920
Last write occurred (msecs): 24
Total writes: 19256
Delayed writes: 0
Blocked in write: yes
Suspend count: 0
Sink buffer : 0xea14d000
Mixer buffer: 0xe989a000
Effect buffer: 0xea14f000
Fast track availMask=0xfe
Standby delay ns=3000000000
AudioStreamOut: 0xeaaa5a08 flags 0x8 (DEEP_BUFFER)
Thread throttle time (msecs): 280
AudioMixer tracks: 0x00000001
Master mono: off
FastMixer not initialized
Stream volumes in dB: 0:-10, 1:-36, 2:-53, 3:-37, 4:-36, 5:-36, 6:0, 7:-36, 8:-29, 9:-96, 10:0, 11:-33, 12:0, 13:0
Normal mixer raw underrun counters: partial=0 empty=0
1 Tracks of which 1 are active
Neutron correctly configured with the mentioned settings above:
24 bit/44.1 kHz audio file
Output thread 0xe9670000 type 1 (DIRECT):
Thread name: AudioOut_18D
I/O handle: 397
TID: 6141
Standby: no
Sample rate: 44100 Hz <-------------------- android sampling eliminated
HAL frame count: 1792
HAL format: 0x6 (pcm24)
HAL buffer size: 10752 bytes
Channel count: 2
Channel mask: 0x00000003 (front-left, front-right)
Processing format: 0x6 (pcm24)
Processing frame size: 6 bytes
Pending config events: none
Output device: 0x8 (WIRED_HEADPHONE)
Input device: 0 (NONE)
Audio source: 0 (default)
Normal frame count: 1792
Last write occurred (msecs): 18
Total writes: 1091
Delayed writes: 0
Blocked in write: yes
Suspend count: 0
Sink buffer : 0xe9668000
Mixer buffer: 0xe8d37000
Effect buffer: 0xe8d25c00
Fast track availMask=0xfe
Standby delay ns=1000000000
AudioStreamOut: 0xeaaa6e98 flags 0x2001 (DIRECT|0x2000)
Stream volumes in dB: 0:-10, 1:-36, 2:-53, 3:-37, 4:-36, 5:-36, 6:0, 7:-36, 8:-29, 9:-96, 10:0, 11:-33, 12:0, 13:0
Normal mixer raw underrun counters: partial=0 empty=0
1 Tracks of which 1 are active
24 bit/96 kHz audio file
Output thread 0xe9b6c000 type 1 (DIRECT):
Thread name: AudioOut_1AD
I/O handle: 429
TID: 8603
Standby: no
Sample rate: 96000 Hz <------------- no android resampling here
HAL frame count: 3840
HAL format: 0x6 (pcm24)
HAL buffer size: 23040 bytes
Channel count: 2
Channel mask: 0x00000003 (front-left, front-right)
Processing format: 0x6 (pcm24)
Processing frame size: 6 bytes
Pending config events: none
Output device: 0x8 (WIRED_HEADPHONE)
Input device: 0 (NONE)
Audio source: 0 (default)
Normal frame count: 3840
Last write occurred (msecs): 25
Total writes: 1214
Delayed writes: 0
Blocked in write: yes
Suspend count: 0
Sink buffer : 0xe8a8c000
Mixer buffer: 0xe8aab000
Effect buffer: 0xe9b60000
Fast track availMask=0xfe
Standby delay ns=1000000000
AudioStreamOut: 0xeaaa5a78 flags 0x2001 (DIRECT|0x2000)
Stream volumes in dB: 0:-10, 1:-36, 2:-53, 3:-37, 4:-36, 5:-36, 6:0, 7:-36, 8:-29, 9:-96, 10:0, 11:-33, 12:0, 13:0
Normal mixer raw underrun counters: partial=0 empty=0
1 Tracks of which 1 are active
Settings confirmed by Neutron's developers to prevent high fidelity output:
- DSP Effect (Device)
- 32-bit Output (IEE 754) | resamples the audio, confirmed in ADB logs
16 bit/44.1 kHz audio file
Output thread 0xe9183380 type 0 (MIXER):
Thread name: AudioOut_15
I/O handle: 21
TID: 1390
Standby: no
Sample rate: 48000 Hz
HAL frame count: 1920
HAL format: 0x1 (pcm16)
This is what the same audio file played looks like without 32-bit Output (IEE 754) being enabled
Output thread 0xe966e000 type 1 (DIRECT):
Thread name: AudioOut_23D
I/O handle: 573
TID: 12619
Standby: no
Sample rate: 44100 Hz
HAL frame count: 1792
HAL format: 0x6 (pcm24)
- Low latency | bypasses high fidelity output, does not work. It's for supporting older devices without Hi-Res capability.
