Selasa, 27 Desember 2011

How to make a diatonic scale

How to make a diatonic scale

Pick a letter from A to G, accidental natural, sharp or flat. Follow through with the natural letters of the alphabet.
A   B   C   D   E   F   G   A
  T   S   T   T   S   T   T  
The pattern of tones and semitones from A to A is TSTTSTT. This is not TTSTTTS. It is not a diatonic scale.
We use accidentals to make a diatonic scale.
  1. The first interval of the diatonic scale is T.
    • Start with the first note (A).
    • A to B is T.
    • B is the second note of the diatonic scale.

  2. The second interval of the diatonic scale is T.
    • Start with the second note (B).
    • B to C is S.
    • B to C# is T.
    • The third note of the diatonic scale is C#.

  3. The third interval of the diatonic scale is S.
    • Start with the third note (C#).
    • C# to D is S.
    • The fourth note is D.

  4. The fourth interval of the diatonic scale is T.
    • Start with the fourth note (D).
    • D to E is T.
    • The fifth note is E.

  5. The fifth interval of the diatonic scale is T.
    • Start with the fifth note (E).
    • E to F is S.
    • E to F# is T.
    • The sixth note is F#.

  6. The sixth interval of the diatonic scale is T.
    • Start with the sixth note (F#).
    • F# to G is S.
    • F# to G# is T.
    • The seventh note is G#.

  7. The seventh interval of the diatonic scale is S.
    • Start with the seventh note (G#).
    • G# to A is S.
    • The eighth note is A, the same as the first.
The diatonic scale of A is:
A   B   C#   D   E   F#   G#   A
  T   T   S   T   T   T   S  

How to work magic

Can a diatonic scale be written to D# ?
No.
D#
Eb
E
Fb
F
E#
F#
Gb
G G#
Ab
A A#
Bb
B
Cb
C
B#
C#
Db
D D#
Eb
D#   E#    G G#   A#   B#X   D D#
Why not?
What is wrong with D# E# G G# A# B# D D#.
Answer: C is missing and G is repeated.
Every letter must be present in a diatonic scale.
What can we do?
We can introduce double sharps and double flats. Fx is G and Cx is D.
This is also wrong D# E# Fx G# A# B# Cx D#
Double sharps and double flats are banned from diatonic scales.
What can we do?
Rename each note to its enharmonic.
Now we have a diatonic scale.
Eb F G AB Bb C D Eb
Every key on the keyboard can be written to a diatonic scale, but not every note name. When the first name you try doesn’t work, switch to its enharmonic. It’s enharmonic will work.
  C#
dB
  D#
Eb
    F#
GB
  G#
AB
  A#
Bb
 
C
B#
D E
Fb
F
E#
G A B
CB

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