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Index: Ocharaku KEYAKI/AKAKEYAKI Review by jinxy245

I'll start off by saying that build quality is . . .
Looking for more information . . .
Even though these are an incredibly light pair of earphones, the fit was . . .
I'll start with a little about myself . . .
The black 'Phase Correction Tube' . . .
This is obviously an oversimplification of what is a more complex technological philosophy . . .
In the end, I’d have to say that Ocharaku did a wonderful job with . . .

Beautifully Crafted, Beautiful Sound



Healthy Bass Not Overdone, Good Detail, Artisanally Beautiful, Bewitching Overall Tonality


Not a Detachable Cable, Subjective Value

Let me start by sincerely thanking Youhey Ohnagi for contacting me on Facebook. I had heard of Ocharaku before, but have never had any direct experience with them, nor have I seen or heard any of their products at any meets or shows. I’m guessing that because I am on the Head-Fi forum on Facebook that Youhey decided to offer me some time with the Flat4-KEYAKI Plus. Whatever the reason, I am certainly glad I got a chance to listen.

I was given 10 days to listen to the Ocharaku Flat4-KEYAKI, after which I retuned them to CD Japan (from whence they came). No other compensation was given to me, and the following review is my own honest opinion (YMMV of course). At the time of this writing, the Flat-4 Keyaki was selling for 85,000 Yen ($767.98 in USD) from CD Japan.

I'll start off by saying that build quality is something I was unsure of at first. One could make the argument that anything this light can’t be well made. Whereas they chose an admittedly beautiful wooden cabinet made from Solid Japanese Zelkova coated with raw lacquer, there is no detachable cable and the remainder of the housing is a liquid crystal polymer.

Also I’ll note that although I would prefer a detachable cable the one provided seems robust enough, with minimal microphonics and a quality 3.5mm Rhodium Plated Stereo Mini Plug (a balanced version is also available).

I couldn’t help but think I was missing something. Even if they do feel light and insubstantial, I imagine that is intentional to keep the earphone better seated in the ear. Many IEMs in this price range and higher use quality plastics and silicone, so I can’t really knock Ocharaku for this.

Looking for more information, I checked the CD Japan website where they noted that this is a “collaborative product between Ocharaku and OAK VILLAGE - a woodcrafts company based in the forests of Takayama, Japan.” Obviously a lot of thought went into the design and overall aesthetic of these earphones. So although they feel somewhat cheap, the actual materials used should stand the test of time. Viewed through the lens of an artisan, you can come away with a much deeper appreciation of what they were trying to achieve.

Accessories, while not exactly skimpy, aren’t overabundant either. What’s included is Comply T-200 Ear Tips (x 2), SpinFit ear tips (x 3 Sizes: S, M, L), L type cable adapter, cleaning cloth, a wooden case (Japanese Zelkova & Paulownia Solid Wood)

and the obligatory Instruction Manual / Warranty Card. Instead of investing in the admittedly lovely storage box, a carry case would have been a welcome addition, maybe a few more tips (at least 2 sets of each size would be nice) and an earwax cleaning tool.

Although this is a light pair of earphones, they are on the larger side and protrude from the ear.

There will be no sleeping on a pillow while using the Flat4 (obviously not named for the shape).
Even though these are an incredibly light pair of earphones, the fit was difficult for me. I often have a challenge finding the right tips, and unfortunately it was more of the same with the Ocharaku.

In the end, the Comply tips required the least amount of adjusting, so I did the majority of my listening with them. Isolation was about average, blocking out most ambient noise adequately, but these wouldn’t be my 1st choice when traveling. The port also occasionally picked up wind noise while moving about outside.

Before I offer my listening impressions, I'll start with a little about myself. I’m about 50 and have less than perfect hearing. I’ve been a music lover for as long as I can remember, and I learned to listen a little more critically during the few years I sold audio equipment (and the more I listen, the more I learn).

My fascination/infatuation with headphones began about 4 years ago, and has only gotten stronger. The majority of my listening was done listening to FLAC, WAV & various MP3s with my Shanling M2, Fiio x3 (1st gen.) or through my HP all in one PC and Audioquest Dragonfly1.2.

My tastes are fairly eclectic, but my listening centered on classic rock, folk, jazz, classical and various genres of EDM. I didn’t burn in the Ocharaku prior to listening, nor did I hear any difference throughout my evaluation.

