Originally Posted by: ivo949I have a problem of how to improvise over this progression:
︳Bmaj Dmaj ︳ F#maj ︳

Which Scale I should use for this progression.

Write out all the notes of the chords in a progression. Determine if those notes are all (or mostly) in one scale or mode. If you find that one chord has "exceptions", then you are looking at a modulation. Alter the scale accordingly, or change the scale when that chord happens.

B major: B, D#, F#
D major: D, F#, A
F# major: F#, A#, C#

These notes are mostly in F# major with the exception of D & A.

So, the B major & F# major chords are a IV & I in the key of F#. The D major is the exception. D major is however part of F# minor! So you could use the F# major scale when the B & F# chords are happening. But then switch to F# minor when the D major chord happens.

B (IV) - D (bVI) - F# (I)

Hope this helps! Have fun improvising!