How come when you have a I-IV-V progression like in the blues I can take the same lick and just transpose it from the root position to the IV and then the V and it sounds ok. So if it was in Em, I could play the same lick in E, then in A then in B and it would work. But if I have a i-II-III progression I can't (in Em) play the same lick in E, then F# then G just transposed and have it sound good?
changing scales over each chord isn't truly necessary. if you're playing in E minor, all the chords will be made up of notes from the E minor scale, and that scale will sound good over any of those chords, generally speaking. Changing the scale along with the chord makes it seem like the band is changing keys every bar... not necessarily against the rules, but that's what it's gonna sound like.

it may be that your moveable lick that works over 1-4-5 progressions still contains only the notes of E minor, and so it just works. In fact, if you look at the scales of those chords:

E minor: E F# G A B C D
A minor: A B C D E F G
B minor: B C# D E F# G A

they have a lot of notes in common... only the F's and C's differ, but they make nice transition notes if you use them right. but when you look at the scales for 1-2-3 progressions in E minor...

E minor: E F# G A B C D
F# mnor: F# G# A B C# D E
G minor: G A Bb C D Eb F

they have far fewer notes in common.

i recommend sticking to scale of the key you're in; it's usually more effective and a bit easier to boot!
Last edited by frigginjerk at Nov 23, 2009,
Depends dude.

The reason it works for I IV and V progressions is that, in a major key (ionian), they are all major chords. If you have i II III thats Emin F#maj G#maj (in E minor) and so any lick using the third wont transpose as well.