Wednesday, May 23, 2007

Tonal Centers

Q: If I were to play, for example over a ii-V in the key of C (Dmin7-G7), is it correct to assume myself playing a D dorian scale over the Dmin7 chord and a G mixolydian scale over the G7 chord. Even though I would still be playing the C major scale, should I think of the scale as a different mode over each diatonic chord? I mean, over the G7 chord am I all of a sudden getting the mixolydian modal sound as opposed to the dorian sound over the chord before? Or should I simply be thinking that the whole thing is dorian?

A: I wouldn't think that much into it. Although, maybe technically you are playing a new mode over each chord, it is a little too much to consider. Think more in tonal centers. What is the sound of the C major scale played over a Dmin7-G7 progression? It is dorian. Whether you play a ii-V or a ii-iii-IV-V progression, the tonal center is revolving around the ii chord, the dorian chord. The only thing that would change this is if you had a functioning V chord resolve to a I chord, this cadence would automatically turn the center of the tonal universe to the I chord. But if the V chord doesn't resolve in a ii-V or something similar, the focus would be on the ii chord. I mean, if you were playing the C major scale over a I-vi-IV-V progression, would all of a sudden everything go minor sounding on the vi chord? Over the IV chord, would everything turn lydian? Even though you might be able to say that you were temporarily playing the aolian mode for a bar, it wouldn't sound so. Nor would the one bar of the IV chord sound lydian. The reason is simply because the major tonality of the major key has been determined, you have started on the I chord and that is what the ear will consider home. The only time it might be safe to think modally over each chord in a diatonic progression is if for example each chord was eight or more bars. I imagine the listener’s ear would start to hear each chord as a different tonal center.
Regardless, you would still be playing the same scale over the whole thing no matter what you named the scale when the diatonic chord changes.

Needless to say, that does not mean that you should take all chords that come after the first chord lightly, even though you might play the same scale over all the chords, you would want to pay special attention to each chord and maybe outline or shoot for chord tones especially on the strong beats where the chord changes. Your ears are your most important tools when improvising, I wouldn't worry too much about pasting names on the scale everytime the chords change, especially if the chords are diatonic to one key.

Links for modes:

Developing a modal practice routine pt.1
Developing a modal practice routine pt.2
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