This chord chart shows some of the most common “chord scales” that are used in the backing of trad tunes. They are meant to be used as a guide and a starting point for understanding the most commonly used chords within each key.
The first scale is in D major and consists of eight chord shapes. The chord roots start with D and progress through the D major scale until it reaches the octave of the D scale. Two chords to note are D/F# and A/C#. These are simply the second inversions of the first and fifth chords. They are substitutes for the F# minor and C# diminished chords which are typically not played traditionally.
The second chord scale is in G major. It follows the same pattern as the scale above but uses five strings instead of four. This chord scale was developed as a way to avoid the use of a capo so that transitions from other keys would be smoother. An alternative way to play in G major would be to use a capo at the fifth fret and use the same shapes of the D major scale. This is an equally valid method for backing tunes in trad music and is probably the most common way.
The third chord scale is in A Dorian. However, most of the time it will be referred to as A minor. This chord scale should not be taken too literally and should only be used as a guide for the chords that could be played but would not always be played. In particular the B minor and C major chords would most likely only be used in passing most of the time and would usually be played minus the third of the chord.
The last chord scale is actually a combination of the E Dorian and E Aeolian scales. Most of the time tunes of either scale are referred to as E minor. Depending on the tune that is being supported the fourth chord (A minor or A major) and the sixth chord (C major or A/C#) of the scale may change. Typically, these chords would either not be played or would be played in passing without playing the third of the chord.
It is important to remember that not all of the chords need to be used when backing a tune or song, In fact, it is often very effective to only use a small set of chords from the full chord scale.
DADGAD_Chord_Scale_Chart