21ed5/4

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← 20ed5/421ed5/422ed5/4 →
Prime factorization 3 × 7
Step size 18.3959¢ 
Octave 65\21ed5/4 (1195.73¢)
Twelfth 103\21ed5/4 (1894.78¢)
Consistency limit 4
Distinct consistency limit 2

21 equal divisions of 5/4 (abbreviated 21ed5/4) is a nonoctave tuning system that divides the interval of 5/4 into 21 equal parts of about 18.4 ¢ each. Each step represents a frequency ratio of (5/4)1/21, or the 21st root of 5/4.

Intervals

Steps Cents Approximate Ratios
0 0 1/1
1 18.396
2 36.792
3 55.188
4 73.584 23/22, 25/24
5 91.979 21/20, 22/21
6 110.375 15/14, 16/15
7 128.771 14/13
8 147.167 13/12
9 165.563 21/19, 23/21
10 183.959 10/9, 19/17
11 202.355 9/8
12 220.751 8/7
13 239.147 15/13
14 257.542 22/19
15 275.938 7/6, 13/11
16 294.334 25/21
17 312.73 6/5
18 331.126 23/19
19 349.522 16/13, 17/14
20 367.918
21 386.314 5/4

Harmonics

Approximation of harmonics in 21ed5/4
Harmonic 2 3 4 5 6 7 8 9 10 11 12
Error Absolute (¢) -4.27 -7.18 -8.53 -8.53 +6.95 -2.38 +5.59 +4.04 +5.59 +6.15 +2.68
Relative (%) -23.2 -39.0 -46.4 -46.4 +37.8 -12.9 +30.4 +22.0 +30.4 +33.5 +14.6
Steps
(reduced)
65
(2)
103
(19)
130
(4)
151
(4)
169
(1)
183
(15)
196
(7)
207
(18)
217
(7)
226
(16)
234
(3)
Approximation of harmonics in 21ed5/4
Harmonic 13 14 15 16 17 18 19 20 21 22 23
Error Absolute (¢) -7.12 -6.64 +2.68 +1.33 +6.75 -0.23 -1.85 +1.33 +8.84 +1.89 -1.49
Relative (%) -38.7 -36.1 +14.6 +7.2 +36.7 -1.2 -10.1 +7.2 +48.1 +10.3 -8.1
Steps
(reduced)
241
(10)
248
(17)
255
(3)
261
(9)
267
(15)
272
(20)
277
(4)
282
(9)
287
(14)
291
(18)
295
(1)