20edf

From Xenharmonic Wiki
Jump to navigation Jump to search
← 19edf20edf21edf →
Prime factorization 22 × 5
Step size 35.0978¢
Octave 34\20edf (1193.32¢) (→17\10edf)
Twelfth 54\20edf (1895.28¢) (→27\10edf)
Consistency limit 7
Distinct consistency limit 6

Intervals

The first steps up to two just perfect fifths should give a feeling of the granularity of this system…

Degrees
1 35.1
2 70.2
3 105.29
4 140.39
5 175.49
6 210.59
7 245.68
8 280.78
9 315.88
10 350.98
11 386.075
12 421.17
13 456.27
14 491.37
15 526.47
16 561.56
17 596.66
18 631.76
19 666.86
20 701.955
21 737.05
22 772.15
23 807.25
24 842.35
25 877.44
26 912.54
27 947.64
28 982.74
29 1017.835
30 1052.93
31 1088.03
32 1123.13
33 1158.23
34 1193.32
35 1228.42
36 1263.52
37 1298.62
38 1333.715
39 1368.81
40 1403.91

Scale tree

If 4\7 (four degrees of 7EDO) is at one extreme and 3\5 (three degrees of 5EDO) is at the other, all other possible 5L 2s scales exist in a continuum between them. You can chop this continuum up by taking "freshman sums" of the two edges - adding together the numerators, then adding together the denominators (i.e. adding them together as if you would be adding the complex numbers analogous real and imaginary parts). Thus, between 4\7 and 3\5 you have (4+3)\(7+5) = 7\12, seven degrees of 12EDO.

If we carry this freshman-summing out a little further, new, larger EDOs pop up in our continuum.

Generator range: 34.28571 cents (4\7/20 = 1\35) to 36 cents (3\5/20 = 3/100)

Fifth Cents Comments
4\7 34.2857
27\47 34.4681
23\40 34.5000
42\73 34.52055
19\33 34.54
53\92 34.5652
34\59 34.5763
49\85 34.5882
15\26 34.6153
56\97 34.6392
41\71 34.6479
67\116 34.6551
26\45 34.6 Flattone is in this region
63\109 34.6789
37\64 34.6875
48\83 34.6988
11\19 34.7368 The generator closest to a just 11/9 for EDOs less than 2000
51\88 34.772
40\69 34.7826
69\119 34.7899
29\50 34.8000
76\131 34.8092 Golden meantone (696.2145¢)
47\81 34.814
65\112 34.8214
18\31 34.8387 Meantone is in this region
61\105 34.8571
43\74 34.864
68\117 34.8718
25\43 34.8837
57\98 34.8980
32\55 34.90
39\67 34.9254
7\12 35.0000
38\65 35.0769
31\53 35.0843 The fifth closest to a just 3/2 for EDOs less than 200
55\94 35.1064 Garibaldi / Cassandra
24\41 35.12195
65\111 35.135
41\70 35.1429
58\99 35.15
17\29 35.1724
61\104 35.1923
44\75 35.2000
71\121 35.2066 Golden neogothic (704.0956¢)
27\46 35.2174 Neogothic is in this region
64\109 35.2294
37\63 35.2381
47\80 35.2500
10\17 35.2941
43\73 35.3425
33\56 35.3571
56\95 35.3684
23\39 35.3846
59\100 35.4000
36\61 35.4098
49\83 35.4217
13\22 35.45 Archy is in this region
42\71 35.4930
29\49 35.5102
45\76 35.5263
16\27 35.5
35\59 35.5932
19\32 35.6250
22\37 35.675
3\5 36.0000

Tunings above 7\12 on this chart are called "negative tunings" (as they lessen the size of the fifth) and include meantone systems such as 1/3-comma (close to 11\19) and 1/4-comma (close to 18\31). As these tunings approach 4\7, the majors become flatter and the minors become sharper.

Tunings below 7\12 on this chart are called "positive tunings" and they include Pythagorean tuning itself (well approximated by 31\53) as well as superpyth tunings such as 10\17 and 13\22. As these tunings approach 3\5, the majors become sharper and the minors become flatter. Around 13\22 through 16\27, the thirds fall closer to 7-limit than 5-limit intervals: 7:6 and 9:7 as opposed to 6:5 and 5:4.