I bought a set of super cheap USB powered computer speakers on sale for $4 at my local grocery store a while back. I figured for $4, I couldn't really go wrong. They ended up being underpowered and just all around not great. So I thought with a few slight modifications (new amplifier, internal battery, etc.) I could turn them into a half decent set of travel speakers. Since they were so cheap to begin with, I'm not too worried if they get damaged/destroyed, so they're ideal little speakers to bring on camping trips and the like.
-Old computer speakers
-Female 3.5mm jack
-Replacement amplifier (Optional. You can reuse the original easily, I just wanted a little more power/quality)
-Battery (I used a 1200mAh LiPo I had lying around)
-Charger for battery
-Misc hardware (Depends on your exact speakers)
-Soldering iron and solder
-Heat shrink tubing or electrical tape
-Screwdriver (if your speakers are screwed together)
-Tweezers (not necessary, but very handy to get into tight spaces)
-Hot glue gun
*Before I begin, I apologize for the lack of pictures from some steps. I got a little too into making it and forgot to take pictures of some of the steps!
I added a video of it playing. Not crazy powerful, but pretty decent for what it is :)
First thing you need to do is take apart your old computer speakers and see what's inside! Obviously every speaker setup is different, so take yours apart however you need to. Mine simply had four #1 Phillips screws in the back of each speaker housing.
If you're keeping the original amplifier, then be careful when removing it. If not, don't worry too much haha. Mine was really crappy, so I decided to replace it with a 3.8w amplifier from Adafruit that I had in my parts box. It was a good choice since my speakers are 3w and the amplifier can run on anywhere between 3 and 5.5 volts, which is perfect for a lithium polymer battery. I cut the male USB and male 3.5mm cables off as close to the amplifier as I could. They're perfectly good cables and can be reused in another project!