I have a pair of pretty good quality Philips headphones but recently I ran over the cable with my chair. The cable was crushed beyond repair and a replacement was hard to find, since it was a relatively old model. So I went on to give my good old headphones a second life as an USB headset. Since the headphones had a detachable cable anyway and plenty of room inside, they did not need much modification and the hack looks fairly professional.
I would suggest using headphones similar to mine, that have room inside for a device about the size of an old-school USB flash memory stick. Also it is necessary that the cable enters from one side only so you don't have to rewire the other side.
Simply put, this instructable details putting a small USB sound card inside a pair of headphones and adding an optional microphone.
Step 1: Components you will need
For this modification you will need:
For the sound card and microphone I ordered from Dealextreme, a Chinese online shopping site. For the lazy ones I have here affiliate links to the sound card and mic including free shipping (you will be supporting me):
However you can get both for less than a dollar each from china on ebay. Check the pictures for what they look like.
In case you would like to make the microphone detachable like I did, you will also need a 3.5mm headphone jack. I got one from my local electronics shop. Make sure, that you get one of those panel-mount jacks that have a threaded ring to keep it from breaking off or bending too much.
Step 2: Prepping
As sad as it is, I don't have any photos of the process. If anything remains unclear, just go ahead and ask me.
As you can see, I had a perfect hole to embed my microphone jack in. After opening up the left speaker I removed the old 2,5mm jack assembly and made the hole a bit bigger to fit in the new jack. Also I desoldered the wires going to the speakers from the old jack.
Next I prepared the sound card. I cracked open the plastic enclosure since I won't be needing it any more. I also desoldered the USB plug from one end and both of the audio jacks from the other. I didn't have the patience to be gentle so I cut the metal on the audio jacks and pulled off the plastic parts. After that I could easily desolder the remaining metal tabs one-by-one. I am going to solder all the wires directly to the pcb in hopes of better fitting it inside the headphones.
Now is a good time to find a spot in the speaker for the sound card so that everything fits back together. I used a bit of tape to hold the sound card in place and put the speaker back together to see, if it closes up again. After finding the perfect place, I fixed it with a drop of hot glue.
For the USB cable I used one of those USB to mini-USB cables that used to come with every device and clutter up your junk drawer. Just snip off the mini-USB end and cut off 2-3 cm of insulation. I kept the shielding intact for later but this isn't strictly necessary. After that I drilled a hole in the speaker so that the cable won't get in the way for the mic later and threaded the cable through the hole.
Step 3: Solder and test
First thing to do now is solder the USB cable to the sound card and make sure, that it still works. On my device the wires went from left to right: black, green, white, red. This should be standard USB pinout and wire colors, unless you have some very weird USB cable. I also took the precaution of soldering the cable screening to where the USB plug's metal tabs were soldered to. After confirming, that windows still recognizes the device, I proceeded wiring the speakers and microphone jack.
The speakers both connect to a common ground point. the second pad or ring connector on a plug is for the right channel and the third or tip connector is for the left channel. My speakers had different color wires suggesting some polarity but it generally shouldn't matter as long as you keep it same for both speakers.
For the microphone jack connection I used two pieces of thin wire I once got from a network cable. Refer to your jack's specification sheet for the correct pins to solder. I soldered the ring and sleeve connectors from the sound card to my jack. It looks like the tip and ring were electrically connected on both the sound card and microphone so I didn't bother with a third wire.
Now is the time to do a final test and check for any mistakes. If you have any doubts about your soldering and even if you don't it is good practice to check for shorts. It will be easier and cheaper to fix your soldering than to fix your computer's power supply. Test, whether the left and right channels aren't mixed up and the microphone works alright. When everything is functional, it's time to glue down the wires and close it all up.
Step 4: Wrapping it up
At this point I put the microphone jack through its hole and tightly screwed on the threaded ring from the other side. I used blobs of hot glue to keep the wires from getting in the way when closing up the speaker.
Also an important step here is to apply liberal amounts of glue around and in the USB cable's hole. You could also tie a knot in it or add a zip-tie to the inside to keep it from ripping off the soldering on the sound card. The idea is to have as little strain on the solder points as possible.
Once you feel secure enough you can screw the headphones back together and try out your uber-cool headset with your favorite FPS game and teamspeak.
Step 5: Afterthoughts
The first thing, I noticed was that the volume is extremely loud. I can use the headphones with a volume setting of 2 comfortably. That is 2 from 100. I suppose one day I will add a voltage divider between the output and speakers but today is not the day. I only use the headset for gaming anyway.
Another thought I had at first was to use a mini-USB port in there so I could detach the USB cable and add an input to connect audio to the speakers directly but I didn't find any panel-mount ports to make it look halfway decent. This just means that I can now use the headset only with a computer.
I do however love the way the LED on the sound card shines through the mesh on the side and blinks while my headset is in use. Makes it look like it was meant to be like that from the factory.
Any other thoughts and comments are welcome.