- Selecting any of the format options under format in Generic Driver | resamples the audio, confirmed in ADB:
Output thread 0xe5803fc0 type 0 (MIXER):
Thread name: AudioOut_D
I/O handle: 13
TID: 1271
Standby: no
Sample rate: 48000 Hz
HAL frame count: 192
HAL format: 0x1 (pcm16)
No custom bit format selected under format:
Output thread 0xe5b32000 type 1 (DIRECT):
Thread name: AudioOut_8D
I/O handle: 141
TID: 10993
Standby: no
Sample rate: 44100 Hz
HAL frame count: 1792
HAL format: 0x6 (pcm24)
Neutron pads 16 bit files to 24 bit to avoid the resampling issue, which is much better than any resampling happening.
- In Phillip G. Anderson's 'Winter', the subbass of the orchestral drums are tighter and more refined. The bass not only has more impact like you would expect from boosting subbass and midbass - the impact is clearer, as in the specific repercussions could be felt (I also felt this with the stock cable but the pure silver upgrade cable does this rumble effect more cleanly and distinctively). The echoes of the drums seem to extend slightly longer, making everything sound more natural.
- In the soundtrack 'What Becomes Of Us' from Final Fantasy Type-0, the female and male choirs sounded somewhat fuller (not in terms of soundstage depth or anything, but rather the opposite of 'thin' sound), I could hear the background layers of vocals a bit better.
- Hammock's 'Ten Thousand Years Won't Save Your Life' sounds fuller and overall more whole. The violins are more intimate and impactful.
- The piano in DJ Okawari's 'Flower Dance' and 'Luv Letter' sounds like they have more presence (not thin or forwarded - the instruments sound more balanced and is comfortably in their respective places), sounding more natural and slightly more real compared to the stock cable.
- The wall of treble in Porter Robinson's 'Sea Of Voices' sounds somewhat more powerful with a higher sense of density.
The improvements isn't just better resolved bass, though that would be the first thing most would notice when not listening analytically. In all of my tracks (even in ones that doesn't boost the bass very much), the bass rumble sounds and feels more detailed - there is more of it when the music presents bass (though still completely silent when it doesn't). Secondary layers of vocals sound more pronounced compared to the stock cable, though I do not notice an increase in treble quantity (which is a good thing as the FLC 8S already has a lot of treble). This makes the FLC 8S feel more powerful, not in a typical bass boosted sort of way, but in terms of offering a more realistic presentation of music. I can definitely see and hear why they call it an 'upgrade cable' for the FLC 8S.
A year after - Impressions update
My initial impressions were too modest. The silver upgrade cable is AMAZING with the sound it enables for the FLC 8S! The newer cables don't seem to have any audible microphonics at all, the cinch is now the same as the stock copper cable (i.e. no longer a cheap looking plastic tube, instead something sturdy and easy to use). No more memory wire that's shown in the impedance adapter picture above, but I've never found the lack of to be an issue (even while cycling) if I wear the cables over my back with the cinch up to the back of my head. And the sound. Everything is somehow even more clear, including the subbass (20 - 40 Hz) and lowbass (40 - 80 Hz) precision and naturalness that I've mentioned previously. I can hear the vocalists' breaths at the beginning of every sentence more easily compared to the stock copper cable, yet it still does not sound fatiguing. The entire frequency spectrum is just rendered better. That ~5% difference in conductivity between copper and silver is absolutely being utilized here (not to mention the expensive 6N 99.9999% silver purity), and if you're familiar with how the FLC 8S braided single crystal copper and silver cable sounds, I would go as far as to say that the differences will present itself to you.
