How one spiral carries an entire side of music
A record does not store each song in a separate circular track. The stylus follows a single groove that winds gradually from the outer edge of the disc toward its center. As the turntable spins, that spiral turns a steady rotation into a moving timeline: the stylus encounters the recorded sound in sequence.
The groove is not a smooth trench. Its walls shift in tiny patterns that correspond to the audio waveform—the changing shape of a sound signal. When the stylus rides over those variations, it moves minutely from side to side and up and down. A cartridge turns those movements into an electrical signal, which an amplifier and speakers convert back into sound.
Two channels fit into the same groove
On a stereo record, the two channels are encoded in the groove’s two walls. Their angled movements let one stylus read left- and right-channel information at the same time. The groove therefore acts less like a pair of separate lanes and more like a single path whose shape carries two related signals.
The spiral also explains why a record’s songs are not physically divided by walls. The visible gaps between tracks are simply wider, quieter stretches of groove; the stylus still travels continuously through them. At the end of the side, it reaches a small runout area near the label, where it can circle until the listener lifts the tonearm.
That uninterrupted path is the record’s basic tradeoff: it stores a whole side in one continuous line, but playback depends on keeping a delicate stylus accurately in that line from beginning to end.
