Note: this guide doesn't create very robust headphones. I'm not sure why; but I recommend using this for temporary use or for headphones that you don't use on the go.
I frequently break my headphones; I've torn cables in my bike wheels, dropped my phone on the aux cable, etc. etc. In this post I'll be covering how to splice headphone cable.
First, strip the cables with a wire stripper until you have a fair amount of bare cable. Note that apple headphone cables have a fair amount of elasticity, so it may seem like you're stripped more than you actually have.
Here's my headphones stripped:
Here's the AUX cable I sacrificed stripped:
Next, you'll need to melt off the protective insulation coating on the headphone cables. Each individual strand is covered in a thin layer of (I think?) resin. To remove this, use a lighter quickly on the wire to remove the coating.
Put on Heatshrink
Always remember to put on heatshrink before you solder! Make sure the heatshrink is sufficiently far away from the soldering iron as not to shrink from the heat of the soldering iron.
Next, solder the wires of the cables. If you're neater than me, you can probably use heat shrink tubing on each individual wire; given that I'm removing the insulation, I just wrap every wire in electrical tape.
As far as coloring goes, many different cables will use different standards. However, a good rule of thumb is: - green: left + - green/gold: left - - red: right + - red/gold: right -
Now, put the heatshrink tubing over the insulated wires and use a heat gun to shrink the tubing.