To get a straight forward modal sound, use progressions/vamps that are completely natural to that mode (don't stray from the 7 related chords).
However, it seems you're more interested in introducing various modal treatments to diatonic major/minor progressions by the use of borrowed chords. The first thing to bear in mind is that all intervals will relate to the root more so than to the passing chords. The next thing to think about is the characteristic notes of parallel modes.
So if the progression is C major, two modes you could easily 'modulate' to are C Lydian and C Mixolydian. (The other two major scales.)
So C Lydian has a #4 in relation to Ionian. Apply that F# to your C major chords to see what Lydian chord choices you may have:
D F# A---D minor becomes D major
B D F#---B diminished becomes B minor
F# A C---F major becomes F# diminished
Throw in D and Bm to your C major progressions to support modulations to the C lydian scale. Also try adding the F# note to other chords.
C Mixolydian has a b7 in relation to Ionian. Apply that Bb to your C major chords to see what Mixolydian chord choices you may have:
G Bb D---G major becomes G minor
Bb D F---B diminished becomes Bb major
E G Bb---E minor becomes E diminished
Throw in B and Gm to your C major progressions to support modulations to the C mixolydian scale. Also try adding the Bb note to other chords....I think you probably get the idea, but I'll do minor for the sake of completeness.
If the progression is Amin, two modes you could easily 'modulate' to are 'A' Dorian and 'A' Phrygian. (The two other minor scales.)
So 'A' Dorian has a #6 in relation to Aeolian. Apply that F# to your A minor chords to see what Dorian chord choices you may have:
D F# A---D minor becomes D major
B D F#---B diminished becomes B minor
F# A C---F major becomes F# diminished
Throw in D and Bm to your A minor progressions to support modulations to the A Dorian scale. Also try adding the F# note to other chords.
'A' phrygian has a b2 in relation to Aeolian. Apply that Bb to your A minor chords to see what Phrygian chord choices you may have:
G Bb D---G major becomes G minor
Bb D F---B diminished becomes Bb major
E G Bb---E minor becomes E diminished
Throw in B and Gm to your A minor progressions to support modulations to the A Phrygian scale. Also try adding the Bb note to other chords....neat how it works out like that i think..
