101ed7

Revision as of 10:49, 27 May 2025 by FloraC (talk | contribs) (Theory: +subsets and supersets)
← 100ed7 101ed7 102ed7 →
Prime factorization 101 (prime)
Step size 33.3547 ¢ 
Octave 36\101ed7 (1200.77 ¢)
Twelfth 57\101ed7 (1901.22 ¢)
Consistency limit 8
Distinct consistency limit 8

101 equal divisions of the 7th harmonic (abbreviated 101ed7) is a nonoctave tuning system that divides the interval of 7/1 into 101 equal parts of about 33.4 ¢ each. Each step represents a frequency ratio of 71/101, or the 101st root of 7.

Theory

101ed7 is closely related to 36edo (sixth-tone tuning), but with the 7th harmonic rather than the octave being just. The octave is stretched by about 1.23 cents. Like 36edo, 101ed7 is consistent to the 8-integer-limit.

Compared to 36edo, 101ed7's harmonics are almost exactly the same, but it has a slightly better 3/1, 7/1, and 13/1, and a slightly worse 2/1 and 5/1 versus 36edo. Overall this means 36edo is still better in the 5-limit, but 101ed7 is better in the 13-limit. (The 7-limit and 11-limit could go either way.)

36edo's 5-limit dominance flips on its head, though, if one approaches it as a dual-5 tuning. In that case, the fact that 101ed7's 5/1 is closer to 50% relative error is actually a good thing, because it means the error on the worse of the two 5/1's is less. So as a single-5 5-limit tuning, 36edo is better. But as a dual-5 5-limit tuning, 101ed7 is better, and as a dual-5, dual-11 31-limit tuning, 101ed7 is exceptional for its size. It is very accurate.

Harmonics

Approximation of harmonics in 101ed7
Harmonic 2 3 4 5 6 7 8 9 10 11 12
Error Absolute (¢) +0.8 -0.7 +1.5 +15.5 +0.0 +0.0 +2.3 -1.5 +16.3 -15.3 +0.8
Relative (%) +2.3 -2.2 +4.6 +46.4 +0.1 +0.0 +6.9 -4.4 +48.7 -46.0 +2.4
Steps
(reduced)
36
(36)
57
(57)
72
(72)
84
(84)
93
(93)
101
(0)
108
(7)
114
(13)
120
(19)
124
(23)
129
(28)
Approximation of harmonics in 101ed7 (continued)
Harmonic 13 14 15 16 17 18 19 20 21 22 23 24
Error Absolute (¢) -4.4 +0.8 +14.7 +3.1 -1.8 -0.7 +5.8 -16.3 -0.7 -14.6 +8.5 +1.6
Relative (%) -13.0 +2.3 +44.2 +9.2 -5.4 -2.1 +17.3 -49.0 -2.2 -43.7 +25.6 +4.7
Steps
(reduced)
133
(32)
137
(36)
141
(40)
144
(43)
147
(46)
150
(49)
153
(52)
155
(54)
158
(57)
160
(59)
163
(62)
165
(64)

Subsets and supersets

101ed7 is the 26th prime ed7, so it does not contain any nontrivial subset ed7's.

Intervals

Steps Cents Approximate ratios
0 0 1/1
1 33.4
2 66.7 27/26
3 100.1 18/17
4 133.4 41/38
5 166.8 43/39
6 200.1 37/33
7 233.5 8/7
8 266.8 7/6
9 300.2 44/37
10 333.5
11 366.9 21/17
12 400.3 29/23, 34/27
13 433.6 9/7
14 467 38/29
15 500.3 4/3
16 533.7
17 567 43/31
18 600.4 41/29
19 633.7
20 667.1
21 700.4 3/2
22 733.8 26/17, 29/19
23 767.2 14/9
24 800.5 27/17
25 833.9 34/21
26 867.2 38/23
27 900.6 32/19, 37/22
28 933.9 12/7
29 967.3 7/4
30 1000.6 41/23
31 1034
32 1067.4
33 1100.7 17/9
34 1134.1
35 1167.4
36 1200.8 2/1
37 1234.1
38 1267.5 27/13
39 1300.8 36/17
40 1334.2
41 1367.5
42 1400.9
43 1434.3
44 1467.6 7/3
45 1501
46 1534.3 17/7
47 1567.7 42/17
48 1601
49 1634.4 18/7
50 1667.7
51 1701.1
52 1734.4
53 1767.8
54 1801.2 17/6
55 1834.5 26/9
56 1867.9
57 1901.2 3/1
58 1934.6
59 1967.9
60 2001.3
61 2034.6
62 2068
63 2101.3 37/11
64 2134.7 24/7
65 2168.1 7/2
66 2201.4
67 2234.8
68 2268.1
69 2301.5 34/9
70 2334.8 27/7
71 2368.2
72 2401.5 4/1
73 2434.9
74 2468.2
75 2501.6
76 2535
77 2568.3
78 2601.7 9/2
79 2635
80 2668.4 14/3
81 2701.7
82 2735.1 34/7
83 2768.4
84 2801.8
85 2835.2 36/7
86 2868.5 21/4
87 2901.9
88 2935.2
89 2968.6
90 3001.9 17/3
91 3035.3
92 3068.6
93 3102 6/1
94 3135.3
95 3168.7
96 3202.1
97 3235.4
98 3268.8
99 3302.1
100 3335.5
101 3368.8 7/1

See also