Ikko OH1s English Review


A Change Within The Series




Construction and Design




  • New, more neutral and balanced profile.
  • Reduced weight and size of the capsules, favouring fit, ergonomics and reducing fatigue during long listening.
  • Excellent midrange.
  • 6 sizes of silicone tips.




  • Cable could be better, it is MMCX and there is no balanced option.
  • The shape of the silicone tips does not help to extract the best sound that the OH1s can offer.
  • The oval mouthpieces are not the most suitable for finding alternatives to the standard tips.
  • The extremes of the sound range are reduced (sub-bass and high treble).


Purchase Link




Link to the Store






Ikko again insists on keeping the OH1 series and adds an «s» to one of its first models, but at twice the price. The profile is quite different. It keeps the characteristic dented outer face, but adopts many new technologies, such as the so-called SVAS (separating vector acoustics system). It continues to use 1 x 10mm DD, with deposited nano carbon diaphragm + 1 x Knowles 33518 BA. The result is an impedance of 32Ω. The body is composed of several parts, made of resin and aviation grade aluminium alloy, to generate a pure and transparent sound, while reducing the weight of the headphones. The sound output of the headphones is oval, the OH1s are more ergonomically designed and improve wearing comfort. The OH1S uses a special resin material for effective sound damping. With Ikko tips, the physical noise reduction is greater. The cable has also been improved and consists of 127μm of high-purity monocrystalline copper, with a silver-plated magnetic core. The package still looks luxurious and with a good and particular collection of Ikko’s own tips.
In this review we will see how these new features influence the sound of the OH1s.





  • Driver Type: 1 DD 1omm with nano carbon deposited diaphragm + 1 BA from Knowles 33518.
  • Frequency Response: 20Hz-40kHz
  • Sensitivity: 109dB/mW
  • Impedance: 32Ω
  • Jack Connector: 3.5m SE straight.
  • Capsule Connection Type: MMCX.
  • Cable length: 1.2m.





The Ikko Gems (this is the name on the box) come in a classic box decorated with an anime girl on the main side. Its dimensions are 202x138x48mm. On the back side are the specifications (in Chinese and English), as well as a picture of the capsule exploded view. In reality, what is described is a cardboard box that wraps around the package and can be removed from the side. Once this operation is done, another decorated cardboard wrapper appears. The front side has a realistic photo of the capsules and the back side is the same as the first wrapper. This second wrapper is removed by resting the box on its lower profile and sliding it upwards. In this way, another chest-style box is exposed. It is completely black, with a fine mesh weave. In the upper right corner is the Ikko logo, in gold lettering, and in the lower middle edge, a yellow painted box, which helps to open the lid. Underneath are the capsules inserted in a thick block of foam, which has a black cardboard with hollow white drawings describing the product’s exploded view. There is also the classic cufflink with the Ikko logo. After lifting this block, there is another level protected by a black cardboard separator, which holds a leather pouch, a box containing the cable and a blister with the silicone and foam tips.
The complete contents are as follows:


  • OH1s capsules.
  • 6 pairs of specially designed Ikko silicone tips in different sizes.
  • 3 pairs of Ikko i-Planet foam tips.
  • 1 MMCX cable.
  • 1 clear brown leather bag.
  • 1 pair of tweezers to remove the filters from the capsule mouthpieces (inside the leather bag).
  • 2 filters for the capsule mouthpieces (inside the leather bag).


Ikko is characterised by attractive and visible packaging, although I find the flat leather bag a bit inappropriate. The tips are of Ikko’s own design, but their final result and impact on the sound is not the best for my taste.



