Modulation is to move from one key to a new key.
(For a description of the Roman Numerals see Roman Numerals and Triads.)
If you play the First Primary Chord and then move the iii up to a IV (a half step) and the V up to a vi (a whole step) you will be playing the Second Primary Chord (second inversion) and you only had to move two fingers.
A triad in second inversion has intervals of a sixth and fourth above the lowest note.
If you play the First Primary Chord and then move the I down to a viio (a half step) and the iii down to a ii (a full step) and add a IV (to make the 7th) you will be playing the Third Primary Chord (first inversion) and you only had to move two fingers.
A triad in first inversion has the intervals of a sixth and a third above the lowest note.
It has now been shown how to play the three major triads (three-key chords) in any key.
To modulate: In the current key, write the 7th chord leading to the new key, followed by the notes in the new key.
Note: The new key does not need to be the next key in the Circle of Fifths.
Example: Bb to Ab7 to Db
Examples below are consecutive progressions in the Circle of Fifths:
Example: F to F7 to Bb
Example: Bb to Bb7 to Eb
Example: Eb to Eb7 to Ab
Example: Ab to Ab7 to Db.
In modulation, there are three chords of concern:
� The last chord in the current key
� The pivot chord - usually the 7th chord leading to the new key
� The first chord in the new key
The chords should share common tones. Sometimes the tones may be different by � step or, less useful, by one step.
The existing chords may need to be modified to support this requirement.
The three chords must be compatible with the preceding and following chords.
When transposing from a flat key to its non-flat key:
Namely: Db to D, Eb to E, Gb to G, Ab to A, or Bb to B.
� The key signature changes from flats to sharps. (b ? #)
� The number of former flats plus the number of current sharps equals seven.
� The music will be the same.
Example: Db with five flats becomes D with two sharps.
When transposing from a non-flat key to its flat key:
Namely: D to Db, E to Eb, G to Gb, A to Ab, or G to Gb.
� The key signature changes from sharps to flats. (# ? b)
� The number of former sharps plus the number of current flats equals seven.
� The music will be the same.
Example: D with two sharps becomes Db with five flats.
When transposing from F to Gb:
� The sum of the flats and sharps equals seven.
� The music will be different.
When transposing from C to Db, from E to F, from G to Ab, or from A to Bb:
� The sum of the flats and sharps equals five.
� The music will be different.
When transposing by a full step:
� The key signature does not change from flats to sharps or sharps to flats.
� The difference in the number of sharps or flats is two.
Example: Db with five flats to Eb with three flats.
Example: D with two sharps to E with four sharps.
The exception is from F to G: The transposition is from one flat to one sharp. (The sum is two.)