great explanation Bert.
I might add that for dominant chords, one is always free to
try the various alterations of tensions.
In other words b9, #9, #11(b5) and #5(b13).
While often in jazz theory people try and explain these
tensions as coming from diminished or alt scales, I find
this to not be supported by their use in practice
(i.e not supported by transcription of the great players).
More often than not the natural tensions from the key
are important.
For example an A7 chord in the key of C may have a b13(#5) note
played against it because F is in the key of C and that would
be the 13th.
However, there are no steadfast rules. The ear is the best guide.
While diminished and alt scales do occur and have purposes,
their importance is greatly overstated. In fact they have,
IMHO, no place except for fairly advanced students and plenty
of great players went throught their whole career never playing
or thinking about diminished or alt scales.
In general the tensions are all one needs to know.
When using dominant tensions, be careful of dominant chords
that are really just minor plagal cadence dominants.
I.e. Cm6/F == F9.
Those dominants don't allow alterations in general.
For example in "just friends":
Bb | | Bbm7 | Eb7 |
F ...
The Eb7 chord is really Bbm6/Eb so the scale (if one wishes to
think that way) is Bb jazz minor and the locked in tensions
for Eb7 are thus 9, #11, 13.
reed
Reed Kotler
http://www.reedkotler.com home of a nice unix like toolset for windows NT/95
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