Cozoy Hera C103 English Review


Remembering A Classical




Construction and Design 70%
Adjustment/Ergonomics 85%
Accessories 70%
Bass 80%
Mids 80%
Treble 70%
Separation 75%
Soundstage 80%
Quality/Price 75%




  • Sub bass.
  • Depth.
  • Sound Recreation.
  • Sweet, calm and natural sound.




  • Cable, it’s fixed and rigid.
  • Reduced treble extension.


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The Cozoy Hera C103 are the first IEMs of a brand created in 2014, which until now designed DAC/Amps. Following their own philosophy, they have been manufactured in metal, starting from a simple ballistic type design, with some personal touches on the back. They have taken special care in the internal design of the acoustic chamber, to contribute to reproduce a natural and immersive sound, that manages to extend both the low and high frequencies, reducing to the minimum the undesired resonances. The driver used is dynamic, built with a double layer membrane of high sensitivity and ultra wide band.





  • Driver Unit: Dinámico de 9.2mm de diámetro.
  • Frequency Response: 10Hz – 20kHz
  • Sensitivity: 103±3dB @1kHz 0.126v
  • Impedance: 32Ω ± 15%
  • Rated Power: 2mW
  • Jack Connector: Straight 3.5mm gold plated
  • Cable: Fixed, length 1.2m.





The Hera C103 comes in a medium sized box, practically square and white, measuring 174x184x62mm. The exterior design is as simple and clean as the IEMs themselves. The box has an outer cardboard cover, with a photo of the IEMs, the brand name, slogan and model on the front. On the back, there is a box giving details about the design, the material used and the cable. On the bottom of the back side, on a red background, the specifications are written. There are also some small photos with the accessories.


Once the outer cardboard has been removed, a black box is discovered, with the brand name on the front only. The box opens like a coffer and inside all the foam moulds are covered with a velvet fabric. In the lid part, the brand is shown again, as well as the web address. In the base part, the IEMs are embedded in the mould, as well as a rigid leather-coated box. This case is shaped like a flat flask, with the name of the brand inscribed on the front. It is quite rigid, opens like a coffer and has a magnetic closing. Inside there is a zip pocket with three pairs of tips, two are black silicone, small and large size. The other pair is blue foam. The third pair of silicone tips, of medium size, comes embedded in the IEMs. The tips have a wide inner channel.


The packaging is great for what you bring, 4 pairs of tips is the minimum required. Thank you for the beautiful transport box, made of leather, both externally and internally. But when it comes down to it, it’s not very practical to use, since it takes up more space than more classic and simple ones. In addition, storing IEMs, due to the rigidity of the cable, is not a quick task. We miss a Velcro tape to pick up the cable and facilitate this task.



Construction and Design


The design of the IEMs is the classic ballistic form, but with an L-shaped cut at the rear. This part is finished in red with artistic patterns. They are made of lightweight, finely polished metal. As I wrote in the presentation, the acoustic chamber has been specially designed to increase the quality of internal reflection and contribute to a brighter, more natural sound.

The cable is made of high purity silver and copper alloy, oxygen free, reinforced with Kevlar fiber. It is fixed, has some rigidity and is prone to take shape.

All parts of the cable are metallic, of the same quality and material as the capsules. The connector is straight, small, but with an ergonomic design that improves the grip of it. The splitter is similar and there is a conical piece to adjust the cables under the chin.

The capsules have no channel indicator mark. They are in the cable, in the plastic cover that protects the connection with them. The letters R and L are inscribed on this case, in a very subtle and unnoticeable way. On the left side, at the other end where the letter L is, there is a protuberance, to contribute to the distinction of each channel.



Adjustment and Ergonomics


The adjustment is free and simple, requires no difficulty and, with the proper tips, the grip is firm, does not move or fall. The smooth, polished shape promotes comfort. Insertion may vary depending on the tips used, as it is possible to use double or triple flange tips. In my case, for the present review, I have used double bridle tips, because I get a somewhat deeper insertion and thus, a closer, fuller and more detailed sound.







