Key signature for writing in modes other than major and minor?

Question

I have trouble deciding what accidentals to put in the key signature for pieces in Dorian, Phrygian, Lydian or Mixolydian modes. There seem to be trade-offs associated with each choice. For example, when writing in G Mixolydian, setting an empty key signature makes it look like C major or A minor. Having the F# in the key signature forces me to put accidentals all over the piece to mark F naturals. I prefer to use (in this example) the key signature of G major and natural signs on every F, especially when writing for choir. Singers with varying reading skills will often unconsciously assume that if the piece has G as the tonic, then it is in G major. The natural sign on every F will help them remember there is something special about it. Is there any kind of convention to follow?

Answer 1

Hi, modes follow the same key signature of their initiated keys. C Major is the scale, D Dorian or G Mixolydian are the modes coming form the C Major Scale. If you write a tune that uses the G Mixolydian, no key signature is fine. Example is Miles Davis's "So What" is in D Dorian, has no key signatures. If we improvise C major or A minor scales, all notes sound great. What determines the modes are the chord progression as much as the scales.