Review of Ocharaku Flat-4 Keyaki Plus and Akakeyaki Plus - by Mimouille

Review of Ocharaku Flat-4 Keyaki Plus and Akakeyaki Plus 
- by Mimouille

1. Disclaimer : 
CDJAPAN (  ) called for reviewers for Ocharaku iems, I applied and was selected (I suspect thanks to my good looks). I received these review samples from CDJAPAN for a period of two weeks. Taking into account the fact that I cannot listen during the weekend due to my family schedule, 2 weeks is quite a short period to get an impression on not only one, but two iems (even if they are variations of the same). In any case, I would like to heartily thank CDJAPAN for this opportunity, their kindness, and efficiency in communication. I would really recommend them to anyone as they are nice, efficient and responsive.

2. Introduction:
There is little need to introduce Mr. Yamagishi, founder of Ocharaku, a legendary Sony engineer who developed essential technologies for their headphones/speakers (Sony Acoustic Turbo-Circuit is a revolutionary concept that enabled earphones to produce a powerful bass and bright treble very effectively).

These two models are the latest TOTL models in the Flat-4 series (begun a few years ago with the Sui and the Kaede, which I owned). These models use Ocharaku proprietary technologies including:
Coupled dynamic drivers facing each other to reduce resonance and vibrations
Phase correction tubes (of different length on these two models)

On top of that, these high end models also use rare woods as material for the central cabinet, in this case Zelkova.

The two models have different length of phase correction tube:
Keyaki Plus (black) : 28mm
Akakeyaki plus (red) : 30mm
This is to adapt to different ear canal sizes. I did the initial tip and source testing with both, compared them for some time, and then settled on the Akakeyaki for my preference. Most impressions concern this model, but I will give a brief comparison of differences.

For more information:
CDJAPAN on Ocharaku:
Tea :
Sound :

3. Build, fit, tips:
Obviously, Mr Yamagishi is a craftsman, with and exquisite attention to detail, and as such, his iems is delicate works of art. The finish is flawless, and beautiful if it fits your taste (not everyone will like the piston engine shape of the barrel, my wife hates it). There is no denying the fact that the wood adds character to it. Packaging is in the image of the content, small, delicate wooden box with the Ocharaku name. Everything here is part of the experience, like sitting in a quiet tea house and being presented with rare blends. Inside the wooden box, you will find a piece of cloth, the IEMs and a selection of tips. The undressing is done, and it is with excitement that you can proceed to tip rolling, but before I do, I need to warn people about the peculiarities of these:
Fit is not for everybody
These are open designs so isolation is limited
They come with a non-detachable cable, which feels very fragile
The jack is excellent quality but seems too large for these IEMs
You can only use these balanced if you get the balanced model with a 4.4 jack, only for Sony WM1A/Z (I didn’t have this model included)
I am obviously testing many tips, the majority of which were not included. These IEMs are very tip dependent, for two reasons:
The fit and shape are a bit original, so depending on the tip, fit and comfort may vary wildly
More than any other universal I have encountered, the tips affects sounds great, and can make these vary from warm and woolly to overly bright and harsh

Finding the right balance is honestly not easy, but the best mix for me was brought by either the Ortofon silicon tips or the included comply foam tips. Be sure to try many combos.

4. Sources:
After tips, source is quite important for these, but also depends on your tastes and tips used. I have tried my three sources: Lotoo Paw Gold Titanium, Chord Mojo and Sony WM1Z. Preference will vary, but here is my take:
LPG : the most raw and resolving experience, may sound harsh with some tips and some badly recording music, not recommend for long relaxed listening sessions, but such authentic expressions of the IEM’s character
Sony WM1Z : very smooth sounding, loses some of the edge of the LPG, but very seamless transitions, wide stage, very peaceful listening. Keep in mind I could only use single ended as I did not have the balanced version of these
Mojo : fairly good compromise, not harsh, yet some edge and energy
I alternated between Mojo and LPG mostly, as I thought they lost some character on the WM1Z. But bear in mind that they really need power, so with the WM1Z balanced, things might have been quite different. In the end the LPG is my favorite : rawness, depth of stage, deep sub bass, resolution.

5. Sound:
It is really hard to qualify the Ocharaku house sound, so I won’t say anything, just try it. Ok I am kidding, but barely. These sound quite different from anything else I own. I don’t think it is useful to qualify each part of the spectrum precisely, as it will not give you a precise image of how they sound. The bass is punchy but quite tight, reaches and rumbles very low, mids are very clear transparent and high sound delicious with the right tips and pairing, but can get harsh otherwise. Stage is wider than deep, and separation is excellent. The tonality is slightly warm, but this is sometimes hard to perceive when the treble gets edgier on certain tracks.
The key word for me is texture: it is unique, instruments sound very accurate (to these untrained ears) and you can really feel the layers of the bass. At the same time, the sound is delicate, which is a trait shared with the SE5 Ultimate (even though they sound quite different).
This being said, they shine mostly with instrumental music, with good recordings, clear vocals. This is where they really show all their abilities. I found that with some lesser rock / punk recordings, they will highlight the congestion that exists on the recording, and some of the harshness. In some modern music with a lot of electronic components to the sound, it can be fatiguing after a while, and also they do not show their full ability.

The Keyaki and Akakeyaki obviously share the same character and tone, but special features are quite different for me. The Keyaki is a bit more deep and narrow, with voices and instruments more crowded in the center, and Akakeyaki is wider and airier, with therefore better separation. Mids are also slightly thicker and more forward. Please keep in mind that this completely personal and related to your own anatomy, so do not expect to reproduce the same results.
I do not compare them to other TOTL IEMs and don’t ask me to, it makes no sense as I own nothing that sounds remotely like them.

6. Conclusion:
I used to own the Ocharaky Flat-4 Kaede which I absolutely loved…in certain moments. Their brilliance was sometimes overshadowed by lack of comfort (for me), lack of isolation and extremely revealing character.
The Keyaki and Akakeyaki keep this brilliance, tame it a little bit, and improve a little on comfort (addition of a neck cinch). These headphones remains works of art, divas, and like divas, they are not all-rounders. But if you like to listen to jazz, vocals, folk, have a fairly powerful source, and do most of your listening in a quiet environment; it doesn’t get much more emotional and raw than this.


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