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Fidue A31s

Fidue A31s In-Ear Earphone Review

Fidue A31s

Brief: Ultra-comfortable entry-level headset from Fidue
MSRP: approx. $40 (manufacturer’s page)
Current Price: $16 from$30 from$30 from; Canada: $39 from CTC Audio
Specs: Driver: Dynamic | Imp: 19Ω | Sens: 101 dB | Freq: 18-20k Hz | Cable: 3.9′ I-plug w/mic & 1-button remote
Nozzle Size: 5.5mm | Preferred tips: Shure Olives; Stock double-flanges; Comply T-100
Wear Style: Straight down or over-the-ear

Accessories (4/5) – Single-flange (3 sizes) and double-flange silicone tips, shirt clip, over-the-ear cable guides (1 pair), and excellent slim plastic carrying case
Build Quality (3.5/5) – The Fidue A31s features compact plastic housings and cabling identical to that of the higher-end A63 model – internally braided and covered in a smooth, glossy sheath. It’s a little stiff and lacks a cable cinch but in my experience these cables tend to be quite durable. Strain relief on the I-shaped 3.5mm plug is average, and there is no external relief on the housings. There are no external L/R markings, either, but the mic makes the right side of the earphones easy to identify
Isolation (3.5/5) – With the stock bi-flange tips or Shure Olives the isolation is very good – the tiny A31s fits in the ear canal very snugly
Microphonics (4/5) – Bothersome when worn cable-down; low when worn cable-up
Comfort (5/5) – It is very difficult to convey just how tiny the A31s is – its disc-shaped housings are barely large enough for a small dynamic driver, making it one of the smallest earphones in my collection. I found that the included eartips run a size small as well – normally I use mediums, but in this case only the largest tips sealed. The design of the stock single-flange tips is somewhat similar to the Westone STAR tips, which is good, but the deep-sealing bi-flange tips may take some getting used to for those not accustomed to IEMs. Aftermarket Shure “Olive” memory foam tips also fit on the A31s’ nozzles and make for one of the most comfortable listening experiences among all IEMs.

Sound (7/10) – The Fidue A31s is a warm and smooth earphone – something along the lines of a (less bassy) Beats by Dre Tour 2.0. Its sound has little in common with Fidue’s higher-end A63 and A71 models, opting instead for heavier lows, a less forward midrange, and even less prominent treble.

The bass is impactful and extended, but suffers from mild bloat, with room for improvement in both texture and control. The bass of the A31s – especially the subbass – is more powerful than that of the Soundmagic E10, but quality is about on-par due to the more pronounced mid-bass hump of the E10.

Still, the A31 is not quite a basshead IEM – its low end is not as deep and powerful as that of the UBSOUND Fighter or the ridiculously bassy JVC HA-FR301. It is warmer than both, however, due to its less prominent treble.

The midrange of the A31s is not at all forward, as the mids of the higher-end A63 and A71 models tend do be. The rolled-off treble and large bass quantity result in some veiling, but also give the sound a very warm and rich tonal character. Neutral-sounding earphones near this price range invariably sound thinner and colder. Even the Astrotec AM-90 – a smooth earphone by balanced armature standards – sounds harsh and bright in comparison to the A31s.

In its price range, the clarity of the A31s is about mid-pack, maybe a touch below average, lagging slightly behind the Soundmagic E10 and the more mid-forward Brainwavz M1. Likewise, despite having more powerful bass, the pricier UBSOUND Fighter is a little clearer too, due in large part to being less rolled-off up top than the A31.

The treble of the A31 is very smooth and laid-back, but somewhat deficient in presence and extension for my taste. It lacks the brighter, crisper character of earphones such as the E10 and even the Brainwavz M1, the latter of which is not a bright-sounding earphone by any stretch. Treble-boosted earphones such JVC’s HA-FR301 Xtreme Xplosives are enormously harsher, bordering on unpleasant when used back-to-back with the more rolled-off A31.

The presentation is adequate, but hindered somewhat in width and dynamics by the rolled-off treble, tending to sound quite soft and lacking the air and openness of many higher-end sets. Soundstage width also lags behind sets with more treble presence, such as the E10 and UBSOUND Fighter.

Select Comparisons

Nuforce NE-600X ($15)

Nuforce’s entry-level NE-600X is a budget-minded bassheads’ delight. The Fidue A31s has less bass than the NE-600X, but bass quality is similar – both earphones sound a bit boomy. The A31s is tonally warmer and its sounds much smoother overall, whereas the NE-600X has greater treble presence and is more v-shaped in response. The extra treble energy of the Nuforce makes it sound clearer, but the A31s is smoother and can appear more natural as a result.

Tekfusion Twinwoofers ($40)

While definitely bass-heavy, the A31s has nowhere near the same amount of depth and impact as the appropriately-named Twinwoofers. The bass of the Twinwoofers is a touch more boomy, but still better than could be expected considering its sizable quantity boost. Despite the more emphasized bass, the midrange of the Twinwoofers is more forward and a little clearer. The A31s is muddier, but its treble is smoother. Tonally, the A31s may actually be more natural than the Twinwoofers, but the clarity gap is not easy to look past.

