Diminished Seventh

In classical music from Western culture, a diminished seventh ( play) is an interval produced by narrowing a minor seventh by a chromatic semitone. For instance, the interval from A to G is a minor seventh, ten semitones wide, and both the intervals from A♯ to G, and from A to G♭ are diminished sevenths, spanning nine semitones. Being diminished, it is considered a dissonant interval.

The diminished seventh is enharmonically equivalent to a major sixth. Its inversion is the augmented second.

The diminished seventh is used quite readily in the minor key, where it is present in the harmonic minor scale between the seventh scale step and the sixth scale step in the octave above.

In an equal tempered tuning, a diminished seventh is equal to nine semitones, a ratio of 29/12:1 (approximately 1.682), or 900 cents. There is no standard just tuning of this interval, but one possibility, assuming the flat submediant is a perfect (5:4) major third below the octave, and the leading tone to be 15:16, would lead to an interval of 128:75, about 925 cents; another interval is 216:125, which is three minor thirds.

The 128:75 just diminished seventh arises in the C harmonic minor scale between B and A♭ by combining B-D, D|F, F-A♭. Play

Other articles related to "seventh, diminished seventh, diminished":

Chord Names And Symbols (popular Music) - Seventh Chords
... A seventh chord is a triad with an added note, which is either a major seventh above the root, a minor seventh above the root (flatted 7th), or a ... Note that the diminished seventh note is enharmonically equivalent to the major sixth above the root of the chord ... When not otherwise specified, the name "seventh chord" may more specifically refer to a major triad with an added minor seventh (a dominant seventh chord) ...
Supertonic
... D-F-A in C major), or iio in a natural minor scale, indicating that the chord is a diminished chord (for example, D-F-A♭ in C natural minor), if in second inversion a six-four ... The supertonic may be raised as part of the common-tone diminished seventh chord, ♯iio7 ... One variant of the supertonic seventh chord is the supertonic diminished seventh with the raised supertonic, which equals the lowered third through enharmonic equivalence (in C D♯=E♭) ...

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