From a few items I picked up at the Goodwill Store, I built a pair of loud, excellent quality computer speakers. This instructable will show you how to modify those crappy computer speakers that usually come with computers. The total amount I spent on this was 9 dollars. It will also show you how to power them off 8 AA batteries for a couple of hours. (The batteries didn't die on mine after running them for 2.5 hours on full volume!) If you're only going to use them as computer speakers, you don't really need to run them on batteries, but it isn't hard to turn them into a portable sound system. The Goodwill Store is an excellent place to look for stuff you need, though you may need to check a couple of times to get all the right stuff. This is my first instructable, so please comment!
Step 1: Getting the Parts
You will need:
a pair of computer speakers
a pair of nice speakers you wish to upgrade to
spare speaker wire
If you want them to be battery powered, you also need:
an 8 AA battery holder
an extra power supply (it needs to fit in the power input, but doesn't have to be the same voltage)
a 12 volt regulator (or whatever voltage yours are)
Here are some things to look out for when you're buying stuff:
Look for a set that comes with a power supply, unless you know you have a spare power supply at home. For some reason Goodwill has a habit of separating the speakers from the power supplies. I don't know why. But you may need to look through the bin of tangled cords for a power supply with the same voltage as your speakers. Also if you want to power them on batteries, you MUST get speakers that are rated for DC power, preferably ones that run at 9 or 12 volts. You may be able to work with other voltages, like 15, but that might get tricky. They really don't need to be nice speakers. Mine are stock Dell speakers that probably came with a computer. The only control is a volume knob. They cost me $3.
You may need to check Goodwill a couple of times before you find an appropriate pair. Look for speakers with a name brand like Sony or Panasonic. These are usually nicer. You should also check the power rating. A pair of 50 watt speakers usually sound a lot better than a 5 watt pair of speakers, even if you aren't going to power them at anything higher than 5 watts.