There are actually 4 versions of the Flat4 available, with only slight differences between them. The Flat4-KEYAKI and Flat4-AKAKEYAKI differ only in the “effective length of the ear canal”, which is set different as represented by the color codes. When they say “effective length of the ear canal” I understand that they mean the length of the ear canal is on average 25 to 30mm, and they tune the earphone to sound best depending on your ear canal.

The black 'Phase Correction Tube' (more on this later) is set for the average length, whereas the red (the ‘AKA’ in AKAKEYAKI means ‘red’ in Japanese) is set for a longer “effective length”. On the CD Japan website, it states: “Sound quality will be better if the effective length is set closer to your ear canal length.” How you are supposed to know the effective length of your ear is not mentioned.

I was sent both the Ocharaku Flat4-KEYAKI Plus and the Ocharaku Flat4-AKAKEYAKI Plus so that I can use the one that sounded best for me (There are also balanced versions of the Flat4-KEYAKI and Flat4-AKAKEYAKI available, hence the mention of 4 versions). I honestly couldn’t detect much of a sound difference (maybe my ear canal is borderline…) so I stuck with the Ocharaku Flat4-KEYAKI Plus, which according to the website “is relatively appropriate for more people than that of its counterpart.”

Any intelligible talk about the sound quality should have some mention of the (as far as I know) unique design Ocharaku utilized for the Flat4. They use what they call a “Twin Equalized Element System” which employs 2 dynamic drivers (they call them a primary element & a secondary element) in the housing, utilizing the aforementioned ‘Phase Correction Tube’ which reportedly ” suppresses the closed-ear canal resonance and eliminates the masking effects, dramatically improving sounding in mid- and high-tone range.”

This is obviously an oversimplification of what is a more complex technological philosophy, which can be seen more in depth on the CD Japan website here.

The Ocharaku Flat4 was slightly challenging to drive, needing just a more volume than most of the IEMs I have on hand, although I was able to reach unsafe listening with any device I tried. When briefly testing with my Samsung Galaxy S7, I was pleasantly surprised at the quality of sound.

While no real competition for higher quality gear (the Samsung, not the Ocharaku), the Samsung/ Ocharaku Flat4 combo was overall a satisfying listen for non-critical listening on the go. I didn’t do much in the way of tip rolling, although I did experiment with Sony tips which did work well. I found the fit to be on par with the included SpinFit tips, and no major discernible change in SQ, so I stuck with the stock tip, trading between the SpinFit & Comply as needed. I found the Comply tips didn’t change the overall sound at all.

That 1st thing that jumps to my mind when I think of the Flat4 is ‘smooth’. I’m not really a fan of using non descriptive elements in my reviews, but there is an easy quality to the sound if you will, lacking hard edges. To break it down more traditionally: I find the sub bass solid with a pleasant amount of emphasis for my tastes. The bass was deep and satisfying, with the mid-bass having a bit less emphasis while being no less engaging. Listening to jazz, double basses sounded woody & acoustic, unlike some IEMs that mar enough to mistake the bass for an electric.

The mids retain the smooth theme, sounding lush, with a good amount of detail. These aren’t what I would call ‘Mid-Head’ earphones, but I found the relaxed smooth presentation addictive with almost everything I listened to, and noticed little to no lack of detail. Male & female voices sounded realistic and consistent with their respective recordings.

The highs have plenty of sparkle, and no major dips or spikes are evident. Cymbals could occasionally sound overly metallic depending on the recording, kind of like a ‘tick’ instead of a ‘ting’, but it did seem track dependent. Soundstage was fairly wide and tall, especially for an IEM, but not overly deep . Complex passages were handled well with very good instrument separation. I was thoroughly engaged listening to classical and big band as well as rock & dance music. In fact, there wasn’t a single type of music that wasn’t well represented by the Ocharaku.

In the end, I’d have to say that Ocharaku did a wonderful job with the Flat4-KEYAKI Plus. Whether or not you feel the investment in Japanese Zelkova and the collaboration with Oak Village was worth it or not may be questionable, I personally cannot deny the beauty of the wooden housing. By the same token, the technology that the Flat4 was designed with can be debated as well, but for me they did achieve a compelling, articulate and enjoyable earphone. I would definitely recommend a demo to anyone shopping for an Earphone in this price range.


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Ocharaku KEYAKI/AKAKEYAKI Review by jinxy245 in Head-Fi


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