35edo: Difference between revisions

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Amazingly, almost the exact same situation occurs with [[7/4]], for which 35edo's best approximation is also just over 1/4 of a step flat (resulting in a very accurate [[7/5]]). If we wish to use the [[4:6:7]] chord, then just like with 4:5:6, it is best to use the flat mapping of 3/2, resulting in a triad of 0–20–28 steps (0–686–960{{C}}). Its inverse, the [[14:21:24|1/(12:8:7)]] chord, is best mapped to 0–20–27 steps (0–686–926{{C}}). Here the damage is split between [[7/4]] and [[12/7]], with both being around 7–9{{C}} flat of just, which is almost the exact same situation as with 5/4 and 6/5. From here, we see that the best approximation of the harmonic seventh chord [[4:5:6:7]] is 0–11–20–28 steps (0–377–686–960{{C}}), while the best approximation of the subharmonic sixth chord [[70:84:105:120|1/(12:10:8:7)]] is 0–9–20–27 steps (0–309–686–926{{C}}).

Overall, we find that 35edo's [[patent val]] is surprisingly accurate overall for the [[7-odd-limit]], with 3/2 being the only interval with high damage. However, this mapping does not work well in the [[9-odd-limit]], as [[9/8]] is tuned over 32{{C}} flat of just at 171{{C}}, and thus other intervals of 9 also become very inaccurate. Instead, 35edo has an accurate approximation of 9/8 at 6\35 (206{{C}}), but to reach it, we must stack one 20\35 fifth and one 21\35 fifth. The 21\35 fifth is the [[5edo]] fifth of 720{{C}}, being around 18{{C}} sharp of just. ~~Even though there~~ are two mappings of the perfect fifth, ~~it all fits well in~~ the ~~end~~, ~~as we will soon see~~.

Overall, we find that 35edo's [[patent val]] is surprisingly accurate overall for the [[7-odd-limit]], with 3/2 being the only interval with high damage. However, this mapping does not work well in the [[9-odd-limit]], as [[9/8]] is tuned over 32{{C}} flat of just at 171{{C}}, and thus other intervals of 9 also become very inaccurate. Instead, 35edo has an accurate approximation of 9/8 at 6\35 (206{{C}}), but to reach it, we must stack one 20\35 fifth and one 21\35 fifth. The 21\35 fifth is the [[5edo]] fifth of 720{{C}}, being around 18{{C}} sharp of just. There are two mappings of the perfect fifth, with some chords preferring the flat fifth, while other chords prefer the sharp fifth.

For example, suppose we want to use the [[6:7:9]] subminor triad. Then the closest approximation of [[7/6]] is 8 steps, and the closest approximation of [[9/7]] is 13 steps. Stacking these approximations gives the triad 0–8–21 steps (0–274–720{{C}}). Here, we use the sharp fifth instead of the flat one, so that [[7/6]] and [[9/7]] are tuned more accurately, being around 7{{C}} and 11{{C}} sharp of just respectively. The best approximation of the supermajor triad [[14:18:21|1/(9:7:6)]] is 0–13–21 steps (0–446–720{{C}}), which also uses the sharp fifth. A similar situation occurs with [[6:9:10]] and its inverse [[10:15:18|1/(9:6:5)]], where the best approximations of [[5/3]] and [[9/5]] are 26\35 and 30\35 respectively, so that the best approximations of 6:9:10 and 1/(9:6:5) are 0–21–26 steps (0–720–891{{C}}) and 0–21–30 steps (0–720–1029{{C}}) respectively, with 5/3 and 9/5 being around 7{{C}} and 11{{C}} sharp respectively. This leads to an approximation of the [[6:7:9:10]] harmonic sixth chord (sometimes known as the ''subminor tetrad'') at 0–8–21–26 steps (0–274–720–891{{C}}), and an approximation of the [[70:90:105:126|1/(9:7:6:5)]] subharmonic seventh chord (sometimes called the ''supermajor tetrad'') at 0–13–21–30 steps (0–446–720–1029{{C}}).

