Wiring a volume control to your internal speaker:

The below instructions tell you how to wire a volume control to the
speaker that's inside your computer. They are by default always set at
high volume, and they don't come with volume controls. This procedure
is not very hard, but if you have never done electronics before you may
feel a little nervous. Don't worry, just follow the instructions carefully
and you'll be all right. Read the whole thing through before you begin
so you know what you're doing. It's basically hooking up a
potentiometer to the speaker's wire. A potentiometer is simply a small
dial-like device which controls how much electricity goes to the speaker,
and hence, how loud it is.

For this, you will need a 1,000 ohm potentiometer. Get it from Radio
Shack. If they don't have one that low in stock, you can get a 5,000 ohm
one, that will work too, but 1,000 is better. You will also need a roll of
22 gauge stranded hook-up wire. Get that from Radio Shack too. You
probably would want to use the "double-barrel" (double stranded) type
of wire (the kind which is actually two wires running side-by-side, joined
by the insulation) instead of single-strand so the job is neater (just one
wire running from the computer to the volume control instead of two).
You'll also need wire cutters, a sharp utility knife, and if you want to do
a good job, a soldering iron. If you're not using the soldering iron, then
you'll need electrical tape.

Find the internal speaker inside your computer. Pick one of the two wires
leading away from it (doesn't really matter which one) and cut it at a
convenient point, somewhere fairly close to its (the wire's) center.
Lengthen the two wire ends you've created by attaching two lengths of
the hook-up wire to them. Attach them either by soldering or simply
tying them on with electrical tape. Soldering is better because that way
the wires won't come apart by accident, but if you don't have a soldering
iron or if you don't want to use one that's fine, use electrical tape
instead. You will need to strip the ends of all four wires a bit with a
utility knife to expose them. Run the two wires you have now outside
your case (you'll probably need to drill a hole (a SMALL hole)
somewhere in it). Now, bring in the potentiometer. On it there will be
three legs (little protruding thingys). Use the centre leg and either one of
the other legs. Attach the ends of the wires to them. You will need to
strip the ends of the wires a bit with a utility knife to expose them. They
can be attached simply by firmly wrapping them around the legs, but for
a really good job, solder them on. But if you don't want to solder, you
can just wrap the wire ends snugly on (but again, soldering is better).
The third remaining leg on the pot (potentiometer) is a ground, but you
don't need to use it for such a low-voltage purpose as this. Mount the
potentiometer somewhere on your desk so it's conveniently close at hand,
then put the cover on your case and you're in business!

Below is a diagram of basically what things should look like. The lines
are the wires, except for the doubled lines which represent the wall of
your computer's case:

                          Potentiometer
                              ณ  ณ
                              ณ  ณ
                          ออออุออุออออ Wall of case
 Motherboard                  ณ  ณ
      ------------------------ู  ภ----------------------
      --------------------------------------------------Speaker