For example, I have several music files that primarily uses the 19 kHz region at certain parts of the track (which the spectrogram shows it being as loud as the bass region; it manifests as faint light note scribbling/wind sound), on the stock copper cable it was audible and kind of there, but with the pure silver cable it was - easily - noticeable and effortlessly presented. Upper frequencies 16k to 20 kHz reminds me somewhat of the Shure KSE1500 (that I've demoed twice, pretty much unparalleled detail in mids and treble but Balanced Armature-ish bass with little to no decay compared to the stunning natural subbass of the FLC 8S's dynamic driver) with the silver upgrade cable, it's just super glorious. Treble sounds more accurate, but not harsh, and the subbass - I can feel the gentle but powerful and clean rumble of the subbass and lowbass in my chest and even down to my stomach if I turn the volume up high in certain tracks (like Nero's 'Promises') with the red thumbstack! Listen to the beginning of Max Richter's 'November' and you can FEEL the precise and clean rumbles with the red thumbstack filter (but it doesn't affect the clarity of the mids at all! Hybrid IEMs huzzah!) I've just mentioned how incredible the FLC 8S's subbass is with the silver upgrade cable, red thumbstack and easy-to-get-a-complete-seal small comply TX400, right? Listening to the combination as I'm writing this, I felt the need to say it again. I've heard top-of-the-line headphones like the Stax SR-009S and the Sennheiser HD820 and they do not compete with the FLC 8S IEM in subbass quality and naturalness at all. If you're looking for an upgrade to the FLC 8S, buy the silver upgrade cable (or if you're uber rich, import the ~2k USD clockwork gear tuning 135 sound combinations FLC Celeste from Hong Kong). I'll resolutely assert that there is no better universal and tunable high fidelity sound than this at the now ~300 USD price range after trying the stock copper for a while then switching back to the silver upgrade cable!
But, of course, this is my subjective perceptions of the improvements I've noticed. While I can definitely pinpoint the more defined subbass and lowbass (Phillip G. Anderson's 'Winter' is a very good example of this, as well as Torsti Spoof's 'Faith'), someone else with different audio equipment, music tastes and several thousand other things may notice something else entirely or nothing different at all. It's all subjective approximation either way. Some people might not be able to distinguish a pair of Beats over the Sennheiser HE 1 in a blind test, and that's okay too. What experience that person perceives and prefers is what matters. For me, the pure silver upgrade cable offers a nice improvement to the sound of the FLC 8S, and with that I'd say it's worth using over more convenient custom cables. After all, I brought the FLC 8S for its incredible sound; if you listen to music through IEMs a lot like me and you enjoy the FLC 8S's tuning capabilities and sound, it might be worth getting if price is not a factor - the pure silver upgrade cable presents a sound that is slightly more real and more complete in all types of music.
Subjectivity to consider
Sound quality is influenced by an astronomical number of factors - the genre of music you like the most (which generally determines the sound signature/IEM you would prefer), the shape of your ear canal, the sources of your music (smartphone versus dedicated amplifier, file quality), the list goes on. All these things could have the potential to affect sound quality drastically (again, dependent on your circumstances) as I've demonstrated with the smallest stock silicone tips and small Comply TX400 in my first impressions of the IEM, so your experiences can and probably will vary to mine. I am from a perspective that clarity and spaciousness above all else matters for high-end headphones, and with that said I am rather aversive to bass and its tendency to make tracks feel like a nightclub party (have used a bass reducer equalizer ever since I've started to listen music more attentively, which I now longer do with the FLC 8S because it is no longer needed - the clarity and balance is incredible). Of course, treble standing out is not a good thing (usually destroys the timbre and harmony of the music) so its a very delicate balance for me in the sound that I prefer. The FLC 8S allows me to achieve this balance and change the sound based on what I feel like listening to (upbeat EDM for biking, Ambient for relaxing/studying) which to me makes it understatedly unique compared to every other IEM on the market. Of course there will be more technically proficient IEMs out there (the electrostatic Shure KSE1500 for example), but the FLC 8S's versatility and comfort to my ear makes it the best use-everyday high fidelity IEM I could imagine. Because everyone will invariably have different experiences and perceptions to audio, I would like to speak from my standpoint, particularly the configuration which have led me to praise the FLC 8S so much. You should get a chance to hear these configurations first before modifying your expectations (for better or worse) of this IEM.
