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.
The diatonic scale of A is:
| A | B | C# | D | E | F# | G# | A | |||||||
| T | T | S | T | T | T | S |
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 |
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| C B# |
D | E Fb |
F E# |
G | A | B CB |
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