Construction and Design


The capsule design has a shape reminiscent of their previous models. This time, however, the capsule is made up of three layers. The outer layer is Ikko’s characteristic dented metal face. There is a central part made of almost transparent resin, which is a unique structure responsible for sound diffusion. The inner side is also made of resin, but black. The capsule is oval and allows the use of special tips. These tips are unusual, although their shape is somewhat dubious, not because of the comfort, but because of the sound offered in the end. Ikko’s own i-Planet foam tips are also included.
The capsule design allows for a smaller size and a clear lighter weight. This is perhaps the highlight of this section. The cable connection has been changed from 2Pin to MMCX. In my opinion, this seems to be a step backwards in design. There are two holes in the capsules, one in the centre of the inner side and one on the edge of the outer side. The mouthpieces are oval and are protected by a resin filter with visible holes. The Ikko logo and a very small letter indicating the channel is written on the outside of the inner side.
At the end, the capsules have 4 separate elements, outer side (aluminium), middle side (resin), inner side (resin) and filter. The divisions can be seen at a glance and the internal design seems quite complex, due to this superior number of parts. The oval shape of the mouthpiece is quite debatable, both for ergonomic and fitting issues, as well as for tip fit issues.
The cable is thinner than you might expect and is two strands composed of 127μm wires of high-purity monocrystalline copper, with a silver-plated magnetic core. As mentioned, the connection is now MMCX and these connectors are protected by black plastic sleeves with the channel lettering inscribed on them. They have a soft angled shape and the cable coming out of them is protected by a semi-rigid black plastic sheath. The cable cover is transparent and reveals blue and red-tinted strands. Both the pin, the splitter piece and the 3.5mm gold-plated connector sleeve are polished and shiny metal cylinders. The Ikko logo is engraved on the jack connector. There is no choice of balanced connection, which is a negative point for a model of this price, when such a connection is becoming increasingly popular. The cable, despite its bombastic description, doesn’t look like much and is very susceptible to being swapped for a balanced cable.
The design is innovative, building on a familiar base. The size is smaller and the weight, too, are the strong points in this section. The cable and the oval mouthpiece is a more debatable design.



Adjustment and Ergonomics


There are two things that improve the ergonomics compared to the OH1 and, above all, the heavy OH10: one is the smaller size and the other is the lower weight. On the downside is the length of the mouthpiece, which is still a bit short, and another negative point is its oval shape. The use of the standard tips doesn’t help me to find a setting that allows me to extract the potential of this new model. I have tried all the standard silicone tips and none of them offers the best version. The bass escapes very easily and I don’t think that’s the real sound, especially not coming from Ikko. So I had to resort to other tips from my collection. In the end, the recurrent big tips with foam filling, homemade, have hit the nail on the head. The internal channel of these allows the oval mouthpiece to fit, they fix the capsules in the bell and extract the best bass they can give, without losing any of the clarity they treasure.
It is clear that despite the effort made by Ikko, the standard tips, the short and oval channel, are not going to be the best solution, neither in terms of fit, nor in terms of final sound. And I find that this can be a problem, because the sound may even sound worse than it really is.







The profile is balanced/neutral, but with a slightly bright mid-centric tendency. The bass is relatively linear, with a weaker sub-bass. The high mids are emphasised, but without sounding sharply clear. The treble is controlled in its initial part with a flash of brilliance before 10khz.





It makes no sense to discuss Ikko’s good work in the low frequency range, given the models they have in their catalogue, such as the OH1 and, especially, the OH10. However, the lower range of the OH1s is far from those IEMS, if we talk about net presence within the overall sound. It is clear that the tuning of the current model is much softer and lighter, taking a back seat to the other ranges. Getting the good tuning that my home hybrid tips provide, the bass feels well represented in the music, but it is never predominant, but a permissive base that offers texture and body to the sound. Bass-lovers will be disappointed if it’s power they’re after, but audiophiles will be very pleased with the level the OH1s are at. Personally, I would have liked a few dB more around 20Hz, keeping the same level in the mid-bass and thus gaining more depth, offering a more physical and sensory base. This is not the case and what is noticeable is a clean mid-bass, without a hint of rubberiness or sluggishness. The decay is quick, there is no aftertaste, no contamination. With this, the respect that the bass has over the rest of the ranges is very high, especially over the upper mids and first treble, whose presence is superior. In a certain way, the colour and sonority of the bass can be a tasty treat, something that can incite us to raise the volume to appreciate them more closely. But the idea is not a good one, because the upper notes will always sound more present, which can be a bit disappointing if you don’t like the neutrality of this low end. That’s why one has to be satisfied with the good texture offered, its descriptive capacity, the remarkable resolution and precision, even the eloquent, if subtle, recreation of planes.