Small size Comply TX400 memory foam with waxguard
Comfortable and removed all sense of sibilance I heard from my first impression of the FLC 8S. For those who believe that the FLC 8S is on the bright side for an IEM, these will very likely change that perception in offering a more balanced and customizable sound.
What have blown me away:
Grey | Grey | No Filter
Immensely coherent and harmonious sound with stunning resolution, forwardness and clarity of the midrange.
Red | Clear | No Filter
Detailed energetic bass response with great clarity. Midbass recessed, but potentially offers a wider space of sound.
________________________________________________
The Sound|s| of the FLC 8S
Filters - Thumbstack [Subbass] | Cylinder [Midbass] | Nozzle [Midrange and Treble]
Colors, most to least respectively:
Thumbstacks
Red
Black
Clear
Cylinders
Black
Grey
Clear
Nozzles
Green - Most treble
Black - Medium mids, second most treble
Gold - Most mids
Blue - Deletes treble and reduces midrange
(I will be calling the black thumbstack filter grey for coherency and color-coordination).
There is actually a lot more to know and discover about the FLC 8S beyond the claimed 36 configurations design. Changing one filter affects the rest of the frequency response and thus the sound. For example, using a clear clear black configuration will push the frequency peak of the black nozzle filters slightly from ~1.3 kHz to somewhere closer to 2 kHz (check out the graph measurements at innerfidelity for a comparison) compared to any other bass filters combination. This means that changing just one filter can have a larger than expected effect on the entire audio spectrum, particularly the midbass cylinder filters which determines how much airflow goes into the IEM. Basically, the FLC 8S can be VERY complex and advanced if you choose to go the advanced tinkering route (someone in this forum added an acoustic dampening cloth to their cylinder filter - the frequency response changes were rather interesting!). On a particular track that I found had too much treble coming from one side, I literally removed the cylinder filter with my hands from that side, WHILE listening to the IEM, and found that side suddenly becoming more coherent! It should be noted that the general issue of disjointed sound found in other hybrid IEMs is nonexistent with the FLC 8S. The combinations of drivers are exceedingly technically well-tuned that they overlap and blend in sound, creating a natural sounding hybrid IEM that doesn't sound off-balanced, being just as whole and pleasing as single-driver type style IEMs (maybe even moreso with the brilliantly clear, wide midrange of no nozzle filters i.e. what the IEM is wholly capable of in terms of 'soundfullness'). Now, I'm not advocating for mismatching the volume and frequency response of the IEM, but it shows the deep potential and customizability of the FLC 8S. I don't think I would be exaggerating in saying that these are perhaps the most customizable IEMs ever released (at least for the time being... new technology are so limited and expensive!)
Since I don't have frequency response graphs to show (the other reviews have already done an excellent job on this), I'll just (not word for word) quote FLC's founder Forrest Wei on precisely what the filters do.
"Without the ULF plug [Thumbstack], the earphone will be like an earbud; you could wear it to run.
Without the LF plug [Cylinder], the midbass is about 2 dB higher.
Without the nozzle, the mids will be higher around 2K Hz - vocal is more forward, the treble will lessen at around 4~5K Hz, sibilance will be less, but the treble would not be so solid and bright."
You could probably get it from his explanation on what the functions of the filters are. The purpose of the filters is to control how much specific sound frequencies are dissipated from the IEM before reaching the nozzle and into your ear. What this means is that there are actually even more (!!!) ways to tune the sound than the stated 36 configurations if you get creative with the no filter combinations.
No Thumbstack filter
This covers the area where the dynamic driver rests. It removes (maybe all) low-end subbass from the IEM and make it sound as if they sit outside your ear, even with a perfect seal. From what I've noticed, this makes energetic EDM tracks or anything reliant on bass sound bad as if the entire low-end frequencies are missing. This may be a good thing on some poorly mastered tracks or orchestral music, but for cohesiveness of sound, using at least the clear thumbstack filter for reduced bass (instead of removing bass entirely) would be recommended for most styles of music.
