Island chords: Difference between revisions
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'''Island chords''' are [[ | '''Island chords''' are [[dyadic chord|essentially tempered chords]] tempered by the island comma, [[676/675]]. | ||
There are 9 triads, 37 tetrads, 51 pentads, 29 hexads and 6 heptads as 2.3.5.13 subgroup [[15-odd-limit]] essentially tempered chords. | There are 9 triads, 37 tetrads, 51 pentads, 29 hexads and 6 heptads as 2.3.5.13 subgroup [[15-odd-limit]] essentially tempered chords. | ||
Line 6: | Line 6: | ||
The palindromic triad consists of two [[semifourth]]s and one [[perfect fifth]], splitting a fourth in two: | The palindromic triad consists of two [[semifourth]]s and one [[perfect fifth]], splitting a fourth in two: | ||
* | * 1–15/13–4/3 with steps of 15/13, 15/13, 3/2. | ||
The inversely related pairs of chords are | The inversely related pairs of chords are | ||
* | * 1–5/4–13/9 with steps of 5/4, 15/13, 18/13, and its inverse | ||
* | * 1–15/13–13/9 with steps of 15/13, 5/4, 18/13; | ||
* | * 1–13/10–18/13 with steps of 13/10, 16/15, 13/9, and its inverse | ||
* | * 1–16/15–18/13 with steps of 16/15, 13/10, 13/9; | ||
* | * 1–15/13–13/10 with steps of 15/13, 9/8, 20/13, and its inverse | ||
* | * 1–9/8–13/10 with steps of 9/8, 15/13, 20/13; | ||
* | * 1–13/12–15/13 with steps of 13/12, 16/15, 26/15, and its inverse | ||
* | * 1–16/15–15/13 with steps of 13/12, 16/15, 26/15. | ||
For tetrads, there are seven palindromic chords and fifteen pairs of chords in inverse relationship. | For tetrads, there are seven palindromic chords and fifteen pairs of chords in inverse relationship. | ||
One of the palindromic tetrads consists of three semifourths and one [[semisixth]], | One of the palindromic tetrads consists of three semifourths and one [[semisixth]], | ||
* | * 1–13/10–3/2–26/15 with steps of 13/10, 15/13, 15/13, 15/13. | ||
Aside from above, the following palindromic tetrad also contains a | Aside from above, the following palindromic tetrad also contains a barbados triad (otonal [[10:13:15|1–13/10–3/2]] chord) and its inversion (utonal [[26:30:39|1–15/13–3/2]] chord), | ||
* | * 1–15/13–13/10–3/2 with steps of 15/13, 9/8, 15/13, 4/3. | ||
The rest five palindromic tetrads are | The rest five palindromic tetrads are | ||
* | * 1–15/13–13/9–5/3 with steps of 15/13, 5/4, 15/13, 6/5; | ||
* | * 1–10/9–13/9–20/13 with steps of 10/9, 13/10, 16/15, 13/10; | ||
* | * 1–15/13–5/4–13/9 with steps of 15/13, 13/12, 15/13, 18/13; | ||
* | * 1–13/12–15/13–5/4 with steps of 13/12, 16/15, 13/12, 8/5; | ||
* | * 1–16/15–15/13–16/13 with steps of 16/15, 13/12, 16/15, 13/8. | ||
The inversely related pairs of chords are | The inversely related pairs of chords are | ||
* | * 1–9/8–13/10–13/8 with steps of 9/8, 15/13, 5/4, 16/13, and its inverse | ||
* | * 1–5/4–13/9–13/8 with steps of 5/4, 15/13, 9/8, 16/13; | ||
