sábado, 7 de marzo de 2015

"Estructuras de Acordes con 7"

chord nametriadseventhabbreviationother comments
dominant seventhmajorminorMm7the most common type of 7th chord having the simplest name, just the number 7 added to the root letter.
For example: C7F7E7 all indicate dominant 7th chords.
major seventh
'major major' chord
Delta chord or Δ chord
majormajorMM7named with the abbreviation Ma7 or Δ
For example: CMa7CΔF#Ma7 indicate major 7th chords.
The abbreviation M7 may also be used. For example: CM7
minor seventhminorminormm7named with the addition of mi7 or -7 to the letter name.
For example: Cmi7Gmi7Dmi7 all indicate minor 7th chords.
C-7D-7A-7 may also be used.
diminished seventh
(also called 'fully diminished seventh')
diminisheddiminisheddd7named with the small raised circle and a 7.
For example: C°7B°7, and D°7 all indicate a fully diminished 7th chord.
half diminished seventh
(also called 'minor seventh flat five' or 'Tristan chord')
diminishedminordm7the name relates them to the minor 7th, but with a lowered or flattened 5th.
For example: Cmi7(b5)Ami7(b5) indicate half diminished chords.
Note: Sometimes half diminished is indicted by a small circle with a slash through it (ø). This symbol is more common in Roman numeral analysis than chord names.
augmented triad, major seventh
(also called 'augmented major seventh')
augmented triad, minor seventh
(also called 'augmented seventh' or 'augmented minor 7th')
minor triad, major seventh
minor Delta chord or -Δ chord
(also called 'minor major seventh')
minormajormM7'Delta' notation is often used for chords like this.
C-Δ is a seventh chord with a minor third, in this case the notes C, E flat, G, B
We also summarise the degree of the scale where each type of seventh chord occurs.
major scalenatural minor scaleharmonic minor scalemelodic minor scale
dominant 7th.VVIIVIV, V
major 7th.
Delta chord
minor 7th.II, III, VII, IV, VIVII
diminished 7th.VII
half diminished 7th.
minor 7th flat 5
augmented major 7th
augmented triad, major seventh
minor triad, major seventh
minor Delta chord
Dominant Seventh Chord
One area of confusion when naming or identifying seventh chords is the use of the term dominant seventh chord.
If you look at the table above summarising the degree of the scale where each type of seventh chord occurs, you will see that the dominant seventh need not lie only on the Vth degree of the scale, the degree we call the dominant. Indeed, in the natural minor scale, the dominant seventh chord lies on the VIIth degree not on the Vth degree.
The point to remember is that the dominant seventh chord is any chord formed by adding a minor seventh to a major triad. Remember too that the chord's note name is determined by its root note. So the chord G B D F is written G7 because the root note is G. G B D is a major triad and F is the minor seventh above G. This chord, therefore, is a dominant seventh chord.
In the key of C major, the notes G B D F form a seventh chord on the Vth degree, i.e. a dominant seventh on the dominant of the scale. This is also true for the C minor natural and C minor melodic scales. However, the same notes, G B D F, are a G7 chord and a dominant seventh on the fourth (IV) degree of the D melodic minor scale.
For completeness, we note finally that the notes G B D F are also a G7 chord and a dominant seventh on the seventh (VII) degree of the A natural minor scale.
Naming Seventh Chords
One useful convention for naming any seventh chord is:
root pitch letter, then chord tokens representing triad quality and seventh quality
For example, an Ab major minor 7 chord: the first term (Ab) tells us the root of the chord; the second term (major) identifies the quality of the triad that forms the lower three notes of the seventh chord; and, the third term (minor) identifies the quality of the interval of the seventh formed between the root and the seventh.
long name examplesshort or abbreviated name(s)chord notes (root to seventh)
F major major 7FM7, FMaj7, F Major 7F A C E
F major minor 7F7, also called 'dominant 7'F A C Eb
F minor major 7FmM7F Ab C E
F minor minor 7Fm7, Fmin7, F minor 7F Ab C Eb
F diminished major 7FdM7F Ab Cb E
F diminished minor 7Fø7, Fm7b5F Ab Cb Eb
F augmented major 7F+M7, FM7#5F A C# E
F augmented minor 7F+7, F7#5F A C# Eb
F diminished 7F°7, Fdim7F Ab Cb Ebb