Sony MDR-XB20EX Inside Look

Here is an inside look at the Sony MDR-XB20EX. I managed to open a pair to have a look, as I was very curious to see the technology. I bought these second-hand on eBay and the seller indicated that only one side was working, and that it could be a broken wire. The wire technology on these headphones is robust and very reliable, and usually, the owners burn the voice coils and then try to get as much money as possible on eBay. As you can see, the wire retainer grip occupies most of the space inside here, and there is a small amount of space left at the top for the sound.

Driver Cavity

The driver cavity seems to have an elliptical curve, which would make a huge difference to the sound.

Ear Canal Pipe

The ear canal pipe is the main part that creates that low bass sound. It is also angled to direct the sound right inside the ear canal. The diameter of the sound guide and its length make a huge difference to the sound.

9 mm Drive Unit

This 9 mm drive unit is the latest Sony technology that offers amazing sound.

Neodymium Magnet

For the magnet assembly, a neodymium magnet usually works well.

Copper-Clad Aluminium Wire (CCAW)

To achieve the wide frequency response, the voice coil has to be extremely light. This means that it will be able to vibrate faster, and provide a better response for the upper frequency range. To achieve this, they used an aluminium wire, which is very light. However, aluminium is a poor conductor of electricity, so they plated it with copper, which does conduct well. This microscopic amount of copper is all that is required to conduct electricity and produce a magnetic field, however it is very delicate and if a large current passes through it, then the coil will go open just as a fuse would.

This technology places a limit on the amount of current the wire can carry, because the conducting surface is very thin. Since it sounds so great, the natural instinct of the owners is to increase the volume, which will eventually damage the coil. There are many sellers on eBay selling damaged headphones as a result.

The purpose of using an aluminium core wire is to make it light. The lighter it is, the faster it can vibrate the diaphragm, and therefore higher the frequency response of the assembly.

Logo

This is the plastic back panel; I managed to carefully pull it off without snapping it. On the other side is the Sony logo.

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