No Cylinder filter
This covers the area where the dynamic driver and two balanced armature drivers are situated. According to Forrest Wei, this option is the most bassy option of all, offering 2 dB more bass than the max bass filter (black cylinder). This is accurate in my experience, as the moment I remove this filter while listening I was greeted with bass energy that wasn't there before. Using no filters here provides more airflow for the dynamic driver, and in increasing midbass controls the presence of the higher end frequencies. Having no filter here at all noticeably reduced the clarity of orchestral tracks, particularly the piano where it became harder to discern the particular notes as you increase the midbass. To reiterate: removing the cylinder filter and using none will actually increase bass presence and energy. The clear filter here gives the dynamic driver the least amount of air (aside from taping over the port completely) for the bass, so you can tune subbass and midbass separately which makes the various interactions with the filters rather interesting - you could come up with some unexpected results by changing this filter in combination with the others!
No Nozzle filter
This is the final filter before the sound reaches your ear, and arguably its removal makes the FLC 8S shine. Using no nozzle filters as FLC founder Forrest Wei says will make vocals sound forward while simultaneously reducing the treble around 5 kHz (which according to the presence range definition you can find in the forums, would make instruments 'more distant and transparent'. I interpreted this as greater clarity and spaciousness on the FLC 8S). With no nozzle filters, the IEM becomes somewhat mid-centric, which would sound unusual if not for the FLC 8S's excellent technical capability. With no nozzle filters in place I was able to pick out minute details that was not present or less noticeable with the black, blue or even gold filters (the green filter was only partially equal with music that extensively utilise/mainly focused on the high ranges above 6 kHz). The sound could actually be characterised as an enhanced gold filter experience. Detail resolution expanded when I took off the gold filters and put the Comply TX400 on in its place. While the default configuration of Grey/Grey/Gold filters was great and supremely harmonious, using no nozzle filters made me felt moved - by the sound, and I found myself involuntarily moving to the rhythm with a smile on my face. No nozzle filters definitely deserves to be heard (can't say the same for no thumbstack filters). It makes the midrange sibilance-free and clear with impressive imaging and a great sense of expansiveness.
I can't say much about the thumbstack and cylinder bass filters as the preferable tuning of these are highly dependent on the music you listen to. Increasing any parts of the bass should eliminate any sibilance (with Comply foam tips plus waxguard) that you might hear on even the most awkwardly mastered tracks. I will say that the subbass of the FLC 8S (with red thumbstack filters) goes very deep. Compared to a V-shaped IEM with more midbass, in the track 'Winter' by Phillip Anderson, the drum parts were seismic (if you have a complete seal with foam tips) and I could feel the specific repercussions of the drum's echoes. With the more midbass V-shaped IEM using the same foam tips, I was not able to feel the same effect, it didn't really came close to reproducing the detailed and powerful subbass of the FLC 8S. With red thumbstack, its pretty strong in the subbass department for sure. Midbass is quality in terms of being detailed, though there isn't as much quantity as there is compared to the subbass (I might not be holistic with this, my last IEM essentially attacks you with midbass) so you might not feel the midbass of the FLC 8S as much as you would feel its subbass. As others have said, low mids are not affected by the tuning components as far as I could hear (i.e. it didn't increase with the configurations I've tried, I guess its an intentional tuning to make the IEM sound more detailed and spacious?) so instruments like violins might be detailed, but not feel as full compared to a midbass elevated IEM (this was with my equipment, I have heard that this aspect improves with dedicated amplifiers so try that out if you have it!). Though I regard the sounds of the no nozzle filters configuration to be the signature highlight of the FLC 8S, the nozzle filters give flavors of sound that could better suit and enhance the music you listen to. Your primary choice of nozzle filter would thus likely be dependent on the frequency ranges that your music tend to produce and emphasise.
Blue Nozzle
Matches | Dark, enclosed, bass-heavy
Listening casually, focusing on other things.
