Dominant seventh sharp ninth chord
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|Component intervals from root|
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|5-32 or 5-limit JI 160:200:240:288:375[a]|
In music, the dominant 7♯9 chord ("dominant seven sharp nine"). This chord is commonly used in most forms of contemporary popular music, including jazz, funk, R&B, hip hop, rock and pop. As a dominant chord in diatonic harmony, it most commonly functions as a turnaround chord, returning to the tonic. However, the 7#9 is also quite frequently used in some styles as a tonic without the resolution typical of a dominant chord.
The chord is also sometimes colloquially known, among pop and rock guitarists, as the Hendrix chord or Purple Haze chord, nicknamed for guitarist Jimi Hendrix, who showed a preference for the chord and did a great deal to popularize its use in mainstream rock music. When used by the Beatles it has also been called the Gretty chord although this can refer to a distinct 6 string version.
Spelling and notation 
There are two main ways to spell the chord, depending on the musical style, kind of musical notation (score or chord symbols), and personal taste. One consists of a dominant seventh chord with an added minor third, placed one or more octaves over the major third; the other consists of a dominant seventh chord with an added augmented ninth. Only the second type of notation can be represented using the common chord symbol notation systems.
Other more uncommon notations and names include major/minor or 7 (add min 3).
Nature of the chord 
The 7#9 chord is commonly used in jazz, blues, R&B, rock and all forms of contemporary popular music. Since it has a major 3rd and flat 7, it is generally considered a dominant chord.
The 7#9 is an altered chord, and it is one option when seeing the chord symbol G7alt. It is functionally a dominant chord, and thus "wants" to resolve to the tonic in diatonic harmony.
Stuart Isacoff has called the chord "funky" or "bluesy", because of the tension "generated between the major third and the augmented ninth"; while Doug Munro deems it as "jazzy" rather than bluesy. Eric Starr says that "the sharp nine tends to be edgier, bluesier, and meaner sounding [than the flat nine]." While the dorian may be the scale most commonly used for the 7♯9, the mixed third allows flexibility including the use of mixolydian, aeolian, and other modes. In jazz, 7♯9 chords, along with 7♭9 chords, are often employed as the dominant chord in a minor ii-V-I turnaround. For example, a ii V I in Cm could be played as: Dm7♭5 - G7♯9 - Cm7.
|V in minor||Blues scale|
|Dominant diminished scale|
|Minor pentatonic scale|
|V in minor||Blues scale|
|Minor pentatonic scale|
The dominant 7♯9 chord appears in impressionist classical music. An example can be heard in Claude Debussy's Feuilles Mortes, from his second book of Préludes (1913). There, the unresolved, dissonant ninth chords (at least a, "C♯7with a "split third" and "added minor ninth") help create, according to Richard Bass, an "utterly sad, desolate character," throughout the piece.
This chord can also be found in serial music. For example, the Elektronische Musik vom Freitag aus Licht (1991–94) by Karlheinz Stockhausen, from an opera composed using formula technique, concludes on this chord.
Jazz and blues 
Hendrix chord 
While this sonority has been previously used in jazz and related styles, one particular voicing of this chord is commonly nicknamed the "Hendrix Chord" among rock guitarists. This association is because it was a favorite of Jimi Hendrix, who did a great deal to popularize its use in mainstream rock music.
The earliest recorded evidence of his use of the chord is on the Isley Brothers "Testify, Parts 1 and 2" (1964), one of his few recordings before the start of his solo career in 1966. The most notable Hendrix song that features the 7♯9 chord is "Purple Haze", while it is also implied in "Foxy Lady", both coming from his 1967 album Are You Experienced?. When performing "Voodoo Child (Slight Return)" live Hendrix later used not only E7♯9, the sharpened ninth chord on the tonic, but also D7♯9 and C7♯9 chords, the subtonic and submediant.
This harmonic device is one of many factors that, according to Gleebeek and Spairo, contribute to "the dirty, raw, metallic, angular sounds of [...] Hendrix songs". It is an example of how he would embellish chords "to add new colours to the music, often derived from his own roots in black music". "In essence," John Perry[disambiguation needed] writes, the Hendrix chord is "the whole of the blues scale condensed into a single chord."
Other musicians 
The chord was used by the Beatles in songs such as "The Word" and "Taxman". McCartney called this a "great ham-fisted jazz chord" that was taught to them by Jim Gretty who worked at Hessey's music shop in Whitechapel, central Liverpool. George Harrison uses it as the penultimate chord of his solo on "Till There Was You".
