Closer Examination

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.