I tested these out with the stock medium silicone tips (offers the most treble extension according to FLC).
| Destroys treble response and reduces the midrange considerably, but offers more bass rumble and presence. Good for having music sit in the background. |
Coming directly from no nozzle filter with the TX400 tips, the blue nozzle sounded immensely muffled in comparison. It sounded so bad initially that I relegated the blue nozzle from the blue container to one of the plastic accessory bags (where I'll likely not touch it ever again). The blue nozzle mimicked the sound of my 5+ years old Apple EarPods quite well (enclosed, filtered, though with incomparably better detail retrieval obviously) so there's that going for it. That sounds way too harsh, because it is (don't actually compare the Apple earbuds to the FLC 8S - the differences exist in parallel dimensions separated by infinity) - its intended to show the MASSIVE difference between the audio clarity of no nozzle filter and the blue nozzle. And I would assume that you're looking at the FLC 8S for its stunning brillance and tendency to make you react passionately to the music. It probably wouldn't be found with the blue nozzle.
With that said, after listening to various tracks for an extended period of time and getting mentally used to the sound, I did notice that they offer more bass and thump. If you manage to get used to the sound of the blue nozzle, then it will still sound good regardless as the technical prowess and tuning of the FLC 8S is phenomenal. The blue nozzle could be regarded as offering a more lounging friendly sound - if you don't focus and listen attentively, they might be good for relaxed listening or just having music sitting in the background while you do something else (might not work if you have a good seal increasing the sense of bass/going for isolation in loud environments). Though after listening with no nozzle filters, I can't imagine why anyone would want to use the blue nozzles, they don't exactly play to the FLC 8S's strengths. Regardless, its a nice option to have if you want to just relax without feeling moved by the sound of the FLC 8S at the best parts of a song.
For listening closely and for intending to use these as the primary filter though - if your music selection consists of something along the line of 60% bass, 30% mids and 10% treble (in every song you listen to), then the blue nozzle might sound good in enhancing the bass feel at the expense of everything else. Whether that would be worth it to you, well, you'll just have to try it and find out.
Who knows, you might enjoy feeling the music more than you do listening to it. If that's the case, the blue nozzle might be of use to you.
Green Nozzle
Matches | Airy, not vocal-oriented, clarity necessitated
Listening to the nimbility and gracefulness of orchestra.
| Quick and precise treble imaging. High amounts of detail at the high ends, amazing for piano. May produce very noticeable sibilance in vocal tracks depending on the bass filter combination used. |
With my previous bass-heavy V-shaped IEM (Degauss Labs Noir), orchestral tracks or anything that emphasises the piano sounded... not good. The boomy midbass contoured and muffled everything, reducing the ability to distinguish the notes of the piano, so everything sounded very muddy and 'samey' as far as orchestral tracks go. Experiencing the green nozzles of the FLC 8S have opened a new door for me in music. A good benchmark for audio clarity of piano would be the track 'Blink' by James Maloney. The piano here is VERY quick and absolutely demands precision and clarity in the higher ranges or else the presentation would be very bad. With a V-shaped sound signature, the piano sounded like a mushed blur. Absolutely no detail could be distinguished because it was so blurry. With the FLC 8S's Clear/Clear/Green combination, I could distinguish every piano note and realized that the piano was actually linearly moving up and down in notes rapidly - and I could hear all of those notes without extensive focus. That is the clarity that these nozzles offer. When I changed the clear cylinder midbass filter to the grey one, it became more difficult to discern the individual notes. So if I were to use the green nozzle, I would definitely only stick to the clear cylinder filter to make sure that the treble isn't reduced from the more open port. Any subbass filter should be fine here for the most part - I didn't notice those directly affecting the clarity of the piano as much as the midbass filters.
A downside of these filters however is the added sibilance and unnaturalness added to vocal tracks. Vocals started to sound like they came out of a cymbals sound mixer instead of an actual human being. 'Chase' in the track Fly Away by Krys Talk/Mendum (the track where I noticed the horrendous sibilance in my inital impression) becomes 'shayse' with the green nozzle. And this was with the small Comply TX400 with waxguard, which is known to reduce and harmonise the treble. I can't imagine how bad the sibilance would be with any other tips (actually, I can - refer to my initial impressions with the unnatural silicone treble blaster-err I mean stock silicone tips).
