I'm new to music theory and I've been learning quite a bit but still have many questions. I would like to know how I could transition between scales on the piano. For example there is a song (a slow song if it matters) in particular where it transitions from D scale to G scale. I was able to decode the transition by ear which results in D C Bm Am7 (would normal Am work?) D G. I would do the bass on my left hand while I do some melody with my right hand. I would like to know what this particular set of notes is called or if there is a specific formula or rule that could help me. Thanks again!
So the bass (I assume) progression is D C Bm Am7 D G, which would be:
- D F# A
- C E G
- B D F#
- A C E G (which is in homage to CMaj from before, hence the added 7th)
- D F# A
- G B D
These are all 7 notes of the G major scale (or E natural minor, but the progression ends on a G chord, so it's definitely major).
The interval between D (the root of the first chord) and G (the root of the last one) is a perfect fifth (7 semitones). This is one of the 2 most common cadences found in music (the other being a transition from a perfect fourth to the tonic).
So, umm, there is no scale transition here, and I don't quite understand your question.
Also, an Xm7 chord will always contain a major triad from a major key relative to X. In your example, we have a CMaj chord (C E G). The relative minor of C (take a look at the Circle of Fourths/Fifths) is A. So if we want to build an Am7 chord, we can simply take A and add the notes of the C major triad on top of it. That's one of the beauties of m7 chords.