* | * 1–5/4–3/2–26/15 with steps of 5/4, 6/5, 15/13, 15/13, and its inverse | ||
* | * 1–6/5–3/2–26/15 with steps of 6/5, 5/4, 15/13, 15/13; | ||
* | * 1–5/4–13/9–20/13 with steps of 5/4, 15/13, 16/15, 13/10, and its inverse | ||
* | * 1–5/4–13/8–26/15 with steps of 5/4, 13/10, 16/15, 15/13; | ||
* | * 1–13/10–3/2–15/8 with steps of 13/10, 15/13, 5/4, 16/15, and its inverse | ||
* | * 1–15/13–3/2–8/5 with steps of 15/13, 13/10, 16/15, 5/4; | ||
* | * 1–13/10–18/13–3/2 with steps of 13/10, 16/15, 13/12, 4/3, and its inverse | ||
* | * 1–13/12–15/13–3/2 with steps of 13/12, 16/15, 13/10, 4/3; | ||
* | * 1–15/13–4/3–3/2 with steps of 15/13, 15/13, 9/8, 4/3, and its inverse | ||
* | * 1–9/8–13/10–3/2 with steps of 9/8, 15/13, 15/13, 4/3; | ||
* | * 1–18/13–3/2–8/5 with steps of 18/13, 13/12, 16/15, 5/4, and its inverse | ||
* | * 1–13/12–3/2–15/8 with steps of 13/12, 18/13, 5/4, 16/15; | ||
* | * 1–15/13–13/10–13/9 with steps of 15/13, 9/8, 10/9, 18/13, and its inverse | ||
* | * 1–10/9–5/4–13/9 with steps of 10/9, 9/8, 15/13, 18/13; | ||
* | * 1–18/13–3/2–26/15 with steps of 18/13, 13/12, 15/13, 15/13, and its inverse | ||
* | * 1–13/12–3/2–26/15 with steps of 13/12, 18/13, 15/13, 15/13; | ||
* | * 1–6/5–13/10–18/13 with steps of 6/5, 13/12, 16/15, 13/9, and its inverse | ||
* | * 1–16/15–15/13–18/13 with steps of 16/15, 13/12, 6/5, 13/9; | ||
* | * 1–15/13–13/10–18/13 with steps of 15/13, 9/8, 16/15, 13/9, and its inverse | ||
* | * 1–16/15–6/5–18/13 with steps of 16/15, 9/8, 15/13, 13/9; | ||
* | * 1–9/8–13/10–18/13 with steps of 9/8, 15/13, 16/15, 13/9, and its inverse | ||
* | * 1–16/15–16/13–18/13 with steps of 16/15, 15/13, 9/8, 13/9; | ||
* | * 1–15/13–16/13–4/3 with steps of 15/13, 16/15, 13/12, 3/2, and its inverse | ||
* | * 1–13/12–15/13–4/3 with steps of 13/12, 16/15, 15/13, 3/2; | ||
* | * 1–15/13–5/4–4/3 with steps of 15/13, 13/12, 16/15, 3/2, and its inverse | ||
* | * 1–16/15–15/13–4/3 with steps of 16/15, 13/12, 15/13, 3/2; | ||
* | * 1–9/8–6/5–13/10 with steps of 9/8, 16/15, 13/12, 20/13, and its inverse | ||
* | * 1–13/12–15/13–13/10 with steps of 13/12, 16/15, 9/8, 20/13. | ||
For pentads, there are one palindromic chord and twenty-five pairs of chords in inverse relationship. | For pentads, there are one palindromic chord and twenty-five pairs of chords in inverse relationship. | ||
The palindromic pentad consists of four semifourths and one [[whole tone]], | The palindromic pentad consists of four semifourths and one [[whole tone]], | ||
* | * 1–9/8–13/10–3/2–26/15 with steps of 9/8, 15/13, 15/13, 15/13, 15/13. | ||
The inversely related pairs of chords are | The inversely related pairs of chords are | ||
* | * 1–6/5–18/13–3/2–26/15 with steps of 6/5, 15/13, 13/12, 15/13, 15/13, and its inverse | ||
* | * 1–13/12–5/4–3/2–26/15 with steps of 13/12, 15/13, 6/5, 15/13, 15/13; | ||
* | * 1–9/8–5/4–3/2–26/15 with steps of 9/8, 10/9, 6/5, 15/13, 15/13, and its inverse | ||
