I've noticed that since I've started composing medieval music, a strange thing has happened. I've managed to compose songs that SEEM as if they are in the key of D minor but the key signature is actually A Minor... I've also made pieces in the key of A that have the key sig. of D minor... Is this something to do with modes? like even though it's in A minor it was done in A Dorian or something like that? I've noticed this in quite a few medieval pieces by King Henry VIII; they end on chords and start on chords that they shouldn't if they were to stay true to the key signature... Is there something to this? Am I going crazy or something? :P

Whee, I just started learning about modes . . .

Anyways, the extra accidentals of a mode may give the impression of another key signature, but really it's not. So don't worry about it, at least, that's what I think, hehe.

Well... ok. But it was just weird since I used virtually no accidentals with a key sig of A minor but the beginning and ending are D minor chords. :P

All the modes starting on the note of A:

Aeolian

A B C D E F G A

Dorian

A B C D E F# G A

Phrygian

A Bb C D E F G A

Locrian

A Bb C D Eb F G A

Ionian

A B C# D E F# G# A

Lydian

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

Mixolydian

A B C# D E F# G A

The phrygian is the one that has the D minor key signature.