User:Overthink/Draft edits: Difference between revisions

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''Notes: Excellent odd harmonics 7, 15, 23, 29, 31, 33, 39, 43, all derived from 84edo; less accurate but still usable 17, 19, 27; also note 3*21 subgroup from 63edo''

21edo contains three [[7edo]] "equiheptatonic" scales, and can be interpreted as 7edo but with the capability to inflect up or down by a quarter-tone. The 7edo subset functions as ~~a basic~~ "diatonic" scale, though ~~maximum~~-~~variety-3~~ options might also be preferable (such as omnidiatonic). In other words, all intervals have "minor", "neutral", and "major" variations, which makes building scales in 21edo rather interesting. If 21edo is analyzed purely diatonically, no chromatic alterations can exist because the chromatic semitone is equal to 0 cents (a fact characteristic of [[whitewood]] temperaments). So, another ~~kind~~ of ~~accidental~~ (such as ups and downs) is usually used instead, though it might be "reskinned" as sharps and flats to aid melodic intuition.

21edo contains three [[7edo]] "equiheptatonic" scales, and can be interpreted as 7edo but with the capability to inflect up or down by a quarter-tone. The 7edo subset functions as an equalized "[[5L 2s|diatonic]]" scale, though non-mos options might also be preferable (such as [[omnidiatonic]]). In other words, all intervals have "minor", "neutral", and "major" variations, which makes building scales in 21edo rather interesting. If 21edo is analyzed purely diatonically, no chromatic alterations can exist because the [[chromatic semitone]] is equal to 0 cents (a fact characteristic of [[whitewood]] temperaments). So, another pair of accidentals (such as ups and downs) is usually used instead, though they might be "reskinned" as sharps and flats to aid melodic intuition.

21edo supports tertian harmony with both 7edo's neutral chords and inflected major and minor chords. The major third is identical to 12edo's, but is a more extreme ~~third~~ in 21edo due to the flatness of the fifth (~~which makes the minor third close~~ to subminor), so that the chords might be more comparable to neogothic chords.

21edo supports {{w|tertian harmony}} with 7edo's flat fifth, containing both 7edo's neutral chords and inflected major and minor chords. The [[5/4]] major third is mapped to 400{{c}}, identical to 12edo's, but the minor third is more extreme in 21edo due to the flatness of the fifth (closer to subminor), so that the chords might be more comparable to [[neogothic]] chords. In fact, [[6/5]] is slightly closer to the 6-step neutral third than the 5-step minor third, meaning 21edo lacks [[consistency]] to the [[5-odd-limit]].

~~In terms of just intonation, outside the 5-limit (where 21edo contains a flat fifth and the familiar but controversial 400c major third),~~ 21edo ~~also~~ closely approximates the ~~harmonics~~ [[7/4]] (a subminor seventh), [[17/16]] (a ~~semitone~~), [[19/16]] (a ~~minor third~~), [[23/16]] (a ~~tritone~~), ~~and~~ [[29/16]] (a ~~minor~~ seventh), ~~with harmonics 7~~, 23, and ~~29 being especially accurate~~ (~~and harmonic 7 being more accurate than in any other edo below 26~~). The intervals [[16/15]] ~~and~~ [[27/16]]~~, if directly~~ approximated, are ~~also very accurate~~. 21edo can be ~~liberally~~ treated as a no-11s 29-limit temperament, ~~but~~ treating 21edo as a 2.15.7.23.27.29 subgroup temperament allows for a more accurate JI interpretation of the tuning, ~~since almost every interval in 21edo can be described as~~ a ~~ratio within the 29~~-odd-limit. 21edo also works well on the 2.9/5.7.11/5.13/5.17/5 subgroup, which is possibly a more sensible way to treat it.

