David-Jubal: Difference between revisions
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'''David-Jubal tuning''' is a musical framework invented by [[John O'Sullivan]] in August, 2026. It is a type of [[just intonation]]. It consists of the use of '''Jubal's scale''' as its pitch gamut, and '''David's chord''' as its primary sonority. (''For contrast, compare to most 21st century Western music which uses the [[12edo]] chromatic scale as its pitch gamut and the (tempered) major and minor triads as its primary sonorities''). | '''David-Jubal tuning''' is a musical framework invented by [[John O'Sullivan]] in August, 2026. It is a type of [[just intonation]]. It consists of the use of '''Jubal's scale''' as its pitch gamut, and '''David's chord''' as its primary sonority. (''For contrast, compare to most 21st century Western music which uses the [[12edo]] chromatic scale as its pitch gamut and the (tempered) major and minor triads as its primary sonorities''). | ||
David-Jubal tuning was designed for [[guitar]]s only, not keyboards. The guitar is tuned to an "open" just chord (David's chord), and fretted with frets corresponding to the notes of Jubal's scale (9 frets). The idea is to play David's chord on any or all of the notes of Jubal's scale, by barring with the index finger just beside the appropriate fret. | David-Jubal tuning was designed for [[guitar]]s only, not keyboards. | ||
The guitar is tuned to an "open" just chord (David's chord), and fretted with frets corresponding to the notes of Jubal's scale (9 frets). The idea is to play David's chord on any or all of the notes of Jubal's scale, by barring with the index finger just beside the appropriate fret. | |||
O'Sullivan describes David-Jubal tuning, the reasoning behind it, and practical instructions for fretting a guitar or similar instrument, on his website: | O'Sullivan describes David-Jubal tuning, the reasoning behind it, and practical instructions for fretting a guitar or similar instrument, on his website: | ||
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; Melodic contexts | ; Melodic contexts | ||
Any just interval n/d is acceptable in a melodic context (notes or chords played sequentially, not simultaneously) if its interval strength is greater than 0.25: | Any just interval n/d is acceptable in a melodic context (notes or chords played sequentially, not simultaneously) if its interval strength is greater than 0.25: | ||
* An interval with a strength value between 0.25 and 0.4999 is a | * An interval with a strength value between 0.25 and 0.4999 is a ''neutral interval''. | ||
* An interval with a strength value between 0.5 and 0.9999 is a | * An interval with a strength value between 0.5 and 0.9999 is a ''strong interval''. | ||
* An interval with a strength value greater than 1.0 is a | * An interval with a strength value greater than 1.0 is a ''very strong interval''. | ||
Over a one octave range the very strong intervals are [[4/3]], [[3/2]] and [[5/3]]; these have a value greater than 1.0 using O'Sullivan's formula. | Over a one octave range the very strong intervals are [[4/3]], [[3/2]] and [[5/3]]; these have a value greater than 1.0 using O'Sullivan's formula. | ||
; Harmonic contexts | ; Harmonic contexts | ||
In chord construction, every interval in a chord must have a strength value greater than 0.5. | |||
; Tempering | ; Tempering | ||
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Jubal's scale is the [[just intonation]] scale: 1/1, 9/8, 7/6, 5/4, 4/3, 3/2, 5/3, 7/4, 15/8, 2/1. | Jubal's scale is the [[just intonation]] scale: 1/1, 9/8, 7/6, 5/4, 4/3, 3/2, 5/3, 7/4, 15/8, 2/1. | ||
O'Sullivan derived it from the harmonic series segment 8-9-10-11-12-13-14-15-16, but replaced [[11/8]] with [[4/3]] and replaced [[13/8]] with [[5/3]], and [[7/6]] was added as well. All the denominators in Jubal's scale are 3-[[prime limit]]. | O'Sullivan derived it from the [[harmonic series]] segment 8-9-10-11-12-13-14-15-16, but replaced [[11/8]] with [[4/3]] and replaced [[13/8]] with [[5/3]], and [[7/6]] was added as well. All the denominators in Jubal's scale are 3-[[prime limit]]. | ||
O'Sullivan has published a document describing rules for composition in David-Jubal tuning: | O'Sullivan has published a document describing rules for composition in David-Jubal tuning: | ||