The best approximation of the harmonic ninth chord [[4:5:6:7:9]] is 0–11–20–28–41 steps (0–377–686–960–1406{{C}}). Here, both mappings of 3/2 are used simultaneously, with the flat mapping occuring at 4:6, and the sharp mapping occuring at 6:9. The mapping of any chord in 35edo can be taken as a subset of the mapping of 4:5:6:7:9, or the mapping of its inverse [[140:180:210:252:315|1/(9:7:6:5:4)]] as 0–13–21–30–41 steps (0–446–720–1029–1406{{C}}), where any interval more complex than the perfect fifth is no more than 11{{C}} out of tune.

The best approximation of the harmonic ninth chord [[4:5:6:7:9]] is 0–11–20–28–41 steps (0–377–686–960–1406{{C}}). Here, both mappings of 3/2 are used simultaneously, with the flat mapping occuring at 4:6, and the sharp mapping occuring at 6:9. The mapping of any chord in 35edo that is a subset of the 9-odd-limit otonal or utonal pentad (up to octave equivalence) can be taken as a subset of the mapping of 4:5:6:7:9, or the mapping of its inverse [[140:180:210:252:315|1/(9:7:6:5:4)]], that being 0–13–21–30–41 steps (0–446–720–1029–1406{{C}}), where any interval more complex than the perfect fifth is no more than 11{{C}} out of tune.

Additionally, many triads are tuned very close to [[delta-rational]] tunings, which may make them sound less out of tune as well. For examples, the approximations of the triads [[4:5:6]], [[10:12:15|1/(6:5:4)]], [[6:7:9]], and [[14:18:21|1/(9:7:6)]] are very close to DR tunings. Voicings of chords that divide the fourth, those being [[6:7:8]], [[21:24:28|1/(8:7:6)]], [[9:10:12]], and [[15:18:20|1/(12:10:9)]], are also tuned fairly close to DR.

==== Caveats of Dual-fifth ====

However, using two mappings of the perfect fifth presents several problems. For example, in JI, there are the [[10:12:15:18]] and [[12:14:18:21]] chords and their inversions, known as [[anomalous saturated suspension]]s, which are dyadically consonant in the 9-odd-limit, even though they are not a subset of the 9-odd-limit otonal or utonal pentad. If we try to map, say, the 10:12:15:18 chord with steps 6/5–5/4–6/5–10/9 (closing at the octave) in 35edo, then the 10:12:15 part suggests mapping the fifth above the root at 20\35, while the 10:15:18 part suggests mapping it to 21\35. As such, one of the 6/5–5/4–6/5–10/9 steps must be mapped to its second-best approximation, close to 3/4 of a 35edo step (about 25 cents) off of just. A similar issue occurs with 12:14:18:21, where one of the 7/6–9/7–7/6–8/7 steps must be mapped to its second-best approximation. Many other chords, such as [[8:10:12:15]], also cannot be mapped without a step being close to 3/4 of a 35edo step off.

Additionally, many structures present in systems with a single fifth do not work well in 35edo. For example, the perfect fifth generates several [[mos scale]], such as the traditional [[diatonic]] scale. The diatonic mos scale does not exist in 35edo, with the 20\35 whitewood fifth generating an [[equalized]] version of the scale, while the 21\35 fifth generates a [[collapsed]] version of the scale. However, there are scales such as 6 6 2 6 6 6 3 which sound similar to diatonic, and this particular scale can be obtained by alternately stacking 21\35 and 20\35 fifths, or [[Hobbled scale|hobbling]] a [[34edo]] or [[36edo]] diatonic scale.

35edo is only one of many dual-fifth systems, with others including [[18edo]], [[23edo]], [[25edo]], [[28edo]], [[30edo]], [[37edo]], and [[40edo]], each with their own unique properties.

