The most sophisticated and most expensive way to generate a signal is the moving-coil system. In this system carefully hand-wound coils are mounted on the cantilever and move in the field of a stationary magnet. The signal is generated directly, with a minimum amount of distortion because there are fewer losses in the transfer from mechanical to electrical signals.
To keep moving mass as low as possible there are usually very few turns of the coil. For example, stationary coils (as in moving-magnet or moving-iron cartridges) may have as many as 3,000 turns of wire. The moving coil may have only 15 or 20 turns, and fewer turns mean lower output voltage.
Fig. 8.19 Moving-coil cartridge
Unless an amplifier is already ...