Luna and hemithirds: Difference between revisions

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m added some intervals of 125
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| 194.4
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| 28/25
| 28/25, 125/112
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| 2
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| 49/25
| 49/25, 125/64
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| 7
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Revision as of 17:17, 1 April 2025

This page on a regular temperament, temperament collection, or aspect of regular temperament theory is being revised for clarity as part of WikiProject TempClean.

The 7-limit hemithirds temperament functions as a strong extension of didacus, the 2.5.7 subgroup temperament, in the range between 25edo and 31edo tuning, defined by tempering out 3136/3125 such that two of its generators (hemithird, ~28/25, around 193.2 cents) reach ~5/4, three reach ~7/5, and therefore five reach ~7/4. Hemithirds extends didacus by tempering out 1029/1024, such that three intervals of ~8/7 reach ~3/2, therefore finding ~4/3 after fifteen generators in total. The canonical extension to the 13-limit tempers out 385/384 and 441/440 to reach ~55/32 at four ~8/7s and therefore ~11/8 at 22 generators down, and then 1001/1000 to interpret the generator as ~143/128 and find ~13/8 at 23 generators up.

Luna is a restriction of hemithirds to the 5-limit that is a microtemperament, supported by such high-precision tuning systems as 118edo and 441edo; another notable tuning of luna is 1000edo. It can further be re-extended to the 7-limit in the form of lunatic by adding 4375/4374 to the comma list, but that extension is extremely complex (finding the 7th harmonic at 113 generators down).

See Hemimean clan #Hemithirds and Luna family #Luna for more information.

Intervals

In the following table, odd harmonics and subharmonics 1–35 are labeled in bold.

# Cents* Approximate ratios
Intervals of extensions
Hemithirds
0 0.0 1/1
1 194.4 28/25, 125/112
2 388.9 5/4
3 583.3 7/5
4 777.7 25/16
5 972.1 7/4
6 1166.6 49/25, 125/64
7 161.0 35/32
8 355.4 49/40, 128/105
9 549.9 175/128
10 744.3 32/21, 49/32
11 938.7 128/75
12 1133.1 40/21
13 127.6 16/15
14 322.0 25/21
15 516.4 4/3
16 710.8 112/75
17 905.3 5/3
18 1099.7 28/15
19 94.1 25/24

* In CWE undecimal didacus

Chords

Tuning spectrum

Gencom: [2 28/25; 196/195 352/351 385/384 625/624]

Gencom mapping: [1 4 2 2 7 0], 0 -15 2 5 -22 23]]

Eigenmonzo
(Unchanged-interval)
Generator
(¢)
Comments
14/13 192.872
12/11 192.948
15/11 192.995
13/10 193.058
16/13 193.066
13/11 193.094
15/13 193.118
13/12 193.120
11/8 193.122
11/10 193.125
18/13 193.144
5/4 193.157
6/5 193.198 5-odd-limit minimax
10/9 193.200
4/3 193.203
16/15 193.210
14/11 193.241 11-odd-limit minimax
9/7 193.283 9-odd-limit minimax
7/6 193.344 7-odd-limit minimax
15/14 193.364
11/9 193.426
8/7 193.765
7/5 194.171