Did you know that the dots on the side of your turntables have a purpose?
Modern record players use electromagnetic devices to convert sound vibrations from a spinning record into electrical signals. These signals are fed to an electronic amplifier that powers loudspeakers or headphones, making the sound much louder. So a record player is a mix of mechanical and electromagnetic technology. A typical record player has a stylus (similar to the needle in Edison’s machine) that bumps up and down in the groove of a vinyl (plastic) disc. The stylus is a tiny crystal of sapphire or diamond mounted at the very end of a lightweight metal bar. As the crystal vibrates in the groove, its microscopic bounces are transmitted down the bar.The stylus fits onto the end of an electromagnetic device called a cartridge, which contains a piezoelectric crystal. The metal bar presses against the crystal and, each time it moves, wobbles the crystal slightly, generating an electrical signal. These signals are fed out to the amplifier to create the sounds heard through speakers or headphones.
Not all record-player cartridges use piezoelectricity. Some have tiny electrical coils and a magnet inside them. When the stylus moves, it pushes the magnet up and down past the coil, generating electrical signals that way.
In this video, our DJ Faculty Llewellyn Hilt explains the significance of the dots on your vinyl turntables, what they represent, and how they can be used.