microgroove

Microgroove refers to the groove geometry used in vinyl records, particularly the long-playing LP format that emerged in the late 1940s. The term originated with record manufacturers such as Columbia Records to distinguish the finer, more closely spaced grooves from the wider grooves used on the earlier shellac 78 rpm records.

By reducing groove width and the distance between adjacent grooves, the microgroove format allowed longer playback per side on a given disc diameter and enabled a standard playback speed of 33 1/3 rpm on 12-inch discs, with typical sides running roughly 20 to 30 minutes. The design also contributed to lower surface noise and improved dynamic range when paired with suitable cutting heads and styluses, and it relied on vinyl (polyvinyl chloride) as the working medium.

Over time, microgroove became the de facto standard for most vinyl records produced after the late 1940s, including LPs and later many 45 rpm singles. The term is largely historical today, referenced mainly in discussions of vinyl's technical and recording history.