The profile is balanced with a slight emphasis on the sub-bass zone. Thus, the result has a point of warmth, but without being too dark, although the highs are soft and moderate.





The lower zone is characterized by the clear emphasis of the sub-bass, which gives a remarkable depth to the sound. The middle zone of the range has no hump, but descends smoothly to 200Hz. In this way, the Hera lack a pronounced bass hit, but their response is more contained and abyssal. Contented, because another good characteristic is the speed, it surprises the good control that Cozoy gets with these IEMs. This virtue can also be seen in the reverberation of the bass, which is not very noticeable, proof of the good work of the internal design of the capsules. The whole is finished off with a dry, compact execution, with a good degree of precision, detail and a quite natural texture, being able to appreciate a notable stratification of the frequencies and a clear differentiation between the bases and the voices, without any interference or clouding in them.





The midrange stand out in their low zone for their pronounced linearity, almost flat from 200Hz to 1500Hz. Thus, both male and female voices enjoy a notable presence, thanks also to the fact that the lower zone does not have a much greater gain over the mids, but that balance predominates. Therefore, there is no pronounced sinking or distancing, neither in the voices, nor in the mids, perceiving the whole as a fairly frontal block, although it does not stand out on the basses. But the great virtue of the middle zone, apart from the good balance with the bass, is its lack of veil, the absence of mud or any kind of sensation of nasal or tinny sound. On the contrary, the vocal range sounds very natural, present in its right measure, free of sibilances, with a very real and harmonious timbre, remarkably sweet, soft and with a good dose of warmth. The clarity and separation is good, but not excellent, the Hera are not analytical IEMs, although the resolution and detail are good, the refinement is very adequate, the sound turns towards a distinctly more mellow and relaxed than sharp.

Finally, there is a slight emphasis around the 2kHz, guilty of a certain spark and flash in the upper zone of the mids, which benefits the whole, providing the sound with liveliness, dynamics and a push to the detail and definition of the zone.





Low highs begin with a smooth peak between 5kHz and 6kHz, but without exceeding the overall balance of the entire frequency range. The drop is then pronounced. The result is that the highs do not enjoy a special resolution or extension, but are quite measured and totally free of peaks, penetrating edges and sibilances. But there is a lack of more extension, clarity, greater definition and air, without the sound being dark and blunt.

In summary, the high zone of the Hera perhaps is the least balanced due to its lack of extension.



Soundstage, Separation


Despite the limited upper zone of these Cozoy, their extension at the other end is notable high and compensates a certain lack of resolution, with a great capacity for depth. The good balance is also noticeable in the spatial arrangement, resulting in a simple mental location of the instruments and their situation on a stage, which is perceived semicircular, with good distance in the distribution. Thanks to this sensation of space, the sound feels clear, without definition or detail overemphasizing.

The Cozoy Hera C103 have a special virtue in the aspect of the sonorous recreation, in spite of its certain lack of extension in the trebles, they manage to stand out in this section thanks to the rest of technical characteristics, managing to generate a moderately big scene, with a realistic and natural distribution, well proportioned, with notable depth and a more than adequate height.





Dunu DN-1000


The first IEM that came to mind after trying the Hera C103 were the Dunu DN-1000 classics. Their Frequency Response is very similar. The Dunu have more global presence in the lower zone, offering more punch in the mid bass, a more bassy sound and warm in general. But its definition there is not as appreciable as in the Cozoy, getting to sound thicker. The voices in the DN-1000 feel somewhat more congested, backward, with some darkness, due to greater density throughout the midrange and greater emphasis on bass. The Cozoy sound cleaner and clearer in that area, liberated in comparison, more open and spaced, showing off their greater depth, separation and scene. The upper zone of both is smoothed, but the extension is greater in the Dunu, although the sound is somewhat sharper, with a point of greater brilliance and better defined in the Hera.

