ECCI YST-02 English Review


The Crest Of The Wave




Construction and Design




  • Attractive design.
  • Good cable, although not suitable for the profile.
  • Remarkable bass quality.
  • Very clear and bright sound.
  • Good ergonomics.




  • Very excited high-midrange.
  • It’s more detailed than musical.
  • The profile is not balanced, because it has a clear tendency towards brightness.
  • The overexposure of the high-mids and details, blurs the scene and loses consistency at the base of many elements.
  • It wants to be very technical, but the micro detail is lost because the macro detail is too exposed.
  • Very few accessories, few tips and no zippered case, only a bag.
  • The size of the packaging is disproportionate to what it comes with.


Purchase Link


Link to the Store




ECCI seems to be an obscure brand from China, hailing from Dongzhan, Guangzhou. Looking for relative information I found that they have some peculiar IEMS (PG200, PR100 MKII, PR200 MKII, PR300 2), as well as several amplifiers (EC-1, Storm-6, Storm-B-3PRO). The aesthetics of these earlier models look like they belong to another era, while this new YST-02 has a more modern design. From this new batch and very similar to this one, there is the YST-03, whose external appearance is the same, but with one more driver. In fact, the YST-02 is a hybrid IEMS that consists of a dynamic driver and a BA customised by the brand itself. As a special feature, this model has a two-way RC frequency divider, very similar to that of bookshelf speakers. The outer face is PVD gold plated, inlaid with dyed natural abalone shells, with high transparency resin. Its texture is jewellery grade. The colour of the natural panel is unique, the abalone shell has an uneven structure in the microscopic angle and can produce bright and different colours. The appearance of the panel is random… Well, after this strange introduction, let’s see what these ECCI YST-02 look like in a more orthodox way.





  • Driver Type: 10mm composite diaphragm + custom ultra-balanced armature.
  • Frequency Response: 5Hz-40kHz
  • Sensitivity: 102dB/Vrms(@1kHz)
  • Impedance: 30Ω ± 15%(@1kHz)
  • Distortion: <1%(@1kHz/1mW)
  • Jack Connector: 3.5mm SE gold-plated.
  • Capsule Connection Type: 2PIN 0.78mm
  • Cable Material: LITZ type silver plated monocrystalline copper.





The ECCI YST-02 comes in a rather square green box, whose dimensions are 140x138x65mm. The design is reminiscent of typical Chinese paintings, with curved line motifs in the background, like waves in the sea. At the top is the brand logo, inlaid with silver ink. Similarly, there is a circle in the centre that does not close at the bottom. Inside are Chinese letters. At the bottom of the box, the model name. On the back is the specifications, in Chinese and English, and the graph with the frequency response, which, to tell the truth, looks very close to my measurement. At the bottom is the brand name. Removed from the outer cardboard is a completely black box with only the brand logo in the upper right corner. Once the lid is opened, there is a black foam mould and a green card that follows the motifs of the outer box. The capsules are embedded in the mould and underneath it is a cloth bag whose embroidery persists in Chinese motifs such as sea waves or clouds in the sky, because of its mixture of white and blue colours. Inside this bag is the cable and a small bag with silicone tips. In a nutshell:


  • The two ECCI YST-02 capsules.
  • One LITZ type cable of silver plated monocrystalline copper, with 2Pin 0.78mm connection and 3.5mm SE connector.
  • 4 pairs of black silicone tips with red core, sizes SxMxL.
  • One cloth bag.
  • One user card/manual.


Minimal contents for the price. The box is big for what little it comes with, a measly set of tips, a decent cable, which doesn’t match the model’s profile, and a bag whose best comment is that it’s attractive, soft and pleasant. But it only serves the purpose of storage, not shock protection.



