3stepbend wrote:ok...so can someone explain something...if this is indeed Am (which seems right, based on the scales being used), how can the B7, E7#9, and D be explained. The chords for Am would be:
I could understand possibly using the B7 as a substitue for Bdim, just not sure how the others fit or why
The B7 is what's known as a Secondary Dominant. It's a common technique where you change a diatonically non-dominant chord (meaning one that follows the proper key signature of the song, like you outlined above) into one with a dominant structure, in order for it to resolve to a different chord than the tonic. II7 is the most common example, resolving to V. Dominant-structured chords always resolve down a 5th, following the circle of 5ths. Or for our string-based thinking, same fret, one higher-pitched string. G7 resolves to C, A7 resolves to D, etc, whether the G7 or A7 belong in the key or not.
#9s are just fun to add to things, especially dominant chords. You can add just about any note to a dominant chord and still have it function as a dominant. Dominant chords are all about creating a tension that then releases to the tonic, so the more weird things you add to it, the more tension you create and the more thoroughly it functions as a dominant. Also the #9 of E7 is F## aka G, which is in either the A minor or A Dorian scale.
The D major is an example of the song being really closer to A Dorian than A Minor, a fairly common thing in both jazz and rock. If you're soloing along and get past the pentatonic, you'll find that F# fits a little better than F. That same F# works harmonically to create a logical D major.