=== Subsets and supersets ===

@@ Line 17: / Line 17: @@
 Amazingly, almost the exact same situation occurs with [[7/4]], for which 35edo's best approximation is also just over 1/4 of a step flat (resulting in a very accurate [[7/5]]). If we wish to use the [[4:6:7]] chord, then just like with 4:5:6, it is best to use the flat mapping of 3/2, resulting in a triad of 0–20–28 steps (0–686–960{{C}}). Its inverse, the [[14:21:24|1/(12:8:7)]] chord, is best mapped to 0–20–27 steps (0–686–926{{C}}). Here the damage is split between [[7/4]] and [[12/7]], with both being around 7–9{{C}} flat of just, which is almost the exact same situation as with 5/4 and 6/5. From here, we see that the best approximation of the harmonic seventh chord [[4:5:6:7]] is 0–11–20–28 steps (0–377–686–960{{C}}), while the best approximation of the subharmonic sixth chord [[70:84:105:120|1/(12:10:8:7)]] is 0–9–20–27 steps (0–309–686–926{{C}}).
-Overall, we find that 35edo's [[patent val]] is surprisingly accurate overall for the [[7-odd-limit]], with 3/2 being the only interval with high damage. However, this mapping does not work well in the [[9-odd-limit]], as [[9/8]] is tuned over 32{{C}} flat of just at 171{{C}}, and thus other intervals of 9 also become very inaccurate. Instead, 35edo has an accurate approximation of 9/8 at 6\35 (206{{C}}), but to reach it, we must stack one 20\35 fifth and one 21\35 fifth. The 21\35 fifth is the [[5edo]] fifth of 720{{C}}, being around 18{{C}} sharp of just. Even though there are two mappings of the perfect fifth, it all fits well in the end, as we will soon see.
+Overall, we find that 35edo's [[patent val]] is surprisingly accurate overall for the [[7-odd-limit]], with 3/2 being the only interval with high damage. However, this mapping does not work well in the [[9-odd-limit]], as [[9/8]] is tuned over 32{{C}} flat of just at 171{{C}}, and thus other intervals of 9 also become very inaccurate. Instead, 35edo has an accurate approximation of 9/8 at 6\35 (206{{C}}), but to reach it, we must stack one 20\35 fifth and one 21\35 fifth. The 21\35 fifth is the [[5edo]] fifth of 720{{C}}, being around 18{{C}} sharp of just. There are two mappings of the perfect fifth, with some chords preferring the flat fifth, while other chords prefer the sharp fifth.
 For example, suppose we want to use the [[6:7:9]] subminor triad. Then the closest approximation of [[7/6]] is 8 steps, and the closest approximation of [[9/7]] is 13 steps. Stacking these approximations gives the triad 0–8–21 steps (0–274–720{{C}}). Here, we use the sharp fifth instead of the flat one, so that [[7/6]] and [[9/7]] are tuned more accurately, being around 7{{C}} and 11{{C}} sharp of just respectively. The best approximation of the supermajor triad [[14:18:21|1/(9:7:6)]] is 0–13–21 steps (0–446–720{{C}}), which also uses the sharp fifth. A similar situation occurs with [[6:9:10]] and its inverse [[10:15:18|1/(9:6:5)]], where the best approximations of [[5/3]] and [[9/5]] are 26\35 and 30\35 respectively, so that the best approximations of 6:9:10 and 1/(9:6:5) are 0–21–26 steps (0–720–891{{C}}) and 0–21–30 steps (0–720–1029{{C}}) respectively, with 5/3 and 9/5 being around 7{{C}} and 11{{C}} sharp respectively. This leads to an approximation of the [[6:7:9:10]] harmonic sixth chord (sometimes known as the ''subminor tetrad'') at 0–8–21–26 steps (0–274–720–891{{C}}), and an approximation of the [[70:90:105:126|1/(9:7:6:5)]] subharmonic seventh chord (sometimes called the ''supermajor tetrad'') at 0–13–21–30 steps (0–446–720–1029{{C}}).