Construction and Design


The capsules are made up of two distinct parts. The outer face is made of abalone shell, flanked by a PVD gold-plated rim. On the base of each of them is the name of the model. The external shape is of African continental type with stylised apex and rounded forms. The inner face appears to be constructed of black, slightly translucent polycarbonate. There are two holes away from the mouthpieces and these appear to be brass, with a thin base, a 4.7mm inner neck and a 5.7mm diameter outer crown. The total nozzle length is 3.5mm. They are protected by a double grille. The outermost one is metallic and has oval openings, but you can see the inner grille is more dense and has much smaller holes.
The connection is 2Pin 0.78mm and is mounted on a rectangular, shallow translucent plastic plate. The connections are gold plated. Next to each plate there is a white letter indicating the channel.
The cable has 4 LITZ strands of silver-plated monocrystalline copper. The connector is a 3.5mm gold-plated connector. The connector sleeve is a smooth cylinder, gently depressed in the centre. It has white Chinese letters written lengthwise. The cable coming out of it is protected at the beginning by a short, whitish-white translucent plastic sleeve, which has two levels. The dividing piece has the same depressed cylinder shape, but is shorter and with bevelled edges. This time without lettering. It does not have a fitting pin. The sleeves of the 2Pin connectors match the rest of the connectors and the pins come out of red and transparent bases, which indicate the colour. A blue mole indicates the polarity of the 2Pin. There is a sleeve for the 3.5mm connector.
The design and the cable is beautiful. As the manufacturer itself describes, it tries to propose a jewellery-grade finish that does not fall into a sober facism. The gold-plating prevents it from being more modern and adds that less attractive point for my taste. The abalone shell outer face gives it a unique and distinctive touch.
The weight is relatively light, it gives the impression of being heavier due to an initial metallic appearance. In reality, this is not the case and although it is not one of the lightest non-metallic capsules, its weight is not high at all.



Adjustment and Ergonomics


The fit is quite good and the slight weight is not noticeable. They fit very well inside the ear cup and don’t rotate once they’re on, thanks to the protrusion on the rim. But for those who think that this appendage might be annoying, it is not at all; at least not for my morphology. The over-ear cable does not irritate and is hardly noticeable. The insertion can vary from shallow to medium, depending on the tips used. The level of insulation is quite good, with my homemade tips filled with foam.
In general, the ergonomics are very good and it is totally valid for external use, walking or light exercise and the fact that it is not metallic means that the weight is not high.







The frequency response has a certain resemblance to the Rtings target. Its profile starts from a balance in the first half, which gets dangerously excited in the mid-highs. This rise is clear and pronounced. To my taste, this breaks the neutrality and homogeneity. Thus, it becomes a profile that can be fatiguing, depending on the genres of music played. I find the silver-plated cable unsuitable for this profile, I would have preferred a pure copper one. It is also advisable to use warm sources to compensate for over clarity and sibilance. I find it necessary to make a good choice of tips to match the profile. Finally, although the impedance is not high (30Ω), they are not easy to move and a powerful or desktop source is necessary to improve performance. Another tip would be to use a copper cable with a balanced connection, taking advantage of the fact that with such a connection you can get more power, even with a simple dongle.





As is usually the case with this type of IEMS with this profile and a good dynamic driver, the bass is of good quality. My regret is that, for my taste, they are neutral. They have a good punch, if the bass is isolated. When listening to music focused on the lower range, one can notice these virtues: a relatively powerful punch, good air movement, concise performance, remarkable texture, quick decay and little aftertaste. This is a skilful bass, with remarkable speed, but it leaves you wanting more quantity and power.
The tuning is rather flat, so the aural emphasis is on the mid bass. It has a very slight dip towards the mids. I would have preferred a slightly more enhanced sub-bass, to compensate for the mid-highs, as these feel above the low range. There is a predominance of the cymbals over the bass drums and this causes me fatigue in the medium term. This fact detracts from a band that appears technical, quite natural in its execution, tone and timbre. Although I think that with a more neutral and homogeneous profile, from 1kHz onwards, it would have been much more accurate, exciting and adequate, always from my personal point of view, of course.





