Columbia and RCA's competition extended to equipment. Some turntables included spindle size adapters, but other turntables required snap-in inserts like this one to adapt RCA's larger 45 rpm spindle size to the smaller spindle size available on nearly all turntables.
After World War II, two new competing formats came on to the market and gradually replaced the standard "78": the 33? rpm (often just referred to as the 33 rpm), and the 45 rpm. The 33? rpm LP (for "long play") format was developed by Columbia Records and marketed in 1948. RCA Victor developed the 45 rpm format and marketed it in 1949, in response to Columbia. Both types of new disc used narrower grooves, intended to be played with a smaller stylus—typically 0.001" (25 µm) wide, compared to 0.003" (76 µm) for a 78—so the new records were sometimes called Microgroove. In the mid-1950s all record companies agreed to a common recording standard called RIAA equalization. Prior to the establishment of the standard each company used its own preferred standard, requiring discriminating listeners to use preamplifier with multiple selectable equalization curves.
A number of recordings were pressed at 16? RPM, but these were mostly used for radio transcription discs or narrated publications for the blind and visually impaired, and were never widely commercially available, although it was still common to see turntables with a 16 RPM speed setting produced as late as the 1970s.
Columbia and RCA's competition extended to equipment. Some turntables included spindle size adapters, but other turntables required snap-in inserts like this one to adapt RCA's larger 45 rpm spindle size to the smaller spindle size available on nearly all turntables.
After World War II, two new competing formats came on to the market and gradually replaced
the standard "78": the 33? rpm (often just referred to as the 33 rpm), and the 45 rpm. The 33? rpm LP (for "long play") format was developed by Columbia Records and marketed in 1948. RCA Victor developed the 45 rpm format and marketed it in 1949, in response to Columbia. Both types of new disc used narrower grooves, intended to be played with a smaller stylus—typically 0.001" (25 µm) wide, compared to 0.003" (76 µm) for a 78—so the new records were sometimes called Microgroove.