ABSTRACT
Th ere is a beautiful symmetry to the principles of electricity that are most commonly used to translate acoustic sound into an electrical signal and then back into sound again. Inside every dynamic microphone (such as a typical PA mike) is a lightweight plastic membrane affi xed to a coil of fi ne wire encircling a cylindrical magnet. Madonna sings, and her sound waves jiggle the membrane, which moves the coil in the fi eld of the magnet, generating a very small electrical current. Th is current is amplifi ed, equalized, fl anged, reverberated, compressed, and fi nally amplifi ed even more before being sent back out to a bigger coil wrapped around an even bigger magnet. Now this shimmering electromagnetic fi eld pushes and pulls against the big magnet (think of the two magnetic Scotty dogs, forever trying to align themselves nose to tail), moving a paper cone back and forth, producing sound waves of…a louder, possibly improved, Madonna.
