Here's what's going on:
The chord sequences that are happening in the minor sections of Blue Bossa are near synonyms of the minor II-V-I progression.
The chords that best express a minor II-V-I in the key of C would be Dmi7(b5)-G7alt-Cmi(MA7).
A 7alt chord contains the b9, #9, #11 and b13. The #11 can also be notated as a b5 interval. The b13 can also be notated as #5. A G7alt, G7(b5) and G7(#5) all share a family resemblence. Because of this they can be substituted for each other.
The scale that best fits an altered chord is called the diminished-whole tone scale. Here's an example that shows that you can play that scale over all three types of chord in the family with good results.
Here's a new version of the Blue Bossa changes where I've transformed the tune to use the most characteristic chord types of the minor II-V-I. In this version, the mi6 chords become mi(MA7) on the same root and the 7(b5) and 7(#5) chords are transformed into 7alt chords on the same root.
You can sing the Blue Bossa melody on top of these changes, no problem. The substituted chords just make the minor portions of the progression sound darker than in the originally posted changes.
I should point out here that minor II-V-I progressions are touchier beasts to handle than major II-V-I sequences. In a major II-V-I you can play notes drawn from the major scale built on I over all of the chord in the sequence. It would be convenient if one scale could be played over all three chords in a minor II-V-I but this unfortunately doesn't work well. If this were so, if the I chord were Cmi(MA7) you would hope that you could play the notes of C melodic minor over all three chords of Dmi7(b5)-G7alt-Cmi(MA7). Your ear may find that this scheme using only C melodic minor sounds acceptable. Despite this, improvisors have found scale choices that seem to better express the feeling of the constituent chords of the minor II-V-I.
Experience shows that the best scale for the II chord of a minor II-V-I is the Locrian(#2) scale built on the root of the II chord. So in our example you would play D Locrian(#2) on the Dmi7(b5). The Locrian(#2) is the sixth mode of a melodic minor scale, so when you play this scale above it's mi7(b5) chord in the progression, you are choosing notes of the F melodic minor chord whose root is a minor 3rd above the root of the chord.
The best scale choice to express the feeling of the V chord (7alt) of a minor II-V-I is the diminished-whole tone scale built on the root of the chord. In our example, we would play a G diminished-whole tone scale above a G7alt chord. Since the diminished-whole tone scale is the seventh mode of the melodic minor scale whose root is a half step higher than the root of the V chord, when we play notes from G diminished-whole tone, we are selecting notes from the Ab melodic scale.
Finally, the scale which best expresses the sound of the I chord in a minor II-V-I is the melodic minor built on the root of the I chord. In our example, you would play the notes of C melodic minor over Cmi(MA7).
Here's how I would parse the key changes used in Blue Bossa:
Bar 1 and 2 is in C minor. Would use the C melodic minor scale.
Bar 3 and 4 are in Eb Major, the relative major key of C minor. Would use the Eb Major scale.
Bars 5 through 8 use a minor II-V-I sequence nearly synonymous with Dmi7(b5)-G7alt-Cmi(MA7). In bar 5 would use D Locrian(#2) for Dmi7(b5) (notes of F melodic minor). In bar 6, would use G diminished-whole tone scale (notes of Ab melodic minor) for the G7alt (or G7#5 or G7b5). In bars 7 and 8 would use C melodic minor over the Cmi(MA7) chord.
Bars 9-12 use the notes of the Db Major scale.
Bars 13-15 are another C minor II-V-I so I would again use the scale choices outlined for bars 5 through 8.
Bar 16 moves momentarily to the parallel major key C Major so would use G mixolydian scale (which uses the notes of C Major).
So what's going on with harmonically with the G7(#5), G7(b5), and G7 chords in this arrangement of Blue Bossa? The G7(#5) and G7(b5) sound like substitutes for G7alt. The G7 used in the last bar of the form is a momentary excursion into the parallel major key.
blog comments powered by Disqus
Please join our community at SongTrellis. Our contributors welcome your comments, suggestions and requests. As soon as you join the site (or login if you are a member) a response form will appear here.
Last update: Friday, August 3, 2001 at 9:45 AM.