The Audio Turntable has been around since 1877 and has also been known as a phonograph and a record player. The term Hi-Fidelity was first termed after the popularity of the turntable grew to be a favorite source for music playback of recorded analog music among audiophiles. There was a drop in its popularity in the mid 80s with the introduction of the compact disc but there has been a huge resurgence and new models have been developed with improvements in all aspects of the original designs.
There are two common designs for magnetic cartridges, moving magnet (MM) and moving coil (MC). Both operate on the same principle of electromagnetic induction. In either type, the stylus itself, usually made of diamond, is mounted on a tiny metal strut called a cantilever, which is suspended using a collar of highly compliant material. This gives the stylus the freedom to move in any direction. On the other end of the cantilever is mounted a tiny permanent magnet (moving magnet type) or a set of tiny wound coils (moving coil type). The magnet is close to a set of fixed pick-up coils, or the moving coils are held within a magnetic field generated by fixed permanent magnets. The movement of the stylus as it tracks the grooves of a record causes a fluctuating magnetic field which causes a small electrical current to be induced in the coils. This current closely follows the sound waveform cut into the record.
The tonearm holds the pickup cartridge over the groove, the stylus tracking the groove with the desired force to give the optimal compromise between good tracking and minimizing wear of the stylus and record groove. The tonearm can be pivoted in several ways allowing it to be free to move in two axes (vertical and horizontal) with a counterbalance to maintain tracking pressure. It must do this while keeping vibrations at a minimum.