The mid-centric tendency of the OH1s is not of an absolute nature. The cleanness of the mids facilitates the presence of the lower midrange and the emphasis on the upper mids finishes the job. The representation is less analytical than I expected and the connection with warm sources tones down the excitement in the upper part of this range, giving it a somewhat more analogue and rounder feel. On the other hand, the pairing with cooler sources doesn’t turn the set into an operating room, but it does bring in an amount of air and space that the OH1s benefit from. And in this respect, the new Ikko is average. Don’t get me wrong, the sound is not congested, but it is not characterised by a very open or expansive feel. Although it is true that the fine tuning of its BA is capable of providing a lot of detail, backed up by its bright tuning. The biggest beneficiary of all this is the timbre of the mid-range, which is enriched by the sum of the above-mentioned consequences, including the low end and the particular tuning of the treble. This is perceived in compositions with few instruments and voices, where they have a special sonority, although natural, with a lot of texture, great definition and descriptive capacity, which gives them a facility to express nuances in a fluid and extremely effective, even easy, way. The sibilances are controlled in a sweet spot, where that characteristic flare appears and stops, ending in a rounded and smooth way, almost as if this peak were drowned in the void, but not the rest of its journey.
Sometimes, the instruments don’t feel as expressive or eloquent as the vocals, maybe it’s because of that more limited scene, that more intimate character that prevents a wider range for them. Although for dense, even oppressive styles, metal, hard rock, with many layers of guitars, drums and cymbals, the OH1s do very well, because they are able to generate a great wall of sound. But at the same time, they are very adept at discerning between all the elements excellently, thanks to their high resolution and level of definition. Really, they are highly recommended for these styles because the good timbre I talked about before, enhances the sound of the guitars and the drums have enough body to integrate perfectly in the recreation of the image. Without a doubt, this is a great discovery in this sense.





As I implied above, the treble has a particular tuning, full of highs and lows. They start slightly depressed and thereafter alternate more or less prominent peaks and valleys. The result is that the flashes are not homogeneous. The tuning tries to bring clarity with the thrust of the mid-highs, and then offers control by suppressing the treble in the first phase. This is good for the sibilance, but loses coherence at other points. Even more so, when there is a powerful flash, to end with a valley, quite marked, that cuts the sensation of air. It is not really a homogeneous treble, although I don’t think that this tuning is the result of chance. I think Ikko has been looking for something, but I can’t find what. There is clarity and transparency, very good definition and detail, resolving power and descriptiveness, as I have already mentioned throughout the review. But the sense of space, distance, separation, air, openness and expansion is more limited. Perhaps they have tried to favour the midrange, rather than show a purer and freer treble, something that also seems to have been done with the low end. In this way, the bands at the extremes seem more like complements to the mid-range, rather than areas for individual showcasing. This partial sacrifice, in my opinion, is not entirely well executed. The lack of air limits further development of the sound, also of its scene and, after all, of musical freedom. If I may use an ambient comparison, the treble of the Ikko OH1s is like a clear, cloudy day.



Soundstage, Separation


And with everything described so far, this section has become quite clear, even before developing it specifically. To come to the point, the scene does not look very big, there is a clear sensation of width, even height, but the perception of depth is not so pronounced. The three-dimensional recreation is average, there is no holographic representation, no large spaces between elements. There is separation, but not a dark or pronounced void. And while the definition and resolution are more than remarkable, the sound doesn’t quite expand due to lack of air. The result is a good scene, albeit a low B-plus. However, while all this might be in clear opposition, the descriptive level, the recreation of detail and nuance goes beyond the mere emphasis of some key areas of the frequency response. Texture, as well as small elements, are shown with a surprising ease. And in the end, good technicalities are not the result of artifice, but of good components and a job well done in this sense. Without a doubt, this technical section is another of the strong and distinctive points of the OH1s, as you would expect from Ikko.





