Tonal Centre

[abracadabra]

Hi,

I´m slowly starting to incorporate a tonal-centre-based approach to my improv and I had a couple of quick questions.

1) For example, in a basic iii-VI7-ii-V7 progression, say in Db (as it is in my Aebersold Maiden Voyage book), as I understand it that means that I could play the Db major scale tones over the whole thing and it should sound fine, but it doesn´t, in fact it sounds totally out of whack on the VI7 chord. Instead I have to play the first two chords as an Eb maj tonal centre and the second two as Db, then it sounds great.

So my question is, why is it called a iii-VI7-ii-V7 if it is from two different tonal centres? Or is that the VI7 has been turned into a dominant chord, instead of a minor one? Cause the iii-VI7-ii-V7 could just as easily be played as I-vi7-ii-V7, which would use only tones from the major scale. Anyway, if I play it as two consecutive ii-V7s from Eb and Db it sounds good, but I want to make sure I understand what I´m doing and why.

2) Also, on D Natural Blues, the progression is:

D7 / G7 / D7 / D7 / G7 / G7 / D7 / F#7b5 B7alt / Em7 / Em7 A7 / D7 B7alt / Em7 A7

On the F#m7b5-B7alt-Em7 I´m playing over an Em tonal centre, and then over the ii-V7 back to D7 I´m playing over a D tonal centre again. It all sounds good like that, but is that the way you guys think of it?

I know I can play all this using just the blues scale and arpeggios, but I´m trying to get another way of looking at it. Thanks for your help!

[mr. beaumont]

"tonal center" does not equate "1 scale." it's as simple as that.

[bako]

Re: iii-VI7-ii-V7

The concept of a tonal center is bigger than any one scale.
There is a class of chords called secondary dominants. These chords have a dominant function to all chords in the key except the I chord.
In Db the Bb7 chord is called V7 of ii. Sometimes it is just called VI7. It alters the scale, replacing Db with D, but not the tonal center.

The Db against Bb7 is a #9. It is not an unusual dominant sound.
The Gb against Bb7 is a b13. It is also the m3rd of the upcoming Ebm7.

You can play this sequence as one key, swapping D for Db on Bb7 if you prefer.
Alternatively you can treat it as 2 separate scales Eb and Db as you mentioned.

[abracadabra]

Thanks, that´s clearer. I´ve found this topic lacking in my books. Actually it was kind of a stupid question now that I think about it.

So what if you have backcycling ii-V7s, eventually arriving at a tonic? The ii-Vs are pulling the listener towards the tonal centre, right? So you can have, theoretically, zillions of ii-Vs backcycling which eventually resolve to a tonic.

Then at what point do you consider the tonic to have changed?

Example, Satin Doll. First chords are (I think, from memory), Dm7 G7, once or twice, and then Em7 A7. So is that a shift in tonal centre from C to D? It sounds like it to me, but I´d like to make sure I understand it.

For example, if instead it went Em7-A7-Dm7-G7, then that would be a clear continuous C tonal centre, your ear being pulled towards it. Am I on the right track?