So I ' ve been writing a song in 128 time based around a circular sounding arpeggioriff with the notes G , B , F #, G and C , F #, A , B . Working as best as I could to figure out the key , I came up with a progression of chords that goes BmG , C # m 7 b 5 , F # m , D 611 , E 611 , G , C # m 7 b 5 . That is a bit of an odd progression based on those notes . For one thing , you have a C # m 7 b 5 , but no C # or E in your starting notes you also lack a couple of notes for the E 611 chord . That doesn ' t necessarily mean they won ' t sound OK with your riff , though . BTW , the G , B , F #, G notes outline a Gmaj 7 . The C , F #, A , B notes outline either an C 13 b 5 chord or an inversion of an Am 6 add 9 . I came up with a progression of chords that goes BmG , C # m 7 b 5 , F # m , D 611 , E 611 , G , C # m 7 b 5 . This mostly fits into the key of D , with the exception being the E chord , which should be a minor . So you could use a mode of the D major scale to solo over it . Since you seem to revolve the progression around the C # m 7 b 5 , you could use the C # locrian mode over everything except the E 611 chord , over which you could shift to the E major scale . Edit Just played it a bit and the E mixolydian seems to fit better over the E 611 than the straightup E major scale in the context of the progression .