91edt

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← 90edt91edt92edt →
Prime factorization 7 × 13
Step size 20.9006¢ 
Octave 57\91edt (1191.33¢)
Consistency limit 2
Distinct consistency limit 2

91 equal divisions of the tritave, perfect twelfth, or 3rd harmonic (abbreviated 91edt or 91ed3), is a nonoctave tuning system that divides the interval of 3/1 into 91 equal parts of about 20.9 ¢ each. Each step represents a frequency ratio of 31/91, or the 91st root of 3.

Intervals

Steps Cents Approximate Ratios
0 0 1/1
1 20.901
2 41.801
3 62.702
4 83.602
5 104.503
6 125.404 29/27
7 146.304 37/34
8 167.205
9 188.105 39/35
10 209.006 35/31
11 229.907
12 250.807
13 271.708
14 292.608
15 313.509 6/5
16 334.41
17 355.31 27/22
18 376.211 41/33
19 397.111 34/27, 39/31
20 418.012
21 438.913
22 459.813
23 480.714 29/22
24 501.615
25 522.515 23/17
26 543.416 37/27
27 564.316 18/13
28 585.217 7/5
29 606.118 27/19
30 627.018 33/23
31 647.919
32 668.819
33 689.72
34 710.621
35 731.521 29/19
36 752.422 17/11
37 773.322
38 794.223
39 815.124
40 836.024 34/21
41 856.925
42 877.825
43 898.726 37/22, 42/25
44 919.627
45 940.527 31/18
46 961.428
47 982.328 37/21
48 1003.229 25/14, 41/23
49 1024.13 38/21
50 1045.03
51 1065.931
52 1086.831
53 1107.732
54 1128.633
55 1149.533 33/17, 35/18
56 1170.434
57 1191.334
58 1212.235
59 1233.136
60 1254.036 31/15
61 1274.937 23/11
62 1295.837 19/9
63 1316.738 15/7
64 1337.639 13/6
65 1358.539
66 1379.44
67 1400.34
68 1421.241
69 1442.142
70 1463.042
71 1483.943
72 1504.844 31/13
73 1525.744 41/17
74 1546.645 22/9
75 1567.545
76 1588.446 5/2
77 1609.347 38/15
78 1630.247
79 1651.148
80 1672.048
81 1692.949
82 1713.85 35/13
83 1734.75
84 1755.651
85 1776.551
86 1797.452
87 1818.353
88 1839.253
89 1860.154
90 1881.054
91 1901.955 3/1

Harmonics

Approximation of harmonics in 91edt
Harmonic 2 3 4 5 6 7 8 9 10 11 12
Error Absolute (¢) -8.67 +0.00 +3.57 -6.53 -8.67 -3.83 -5.10 +0.00 +5.70 +7.90 +3.57
Relative (%) -41.5 +0.0 +17.1 -31.3 -41.5 -18.3 -24.4 +0.0 +27.3 +37.8 +17.1
Steps
(reduced)
57
(57)
91
(0)
115
(24)
133
(42)
148
(57)
161
(70)
172
(81)
182
(0)
191
(9)
199
(17)
206
(24)
Approximation of harmonics in 91edt
Harmonic 13 14 15 16 17 18 19 20 21 22 23
Error Absolute (¢) -9.60 +8.41 -6.53 +7.14 +6.69 -8.67 +2.23 -2.96 -3.83 -0.76 +5.88
Relative (%) -45.9 +40.2 -31.3 +34.2 +32.0 -41.5 +10.7 -14.2 -18.3 -3.7 +28.1
Steps
(reduced)
212
(30)
219
(37)
224
(42)
230
(48)
235
(53)
239
(57)
244
(62)
248
(66)
252
(70)
256
(74)
260
(78)