26edo

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Revision as of 03:12, 7 March 2026 by Lumithesilly (talk | contribs) (added steps to the thirds table)
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26edo, or 26 equal divisions of the octave, is the equal tuning featuring steps of (1200/26) ~= 46.15 cents, 26 of which stack to the perfect octave 2/1.

Theory

JI approximation

26edo is characterized by a flat tuning of harmonics 3, 5, and 13 and slightly sharp but accurate tunings of 7 and 11. Although its primes 3, 5, and 13 are damaged, 26edo can be used as a 13-limit temperament as it is consistent to the 13-odd-limit. Additionally, the fact that primes 3 and 13 are flat by about the same amount and 5 is flat by about double that means that intervals such as 13/12 and 10/9 are approximated well. The accurate 7 combined with the flat 5 means that 7/5 and 10/7 are both mapped to the 600¢ half octave tritone, tempering out 50/49. 16/13 and 11/9 are mapped to the same interval as 5/4, tempering out 65/64, 144/143, and 45/44.


Approximation of prime harmonics in 26edo
Harmonic 2 3 5 7 11 13 17 19 23 29 31
Error Absolute (¢) 0.0 -9.6 -17.1 +0.4 +2.5 -9.8 -12.6 -20.6 +17.9 -14.2 +8.8
Relative (%) 0.0 -20.9 -37.0 +0.9 +5.5 -21.1 -27.4 -44.6 +38.7 -30.8 +19.1
Steps

(reduced)

26

(0)

41

(15)

60

(8)

73

(21)

90

(12)

96

(18)

106

(2)

110

(6)

118

(14)

126

(22)

129

(25)

Edostep interpretations

26edo's edostep has the following 13-limit interpretations:

  • 25/24 (the difference between 5/4 and 6/5)
  • 33/32 (the difference between 4/3 and 11/8)
  • 36/35 (the difference between 5/4 and 9/7)
  • 49/48 (the difference between 8/7 and 7/6)

Intervals and notation

Similar to 19edo, 26edo can be notated entirely with standard diatonic notation, with #/b = 1\26 and x/bb = 2\26. The equivalences are Cx = Dbb, E# = Fbb, and Ex = Fb.


Compositional theory

Thirds in 26edo
Quality Farminor Supraminor Submajor Farmajor
Cents 277 323.1 369.2 415.4
Just interpretation 7/6 6/5 5/4, 16/13 14/11, 9/7
Steps 6 7 8 9

Chords

This page or section is a work in progress. It may lack sufficient justification, content, or organization, and is subject to future overhaul.

TODO:

  • write about flattone

Scales

This page or section is a work in progress. It may lack sufficient justification, content, or organization, and is subject to future overhaul.


ViewTalkEditEqual temperaments
EDOs
Macrotonal 57891011
12-23 121314151617181920212223
24-35 242526272931323435
36-47 36373940414344454647
48-59 4850515354565758
60-71 60636465676870
72-83 72778081
84-95 848789909394
Large EDOs 99104111118130140152159171217224239270306311612665
Nonoctave equal temperaments
Tritave 4913172639
Fifth 891120
Other