Speed reliability of cassette and tape players.

The playback speed of tape players directly affects the accuracy of some fitness tests. New and used portable cassette (n = 28) and tape (n = 16) players were generally found accurate (playback speed error less than 2% tolerance limit). The apparatus showed almost no speed variation over four consecutive trials. Four portable cassette players were also checked three times over ten days without any appreciable change in speed. Four cassette players (14%) were, however, found inaccurate making it necessary to possess a rapid method of checking speed accuracy. Similar or better results were found for open reel tape recorders.