The Alchemy of Analog: How a Record Works

A record is not smooth. It contains a single, continuous groove that spirals from the outer edge to the center. Think of it as a microscopic canyon. The walls of this canyon are not straight; they are etched with microscopic variations—a physical map of the original sound waves. The left wall of the groove holds the information for the left stereo channel, and the right wall holds the right channel.

The tip of the needle, called the stylus, is a finely polished diamond that is shaped to sit perfectly within that groove. As the record spins, the stylus is pulled along the path of this canyon, tracing every microscopic bump and wiggle on both walls thousands of times per second.

The stylus is attached to a cantilever, which has a small magnet on the other end. All of this is housed inside the cartridge. As the stylus vibrates, it moves the magnet back and forth between two sets of tiny wire coils (one for the left channel, one for the right). This movement generates a very small, but precise, electrical signal in the coils—a perfect electronic copy of the physical map in the groove.

The electrical signal from the cartridge is incredibly weak. Before a regular amplifier can use it, it needs to be boosted. This is the job of the phono preamp. It performs two crucial tasks: it amplifies the signal to a usable level, and it applies the RIAA equalization curve, which restores the proper tonal balance to the music. Without this stage, the music would sound thin, tinny, and almost silent.