* | * 1–6/5–4/3–3/2–26/15 with steps of 6/5, 10/9, 9/8, 15/13, 15/13; | ||
* | * 1–6/5–18/13–3/2–26/15 with steps of 6/5, 13/12, 15/13, 15/13, 15/13, and its inverse | ||
* | * 1–15/13–5/4–3/2–26/15 with steps of 15/13, 13/12, 6/5, 15/13, 15/13; | ||
* | * 1–9/8–18/13–3/2–26/15 with steps of 9/8, 16/13, 13/12, 15/13, 15/13, and its inverse | ||
* | * 1–9/8–13/10–3/2–13/8 with steps of 9/8, 15/13, 15/13, 13/12, 16/13; | ||
* | * 1–5/4–3/2–8/5–26/15 with steps of 5/4, 6/5, 16/15, 13/12, 15/13, and its inverse | ||
* | * 1–6/5–3/2–26/15–15/8 with steps of 6/5, 5/4, 15/13, 13/12, 16/15; | ||
* | * 1–5/4–3/2–13/8–26/15 with steps of 5/4, 6/5, 13/12, 16/15, 15/13, and its inverse | ||
* | * 1–6/5–3/2–26/15–24/13 with steps of 6/5, 5/4, 15/13, 16/15, 13/12; | ||
* | * 1–15/13–13/9–5/3–15/8 with steps of 15/13, 5/4, 15/13, 9/8, 16/15, and its inverse | ||
* | * 1–9/8–13/10–13/8–15/8 with steps of 9/8, 15/13, 5/4, 15/13, 16/15; | ||
* | * 1–15/13–18/13–3/2–8/5 with steps of 15/13, 6/5, 13/12, 16/15, 5/4, and its inverse | ||
* | * 1–13/12–13/10–3/2–15/8 with steps of 13/12, 6/5, 15/13, 5/4, 16/15; | ||
* | * 1–5/4–4/3–3/2–26/15 with steps of 5/4, 16/15, 9/8, 15/13, 15/13, and its inverse | ||
* | * 1–9/8–6/5–3/2–26/15 with steps of 9/8, 16/15, 5/4, 15/13, 15/13; | ||
* | * 1–15/13–13/10–3/2–15/8 with steps of 15/13, 9/8, 15/13, 5/4, 16/15, and its inverse | ||
* | * 1–15/13–13/10–3/2–8/5 with steps of 15/13, 9/8, 15/13, 16/15, 5/4; | ||
* | * 1–13/10–18/13–3/2–8/5 with steps of 13/10, 16/15, 13/12, 16/15, 5/4, and its inverse | ||
* | * 1–13/12–15/13–3/2–15/8 with steps of 13/12, 16/15, 13/10, 5/4, 16/15; | ||
* | * 1–13/10–18/13–3/2–9/5 with steps of 13/10, 16/15, 13/12, 6/5, 10/9, and its inverse | ||
* | * 1–13/12–15/13–3/2–5/3 with steps of 13/12, 16/15, 13/10, 10/9, 6/5; | ||
* | * 1–9/8–5/4–13/8–26/15 with steps of 9/8, 10/9, 13/10, 16/15, 15/13, and its inverse | ||
* | * 1–15/13–16/13–8/5–16/9 with steps of 15/13, 16/15, 13/10, 10/9, 9/8; | ||
* | * 1–13/10–3/2–13/8–26/15 with steps of 13/10, 15/13, 13/12, 16/15, 15/13, and its inverse | ||
* | * 1–13/10–3/2–8/5–26/15 with steps of 13/10, 15/13, 16/15, 13/12, 15/13; | ||
* | * 1–13/10–3/2–26/15–15/8 with steps of 13/10, 15/13, 15/13, 13/12, 16/15, and its inverse | ||
* | * 1–13/10–18/13–3/2–26/15 with steps of 13/10, 16/15, 13/12, 15/13, 15/13; | ||
* | * 1–13/10–3/2–13/8–15/8 with steps of 13/10, 15/13, 13/12, 15/13, 16/15, and its inverse | ||
* | * 1–15/13–3/2–8/5–24/13 with steps of 15/13, 13/10, 16/15, 15/13, 13/12; | ||
* | * 1–6/5–13/10–18/13–3/2 with steps of 6/5, 13/12, 16/15, 13/12, 4/3, and its inverse | ||
* | * 1–13/12–15/13–5/4–3/2 with steps of 13/12, 16/15, 13/12, 6/5, 4/3; | ||
* | * 1–15/13–5/4–4/3–3/2 with steps of 15/13, 13/12, 16/15, 9/8, 4/3, and its inverse | ||
* | * 1–9/8–6/5–13/10–3/2 with steps of 9/8, 16/15, 13/12, 15/13, 4/3; | ||
* | * 1–9/8–13/10–18/13–3/2 with steps of 9/8, 15/13, 16/15, 13/12, 4/3, and its inverse | ||
