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A minor scale in musical theory is a diatonic scale whose third scale degree is an interval of a minor third above the tonic. While some definitions of minor scale encompass modes with the minor third, such as Dorian mode, most musicians use the term to refer to the natural minor, harmonic minor, and melodic minor scales described below. Also, compare major and minor.
Types of minor scales
Finding key signatures Minor modes use the same set of key signatures as major modes; whichever signature corresponds to the step pattern of the natural minor scale is considered the key signature for that minor mode. The major and minor keys which share the same signature are called relative; so C major is the relative major of A minor, and C minor is the relative minor of E-flat major. The relative major is found by raising the minor tonic note by a tone and a semitone, which is three half-steps in equal temperament, and in any event an interval of a minor third. If you know that the key signature of G major has one sharp (see major scales for how to find this), then its relative minor, E minor, also has one sharp in its key signature. This table illustrates the relative major key signatures for minor scales. The following are enharmonic equivalents: Additional note: it is possible to construct scales which cannot be written purely using a key signature, such as D-flat minor; double sharps/double flats can be written as accidentals, but not as part of a key signature. For example: D♭ Minor Key Signature: B♭ + E♭ + A♭ + D♭ + G♭ + C♭ + F♭ + B♭♭ (the B♭ is now double flatted) D♭ Natural Minor = D♭ E♭ F♭ G♭ A♭ B♭♭ C♭ D♭ D♭ Melodic Minor (Ascending + Descending) = D♭ E♭ F♭ G♭ A♭ B♭ C D♭ C♭ B♭♭ A♭ G♭ F♭ E♭ D♭ D♭ Harmonic Minor = D♭ E♭ F♭ G♭ A♭ B♭♭ C D♭ On rare occasions, short passages of music will be written in an enharmonic scale (in this case, C-sharp minor, which only has four sharps in its key signature, compared to the theoretical eight flats required for D-flat minor). Circles of thirds All three of the variant forms of the minor scale possess a complete circle of three major and four minor thirds in various arrangements. If M is a major third and m a minor third, then starting from the tonic (eg A in A minor) we have mmMmmMM for the natural minor scale, mmMmMMm for the harmonic minor scale, and mmMMMmm for the ascending melodic minor. The major diatonic scale is simply a transposition of the natural minor scale, and the harmonic major scale is an inverted form of the harmonic minor scale, so all of these workhorse scales of the diatonic system possess such a circle of thirds. These circles only close in meantone tunings, since three major and four minor thirds exceed two octaves by 81/80, the syntonic comma, in just intonation. Two major thirds in succession in such a circle gives an augmented triad, and two minor thirds a diminished triad. A major third followed by a minor third gives a major triad, and a minor third followed by a major third a minor triad. Hence all seven scale degrees have some variety of triad over that degree for all of these scales. See also Reference | ||||||||||
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