The Record’s Last Groove Is a Mechanical Loop
A record’s music is cut into a spiral: the stylus gradually travels inward as the disc spins, tracing tiny side-to-side and up-and-down changes in the groove that become sound. At the end of the program, the spiral gives way to a runout area. Its groove guides the stylus toward the label, then a circular section keeps it moving around the same track instead of inward.
That circular track is called a locked groove. “Locked” does not mean the stylus is stuck; it means it is held in a repeating path. The platter continues turning, so any sound encoded in that circle plays again on every rotation. A loop can be an intentional musical or comic flourish, but the groove may also produce only the soft hiss and crackle of the record’s surface.
Why the Record Doesn’t Stop by Itself
The stylus follows the groove; it does not recognize when a song is over. On a manual turntable, the listener lifts the tonearm. Some automatic players use a mechanism that returns the arm near the record’s center, responding to its position rather than to the music itself. A locked groove gives that final stretch a stable place to wait if the arm is left down.
The result is a small mismatch between sound and machine: the music can be finished while the record keeps turning. When artists place audio in the final circle, they turn that otherwise practical endpoint into a loop with no built-in last repeat—the listener decides when it ends.