Fidue A63 ($60)

Fidue’s $60 A63 model is one of my recommended sets for a warmer sound in its price range. It’s an interesting earphone, providing a slight bass boost but still keeping its mids center-stage. The A31s is significantly bassier, boasting greater bass depth and impact, but less control. The tone of the A31s is even warmer than that of the A63, but its midrange is overshadowed somewhat by the low end. The A63 has significantly more midrange presence, resulting in more upfront vocals and instruments. It sounds clearer overall and its treble presence and extension are better, too. The A63 is still not a neutral earphone by any means, but compared to the warm and bassy A31s, it is pretty balanced.

Value (8/10) – Jumping into the competitive mid- and high-end in-ear earphone markets with their first few releases, the folks at Fidue have now taken a step back with the more consumer- (and wallet-) friendly A31s. The A31s offers a well-executed consumer sound signature – bassy, warm, smooth, and very non-fatiguing, albeit lacking somewhat in clarity and treble energy. Its largest asset is its small size, which, with the right eartips, makes it one of the most comfortable IEMs available at any price. Add to that the headset functionality, decent noise isolation, and the excellent easily-pocketable carrying case (one of my favorite cases, period), and the sum value is very good. 

Pros: Good noise isolation; impossibly tiny design is extremely comfortable, especially with foam eartips; warm, bassy, non-fatiguing sound
Cons: Deep-insertion tips may take some getting used to; rolled-off treble results in somewhat muddy audio



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Living in the fast-paced city of Los Angeles, ljokerl has been using portable audio gear to deal with lengthy commutes for the better part of a decade. He spends much of his time listening to music and occasionally writes portable audio reviews across several enthusiast sites, focusing mostly on in-ear earphones.


8 Responses

  1. ljokerl – I’ve finally found exactly what i was looking for – the A31s – thanks to your excellent review. I’ve just ordered 2 sets on Amazon, convinced as i am that together with the Shures, they will give me the comfort i need with my baby sized ear canals. The treble roll off might be mitigated by boosting treble a little with high end EQ perhaps?

    I live in Vietnam, so visiting headphone shops is not easy, and even looking at pictures on Amazon / ebay the size and length of the nozzle is rarely shown. Yet even if i spend $500 on a par of in ear buds, if they’re too big – then I’ve totally wasted my money. I’m not falling for that again.

    It’s taken me 4 hours to research the market, which is probably a small fraction of the length of time it took you to prepare the review. Thanks!

  2. Hi Have you reviewed any IEM’s this year that are a competitor for the for the a31’s in the comfort stakes? Despite their shortcomings they are still my goto IEM’s because I can keep them in my ears , well at least with Shure olives I can

  3. They’ll all fit the A31s so it really depends on your ears. The silicone Fidue tips run small so I’d get the small Olives if you’re using the small or medium Fidue tips, medium Olives if you’re using the large or double-flange ones (I always use medium Olives, and I have average ear canals), and large Olives if none of the Fidue tips are nearly big enough.

  4. Hey,

    I bought the a31s based on your review and recommendations for daily use and I really like them. The only thing that I don’t like so much is the design of their ear tips. I settled with the bi-flange tips, but struggle to get a proper seal many times. You mentioned about Shure “Olive” memory foam tips, but the amazon site has 3 different sizes – small, medium and large. Which size should I select for the a31s?

    Thank you.

  5. I don’t have any experience with the Zero Audio IEMs. The A31s sounds very different from the GR02 BE – the treble is almost nonexistent in comparison to the rather present (and occasionally sibilant, as you mentioned) treble of the VSonics. The S0 is not as different from the GR02 BE, but it has less bass and I think you could do better on the clarity front if you wanted.

    The Xiaomi Piston 2 would probably be easiest to get your hands on (just make sure you get a genuine one) and will give you strong bass with less sibilance and a nice soundstage, for not very much money:

    If you want something even smoother (but still with better treble presence than the A31s), the Sony MH1C might be worth looking for. It’s got a flat j-cable, which is annoying, but potentially worth dealing with for the quality of sound you’re getting. The bass is a little tighter compared to the Piston 2 as well. These can often be found on ebay without retail packaging for under $40 because they come with quite a few Sony smartphones

  6. Hey Joker,

    So 4 months ago, I got a pair of Vsonic GR02 Bass Editions but unfortunately at first, I noticed a bit of sibilance, and a month later the housings snapped, the cables split from inside the housings, it was a disaster lol. I think maybe it’s a problem of the new batch. Anyways, not the matter.

    The thing is, I loved the sound sig of the IEM. By loved, I mean I was enamored by it. I let it burn in inside my ears and I felt it. I felt the thumping bass. And it felt like with more powerful sources, the bass got more punchy or something, idk. Maybe just me.

    Anyways, the thing is, i’m a student living in a third world country, and, well, I can’t afford much. My budget is within 50$ and I have the option to get anything that isn’t from aliexpress such as,

    Zero Audio Carbo Basso,
    Zero Audio Carbo Tenore,
    Fidue A31s,
    Brainwavz S0,
    etc etc.

    The thing is, I listen to EDM, Dubstep, and Rap. The thing I like the most is the PUNCHY, Hard hitting BASS. Not the bloaty ones found in FX1X. I don’t mind recessed mids. Extended soundstage is always welcome as I am a gamer as well but I don’t care about it that much. I’ll take care of the iems this time around as well, they’ll be receiving an aftermarket hard case this time.

    So yes. I want something that doesn’t have harsh, ear raeping trebles with hard hitting bass. Can you suggest some? thanks. 😀

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