The chords Bb major, D major, A major, G# major
If all of these chords were moved up two frets (capo on 2nd fret) what key would this make ?
A capo on the 2nd fret just raises everything by a whole step (or two half steps)


Bb/A# major becomes C major (A#/Bb -> B -> C)
D major  becomes E major  (D -> Eb -> E)
A major becomes B major (A -> A#/Bb -> B)
G#/Ab major becomes A#/Bb major (G#/Ab -> A -> A#/Bb)

And the same goes for the key.
That's a bit mixed up to call it any particular key. I would tend to call it key of D.  Using the capo on 2nd fret I would call it key of E  (C. E, B, Bb).  I would rather use the standard concert C,E, B, Bb without the capo.
A transposition chart will allow you to change chords to any progression you desire.
What song is this?
The "Bb" should be called "A#" to make it consistent with the other chords, which either have sharps in them, or are from keys with sharps.

However now you have, G#, A, & A#, all as major chords. That isn't any recognized key or mode. So basically you should name it by the way it makes you feel. However, don't expect everyone to play along..

Those chords aren't anything I would put past a metal band though. You still wouldn't be able to call the song in "X" key.
Last edited by Captaincranky at Jul 5, 2017,