I also noticed that everything had less sound decay in general, because the treble would just move from one note to another quickly without really letting it fade away naturally (like the sounds coming from the dynamic driver, which sounded more natural). As such, this nozzle is definitely not 'main-use'-able unless your music selection consists mostly of vocaless tracks. Would the green nozzle be worth keeping around for changing? Again, that is up to you and whether you like treble or not. The green nozzle filters does not destroy the spaciousness of the music like the blue filter does (actually it could be seen as enhancing it slightly), but it does destroy any sense of naturalness if your music is particularly vocal heavy. All in all, the green nozzle filter is a nice option for those looking to enhance their piano listening experience. It has the potential to make orchestral imaging astonishingly wonderful.
Gold Nozzle
Matches | Smooth, intimate, sibilant recordings
The fullness of vocals.
Referred by many as 'liquid vocals', the gold nozzle pushes the emphasis towards the ~2 kHz range while reducing treble noticeably around 8 kHz (resulting in it eliminating sibilance really well). It helps with the finish of the vocals, making them sound more 'complete' in a sense. The tradeoff is that there can be a lesser sense of space because the vocal is closer to you (though imaging and soundstage is excellent like the other non-blue nozzles), but it's definitely not as enclosed as the blue nozzle.
This nozzle can help with tonality and naturalness for some because it smoothens out the sound while bringing vocals to the center stage. It offers a slightly more natural decay of sound compared to the black nozzle for example at the expense of treble details. Treble is definitely pushed back with the gold nozzle, so that is something to take into consideration. You won't feel like being surrounded by clouds with this nozzle, but rather you'd feel like you're comfortably on the ground, at the front seat of a live performance. The gold nozzle sets out what it aims to do really well, and should work well with all styles of vocal music.
In sacrificing some airyness (treble) for a smooth tonality, I can definitely see a lot of people enjoying this nozzle filter.
Black Nozzle
Matches | Neutral, most music, forwarded instruments
No particular emphasis on anything. Easeful reference balancing.
This nozzle is quite neat (literally). According to innerfidelity measurements, they roughly emphasise the ~1.3 kHz and ~9 kHz ranges, so they could help with providing a fuller sound at higher ranges (for reference, the green nozzle filters also emphasise these ranges). Actually, comparing the black nozzle and green nozzle frequency response graphs, you could say that the black nozzle filter is the more balanced version of the green nozzle. It is the filter with the second most amount of treble (roughly ~4 dB higher than gold nozzle it looks like) and as such you might notice slight sibilance on a few tracks (increasing midbass helps alleviate this). It can work very well for those looking for a more linear extension and sound. I can't really say much else about this nozzle however, because nothing really stands out in my tracks to me using this. Is that a good or a bad thing? You decide.
Grey | Grey | None
Matches | Everything
Clarity and reference sound comes to life.
This, to me is the absolute highlight of the FLC 8S's coherent tuning and preeminent midrange. To reiterate on what no nozzle does: "without the nozzle, the mids will be higher around 2K Hz - vocal is more forward, the treble will lessen at around 4~5K Hz". From my listening, some definitions and playing around with a music editing tool and increasing/decreasing those specific ranges, I've found that this gives the most spacious, yet complete sound of all the nozzles. Listening to 'Times Like These' by The Eden Project, the vocals are paramount, spacious and effortlessly clear while the entire track emanated energy that made me feel the need to move along with it. I hadn't realised that the chorus had more than one vocal sound (there's another layer of vocals, who could've guessed with that clear singing!) before listening to it with the FLC 8S. Likewise, the awesome 'Wake Up' sung by the same person sounds incredibly passionate with this configuration - I could hear them breathing in lows and highs (I could differentiate how they breathed for each word they spoke with the no nozzle filter) without any sense of sibilance. It really, really is amazing how clear these are. With experiences like these on a constant basis across all of my music, I knew immediately from early listening that these were absolutely worth the price point (and I would say even more! The pure silver upgrade cable is an option...) - these sound coherent on every genre that I listen to, from classical/orchestral or ambient (which tends to sound blurry and congested when there is too much bass and little midrange - the FLC 8S is revelatory for me here!) to EDM (tune the FLC 8S to lift the bass and hear the pumping adrenaline beat!). These genres of music could not be further apart in terms of sound signature and emphasis - EDM needing midbass and midrange while Ambient needing midrange, treble and reduced bass. With the right sound tuning of the FLC 8S, such as this one (you might find others depending on your equipment!), both sounds amazing without the need for an equalizer or anything similar (unlike the other IEMs I've listened to. Equalizer can't make those excessively exaggerated peaks found in non-neutral, boosted IEMs sound good, believe me I've tried). Using lossless files, this IEM is incredible in evoking the more subtle details of well-mastered tracks. What is yet amazing is that you can still improve the already awe-inspiring sound with some advanced tinkering and better amplifier combos (+ impedance adapter) as well as using an equalizer (though absolutely not needed!). The FLC 8S sounds amazing at low volumes, and even better with a good impedance adapter and source at higher volumes! Still hearing some treble standing out? Remove the cylinder midbass filter from the right ear piece of the FLC 8S and feel the music even more!
