The overwhelming majority of records manufactured have been of certain sizes, playback speeds, and appearance. However, since the adoption of the gramophone record, a wide variety of records have also been produced that do not fall into these categories. The most common sizes for gramophone records are 12-inch, 10-inch. Early American shellac records were all 7-inch until 1901, when 10-inch records were introduced, 12-inch records joined them in 1903. By 1910, other sizes were retired and nearly all discs were either 10-inch or 12-inch, in Europe, early 10-inch and 12-inch shellac records were produced in the first three decades of the twentieth century. 7-inch childrens records were sold before World War II but nearly all were made of brittle shellac, in the late 1940s, small plastic records, including some small picture discs, replaced them. Ten-inch childrens records were made as well, but the 7-inch size was more compatible with small hands, the 7-inch size was also used for flexi discs which were popular in Japan where they were known as sound-sheets and were often in traditional round format. In other areas, flexi discs were usually square and often included in a magazine, numerous unusual diameters have been produced since the early 1900s ranging from 2 to 19.7 inches. Oddly shaped discs were also produced, the most common rotational speeds for gramophone records are 33 1⁄3 revolutions per minute,45 RPM, and 78 RPM. Throughout the history of the industry, however, numerous unusual turn-speeds ranging from 3 to 130 RPM have been utilized for a variety of purposes. In the early 1920s, the World Record Company in the U. K. introduced longer-playing records with speeds measured in inches per second rather than revolutions per minute and this is known as the CLV format, as opposed to the usual CAV format. Of course, only special World records could be used, the World system was a commercial failure. The principle, first proposed in a fundamental U. S, compact discs and DVDs use the CLV format to make efficient use of their surface areas. Both machines recorded at a pitch, but the Grey Audograph could only record at one linear speed allowing 15 minutes per side of a 7-inch disc. The CGS or Memovox, on the hand, had a High Fidelity speed as well as a Speech speed. In the 1970s, Atlantic Records started producing a series of albums later designated on a known as Syntonic Research. Each album consisted of two tracks, usually at least half an hour long per side, of sounds recorded of various locations. There were a few dozen made and these were mostly used for soundscape or relaxation purposes
single sided LP with one off-center and one concentric groove cut by Janek Schaefer 2001
Polish sound postcards, one example of unusual gramophone records (1950s)
An example of the 5-inch format resting on a 7-inch single for comparison.
In the early 1920s, the Edison Records "Diamond Disc" label–here featuring the popular duo of Billy Jones and Ernest Hare–were intended for playback at 80 RPM.