* | * 1–13/12–15/13–4/3–3/2 with steps of 13/12, 16/15, 15/13, 9/8, 4/3; | ||
* | * 1–15/13–13/10–18/13–3/2 with steps of 15/13, 9/8, 16/15, 13/12, 4/3, and its inverse | ||
* | * 1–13/12–15/13–13/10–3/2 with steps of 13/12, 16/15, 9/8, 15/13, 4/3; | ||
* | * 1–18/13–3/2–8/5–26/15 with steps of 18/13, 13/12, 16/15, 13/12, 15/13, and its inverse | ||
* | * 1–13/12–3/2–26/15–15/8 with steps of 13/12, 18/13, 15/13, 13/12, 16/15; | ||
* | * 1–18/13–3/2–8/5–9/5 with steps of 18/13, 13/12, 16/15, 9/8, 10/9, and its inverse | ||
* | * 1–13/12–3/2–5/3–15/8 with steps of 13/12, 18/13, 10/9, 9/8, 16/15; | ||
* | * 1–13/12–3/2–13/8–15/8 with steps of 13/12, 18/13, 13/12, 15/13, 16/15, and its inverse | ||
* | * 1–13/12–3/2–13/8–26/15 with steps of 13/12, 18/13, 13/12, 16/15, 15/13; | ||
* | * 1–9/8–6/5–13/10–18/13 with steps of 9/8, 16/15, 13/12, 16/15, 13/9, and its inverse | ||
* | * 1–16/15–15/13–16/13–18/13 with steps of 16/15, 13/12, 16/15, 9/8, 13/9; | ||
* | * 1–13/12–15/13–5/4–4/3 with steps of 13/12, 16/15, 13/12, 16/15, 3/2, and its inverse | ||
* | * 1–16/15–15/13–16/13–4/3 with steps of 16/15, 13/12, 16/15, 13/12, 3/2. | ||
For hexads, there are three palindromic chords and thirteen pairs of chords in inverse relationship. The palindromic chords are | For hexads, there are three palindromic chords and thirteen pairs of chords in inverse relationship. The palindromic chords are | ||
* | * 1–13/12–5/4–3/2–26/15–15/8 with steps of 13/12, 15/13, 6/5, 15/13, 13/12, 16/15; | ||
* | * 1–13/12–15/13–5/4–3/2–5/3 with steps of 13/12, 16/15, 13/12, 6/5, 10/9, 6/5; | ||
* | * 1–13/12–3/2–13/8–26/15–15/8 with steps of 13/12, 18/13, 13/12, 16/15, 13/12, 16/15. | ||
The inversely related pairs of chords are | The inversely related pairs of chords are | ||
* | * 1–15/13–5/4–4/3–3/2–26/15 with steps of 15/13, 13/12, 16/15, 9/8, 15/13, 15/13, and its inverse | ||
* | * 1–9/8–6/5–13/10–3/2–26/15 with steps of 9/8, 16/15, 13/12, 15/13, 15/13, 15/13; | ||
* | * 1–9/8–13/10–3/2–13/8–26/15 with steps of 9/8, 15/13, 15/13, 13/12, 16/15, 15/13, and its inverse | ||
* | * 1–9/8–13/10–18/13–3/2–26/15 with steps of 9/8, 15/13, 16/15, 13/12, 15/13, 15/13; | ||
* | * 1–9/8–6/5–18/13–3/2–26/15 with steps of 9/8, 16/15, 15/13, 13/12, 15/13, 15/13, and its inverse | ||
* | * 1–13/12–5/4–4/3–3/2–26/15 with steps of 13/12, 15/13, 16/15, 9/8, 15/13, 15/13; | ||
* | * 1–6/5–4/3–3/2–8/5–26/15 with steps of 6/5, 10/9, 9/8, 16/15, 13/12, 15/13, and its inverse | ||
* | * 1–9/8–5/4–3/2–26/15–15/8 with steps of 9/8, 10/9, 6/5, 15/13, 13/12, 16/15; | ||
* | * 1–6/5–13/10–18/13–3/2–26/15 with steps of 6/5, 13/12, 16/15, 13/12, 15/13, 15/13, and its inverse | ||
* | * 1–13/12–15/13–5/4–3/2–26/15 with steps of 13/12, 16/15, 13/12, 6/5, 15/13, 15/13; | ||
* | * 1–6/5–18/13–3/2–26/15–24/13 with steps of 6/5, 15/13, 13/12, 15/13, 16/15, 13/12, and its inverse | ||
