70edo: Difference between revisions

Dave Keenan (talk | contribs)
added Sagittal notation
ArrowHead294 (talk | contribs)
mNo edit summary
Line 1: Line 1:
{{Infobox ET}}
{{Infobox ET}}
{{EDO intro|70}}
{{ED intro}}


== Theory ==
== Theory ==
This tuning was singled out by [[William Stoney]] in his article "Theoretical Possibilities for Equally Tempered Systems" (in the book [https://monoskop.org/images/c/c3/Lincoln_Harry_B_ed_The_Computer_and_Music_1970.pdf The Computer and Music]) as one of the six best systems of size 72 or smaller, along with [[72edo|72]], [[65edo|65]], [[58edo|58]], [[53edo|53]], and [[41edo|41]]. These other systems have had notice paid to them, but the same does not seem to be true of 70, which seems to have been ignored ever since, despite its excellent fifth, which is the 4th number in the convergent sequence to the [[Logarithmic approximants #Argent_temperament|silver ratio]], following [[29edo]], [[12edo]] & [[5edo]] and preceding [[169edo]]. The fifth 41\70 is the true center of the diatonic tuning spectrum, as it is the [[geometric mean]] of 3\[[5edo]] and 4\[[7edo]].
This tuning was singled out by [[William Stoney]] in his article "Theoretical Possibilities for Equally Tempered Systems" (in the book [https://monoskop.org/images/c/c3/Lincoln_Harry_B_ed_The_Computer_and_Music_1970.pdf The Computer and Music]) as one of the six best systems of size 72 or smaller, along with [[72edo|72]], [[65edo|65]], [[58edo|58]], [[53edo|53]], and [[41edo|41]]. These other systems have had notice paid to them, but the same does not seem to be true of 70, which seems to have been ignored ever since, despite its excellent fifth, which is the 4th number in the convergent sequence to the [[Logarithmic approximants #Argent_temperament|silver ratio]], following [[29edo]], [[12edo]], and [[5edo]] and preceding [[169edo]]. The fifth 41\70 is the true center of the diatonic tuning spectrum, as it is the [[geometric mean]] of 3\[[5edo]] and 4\[[7edo]].


The [[patent val]] for 70edo [[tempering out|tempers out]] [[2048/2025]], making it a [[diaschismic]] system. An alternative mapping is 70c, with a flat rather than a sharp major third, tempering out [[32805/32768]]. In the [[7-limit]], the patent val tempers out [[126/125]], [[2430/2401]] and [[5120/5103]], and provides the optimum patent val for the [[kumonga]] temperament. The 70c val tempers out [[50/49]], making it a tuning for [[doublewide]] even better than the optimal patent val. The 70cd val tempers out [[225/224]] and [[3125/3087]] instead. The alternative mapping begins to make more sense in the [[11-limit]] and higher, where the patent val tempers out [[99/98]] and [[121/120]] in the 11-limit, [[169/168]] and [[352/351]] in the [[13-limit]], and [[221/220]] in the [[17-limit]]. 70cd on the other hand, with flat 5 and 7, tempers out [[100/99]] and [[245/242]] in the 11-limit, [[105/104]] and [[196/195]] in the 13-limit, and [[154/153]] and [[170/169]] in the 17-limit. 70 also makes sense as a no-5 or -7 system, tempering out [[131769/131072]] in the 11-limit, [[352/351]] and [[2197/2187]] in the 13-limit, and [[289/288]] and [[1089/1088]] in the 17-limit.
The [[patent val]] for 70edo [[tempering out|tempers out]] [[2048/2025]], making it a [[diaschismic]] system. An alternative mapping is 70c, with a flat rather than a sharp major third, tempering out [[32805/32768]]. In the [[7-limit]], the patent val tempers out [[126/125]], [[2430/2401]] and [[5120/5103]], and provides the optimum patent val for the [[kumonga]] temperament. The 70c val tempers out [[50/49]], making it a tuning for [[doublewide]] even better than the optimal patent val. The 70cd val tempers out [[225/224]] and [[3125/3087]] instead. The alternative mapping begins to make more sense in the [[11-limit]] and higher, where the patent val tempers out [[99/98]] and [[121/120]] in the 11-limit, [[169/168]] and [[352/351]] in the [[13-limit]], and [[221/220]] in the [[17-limit]]. 70cd on the other hand, with flat 5 and 7, tempers out [[100/99]] and [[245/242]] in the 11-limit, [[105/104]] and [[196/195]] in the 13-limit, and [[154/153]] and [[170/169]] in the 17-limit. 70 also makes sense as a no-5 or -7 system, tempering out [[131769/131072]] in the 11-limit, [[352/351]] and [[2197/2187]] in the 13-limit, and [[289/288]] and [[1089/1088]] in the 17-limit.
Line 20: Line 20:


== Notation ==
== Notation ==
===Sagittal notation===
=== Ups and downs notation ===
====Evo flavor====
Using [[Helmholtz–Ellis]] accidentals, 70edo can be notated using [[ups and downs notation|ups and downs]]:
{{Sharpness-sharp7}}


=== Sagittal notation ===
==== Evo flavor ====
<imagemap>
<imagemap>
File:70-EDO_Evo_Sagittal.svg
File:70-EDO_Evo_Sagittal.svg
Line 34: Line 37:
</imagemap>
</imagemap>


====Revo flavor====
==== Revo flavor ====
 
<imagemap>
<imagemap>
File:70-EDO_Revo_Sagittal.svg
File:70-EDO_Revo_Sagittal.svg