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[TITLE]MAJOR DIATONIC SCALE (SDM)
Scales are composed by note sequences and semitone intervals. A CROMATIC interval exists among two nearest notes of the same scale degree (C and C#, F and F# ...), while the interval among 2 notes of 2 different degrees is called DIATONIC (C and Db, E and F, B and C, C# and D...).
The SDM is a reference scale for all the others, and it is arranged by specific diatonic intervals. Observing it in a C tonality we'll see that it considers all the full notes: C, D, E, F, G, A, B.
[IMG]sdm_do.png
 
For T=tone and S=semitone, this is its intervals scheme:
[IMG]DO_ionico.png
 
Each SDM note must be considered as a scale degree; 7 notes means 7 degree: 1,2,3,4,5,6,7, and we can also enumerate the considered semitones: 1,3,5,6,8,10,12. The SDM is also called Ionic scale.
Degrees are important to calcoulate other scales, and they are definited as follow:
>tonic (I)
>supertonic (II)
>mediant (III)
>subdominant (IV)
>dominant (V)
>submediant (VI)
>subtonic (VII)
>Octave (VIII)
 
We can calcoulate the SDM of every note simply referring to the C SDM, palying every degree but starting from the current scale tonic (1st scale degree).
I.e. a SDM in D tonality is composed by D, E, F#, G, A, B, C#, because we have to follow exactly the C SDM structure and respect every interval. First interval among 1st and 2nd degree (C - D) is composed by 1 tone, so we have D and E; the second one is again of 1 tone (D - E) so our 3th D SDM degree will be a F# (E - F# = 1 tone), and so on.
To know every scale degrees and notes, look at the C scales in Scales Tool and press [4] key.
 
Scales start from the tonic (C scale starts from C note, E scale from E etc.): a simple method to play every scale with a guitar is to find the tonic on the 6th string and start to play the scale considering 2 or 3 notes for each string. I.e. play C Ionic starting from the 8th key, 6th string.
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