Science Buddies
Science Buddies: Rock On! Recording Digital Data With Magnets
This is a straightforward project that shows you how data can be digitized and stored on magnetic recording media. You'll learn how alpha-numeric characters are digitized, and you'll use bar magnets to represent the individual data...
Other
University of California: Analog Recording of Sound
A great site explaining the fundamentals of recording sound. The site features great diagrams on how recording works as well as analog tapes.
Other
Simon Fraser University: Sound Synthesizer
At this site from the Simon Fraser University, you can scroll to the bottom of this page on sound synthesizers for a brief paragraph explaining what digital synthesizers are.