Experiment 27: Loudspeaker Destruction
242 Chapter 5
Experiment 27: Loudspeaker Destruction
I’d like you to sacrifice a 2-inch loudspeaker, even though it means wasting the
$5 or so that it probably costs. Actually, I don’t consider this a waste, because
if you want to learn how a component works, there’s no substitute for actually
seeing inside it. You might also have such a speaker already, part of a piece of
cast-off personal electronics or toy you have in your basement.
You will need:- Cheapest possible 2-inch loudspeaker. Quantity: 1. Figure 5-24 shows a
typical example.
Procedure
Turn the loudspeaker face-up (as shown in Figure 5-25) and cut around the
edge of its cone with a sharp utility knife or X-Acto blade. Then cut around
the circular center and remove the ring of black paper that you’ve created.
The result should look like Figure 5-26: you should see the flexible neck of the
loudspeaker, which is usually made from a yellow weave. If you cut around its
edge, you should be able to pull up the hidden paper cylinder, which has the
copper coil of the loudspeaker wound around it. In Figure 5-27, I’ve turned it
over so that it is easily visible. The two ends of this copper coil normally re-
ceive power through two terminals at the back of the speaker. When it sits in
the groove visible between the inner magnet and the outer magnet, the coil
reacts to voltage fluctuations by exerting an up-and-down force in reaction
to the magnetic field. This vibrates the cone of the loudspeaker and creates
sound waves.
Large loudspeakers in your stereo system work exactly the same way. They just
have bigger magnets and coils that can handle more power (typically, as much
as 100 watts).
Whenever I open up a small component like this, I’m impressed by the preci-
sion and delicacy of its parts, and the way it can be mass-produced for such a
low cost. I imagine how astonished the pioneers of electrical theory (such as
Faraday and Henry) would be, if they could see the components that we take
for granted today. Henry spent days and weeks winding coils by hand to create
electromagnets that were far less efficient than this cheap little loudspeaker.Figure 5-25. Loudspeaker ready for creative
destruction.
Figure 5-26. The cone has been removed. Figure 5-27. The neck of the cone has been
pulled out. Note the coil of copper wire,
which fits precisely in the groove between
two magnets in the base of the speaker.Figure 5-24. A 2-inch loudspeaker can be
instructively destroyed with a utility knife
or X-Acto blade.