DIY: Turn AKG K420 into Bluetooth Headphones

If you're interested in converting your wired headphones to Bluetooth, this article might be just what you need.

Take the AKG K420, for example — a model that doesn't get much use anymore. How can you transform it into a Bluetooth 4.0 headset? The key is a CSR8645 Bluetooth chip.

You can either purchase the CSR8645 chip directly, or salvage it from an old or unused Bluetooth headset. Here's an example of the kind of headset that might contain the chip:

After disassembling it, you'll find the mainboard inside — featuring the CSR8645 chip.

Carefully remove the mainboard and detach the USB connector.

Don't worry about fitting the board into the K420 — it's a four-layer PCB, so although it's a bit tricky, it's doable with some patience.

Next, enlarge the original cable port on the K420 to install a power switch.

On the other side, you'll need to install a battery and a charging board. Place the USB port in the original cable exit.

Here's what the final result looks like — not bad at all. The sound quality holds up well, too. The only imperfection is that the wire connecting the left and right sides can't be completely hidden.

Done!