17edt: Difference between revisions

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17edt is closely related to [[13edt]], the Bohlen-Pierce division, because they share the feature of tempering out 245/243, so that the interval of [[9/7]] stacked twice results in [[5/3]]. Therefore, like 13edt, 17edt's 9/7 generates an enneatonic Lambda ([[4L 5s (3/1-equivalent)|4L 5s]]) scale. If 13edt can be considered an analogue of [[12edo]] as the basic tuning of this scale, 17edt is an analogue of [[17edo]] as the hard 3:1 tuning. While the approximation of 5/3 and 7/3 is less good than that of 13edt, this scale has a good approximation of 11/9 (given the context of the weak 5/3 and 7/3), which is in fact the size of the large step, as it is equated to [[25/21]] by virtue of tempering out 77/75.

17edt is also very notable in that its generator spans 4 steps, meaning that it is divisible into 2; and the interval [[27/7]] spans 21 steps, meaning it is divisible into 3. These lead to weak extensions of [[BPS~~]] (the temperament defined in 3.5.7 by tempering out 245/243)~~ known as [[Dubhe]] (which splits the 9/7 generator into two intervals of [[17/15]], tempering out [[2025/2023]] as the additional comma in 3.5.7.17), and [[Mintra]]/Mintaka (which splits 27/7 into three intervals of 11/7, tempering out [[1331/1323]] as the additional comma in 3.5.7.11), respectively. 17edt in fact supports basic tunings of Dubhe[9] (which is [[8L 1s (3/1-equivalent)|8L 1s]]) and Mintaka[12] (which is [[5L 7s (3/1-equivalent)|5L 7s]], i.e. a macro-chromatic scale). Therefore 17edt is important as the smallest nontrivial tuning to support each, and it is remarkable for providing such an efficient intersection of temperaments in the 3.5.7.11.17 subgroup, despite being an extremal tuning of most of these (specifically since Mintaka asks for an 11/7 tuned flat, rather than close to just; and the 9/7 is highly overtempered for BPS) and losing much accuracy compared to more optimal tunings.

17edt's tuning of [[BPS]] (the temperament defined in 3.5.7 by tempering out 245/243) is also very notable in that its generator (9/7) spans 4 steps, meaning that it is divisible into 2; and the interval [[27/7]] spans 21 steps, meaning it is divisible into 3. These lead to weak extensions of BPS known as [[Dubhe]] (which splits the 9/7 generator into two intervals of [[17/15]], tempering out [[2025/2023]] as the additional comma in 3.5.7.17), and [[Mintra]]/Mintaka (which splits 27/7 into three intervals of 11/7, tempering out [[1331/1323]] as the additional comma in 3.5.7.11), respectively. 17edt in fact supports basic tunings of Dubhe[9] (which is [[8L 1s (3/1-equivalent)|8L 1s]]) and Mintaka[12] (which is [[5L 7s (3/1-equivalent)|5L 7s]], i.e. a macro-chromatic scale). Therefore 17edt is important as the smallest nontrivial tuning to support each, and it is remarkable for providing such an efficient intersection of temperaments in the 3.5.7.11.17 subgroup, despite being an extremal tuning of most of these (specifically since Mintaka asks for an 11/7 tuned flat, rather than close to just; and the 9/7 is highly overtempered for BPS) and losing much accuracy compared to more optimal tunings.

== Intervals ==

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 edt is closely related to [[13edt]], the Bohlen-Pierce division, because they share the feature of tempering out 245/243, so that the interval of [[9/7]] stacked twice results in [[5/3]]. Therefore, like 13edt, 17edt's 9/7 generates an enneatonic Lambda ([[4L 5s (3/1-equivalent)|4L 5s]]) scale. If 13edt can be considered an analogue of [[12edo]] as the basic tuning of this scale, 17edt is an analogue of [[17edo]] as the hard 3:1 tuning. While the approximation of 5/3 and 7/3 is less good than that of 13edt, this scale has a good approximation of 11/9 (given the context of the weak 5/3 and 7/3), which is in fact the size of the large step, as it is equated to [[25/21]] by virtue of tempering out 77/75.
-edt is also very notable in that its generator spans 4 steps, meaning that it is divisible into 2; and the interval [[27/7]] spans 21 steps, meaning it is divisible into 3. These lead to weak extensions of [[BPS]] (the temperament defined in 3.5.7 by tempering out 245/243) known as [[Dubhe]] (which splits the 9/7 generator into two intervals of [[17/15]], tempering out [[2025/2023]] as the additional comma in 3.5.7.17), and [[Mintra]]/Mintaka (which splits 27/7 into three intervals of 11/7, tempering out [[1331/1323]] as the additional comma in 3.5.7.11), respectively. 17edt in fact supports basic tunings of Dubhe[9] (which is [[8L 1s (3/1-equivalent)|8L 1s]]) and Mintaka[12] (which is [[5L 7s (3/1-equivalent)|5L 7s]], i.e. a macro-chromatic scale). Therefore 17edt is important as the smallest nontrivial tuning to support each, and it is remarkable for providing such an efficient intersection of temperaments in the 3.5.7.11.17 subgroup, despite being an extremal tuning of most of these (specifically since Mintaka asks for an 11/7 tuned flat, rather than close to just; and the 9/7 is highly overtempered for BPS) and losing much accuracy compared to more optimal tunings.
+edt's tuning of [[BPS]] (the temperament defined in 3.5.7 by tempering out 245/243) is also very notable in that its generator (9/7) spans 4 steps, meaning that it is divisible into 2; and the interval [[27/7]] spans 21 steps, meaning it is divisible into 3. These lead to weak extensions of BPS known as [[Dubhe]] (which splits the 9/7 generator into two intervals of [[17/15]], tempering out [[2025/2023]] as the additional comma in 3.5.7.17), and [[Mintra]]/Mintaka (which splits 27/7 into three intervals of 11/7, tempering out [[1331/1323]] as the additional comma in 3.5.7.11), respectively. 17edt in fact supports basic tunings of Dubhe[9] (which is [[8L 1s (3/1-equivalent)|8L 1s]]) and Mintaka[12] (which is [[5L 7s (3/1-equivalent)|5L 7s]], i.e. a macro-chromatic scale). Therefore 17edt is important as the smallest nontrivial tuning to support each, and it is remarkable for providing such an efficient intersection of temperaments in the 3.5.7.11.17 subgroup, despite being an extremal tuning of most of these (specifically since Mintaka asks for an 11/7 tuned flat, rather than close to just; and the 9/7 is highly overtempered for BPS) and losing much accuracy compared to more optimal tunings.
 == Intervals ==