-The best approximation of the harmonic ninth chord [[4:5:6:7:9]] is 0–11–20–28–41 steps (0–377–686–960–1406{{C}}). Here, both mappings of 3/2 are used simultaneously, with the flat mapping occuring at 4:6, and the sharp mapping occuring at 6:9. The mapping of any chord in 35edo can be taken as a subset of the mapping of 4:5:6:7:9, or the mapping of its inverse [[140:180:210:252:315|1/(9:7:6:5:4)]] as 0–13–21–30–41 steps (0–446–720–1029–1406{{C}}), where any interval more complex than the perfect fifth is no more than 11{{C}} out of tune.
+The best approximation of the harmonic ninth chord [[4:5:6:7:9]] is 0–11–20–28–41 steps (0–377–686–960–1406{{C}}). Here, both mappings of 3/2 are used simultaneously, with the flat mapping occuring at 4:6, and the sharp mapping occuring at 6:9. The mapping of any chord in 35edo that is a subset of the 9-odd-limit otonal or utonal pentad (up to octave equivalence) can be taken as a subset of the mapping of 4:5:6:7:9, or the mapping of its inverse [[140:180:210:252:315|1/(9:7:6:5:4)]], that being 0–13–21–30–41 steps (0–446–720–1029–1406{{C}}), where any interval more complex than the perfect fifth is no more than 11{{C}} out of tune.
 Additionally, many triads are tuned very close to [[delta-rational]] tunings, which may make them sound less out of tune as well. For examples, the approximations of the triads [[4:5:6]], [[10:12:15|1/(6:5:4)]], [[6:7:9]], and [[14:18:21|1/(9:7:6)]] are very close to DR tunings. Voicings of chords that divide the fourth, those being [[6:7:8]], [[21:24:28|1/(8:7:6)]], [[9:10:12]], and [[15:18:20|1/(12:10:9)]], are also tuned fairly close to DR.
+==== Caveats of Dual-fifth ====
+However, using two mappings of the perfect fifth presents several problems. For example, in JI, there are the [[10:12:15:18]] and [[12:14:18:21]] chords and their inversions, known as [[anomalous saturated suspension]]s, which are dyadically consonant in the 9-odd-limit, even though they are not a subset of the 9-odd-limit otonal or utonal pentad. If we try to map, say, the 10:12:15:18 chord with steps 6/5–5/4–6/5–10/9 (closing at the octave) in 35edo, then the 10:12:15 part suggests mapping the fifth above the root at 20\35, while the 10:15:18 part suggests mapping it to 21\35. As such, one of the 6/5–5/4–6/5–10/9 steps must be mapped to its second-best approximation, close to 3/4 of a 35edo step (about 25 cents) off of just. A similar issue occurs with 12:14:18:21, where one of the 7/6–9/7–7/6–8/7 steps must be mapped to its second-best approximation. Many other chords, such as [[8:10:12:15]], also cannot be mapped without a step being close to 3/4 of a 35edo step off.
+Additionally, many structures present in systems with a single fifth do not work well in 35edo. For example, the perfect fifth generates several [[mos scale]], such as the traditional [[diatonic]] scale. The diatonic mos scale does not exist in 35edo, with the 20\35 whitewood fifth generating an [[equalized]] version of the scale, while the 21\35 fifth generates a [[collapsed]] version of the scale. However, there are scales such as 6 6 2 6 6 6 3 which sound similar to diatonic, and this particular scale can be obtained by alternately stacking 21\35 and 20\35 fifths, or [[Hobbled scale|hobbling]] a [[34edo]] or [[36edo]] diatonic scale.
+edo is only one of many dual-fifth systems, with others including [[18edo]], [[23edo]], [[25edo]], [[28edo]], [[30edo]], [[37edo]], and [[40edo]], each with their own unique properties.
 === Subsets and supersets ===