21edo closely approximates the [[octave-reduced]] [[harmonic]]s [[7/4]] (a subminor seventh), [[15/8]] (a major seventh), [[23/16]] (a wide tritone), [[29/16]] (a supraminor seventh), [[31/16]] (a supermajor seventh), [[33/32]] (a quartertone), [[39/32]] (a neutral third), and [[43/32]] (an acute fourth). The intervals [[17/16]], [[19/16]], [[27/16]] are approximated less accurately, but are still usable. 21edo can be crudely treated as a no-11s 31-limit temperament, though the lack of consistency will give some unusual results, such as [[10/9]] being mapped wider than [[9/8]]. However, treating 21edo as a 2.15.7.33.39.23.29.31.43 subgroup temperament allows for a more accurate JI interpretation of the tuning, with a maximum error of any 43-odd-limit interval in this subgroup being 6.4{{c}}. These approximations derive from and are inherited by [[84edo]], which covers a large number of primes in high limits. 21edo also works well on the 2.27.9/5.7.11/5.13/5.17/5 subgroup, which is derived from [[63edo]], which is possibly a more sensible way to treat it.

In terms of interval regions, 21edo possesses four types of ~~2nd~~ (subminor, minor, submajor, and supermajor), three types of ~~3rd~~ (subminor, neutral, and major), a "third-fourth" (an interval that can function as either a supermajor 3rd or a narrow 4th), a wide (or acute) 4th, and a narrow tritone, as well as the octave-inversions of all of these intervals.

In terms of interval regions, 21edo possesses four types of 2nds (subminor, minor, submajor, and supermajor), three types of 3rds (subminor, neutral, and major), a "third-fourth/naiadic" (an interval that can function as either a supermajor 3rd or a narrow 4th), a wide (or acute) 4th, and a narrow tritone, as well as the octave-inversions of all of these intervals.

Because 21edo is a Fibonacci edo, it contains an approximation to the [[logarithmic phi]] superfifth, which generates golden MOS scales ~~8L 5s~~, 5L 3s, and ~~3L 2s~~.

Because 21edo is a {{W|Fibonacci sequence|Fibonacci}} edo, it contains an approximation to the [[logarithmic phi]] superfifth, which generates golden MOS scales [[3L 2s]], [[5L 3s]], and [[8L 5s]], with 21edo itself being an equalized version of [[13L 8s]].

Thanks to its sevenths, 21edo is an ideal tuning for its size for [[metallic harmony]].