The mid-range presents the classic IEMS ambivalence with over-emphasised mid-highs. While the first half is really in keeping with what the low end proposes, with a good transition, some warmth and colour, an adequate physical and corporeal base. The second half rises towards the clouds, crossing my threshold of bearable and pleasant. We’re talking 12 or 13dB of pinna gain, an excitement that turns the bass into neutrals and offers a piercing presentation of female vocals, cymbals and sibilance. I’ve paired it with my warmer sources, such as the Aune Flamingo for its TUBE output and also with the iFi Zen Can amp, to make the review more bearable and it’s true that I get a more acceptable tone and timbre, which doesn’t get out of bright naturalness, but which persists over time, being fatiguing to my ears, more used to more prominent bass, softer mids and treble that can go a little beyond neutral. Thus, I can’t speak of balance in the mid-range, in the aspect of its profile. Other things are the level of clarity, the technical ability, the feeling of transparency, the level of separation, the precise, concise presentation, the level of resolution and the ability to extract detail that ECCIs possess. Again, it is necessary to have a well-powered source for the YST-02s to shine. But, even so, the overexposure of the mid-highs struggles to keep a lot of detail and nuance in front, which eventually ends up overpowering each other, obscuring micro detail and losing both tonal and descriptive richness. In short, I hear more harmonics, details, sparkles, nuances and accompanying elements than the actual voices or instruments, making the music splashy, but not quite a cage of crickets. I insist that the excitement of the pinna gain does not imply a more technical, skilful, clear, transparent or natural sound. It is a way of forcing the sound. And when this is the case, harmony is lost, secondary elements are enhanced and the musicality of the whole is lost. If this gain had been softened, it would have been a different story, because the base is good and the skills demonstrated are above average.





The treble is concentrated in the first half of the range, forgetting a little about the upper range. Starting from a high level, they have a slight drop in control which is in keeping with the end of the mids, but which does not help to make the whole homogeneous and balanced. The BA driver is used for the higher frequencies and I think it serves as a reinforcement for a full-range dynamic driver, which has been filtered by the crossover and enhanced by the BA driver. In this way, the transition is seen to be adequate, but the BA timbre appears subtly in the flares, harmonics and higher notes.
There is a clear exposure of the treble, reaching a considerable height, with a sharp, sparkling and vivid projection. Not bad in itself, but if isolated it can seem a little high. Those who like a strong treble and don’t mind a slight BA timbre are welcome. Those who prefer soft, melodious and pleasant treble will get salt and pepper here. But I insist again that this is not a disproportionate high end, it retains a slightly elevated, bright timbre, with that BA essence, but within an excited naturalness. Although I would have preferred this driver to have provided a little more extension in the air zone.



Soundstage, Separation


There is a war between the innate technical abilities of the IEM itself and those provided by the tuning. In essence, the ECCI YST-02s are remarkable, but I feel that they have been forced by a tuning that has sought to emphasise detail rather than music. This has resulted in a mix where the sum is not 1+1=2, but rather below, even counterproductive. A level of transparency has been forced without a sufficient amount of air, which means a less obvious background and a lower level of separation. There is an obvious technical ability, which does not overwhelm. The resolution is obviously exposed, but the over-excitement makes its presence predominant, without ever disappearing from the music, which increases the sense of fatigue, lingering brightness and a descriptive and informative perception that is too high. Too much detail, less music. When, in the end, such a level of resolution is not adequate for micro detail but for medium or more obvious detail.
Thanks to a good level of clarity and forced transparency, the scene appears wide, clean, relatively well focused, with an adequate level of height and enveloping feeling. Dappled detail brings the scene closer and limits the sense of depth. If the genre is presented free of such artefacts, this depth can be felt more clearly, as well as a more realistic instrumental positioning. Otherwise, it will look like a flash photo of a shiny object, the flashes obscuring what is important.





