Half-diminished seventh chord: Difference between revisions

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In just intonation: added 1/1 – 7/6 – 7/5 – 7/4
 
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* (Meantone) 1/1 ‒ [[6/5]] ‒ [[36/25]] ‒ [[9/5]], with steps 6/5, 6/5, 5/4
* (Meantone) 1/1 ‒ [[6/5]] ‒ [[36/25]] ‒ [[9/5]], with steps 6/5, 6/5, 5/4


In [[starling]] temperament, which [[tempering out|tempers out]] [[126/125]], the ~36/25 diminished fifth is equated with ~[[10/7]], reducing the chord to the [[7-odd-limit]] as an [[essentially tempered chord]]:
In [[starling]] temperament, which [[tempering out|tempers out]] [[126/125]], the ~36/25 diminished fifth is equated with ~[[10/7]], reducing the chord to the [[9-odd-limit]] as an [[essentially tempered chord]]:


* (Starling) 1/1 ‒ [[6/5]] ‒ [[10/7]] ‒ [[9/5]], with steps 6/5, 6/5, 5/4
* (Starling) 1/1 ‒ [[6/5]] ‒ [[10/7]] ‒ [[9/5]], with steps 6/5, 6/5, 5/4


In [[archytas]] temperament, which tempers out [[64/63]], a ~[[16/9]] minor seventh is equated with ~[[7/4]], a ~64/45 diminished fifth is equated with ~[[7/5]], and the ~[[35/24]] ratio between ~7/4 and ~6/5 is equated with a ~[[3/2]] perfect fifth, yielding another 7-odd-limit essentially tempered chord:
[[Septimal meantone]], which is well-represented by the historically prevalent [[quarter-comma meantone]], tempers together all three of the tritones (10/7~36/25~64/45) and sevenths (9/5~16/9~25/14), so either of the above interpretations may be relevant for half-diminished seventh chords found in common-practice music. (→ [[Didymic chords #Dominant seventh chord]])
 
In [[archytas]] temperament, which tempers out [[64/63]], a ~[[16/9]] minor seventh is equated with ~[[7/4]], a ~64/45 diminished fifth is equated with ~[[7/5]], and the ~[[35/24]] ratio between ~7/4 and ~6/5 is equated with a ~[[3/2]] perfect fifth, yielding a [[7-odd-limit]] essentially tempered chord:


* (Archytas) 1/1 ‒ 6/5 ‒ 7/5 ‒ 7/4, with steps 6/5, 7/6, 5/4
* (Archytas) 1/1 ‒ 6/5 ‒ 7/5 ‒ 7/4, with steps 6/5, 7/6, 5/4
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In the [[7-limit]]:
In the [[7-limit]]:
* [[5:6:7:9]] is a highly [[concordant]] 7-limit interpretation of the half-diminished seventh, found in the [[Ringer_scale|Ringer 5]] scale and [[Euler-Fokker genus|genus]]3<sup>2</sup>{{dot}}5{{dot}}7, and tempered together with 45:54:64:81 in archytas temperament.
* [[5:6:7:9]] is a highly [[concordant]] 7-limit interpretation of the half-diminished seventh, found in the [[Ringer_scale|Ringer 5]] scale and [[Euler-Fokker genus|genus]] 3<sup>2</sup>{{dot}}5{{dot}}7, and tempered together with 45:54:64:81 in archytas temperament.
* [[60:70:84:105]] (1/1 - 7/6 - 7/5 - 7/4) is a subharmonic chord.  
* [[20:24:28:35]] is a [[condissonant]] chord found in genus 3{{dot}}5{{dot}}7, and tempered together with 45:54:64:80 in archytas temperament.
* [[20:24:28:35]] is a [[condissonant]] chord found in genus 3{{dot}}5{{dot}}7, and tempered together with 45:54:64:80 in archytas temperament.
* [[35:42:50:63]] is a [[condissonant]] chord found in genus 3<sup>2</sup>{{dot}}5<sup>2</sup>{{dot}}7, and tempered together with 25:30:36:45 in starling temperament.
* [[35:42:50:63]] is a [[condissonant]] chord found in genus 3<sup>2</sup>{{dot}}5<sup>2</sup>{{dot}}7, and tempered together with 25:30:36:45 in starling temperament.

Latest revision as of 23:42, 27 September 2024

English Wikipedia has an article on:

A half-diminished seventh chord is a tetrad comprising a root, a minor third, a diminished fifth, and a minor seventh.

In temperaments

In meantone (including 12edo), on which traditional tonal harmony is built, the interval of a diminished fifth tempers together 36/25~64/45~1024/729, and the minor seventh tempers together 9/5~16/9, giving a chord with an intervallic odd limit of 25:

  • (Meantone) 1/1 ‒ 6/5 ‒ 36/25 ‒ 9/5, with steps 6/5, 6/5, 5/4

In starling temperament, which tempers out 126/125, the ~36/25 diminished fifth is equated with ~10/7, reducing the chord to the 9-odd-limit as an essentially tempered chord:

  • (Starling) 1/1 ‒ 6/5 ‒ 10/7 ‒ 9/5, with steps 6/5, 6/5, 5/4

Septimal meantone, which is well-represented by the historically prevalent quarter-comma meantone, tempers together all three of the tritones (10/7~36/25~64/45) and sevenths (9/5~16/9~25/14), so either of the above interpretations may be relevant for half-diminished seventh chords found in common-practice music. (→ Didymic chords #Dominant seventh chord)

In archytas temperament, which tempers out 64/63, a ~16/9 minor seventh is equated with ~7/4, a ~64/45 diminished fifth is equated with ~7/5, and the ~35/24 ratio between ~7/4 and ~6/5 is equated with a ~3/2 perfect fifth, yielding a 7-odd-limit essentially tempered chord:

  • (Archytas) 1/1 ‒ 6/5 ‒ 7/5 ‒ 7/4, with steps 6/5, 7/6, 5/4

Alternately, if we take the ~9/5 minor seventh instead, archytas gives a 9-odd-limit essentially just chord, tempering together 5:6:7:9 with 45:54:64:81:

  • (Archytas) 1/1 ‒ 6/5 ‒ 7/5 ‒ 9/5, with steps 6/5, 7/6, 9/7

In just intonation

In the 7-limit:

  • 5:6:7:9 is a highly concordant 7-limit interpretation of the half-diminished seventh, found in the Ringer 5 scale and genus 32 ⋅ 5 ⋅ 7, and tempered together with 45:54:64:81 in archytas temperament.
  • 60:70:84:105 (1/1 - 7/6 - 7/5 - 7/4) is a subharmonic chord.
  • 20:24:28:35 is a condissonant chord found in genus 3 ⋅ 5 ⋅ 7, and tempered together with 45:54:64:80 in archytas temperament.
  • 35:42:50:63 is a condissonant chord found in genus 32 ⋅ 52 ⋅ 7, and tempered together with 25:30:36:45 in starling temperament.

In the 5-limit:

  • 25:30:36:45 is found on iiiø7 (54) and viø7 (53) in the duodene.
  • 45:54:64:80 found on viiø7 (158) in Ptolemy's intense diatonic scale (Zarlino), perhaps the most common 5-limit diatonic. It is also found on Vø7 (32) in the duodene.
  • 45:54:64:81, another preimage of the meantone half-diminished seventh chord, is found in genus 34 ⋅ 5, and tempered together with 5:6:7:9 in archytas temperament.
  • 135:160:192:240 is found on iiø7 (98) and ♯ivø7 (4532) in the duodene.