Although the stylus-to-groove speed at the outer edge of a 12 inch (30 cm)
record is adequate (just under 20 inches (50 cm) per second), as the stylus
gets closer to the inside edge, the relative speed gets slower and slower, even
though the record turns at the same angular velocity.
At the inside, the speed is almost down to a third of what it was originally,
and the undulations of the groove have to be more condensed.
The result is a noticeably inferior sound quality.