Originally Posted by: TheRev8I am the guitarist in a 3 piece band and we are playing the Thin Lizzy Track 'Don't Believe a Word' , which obviously has some lovely 2 guitar harmony lines in it.

That tune is in A minor, but TL recorded it in slack tuning (tuned down one-half step to E-flat).

The intro riff is in octave unisons, then diatonic thirds. But the lower guitar plays an F#, so that's A dorian.

Once the verse & chorus starts in you're back to straight A minor, because there is a harmonized line over the A minor chord then the D minor chord.

Hope that helps!