QUESTION ABOUT THE SONG "JESSICA"

[BENNY.W]

i got the transcript to the song "jessica" by the allman bros and i dont understand why if the main key of the song is "a" why or how is there a "g chord" in the progression? at the guitar solo the key changes to "d "and there is a "c chord" in that progresion.i thought the key of a had a g# and the key of d had a c#. why even put a key signature on music if the progression isn't true to the key? thanks for any help

[Ed Fuqua]

Look at the melody, not the harmony. The harmony of a composition does not have to be diatonic, if the melody is roughly diatonic (adheres mostly to the key signature without much usage of added accidentals) then you apply a key signature so you don't have to remind everybody every time that it's an Eb, not an E.

[dougjwray]

(To the OP, not Ed):
Well, you've got a point if you're considering "classical" music, where these things are taken seriously.
But in rock and other pop music, you'll find that the key signature often mainly indicates the "home base" of the tune, and that chords not occurring naturally (i.e. diatonically) will turn up often, with only accidentals in the notation to accomodate them.
Hope this helps. Maybe someone else can explain it better.

[BENNY.W]

thank you everyone , it does help

[Jim Nazium]

It's pretty common in rock and pop music to have chords other than the 7 diatonic chords. Often they come from a "temporary" key change. You can think of the G chord as the 7 chord from A minor, so it's like the tune temporarily went from A major into A minor. Same goes for the C chord in the part that's in D major. This is a very common device.

[BENNY.W]

i see your angle,thanks

[DocBop]

Looks like use of Parallel Key. The song in key of A and the G chord is borrowed from key of A Minor. Pop/Rock tunes do this all the time.