18L 9s is a 2/1-equivalent (octave-equivalent) moment of symmetry scale containing 18 large steps and 9 small steps, with a period of 2 large steps and 1 small step that repeats every 133.3 ¢, or 9 times every octave. 18L 9s is a child scale of 9L 9s, expanding it by 9 tones. Generators that produce this scale range from 44.4 ¢ to 66.7 ¢, or from 66.7 ¢ to 88.9 ¢. Scales of the true MOS form, where every period is the same, are proper because there is only one small step per period.

↖ 17L 8s ↑ 18L 8s 19L 8s ↗
← 17L 9s 18L 9s 19L 9s →
↙ 17L 10s ↓ 18L 10s 19L 10s ↘
Scale structure
Step pattern LLsLLsLLsLLsLLsLLsLLsLLsLLs
sLLsLLsLLsLLsLLsLLsLLsLLsLL
Equave 2/1 (1200.0 ¢)
Period 1\9 (133.3 ¢)
Generator size
Bright 1\27 to 1\18 (44.4 ¢ to 66.7 ¢)
Dark 1\18 to 2\27 (66.7 ¢ to 88.9 ¢)
TAMNAMS information
Related to 9L 9s
With tunings 1:1 to 2:1 (soft-of-basic)
Related MOS scales
Parent 9L 9s
Sister 9L 18s
Daughters 27L 18s, 18L 27s
Neutralized 9L 18s
2-Flought 45L 9s, 18L 36s
Equal tunings
Equalized (L:s = 1:1) 1\27 (44.4 ¢)
Supersoft (L:s = 4:3) 4\99 (48.5 ¢)
Soft (L:s = 3:2) 3\72 (50.0 ¢)
Semisoft (L:s = 5:3) 5\117 (51.3 ¢)
Basic (L:s = 2:1) 2\45 (53.3 ¢)
Semihard (L:s = 5:2) 5\108 (55.6 ¢)
Hard (L:s = 3:1) 3\63 (57.1 ¢)
Superhard (L:s = 4:1) 4\81 (59.3 ¢)
Collapsed (L:s = 1:0) 1\18 (66.7 ¢)
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This MOS scale is associated with ennealimmal temperament.

Scale properties

This article uses TAMNAMS conventions for the names of this scale's intervals and scale degrees. The use of 1-indexed ordinal names is reserved for interval regions.
  Template:MOS data is deprecated.

Details: Please use the following templates individually: MOS intervals, MOS genchain, and MOS mode degrees

Scale tree

Scale tree and tuning spectrum of 18L 9s
Generator(edo) Cents Step ratio Comments(always proper)
Bright Dark L:s Hardness
1\27 44.444 88.889 1:1 1.000 Equalized 18L 9s
6\153 47.059 86.275 6:5 1.200
5\126 47.619 85.714 5:4 1.250
9\225 48.000 85.333 9:7 1.286
4\99 48.485 84.848 4:3 1.333 Supersoft 18L 9s
11\270 48.889 84.444 11:8 1.375
7\171 49.123 84.211 7:5 1.400
10\243 49.383 83.951 10:7 1.429
3\72 50.000 83.333 3:2 1.500 Soft 18L 9s
11\261 50.575 82.759 11:7 1.571
8\189 50.794 82.540 8:5 1.600
13\306 50.980 82.353 13:8 1.625
5\117 51.282 82.051 5:3 1.667 Semisoft 18L 9s
12\279 51.613 81.720 12:7 1.714
7\162 51.852 81.481 7:4 1.750
9\207 52.174 81.159 9:5 1.800
2\45 53.333 80.000 2:1 2.000 Basic 18L 9s
9\198 54.545 78.788 9:4 2.250
7\153 54.902 78.431 7:3 2.333
12\261 55.172 78.161 12:5 2.400
5\108 55.556 77.778 5:2 2.500 Semihard 18L 9s
13\279 55.914 77.419 13:5 2.600
8\171 56.140 77.193 8:3 2.667
11\234 56.410 76.923 11:4 2.750
3\63 57.143 76.190 3:1 3.000 Hard 18L 9s
10\207 57.971 75.362 10:3 3.333
7\144 58.333 75.000 7:2 3.500
11\225 58.667 74.667 11:3 3.667
4\81 59.259 74.074 4:1 4.000 Superhard 18L 9s
9\180 60.000 73.333 9:2 4.500
5\99 60.606 72.727 5:1 5.000
6\117 61.538 71.795 6:1 6.000
1\18 66.667 66.667 1:0 → ∞ Collapsed 18L 9s
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