The Vinyl Groove & Stylus Physics: A Journey Through Analog Sound

Groove Encoding

Vinyl records store audio as modulations in a spiral groove etched onto the surface of the record. The stylus, or needle, follows these grooves and converts their physical variations into electrical signals that can be amplified and converted back to sound.

The linear speed of the groove decreases towards the center of the record due to its constant angular velocity. This means that as the stylus moves inward, it encounters fewer grooves per unit time, resulting in a higher pitch for the same frequency modulation.

Stylus Dynamics

The stylus must be designed to accurately track the groove while minimizing wear and distortion. Its tip shape and materials are critical; diamond-tipped styli are common due to their durability and ability to maintain a sharp point.

As the stylus tracks the groove, it experiences forces that can cause it to deviate from the ideal path. These deviations must be minimized for high-fidelity playback.

Waveform Reconstruction

When the stylus is in contact with a groove, it creates an electrical signal proportional to the groove's depth and shape. This signal is then amplified and converted into sound by an audio system.

The reconstructed waveform must be accurately represented for faithful reproduction of the original recording; any distortion or noise can degrade the quality of the playback.

Pitch Control

Changing the platter speed with a pitch fader alters the rate at which the groove is traversed by the stylus. This effectively changes the perceived frequency of the sound, allowing for pitch shifting without altering the tempo.

In practice, this can be used to play older records at their intended speed or to create unique audio effects.

Frequently asked questions

Try it live

Everything above runs in your browser — open Vinyl Groove & Stylus Physics Simulator (2D) and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.