Dunu Titan S


The Dunu Titan S is arguably an analogue version of a balanced/neutral profile. Their mid-high emphasis is controlled, with a pinna gain that is not quite as high as that of the ECCIs, but is in turn well flanked by a relatively sharp treble control zone, which limits the expansive power of the mid-treble transition emphasis. With a very similar low end, subtly higher in the ECCIs, both IEMS advocate a restrained low end, with good texture and technical ability. What happens in the Titan S is that the mids are resolved in a way that is more favourable to the overall interests of the music played on them. Without having the analytical ability of the Hidizs MS2s, the Titan S’s navigate in that more pleasant zone that does not forget a present mid-high exposure, but with a more neutral bass.
I find a lot of similarities in the bass behaviour. Both have a very similar tuning in this range and both characteristics and technical abilities are similar. Even the texture, the presence and the punch is similar. What changes is the brightness, the dryness and I think the speed. I prefer the darker and more natural timbre of the Titan S, as well as that dryness I am talking about, because it is less contaminated by the high frequencies.
In the midrange, surprisingly, the male voices seem more forward on the ECCIs, perhaps because of the projection of detail and the level of clarity. In the Dunu, however, the timbre is more accurate and the sibilance is more controlled, even in those male voices. Everything is more harmonious and pleasing in the Titan S. In the female voices, both the body and the physicality are more exuberant in the Dunu. There is a clear emphasis on the base and not on the details, something that offers superior realism. And all this without the details being hidden, or suffering, as they do in the ECCIs.
It is clear that the high end of the YST-02s rises higher and has a brighter timbre. The Titan S are surprising for their level and presence. But the brightness is clearly superior in the ECCIs. It is noticeable that the tuning is different and although I can’t say that the Dunu’s are completely smooth, they don’t have the initial explosion of the YST-02’s. But this is only in the first part. But this is only in the first part. After that, both in pure extension and in air the Dunu are better.
All this affects scene exposure, image, detail, separation, dark background feeling, focus and positioning of the elements. As ECCIs are more concerned with details, the body of the elements are more diffuse and depth is lost. In the Dunu, as this exposure is more realistic, the focus is more normal, the laterality is superior, the depth is appreciable and the positioning more coherent. Separation is also felt on top, as is the size of the scene.



Hidizs MS2


Going back to MS2 is like taking a break. I think the Hidizs chart is much more appropriate. It is a hybrid that is not the same, because the frequency division is different. Whereas the ECCIs seem to have a full-range dynamic driver complemented by a high-frequency BA; the MS2 has a dedicated bass DD, with a BA for mids and highs. Even so, both the mids and highs of the MS2s are better tuned than the ECCIs. There is more treble extension, air, better transition, naturalness, homogeneity and balance in the Hidizs. They don’t have the explicit capability of the YST-02s, but the music doesn’t need it, what it needs is a more organic and somewhat warmer sound. This is taken care of by a more emphasised DD in the low-mid range (some more sub-bass would have been preferable), which brings warmth and physicality to the low end. Also to the upper mids, achieving a more euphonic presence and timbre. The details are less explicit, but I praise the technical ability of its BA driver, which sounds more realistic and much less forced. Here the details don’t just pop out of the window, but are where you expect them to be, forming a more coherent, appropriate and musical representation. The tuning does not struggle to overpower the technicalities, but the definition is more explicit and is shown in its proper measure, without being hindered or muddied. This is what superior technical and analytical ability is all about.
The sound might even seem darker, comparatively speaking, but it is not. The Hidizs offer a reference and the ECCIs an exception. This is how the scene is presented more in accordance, with a more proportionate exposition, with a palpable depth, a patent laterality and a harmonic instrumental positioning, in accordance, more in line with a more logical and normal presentation.
Finally, the Hidizs MS2s are much easier to move than the ECCI YST-02s.





The ECCI YST-02 are specialised IEMS. I don’t consider them to be for every enthusiast. I’m sure their audience will find them great, but I can’t consider them all-rounders.
The value for the price is pretty good, they are well built, comfortable, the design is attractive, they are not heavy, the cable is good, although it is not in line with the sound profile. Starting with the low end, perhaps the strongest point of these IEMS. They possess remarkable quality and technical abilities. The mids can be a mixture of sensations. It can work very well, depending on the genre, but the excitement of the upper-mids can easily fatigue those ears sensitive to this area. I think ECCI focus more on the details than on the music itself and it has a bright imbalance, which can make it unpleasant. The high end works relatively well, as long as you are tolerant of the level of crisp sparkle exposed. It is in keeping with the end of the mids, but it polarises the sound too much towards a very bright version of reality. And this is something that can negatively influence many aspects of the sound.
It is clear that I am not a fan of this profile, but neither should I demonise IEMS, which has good quality, albeit a somewhat compromised tuning, for my personal taste.



Sources Used During the Analysis


  • Aune Flamingo.
  • Hidizs XO.
  • Earmen Angel.
  • TempoTec Variations V6.
  • Hidizs AP80 PRO-X Red Copper Limited Edition.
  • ACMEE MF02s.
  • xDuoo XD05 BAL.
  • S.M.S.L Sanskrit 10th MKII + iFi ZEN CAN.