In case you weren’t around in the vinyl era or can’t remember anymore: vinyl record players are electromagnetic devices that change sound vibrations into electrical signals through the needle placed on the spinning record. The following microscopic images allow a close glimpse into how the process actually looks like.
The needle, or stylus of a record player is one of several parts that make up a transducer, which converts the mechanical energy from the sound waves into electrical energy, which is then sent into the amplifier and out to the speakers.
The heart of the system also contains coils, magnets, cantilever, and a body within a cartridge.
When a vinyl record spins on the record player, the stylus moves through the record’s grooves (oh wait, so that’s where ‘grooving comes from…). The stylus is made of an industrial gemstone (often diamond) and is attached to the record arm to actually ‘read’ the grooves on the record by generating an electric signal and transfering it via the cartridge to the amplifier.
The two sides of a groove represent the right- and left-channel audio information. The side closest to the outside edge of the record carries the right-channel signal.
The information that is converted into a signal by the stylus can be stored in an area as small as a micron (one-thousandth of a millimetre). So the scale of the task of retrieving the information on the entire record is immense, which also explains the sensitivity of record players to external vibrations and other disturbances.
Here’s how a stylus actually ‘ploughs’ the vinyl for the signal:
Fun fact: those little grooves you see on the record would be roughly 500 meters long given it was possible to unwind them into a straight line.