Hi, I've disassembled an old laptop, and I remember it had a nice sound. I've taken the 2 stereo speakers, and they have 2 cables:

One speaker has one red and one black cable
The other one has a white and blue cable

I've "soldered" (weak joint so it's temporal) them in an audio jack plug 3.5 mm, connected it to my actual notebook headphones out, and they worked, although sounded really low.

First question is...
How do I know which cable of each speaker is the ground, and which one the right/left channel cable?

What happens if I connect the ground cable to the right channel pin, and viceversa?

Since it's AC, the diaphragm should move in the other way it's supposed to move, but that should be right, shouldn't it?

Second question:
I suppose I need an amplifier (which needs a battery, damn). I wanted to make a portable pair of speakers using them. I "thought" (I was quite sure I was wrong) if I soldered them to a jack plug and use them as I would use a pair of headphones, they would work and sound as loud as they did in the laptop, but they sound really low.

What do I need to do to transform them into a pair of portable speakers?

My guess is that I need an amplifier, a battery and the speakers. But I don't know how to proceed to make it work.

 

The sound from the front of a speaker is antiphase to the sound from the back so they need to be in a box to stop the sounds cancelling. that will make them louder.

 

First off, there is no guarantee that one of each of the speaker wire pairs is ground. If the speakers are driven BTL (bridge-tied load), there are two output wires driven 180 degrees out of phase, and no chassis or signal ground. This trick doubles the effective voltage across the speaker, which is a 4x power increase. Very handy way to get decent volume in a low voltage, single supply system.

ak

 

They are already in a box, I only unplugged the connector that was in the laptop, so that left me a pair of speakers, each one in a little box. There are 2 wires coming out of that box. So one must be ground and the other the right/left channel, respectively.