The chord is favored by Pixies lead guitarist Joey Santiago, with D7♯9, reminiscent of the opening to "A Hard Day's Night", opening and being called the "secret ingredient," to the song "Here Comes Your Man" and "brutally scraped" F7♯9 featured on the chorus to "Tame" against the three chord rhythm guitar part's D, C, and F chords.
- A just major third (5/4), perfect fifth (3/2), minor seventh (9/5), and augmented second (75/64). Many other just tunings are possible, with higher limits allowing overtone tunings using smaller whole-number ratios, such as 10:12:14:19 or 20:24:28:37.
- Isacoff, Stuart (1987). The 20-Minute Chords & Harmony Workout, p.111. ISBN 978-0-943748-41-2.
- Van Nuys, Calif: Alfred Publishing; New York: Penguin (2007). The Complete Idiot's Guide to Rock Guitar Songs, edited by Mike Sanders, Phil Kitchel, and Janette Lynn, p.58. ISBN 0-7390-4628-4.
- Shapiro, Harry and Caesar Glebbeek (1995). Jimi Hendrix: Electric Gypsy, p.144. ISBN 0-312-13062-7.
- "The 'Hendrix Chord'", Fender.com. Accessed 29 February 2012.
- Pedler, Dominic (2003). The Songwriting Secrets of the Beatles, p.437. Omnibus Press. London. ISBN 978-1-4234-1345-5.
- "The Hendrix Chord", Aeoliancadenece.co.uk. Accessed 28 February 2012.
- Pease Pulling, pp. 33,76,77.
- Waite, p. 53.
- Valerio Bebop Jazz Piano, pp. 10,21.
- Esterowitz, p. 68.
- Stephenson, Ken (2002). What to Listen for in Rock: A Stylistic Analysis, p.84. ISBN 978-0-300-09239-4.
- Munro, Doug (2001). Jazz Guitar: Bebop and Beyond, p.58. ISBN 0-7579-8281-6.
- Eric Starr, Nelson Starr (2008). Everything Bass Guitar Book: From Lines and Licks to Chords and Charts - All You Need to Find Your Groove, unpaginated. ISBN 978-1-59869-483-3.
- Gill, Danny (2001). Practice Trax for Guitar[sic], p.13. ISBN 0-634-02621-6.
- Valerio, Post-Bop Piano.
- Bass, Richard (Autumn, 1994). "Models of Octatonic and Whole-Tone Interaction: George Crumb and His Predecessors", p.161, Journal of Music Theory, Vol. 38, No. 2., pp. 155-186. .
- Bruhn, Siglund (2007). Images and Ideas in Modern French Piano Music, p.172 and 174. ISBN 978-0-945193-95-1.
- Jerome Kohl, "Der Aspekt der Harmonik in Licht", in Internationales Stockhausen-Symposion 2000: Licht: Musikwissenschaftliches Institut der Universität zu Köln, 19. bis 22. Oktober 2000: Tagungsbericht, edited by Imke Misch and Christoph von Blumröder, 116–32. Signale aus Köln: Musik der Zeit 10 (Münster: Lit-Verlag, 2004): p.120. ISBN 3-8258-7944-5.
- Radio: "Shiver down the backbone - Jimi Hendrix comes to Radio 3", The Spectator, by Kate Chisholm, Wednesday, 21st November 2007
- Roby, Steven (2002). Black Gold: The Lost Archives of Jimi Hendrix, p.32. ISBN 0-8230-7854-X.
- Perry, John (2004). Jimi Hendrix's Electric Ladyland, p.120-121. ISBN 0-8264-1571-7.
- Pedler (2003), p.440-441.
- Sisario, Ben (2006). Doolittle, p.82 and 90. ISBN 0-8264-1774-4.
Further reading 
- Hanford, John. "With the Power of Soul: Jimi Hendrix in Band of Gypsys" Ph.D. dissertation, University of Washington, 2003.
- van der Bliek, Rob. "The Hendrix Chord: Blues, Flexible Pitch Relationships, and Self-standing Harmony," Popular Music 26:2 (May 2007), pp 343–364.
- Ted Pose, Ken Pulling (2001). Michael Gold, ed. Modern Jazz Voicings (Paperback ed.). Berklee Press. ISBN 0-634-01443-9.
- Waite, Brian (1987). Modern Jazz Piano: A study in harmony and improvisation (Hardback ed.). Wise Publications. ISBN 0-7119-08-41-9.
- Valerio, John (2003). Bebop Jazz Piano. Hal Leonard. ISBN 0-634-03353-0.
- Valerio, John (2005). Post-bop Jazz Piano. Hal Leonard. ISBN 0-634-06123-2.
- Esterowitz, Michael (1987). How To Play From A Fake Book. Ekay Music. p. 168. ISBN 0943748194, 9780943748191 Check
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