Many of you are probably unfamiliar with the Head-Direct company. In short it is a online retailer that specializes in headphones and earphones. This company is the official retailer of many more or less unknown Asian brands like for example Yuin and Dowin. Head-Direct has a lot of interesting earphones and headphone amps.
The earphones I will be taking a look at today are called Yuin OK2s which is the OK1's little brother. Where the OK1s are high impedance the OK2s are made for use with most modern DAPs. The OK2’s impedance is only 16 Ohms like most ordinary earbuds made today. This makes them ideal for a somebody looking to upgrading their portable rig with a serious pair of earbuds. The OK2s can function both as normal earbuds and as in-ears which makes them quite unique.
The packaging is not final for the Yuin OK2s so the sample I just came in a number of small plastic bags. With the OK2s you get a lot of tips. You get three different sized single flange tips, one double flange tip, and a rubber earbud cover. Just like its bigger brother, the OK2s can be used both as canalphones and as earbuds. In order to convert them from earbuds to earphones all you got to do is screw on a plastic barrel and apply a tip on its end.
The tip selection that comes with the OK2s is the same as that of the OK1s. Only difference in the bundle is the lack of the 1/8" to 1/4" adapter. Since the OK2s are aimed at portable use it is a completely reasonable decision since all never DAPs have a 1/8" headphone out. Unlike the OK1s the OK2s have a fairly low impedance which makes them really easy to drive. The impedance rating listed is 16 Ohms and the efficiency is high. This is great because it allows you to run them off your DAP without having to lug around an amplifier to make them sound their best.
Appearance wise there is no difference between the Yuin OK2s and the rest of the OK-series earphones. They all have the exact same exterior design and cable from what I can see. The cable has been improved a lot in comparison to the one of the old Yuin PK-series earphones. Where the PK-series earbuds had a flimsy plastic type cable the new OK-series earphones feature a nice solid cable with a rubber jacket. Another big change in the design is the fact that the OK2 earphones feature a metal rim around the sound hole. It is there so that you can screw on the different canalphone adapters.
The OK2s look quite good from the side. All of the earbuds in the OK-line look the same with the only difference being the OK1/2/3 logo on the side of the stem. The general build quality of the OK-series earbuds is really good. The joints are not seamless, but they are bonded together in a very durable manner. The plastic used seems fairly tough and it does not give way to pressure easily.
On each of the earbuds there is a small left / right indication marker. On the PK1s it was the same color as the logos on the side, but on the OKs it has been toned down a bit which is kind of annoying because it makes it harder to spot which earbud goes where. The problem is particularly apparent when you are in a poorly lit room.
The OK2's driver looks quite like the one in the OK1 earbuds. Even though they share the same design with the parabolic shaped surface they are not completely alike. The absolute biggest difference between the two versions of the driver is their impedance, where the OK1's driver is a 150 Ohm one, the OK2 has an impedance of only 16 Ohms. One of the areas has undergone major changes since the PK1 is the driver and the area around it. Instead of having a pierced plastic plate in front of the driver the new OK2s have metal grill and that is adhered to a metal rim. The metal that goes around the periphery of the earbud has small vents in it as well.
The canalphone adapters are screwed into a threaded hole just in front of the driver. This is an extremely easy task to do. The thread is made of metal just like the outer rim and since the adapters are made of plastic the chance of you ruining anything more than just a cheap adapter is relatively slim.
With the OK2s you get three different length canalphone adapters. The size difference between the short and the medium one is huge, whereas the size difference between the medium and long one is very small.
Above you can see the different adapters mounted in the OK2s. The right most picture shows them with the large canalphone adapter mounted. One of the problems with the design is that the adapters sit straight on the earbud so there is no offset angle. And since a human earcanal points down and backwards from the inner ear, it is hard to get a good seal. The problem is that in order to get the adapter to align with your earcanal you have to angle the body of the earphone and due to its design it will either push against your concha or the upper area of your earlobe. This causes the seal to break very easily.
The tip selection that comes with the OK2s is quite good. You get three pairs of single flange tips along with one pair of double flanges. Besides that you also get a pair of rubber earbud covers instead of the usual foam covers. The tips are the same size as the ones Ultimate Ears IEMs use so you should be able use some Comply T400 tips on these earphones.
The rubber covers function quite well and are very comfortable to use. They do have one small advantage over the foam covers and that is durability. Besides that they are a bit easier to clean.
The mini-jack is really slim and quite durable. The plastic is thick and the cable exits the jack through a rubber stress relief.
The Yuin OK2s are not the most demanding earphones when it comes to power, however, they do need a quite powerful and clean headphone-out to sound their best. This is definitely an advantage over the Yuin OK1s and PK1s because you do not have to carry around a portable headphone amplifier when you are on the move. To test these earphones I used both my Octavart "The One" DAC & Amp and my Cowon iAudio i7 sometimes along with the Go-Vibe V6. Just like its bigger brother I had the OK2s burning in for almost 100 hours before I did some serious listening.