NF Audio NM2+


As if it were a more extreme version of the present Ikko OH1s, there are the NF Audio NM2+. And they are more extreme because their tuning in the upper midrange and treble point proves it. The NM2+ are risky, so much so, that they make the OH1s soft and warm. But starting with the low end, the NM2+s present a slightly but noticeably greater power in this range, as they have a more energetic and deeper punch, with a higher and more sensory sub-bass, capable of filling the bass body and generating a fuller and more vigorous feel. It even seems that the low end of the NF Audio is more accurate, enjoying slightly more speed as well as punch. The Ikko’s are lighter in this range and offer very well-defined, high-resolution LFOs, but the less accentuated sub-bass detracts from the overall power.
In the mid-range, as I say, the NM2+s make the OH1s warm and soft. The NF Audio are much brighter, but their edges are also much sharper. These sharp edges are a double-edged sword. It is clear that their expression is more analytical, but also more risky, becoming more penetrating. Compared to the Ikko, they might even be irritating. But the amount of information they manage to extract compared to the OH1s is superior, exposing it much more clearly and in the foreground. Their problem is that this overexposure is dangerous; sensitive ears may prefer a softer, more controlled presentation, such as that offered by the Ikko. They may not be as revealing, but they are much safer. The exposure of details is not so much in view, but they have a good definition, even a remarkable analytical level, which allows you to see the smallest nuances, even if you need to pay more attention. On the other hand, the NM2+ draw the voices on a close and superior plane, especially the female voices. The Ikko’s blend these more with the music, giving them a softer, less bright tone and a comparatively more reserved representation. The instrumentation of the NF Audio is also clear, both in its edges and nuances, as well as its body, although the tone and timbre is brighter. The Ikko’s are more honeyed, more muted by comparison, but also more polite. In the upper range, the NM2+ hold nothing back and start strong, almost diametrically opposed to the Ikko. It is in the upper mids and in the first treble that the differences between the two models are most significant. But this difference is such that it polarises the sound of the two IEMS and makes them play differently. It is clear that the bass also has an influence, but less than the treble, because a higher amount of air is also perceived in the NF Audio. This adds more separation, distance, even dynamics, gaining a darker background, which is more easily perceived. The sound of the Ikko’s is more cohesive and lacks the freshness that the greater amount of air brings. Thus, the soundstage is bigger, deeper and rounder on the NM2+, while the OH1s offer a flatter representation.
If someone is looking for a smoother, warmer and more secure tuning than the NM2+, while maintaining a relatively mid-centric profile, the OH1s could be a good alternative. But if you’re looking for a more explicit and vigorous sound, you’ll go for the NM2+s, as long as they are clear about their more treble-oriented profile.





Ikko is once again releasing a new model in its OH series and continues to rely on the Knowles 33518 BA driver, together with a new 10mm dynamic driver. But the real revolution lies in the design of its new internal cavity, which adopts SVAS technology. The new three-part capsule and the new oval mouthpiece are no slouch either. The result is a smaller and lighter capsule. To top it all off, the OH1s come with Ikko I-Planet foam tips and specially shaped silicone tips.
In terms of sound, the OH1s move away from the profile of the previous OHs, seeking a better balance between the three bands. The result is a sound whose midrange is enriched by the treble and bass, at the expense of reducing the prominence of these side bands. This is not a purely mid-centric IEM, but it is a more neutral alternative to its bass-heavy OH-series siblings. This makes the OH1s a more refined and, why not say it, audiophile sound signature.



Sources Used During the Analysis


  • ACMEE MF02s.
  • Zishan Z4.
  • Tempotec Sonata E44.
  • Hidizs S9 Pro.
  • Earmen Sparrow.
  • S.M.S.L Sanskrit 10th MKII + iFi ZEN CAN.