Diapason

Diapason may refer to:


 * Diapason (interval), the name of the just octave in Pythagorean tuning
 * Diapason (pipe organ), a tonal grouping of the flue pipes of a pipe organ
 * Diapason (magazine), a French classical music magazine
 * The Diapason (magazine), an American magazine for organ builders and players
 * Diapason normal, the official French standard of concert pitch
 * Diapason, a 1978 novel by Thomas Sullivan