* | * 1–13/12–5/4–3/2–13/8–26/15 with steps of 13/12, 15/13, 6/5, 13/12, 16/15, 15/13; | ||
* | * 1–6/5–13/10–3/2–8/5–26/15 with steps of 6/5, 13/12, 15/13, 16/15, 13/12, 15/13, and its inverse | ||
* | * 1–15/13–5/4–3/2–26/15–15/8 with steps of 15/13, 13/12, 6/5, 15/13, 13/12, 16/15; | ||
* | * 1–6/5–4/3–3/2–26/15–24/13 with steps of 6/5, 10/9, 9/8, 15/13, 16/15, 13/12, and its inverse | ||
* | * 1–9/8–5/4–3/2–8/5–26/15 with steps of 9/8, 10/9, 6/5, 13/12, 16/15, 15/13; | ||
* | * 1–5/4–3/2–13/8–26/15–15/8 with steps of 5/4, 6/5, 13/12, 16/15, 13/12, 16/15, and its inverse | ||
* | * 1–6/5–3/2–8/5–26/15–24/13 with steps of 6/5, 5/4, 16/15, 13/12, 16/15, 13/12; | ||
* | * 1–15/13–13/10–18/13–3/2–8/5 with steps of 15/13, 9/8, 16/15, 13/12, 16/15, 5/4, and its inverse | ||
* | * 1–13/12–15/13–13/10–3/2–15/8 with steps of 13/12, 16/15, 9/8, 15/13, 5/4, 16/15; | ||
* | * 1–13/10–18/13–3/2–8/5–26/15 with steps of 13/10, 16/15, 13/12, 16/15, 13/12, 15/13, and its inverse | ||
* | * 1–13/12–15/13–3/2–26/15–15/8 with steps of 13/12, 16/15, 13/10, 15/13, 13/12, 16/15; | ||
* | * 1–13/10–18/13–3/2–8/5–9/5 with steps of 13/10, 16/15, 13/12, 16/15, 9/8, 10/9, and its inverse | ||
* | * 1–13/12–15/13–3/2–5/3–15/8 with steps of 13/12, 16/15, 13/10, 10/9, 9/8, 16/15; | ||
* | * 1–9/8–6/5–13/10–18/13–3/2 with steps of 9/8, 16/15, 13/12, 16/15, 13/12, 4/3, and its inverse | ||
* | * 1–13/12–15/13–5/4–4/3–3/2 with steps of 13/12, 16/15, 13/12, 16/15, 9/8, 4/3. | ||
Finally, there are three pairs of heptads in inverse relationship: | Finally, there are three pairs of heptads in inverse relationship: | ||
* | * 1–9/8–6/5–13/10–18/13–3/2–26/15 with steps of 9/8, 16/15, 13/12, 16/15, 13/12, 15/13, 15/13, and its inverse | ||
* | * 1–13/12–15/13–5/4–4/3–3/2–26/15 with steps of 13/12, 16/15, 13/12, 16/15, 9/8, 15/13, 15/13; | ||
* | * 1–13/12–5/4–3/2–13/8–26/15–15/8 with steps of 13/12, 15/13, 6/5, 13/12, 16/15, 13/12, 16/15, and its inverse | ||
* | * 1–13/12–15/13–5/4–3/2–26/15–15/8 with steps of 13/12, 16/15, 13/12, 6/5, 15/13, 13/12, 16/15; | ||
* | * 1–13/12–15/13–5/4–4/3–3/2–5/3 with steps of 13/12, 16/15, 13/12, 16/15, 9/8, 10/9, 6/5, and its inverse | ||
* | * 1–13/12–15/13–5/4–3/2–5/3–15/8 with steps of 13/12, 16/15, 13/12, 6/5, 10/9, 9/8, 16/15. | ||
Equal temperaments with island chords include {{Optimal ET sequence|10, 15, 19, 24, 29, 34, 43, 53, 58, 72, 77, 87, 111, 130, 140, 164, 183 and 217}}. | Equal temperaments with island chords include {{Optimal ET sequence| 10, 15, 19, 24, 29, 34, 43, 53, 58, 72, 77, 87, 111, 130, 140, 164, 183 and 217 }}. | ||
== See also == | == See also == | ||
* [[Arto and | * [[Arto and tendo theory]] | ||
* [[The Archipelago]] | * [[The Archipelago]] | ||
[[Category:15-odd-limit]] | [[Category:15-odd-limit chords]] | ||
[[Category:Essentially tempered chords]] | [[Category:Essentially tempered chords]] | ||
[[Category:Triads]] | [[Category:Triads]] |