The Cozoy Hera, to have only one dynamic driver, seem an evolution in sound with respect to the Dunu DN-1000, they improve in resolution, balance and equilibrium. In addition, they are more comfortable, lighter and ergonomic. Even the cable is better, more resistant, even though it is equally fixed.



1More Triple Driver


Other IEMs with a warm sound and treble content are the 1More Triple Driver. In this case the 1More are even warmer, darker, with less detail, less brightness and a denser and less refined sound. In the lower zone the 1More stand out for having a more pronounced mid bass, but significantly less sub bass than the Hera. Thus, they do not reach the level of depth offered by the Cozoy. Both in the bass and low mids, the 1More offer a more congested and diffuse sound. The C103, however, have greater clarity and a cleanliness that differentiates them for the better. Voices also have greater definition, more presence, clarity, timbre and better resolution than Triple Drivers, which sound more distant, dark and blunt. In the rest of the mid zone the Hera have the same virtues over the 1More, especially a greater definition, a more analytical sound than the too soft 1More, with greater predominance of distance and instrumental separation, better detail and micro detail, a more refined sound, clearer and better resolution.

The high zone begins very contained in the 1More and that is noticeable enough in the signature of the sound, that suffers of spark and brightness. The Hera have a slight peak in the first highs that favors the clarity, the detail and contributes to the sound a capacity of resolution and light that the Triple Driver lack. In addition, it provides a better balance, equilibrium and naturalness to the overall.

The 1More have a more congested and dense scene. The Hera boast the highest separation and resolution to clearly win the game in this regard, both in width and height and instrumental placement.



Ikko OH1


Other IEMs, whose frequency response is very similar, especially from the lower zone to the central zone, are the Ikko OH1. Both IEMs have a fairly deep low zone and similar response and performance in this range. The Hera have a pinch of more sub-bass while the Ikko have a little more accent from the mid-bass onwards. Even so, the timbre of the lower zone is not the same in both, but the analytical profile of the Ikko and the warmth of the Hera leave their clear mark on it.

But the real differences are in the central zone. Here the Ikko are the real protagonists, first, because they offer an obvious emphasis on the upper mid-zone, this characteristic has an enormous impact on their profile. Their sound seems more frontal, comparatively more aggressive and cold than that of the more relaxed and warm Hera. The OH1s offer a finer, more analytical sound, with greater accent on detail and resolution. This can also cause it to sound more penetrating and, over time and according to the recordings, more distasteful. The Hera sound much more relaxed in this area, offering a more natural, pleasant softness and more suitable for long listening.

The presence of the voices is similar in both, although they sound closer and more frontal in the Ikko, but the approach is different, warm and mellow in the Hera, cold and analytical in the OH1.

In the high range, the Ikko predominate offering more presence and extension. The treble are sharper, penetrating and crunchier in the OH1. The Hera have a good balance in the lower area of the highs, but then the presence decays comparatively compared to the Ikko.

The clarity of the Ikko over the Hera is obvious, the level of detail is superior, as well as their resolution. But this doesn’t make their scene any bigger than the Hera. The more frontal and explicit sound of the OH1 takes away some depth and their scene does not widen as much as that of the Cozoy, whose separation is based more on creating a greater instrumental distance than on a separation of details.





The Cozoy Hera C103 has a clear tendency to become a classic, the form, the design, the construction, the materials used, the dynamic driver, the almost analogical sound, even the fixed cable … bring that old air. But it really is a renewed classic, a good example of balanced and sweet sound, which is forged by combining the excellence of the driver used and the design of its acoustic chamber. Among its virtues, its naturalness, softness, warm balance and its remarkable scene stand out. The use of a fixed cable is not a current trend and the limitation in the upper zone produces a sound sensation far from the Hi-Res fashion.

But none of this should tarnish a good start for the Cozoy brand in its first foray into the world of IEMs, because it is undoubtedly a good classic that never fails.



Sources Used During the Analysis


  • Burson Playmate
  • F.Audio S1
  • xDuoo X3II