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The equal division of 9/2 (ed9/2) is a tuning obtained by dividing two octaves and a Pythagorean major second (9/2) into a number of equal steps.


Division of 9/2 into equal parts does not necessarily imply directly using this interval as an equivalence. The question of equivalence has not even been posed yet. Many, though not all, of these scales have a perceptually important false octave, with various degrees of accuracy.

Incidentally, one way to treat 9/2 as an equivalence is the use of the 9:10:14 chord as the fundamental complete sonority in a very similar way to the 4:5:6:(8) chord in meantone. Whereas in meantone it takes four 3/2 to get to 5/1, here it takes seven 14/9 to get to 10/9 (tempering out the comma 215233605/210827008 in the 9/2.5.7 fractional subgroup). This temperament yields 7-, 10-, 17-, and 27-note mos scales.