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 ''Notes: Excellent odd harmonics 7, 15, 23, 29, 31, 33, 39, 43, all derived from 84edo; less accurate but still usable 17, 19, 27; also note 3*21 subgroup from 63edo''
-edo contains three [[7edo]] "equiheptatonic" scales, and can be interpreted as 7edo but with the capability to inflect up or down by a quarter-tone. The 7edo subset functions as a basic "diatonic" scale, though maximum-variety-3 options might also be preferable (such as omnidiatonic). In other words, all intervals have "minor", "neutral", and "major" variations, which makes building scales in 21edo rather interesting. If 21edo is analyzed purely diatonically, no chromatic alterations can exist because the chromatic semitone is equal to 0 cents (a fact characteristic of [[whitewood]] temperaments). So, another kind of accidental (such as ups and downs) is usually used instead, though it might be "reskinned" as sharps and flats to aid melodic intuition.
+edo contains three [[7edo]] "equiheptatonic" scales, and can be interpreted as 7edo but with the capability to inflect up or down by a quarter-tone. The 7edo subset functions as an equalized "[[5L 2s|diatonic]]" scale, though non-mos options might also be preferable (such as [[omnidiatonic]]). In other words, all intervals have "minor", "neutral", and "major" variations, which makes building scales in 21edo rather interesting. If 21edo is analyzed purely diatonically, no chromatic alterations can exist because the [[chromatic semitone]] is equal to 0 cents (a fact characteristic of [[whitewood]] temperaments). So, another pair of accidentals (such as ups and downs) is usually used instead, though they might be "reskinned" as sharps and flats to aid melodic intuition.
-edo supports tertian harmony with both 7edo's neutral chords and inflected major and minor chords. The major third is identical to 12edo's, but is a more extreme third in 21edo due to the flatness of the fifth (which makes the minor third close to subminor), so that the chords might be more comparable to neogothic chords.
+edo supports {{w|tertian harmony}} with 7edo's flat fifth, containing both 7edo's neutral chords and inflected major and minor chords. The [[5/4]] major third is mapped to 400{{c}}, identical to 12edo's, but the minor third is more extreme in 21edo due to the flatness of the fifth (closer to subminor), so that the chords might be more comparable to [[neogothic]] chords. In fact, [[6/5]] is slightly closer to the 6-step neutral third than the 5-step minor third, meaning 21edo lacks [[consistency]] to the [[5-odd-limit]].
-In terms of just intonation, outside the 5-limit (where 21edo contains a flat fifth and the familiar but controversial 400c major third), 21edo also closely approximates the harmonics [[7/4]] (a subminor seventh), [[17/16]] (a semitone), [[19/16]] (a minor third), [[23/16]] (a tritone), and [[29/16]] (a minor seventh), with harmonics 7, 23, and 29 being especially accurate (and harmonic 7 being more accurate than in any other edo below 26). The intervals [[16/15]] and [[27/16]], if directly approximated, are also very accurate. 21edo can be liberally treated as a no-11s 29-limit temperament, but treating 21edo as a 2.15.7.23.27.29 subgroup temperament allows for a more accurate JI interpretation of the tuning, since almost every interval in 21edo can be described as a ratio within the 29-odd-limit. 21edo also works well on the 2.9/5.7.11/5.13/5.17/5 subgroup, which is possibly a more sensible way to treat it.
+edo closely approximates the [[octave-reduced]] [[harmonic]]s [[7/4]] (a subminor seventh), [[15/8]] (a major seventh), [[23/16]] (a wide tritone), [[29/16]] (a supraminor seventh), [[31/16]] (a supermajor seventh), [[33/32]] (a quartertone), [[39/32]] (a neutral third), and [[43/32]] (an acute fourth). The intervals [[17/16]], [[19/16]], [[27/16]] are approximated less accurately, but are still usable. 21edo can be crudely treated as a no-11s 31-limit temperament, though the lack of consistency will give some unusual results, such as [[10/9]] being mapped wider than [[9/8]]. However, treating 21edo as a 2.15.7.33.39.23.29.31.43 subgroup temperament allows for a more accurate JI interpretation of the tuning, with a maximum error of any 43-odd-limit interval in this subgroup being 6.4{{c}}. These approximations derive from and are inherited by [[84edo]], which covers a large number of primes in high limits. 21edo also works well on the 2.27.9/5.7.11/5.13/5.17/5 subgroup, which is derived from [[63edo]], which is possibly a more sensible way to treat it.
-In terms of interval regions, 21edo possesses four types of 2nd (subminor, minor, submajor, and supermajor), three types of 3rd (subminor, neutral, and major), a "third-fourth" (an interval that can function as either a supermajor 3rd or a narrow 4th), a wide (or acute) 4th, and a narrow tritone, as well as the octave-inversions of all of these intervals.
+In terms of interval regions, 21edo possesses four types of 2nds (subminor, minor, submajor, and supermajor), three types of 3rds (subminor, neutral, and major), a "third-fourth/naiadic" (an interval that can function as either a supermajor 3rd or a narrow 4th), a wide (or acute) 4th, and a narrow tritone, as well as the octave-inversions of all of these intervals.
-Because 21edo is a Fibonacci edo, it contains an approximation to the [[logarithmic phi]] superfifth, which generates golden MOS scales 8L 5s, 5L 3s, and 3L 2s.
+Because 21edo is a {{W|Fibonacci sequence|Fibonacci}} edo, it contains an approximation to the [[logarithmic phi]] superfifth, which generates golden MOS scales [[3L 2s]], [[5L 3s]], and [[8L 5s]], with 21edo itself being an equalized version of [[13L 8s]].
 Thanks to its sevenths, 21edo is an ideal tuning for its size for [[metallic harmony]].