"Clarity" and "legendary variety of sound"
I previously used the Degauss Labs Noir, a V-shaped hybrid (1 dynamic driver & 1 balanced armature) IEM with a midbass boost. I'll compare the Noir with the FLC 8S back and forth to describe what I mean by clarity and effortlessness, at least from the perspective of a non-super enthusiast. The Noir is by all means a good IEM, excellent for its goal of sounding energetic and impactful, but I do not even doubt for a second in saying that the FLC 8S offers (much) (but-I-wouldn't-say-that-the-Noirs-are-bad) greater clarity and detail retrieval - it's immensely obvious because the less pronounced details stand out and make an impression on you. For example, with the track Quasar by Michael FK you can hear subtle, multiple layers of airy voices throughout the entire track, effortlessly presented with the FLC 8S at medium volume while I have to increase the volume to loud to even hear the layered voices on the Noir. While this is partially due to the characteristic of the Noir in having a V-shaped sound signature with bass boost (the combination generally reduces the ability to pick up subtle details due to a recessed midrange), reducing the bass with an equaliser did not make hearing the details easier. You have to squint and listen closely to hear the details, and even at ear-destroying volumes the Noir does not resolve all the details that FLC 8S does so effortlessly. Swapping back and forth between the IEMs there are so many echoes and sounds that I have never heard before when quickly changing to the FLC 8S, such as the echoes of the speech found in Moonlight by Rameses B. Effortlessness also improves other aspects such as airyness - the airy treble in Porter Robinson's Sea Of Voices is so awesome, easy to listen to and clear! By 'detail' I mean the character of the sound, so for example while the Noir produces much more bass, the bass is just "bass" and sounds like what you'd typically expect. The FLC 8S is able to produce the same amount of bass at a greater level of detail, allowing you to discover new things each time you listen, which makes re-listening to your music fun and exciting. The nuances of tracks presents itself to me clearly and distinctively and does not need me to critically listen so that I may hear them.
Want to be mind-blown even further? Listen to
Red | Clear | None
and feel the clarity of sound!
It sounds absurd, but I actually feel moved listening to the FLC 8S even without the energetic tuning due to the sheer clarity and detail presented that I have never noticed before. Put simply, the music feels more 'alive' despite not presenting that exciting V-shaped sound that is highly popular among IEMs currently. It's an incredible hallmark of high fidelity audio that makes pursuing music truly rewarding, and the FLC 8S offers this astronomical leap more seen in $1000+ headphones at a $350 price point. It's astonishing what FLC have accomplished as a new company with the 8S - they didn't just make an amazing in-ear monitor that surpasses the typical downfalls and flaws, they made one that could potentially sound like 5 distinct IEMs (and potentially much more if you're crafty) for the price of one, with its own breathtakingly beautiful midrange character. The FLC 8S doesn't just stand out, it shines with the face of a thousand suns, and should be the premier headphone recommendation for those looking to take a flexible and unregrettable step into higher fidelity sound. For some, it could be their last pick for the foreseeable future of driver-based headphones, and in which case I can definitely see why. The FLC 8S is the most versatile headphone out there right now, and its clarity, resolution and uniqueness could be appreciated for decades to come.