7-limit: Difference between revisions

Music: +ben johnston's work
+edo approx. section. Don't wanna include 7d and 8d so let's start the sequence with 10edo
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{{Prime limit navigation|7}}
{{Prime limit navigation|7}}
{{Wikipedia|7-limit tuning}}
{{Wikipedia|7-limit tuning}}
The '''7-limit''' or 7-prime-limit consists of rational intervals where 7 is the highest allowable [[prime]] factor, so that every such interval may be written as a ratio of integers which are products of 2, 3, 5 and 7. This is an infinite set and still infinite even if we restrict consideration to a single octave. Some examples within the octave include [[7/4]], [[7/5]], [[7/6]], [[9/7]], [[15/14]], [[21/16]], [[21/20]], [[35/27]], [[49/36]], and so on.
The '''7-limit''' or 7-prime-limit consists of rational intervals where 7 is the highest allowable [[prime]] factor, so that every such interval may be written as a [[ratio]] of integers which are products of 2, 3, 5 and 7. This is an infinite set and still infinite even if we restrict consideration to a single octave. Some examples within the octave include [[7/4]], [[7/5]], [[7/6]], [[9/7]], [[15/14]], [[21/16]], [[21/20]], [[35/27]], [[49/36]], and so on.


The [[7-odd-limit]] refers to a constraint on the selection of [[Just intonation|just]] [[Interval class|intervals]] for a scale or composition such that 7 is the highest allowable odd number, either for the intervals of the scale, or the ratios between successive or simultaneously sounding notes of the composition. The complete list of 7 odd-limit intervals within the octave is [[1/1]], [[8/7]], [[7/6]], [[6/5]], [[5/4]], [[4/3]], [[7/5]], [[10/7]], [[3/2]], [[8/5]], [[5/3]], [[12/7]], [[7/4]], [[2/1]], which is known as the [[Wikipedia:Tonality diamond|7-limit tonality diamond]].
The [[7-odd-limit]] refers to a constraint on the selection of [[Just intonation|just]] [[Interval class|intervals]] for a scale or composition such that 7 is the highest allowable odd number, either for the intervals of the scale, or the ratios between successive or simultaneously sounding notes of the composition. The complete list of 7 odd-limit intervals within the octave is [[1/1]], [[8/7]], [[7/6]], [[6/5]], [[5/4]], [[4/3]], [[7/5]], [[10/7]], [[3/2]], [[8/5]], [[5/3]], [[12/7]], [[7/4]], [[2/1]], which is known as the [[Wikipedia:Tonality diamond|7-limit tonality diamond]].
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For a variety of reasons, common-practice music has been somewhat stuck at the 5-limit for centuries, though 7-limit intervals have a characteristic jazzy sound which is at least partially familiar. Music in the 7-limit thus represents a large step forward, although not as much as [[11-limit|11-]] or [[13-limit]], which usually sound much more exotic.
For a variety of reasons, common-practice music has been somewhat stuck at the 5-limit for centuries, though 7-limit intervals have a characteristic jazzy sound which is at least partially familiar. Music in the 7-limit thus represents a large step forward, although not as much as [[11-limit|11-]] or [[13-limit]], which usually sound much more exotic.


A list of [[edo]]s which tunes the 7-limit with more accuracy: {{EDOs| 5, 9, 10, 12, 19, 27, 31, 41, 53, 72, 99, 171, 441, 612 }} and so on. Another list of edos which tunes the 7-limit well relative to their size ([[TE relative error|relative error]] < 5%): {{EDOs| 12, 19, 31, 41, 53, 72, 99, 118, 130, 140, 152, 171, 183, 202, 212, 217, 224, 229, 239, 243, 251, 270, 282, 289, 301, 311, 323, 354, 369, 373, 383, 388, 395, 400, 410, 414, 422, 441, 453, 460, 472, 482, 494, 525, 544, 566, 571, 581, 593, 612 }} and so on.  
== Edo approximation ==
Here is a list of [[edo]]s which tunes the 7-limit with more accuracy (decreasing [[TE error]]): {{EDOs| 10, 12, 19, 27, 31, 41, 53, 72, 99, 171, 441, 612, }}.  


== List of intervals in the 7-prime-limit and 81-odd-limit ==
Here is a list of edos which tunes the 7-limit well relative to their size ([[TE relative error]] < 5%): {{EDOs| 12, 19, 31, 41, 53, 72, 99, 118, 130, 140, 152, 171, 183, 202, 212, 217, 224, 229, 239, 243, 251, 270, 282, 289, 301, 311, 323, 354, 369, 373, 383, 388, 395, 400, 410, 414, 422, 441, 453, 460, 472, 482, 494, 525, 544, 566, 571, 581, 593, 612, … }}.
 
== Intervals ==
Here is a table of intervals in the 7-prime-limit and 81-odd-limit.


{| class="wikitable center-1 right-3"
{| class="wikitable center-1 right-3"