Hi Lee,
I’ve now worked through the entire Guitar Theory book and feel I’ve got to a better place to understand and break down many parts of songs. I have a question that is quite general regarding many of the 80’s rock and hair bands type of music.
The song I am working on in transcribed with a key signature of A (3 sharps). The intro begins with a riff using D5, A5, G5, D5 repeat and then the verse goes into A5, D/A, G/A, D/A, A5
Overall the tonality is definately A, and thats where the opening riff seems at rest. If its transcribed in the key signature of A, and the tonality is A, the opening riff is IV, I, bVII, I. I don’t understand why the G is not a G#. It sounds better as as a G, and many early AC/DC songs are use these three chords (A, D & G) and are in the key of A, but if the key signature is A, why is the seventh chord flattened. As you mention in the text, many people say its Mixolydian – but that does not seem correct! I thought perhaps the song would have better been transcribed in C with an A tonality (relative minor) and that fits because all the chords are essentially V chords.
Cheers
Without knowing the song or seeing the transcription you are referring to, it’s hard to say – it could be the melody is dictating the key. Sometimes the sheet music is wrong or over-simplified. However, with the chords that you’ve mentioned, my initial thought is the key of D major. D G and A = I-IV-V.
The I-IV-V chords can only belong to together in one key, the order they are played is irrelevant to the key signature. If the key signature is D major but the tonality is A then that would probably make it A mixolydian, which would explain the G being natural.
