25/16: Difference between revisions
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'''25/16''', the '''classic(al) augmented fifth''' or '''diptolemaic augmented fifth''' is the interval obtained by stacking two [[5/4]] major thirds, however, it gains additional [[isoharmonic chord|isoharmonic]] identity from its position between [[11/8]] and [[7/4]], so it can frequently be used in conjunction with those, even in chords. It is [[100/99]] sharp of [[99/64]], and tempering out 100/99 makes 1-5/4-25/16 into the [[ptolemismic chords|ptolemismic augmented triad]]. | '''25/16''', the '''classic(al) augmented fifth''' or '''diptolemaic augmented fifth''' is the interval obtained by stacking two [[5/4]] major thirds, however, it gains additional [[isoharmonic chord|isoharmonic]] identity from its position between [[11/8]] and [[7/4]], so it can frequently be used in conjunction with those, even in chords. It is [[100/99]] sharp of [[99/64]], and tempering out 100/99 makes 1-5/4-25/16 into the [[ptolemismic chords|ptolemismic augmented triad]]. | ||
== Names == | |||
While this interval has been referred to as the ''classic'' or ''classical'' augmented fifth for some time, the term "diptolemaic" [https://discord.com/channels/332357996569034752/516067802864549890/912167264789364736 was coined on Discord] by [[Flora Canou]] while discussing a proposal for a consistent naming scheme for different 5-limit intervals with [[User:Aura|Aura]]. The concept of "diptolemaic" intervals builds on the concept of "ptolemaic"<ref>[https://marsbat.space/pdfs/JI.pdf ''Fundamental Principles of Just Intonation and Microtonal Composition''] by Thomas Nicholson and Marc Sabat —"'Ptolemaic' refers to intervals combining only the primes 2, 3, and 5."</ref> intervals, with "diptolemaic" intervals being those that have two factors of 5 in their [[monzo]] and differ from their Pythagorean counterparts by two instances of [[81/80]] in the direction of ratio simplicity— for instance, 25/16 differing from [[6561/4096]]—, while 5-limit intervals that differ from their Pythagorean counterparts by a single instance of 81/80 in the same direction are simply called "ptolemaic" intervals. | |||
== See also == | == See also == | ||
* [[32/25]] – its [[octave complement]] | * [[32/25]] – its [[octave complement]] | ||
== References == | |||
<references/> | |||
[[Category:Fifth]] | [[Category:Fifth]] | ||
[[Category:Augmented fifth]] | [[Category:Augmented fifth]] | ||
[[Category:todo:expand]] | [[Category:todo:expand]] | ||