The OK2s do sound very good just running straight off a good DAP. I was quite surprised to find that the sound quality being run straight out of my Cowon was incredibly clear and had plenty of definition both in the highs and lows. The OK2s are not that far behind the OK1s in terms of sound quality as one might think. The real difference between the two as I see it is detailing and speed, where the OK1s had a remarkably fast presentation the OK2s are a bit less refined. This is noticeable with percussion and on some tracks with lots of instruments. The sound stage and separation was not quite on par with that of the OK1s, but it was not too shabby either. It still has a bit of layering, but the sound is not as clear and transparent as that of the OK1s coupled with a good amplifier.
What surprised me a lot is that the OK2 seem to have far better control of the bass compared to my old PK1, even when the PK1 are amped they still have a hard time matching the speed and control that the OK2s offer. The PK1s do have a lot more bass and mid bass, which is far from as refined as that of the OK2s. The only thing that the OK2s lack in comparison to the old PK1s is the punch, the PK1s have a much more powerful presence when it comes to percussion and other intense sounds. The highs are brilliant on the OK2s, in that respect they sound a lot like the OK1s. The highs are not quite as detailed as that of the OK1s , which you can clearly hear when you are either listening to classical or even just listening intensely to the hi-hats' sound, it is a bit more brittle and less coherent on the OK2s than it is on the OK1s, but again it is a subtle difference.
The funny thing about the OK2s and OK1s is that they share the same sound signature, they both have a very neutral sound that does not overemphasize any part of the spectrum which I find great. The OK2s have a wee bit less bass than the OK1s and it does not go quite as deep. The bass is not boomy on either the OK2s or 1s and there is not a lot of it either so these earphones are definitely for people seeking better tonal balance and refinement rather than amount of bass. In comparison to its bigger brother the OK2 lack a little bass and precision in the same area. That being said the bass quality of the OK2s is still miles ahead of my other earbuds which include JVC Gumy 'phones, Sennheiser MX500. Where the OK1 really excel at detail the OK2 are a bit less precise and lack some refinement that being said they are still really good for a pair of earbuds.
When comparing the OK2s to the OK1s and PK1s unamped I definitely prefer the OK2s, because they do not sound as dull without an amp. So if you are looking for a pair of great earbuds and do not plan on buying an amp you should definitely try the OK2s. In comparison to the OK2s the OK1s have even better detailing and speed, the mids of the OK2s just lacks a little bit of definition and texture to be on par with the OK1s.
As earbuds the OK-series are highly recommendable. When fitted with the canalphone adapters the OKs are not all that good. I was only able to get a good seal about 1/10th of the times I inserted them, and I lost the seal shortly after insertion. The problem is that the canal adapters extend from the main body of the earphones in a 90 degree angle and therefore do not align well with your ear canals. A normal canal points downwards and backwards coming from your inner ear. And since there is no offset compared to the body of the earphones they misalign. In order to compensate for that you have to angle the whole earphone which in turns forces you to press them against either your earlobe with the big adapter or your ear's concha with the short adapter on. No matter what you do, your ear's anatomy ruins the fit. This is in my opinion a major design flaw because it is not anatomically correct.
Comfort wise the OK-series is just as good as the older PK1s. The body of the OKs comes a bit nearer to your ear canal, but it does not hurt comfort at all.
The OK2s benefit a bit from amping, but nowhere near as much as the OK1s and PK1s. The differences are minute and I do not think that they are worth spending time and pocket space on amping. Of course this depends on your DAP, but generally you gain very little from amping the OK2s.
The newer OK-series earphones are constructed fairly well. The build quality is quite tough and the plastic pieces seem to be bonded together nicely. The finish is not that good and you can clearly see where the parts have been joined together. They do seem really sturdy and can take a lot of abuse before giving way.
Value and Conclusion
- Sound quality
- Good sound stage for an earbud
- Durable design
- Can be run straight out of a DAP and still sound good
- Easy to use on the move
- Do not function well as IEMs
The Yuin OK2s are not that far from being OK1s for better or worse. They feature the exact same and barely functional canalphone adapter system and have the same appearance. The OK2s are not that far behind in terms of sound quality of the OK2s which is a real pro. These little earbuds sound great just being run straight out of a normal DAP. The sound signature is balanced and pleasant to listen to over an extended period of time and has a lot of things going for it.
One of the major downsides to the OK1s is that they are very demanding where the OK2s are almost the exact opposite. They are a bit harder to drive than low impedance IEMs, but far from as tough to drive as the Yuin OK1s or PK1s for that matter. Because they are low impedance you can run them off almost any DAP out there and still get great sound quality. This is ideal if you do not want to invest in a portable headphone amplifier nor carry such a device around when you want to listen to your music.
The convenience factor with these earbuds is really good, as a package you get a lot of performance without having to go to the extremes. And in terms of sound quality they do have the edge being run straight out of a good DAP.
These earphones fail when it comes to use as IEMs, they simply do not fit well enough. This problem is hard to overcome due to some limitations in the design, ie. offset angle between canalphone adapter and earbud plus the size of the earbud.
If you do not care about having a pair of pseudo canalphones and use them as normal earbuds you are in for quite a treat since the sound quality is far ahead of that offered by normal earbuds. They are still pricey, but they do offer a somewhat spectacular sound quality.