Slightly away from the original question, but looking at the minor 251 in jazz...

From my studies;

The 'standard' minor 251 progression in C in Jazz is:

D half diminished (D, F, Ab, C)

G Alt ( G B D# F)

C-6 (C Eb A)

I am currently practicing this sequence using BIAB. I typed in minor 251 into the song search and this is the sequence used.

The first chord is half diminished, rather than diminished. Talking in C the seventh note of a diminished scale would be A (usually thought of as a 6th of a major) which is confusin, a diminished 7th chord is therefore C Eb Gb A.

A Half diminished C chord starts of like a 'real diminished' C Eb and Gb, but then it jumps to a Bb. This makes it more compatible with the dominant sound, it does add two tension tones but it sounds the dominant or flat seventh.

The special thing about this chord is it appears as a mode of the major scale. Its the chord built in thirds from the (maj) seventh - the locrian chord so to speak. It shares three tones with the myxolydian too, so its an easy sub for that.

I hope this is all correct. Do people get the original question? If its true that the natural minor (built on sixth mode of major) is the minor used to establish the key of a song, why does the Jazz 251 feature a major sixth rather than a flat 6th as in the natural minor?

I suppose the only answer is it must be a convention.


This minor thinking all gets murky. I am realising that both in classical and Jazz a natural 3rd is used on the fifth mode of the 'natural' minor key. This is to improve the voice leading by introducing a leading tone or major seventh of the key (third of the chord). This gives better tension to be released in a V I.

It seems to me that the distinctions between 'natural minor' and melodic and harmonic minor scales are all about this note substitution - the leading tone (of the key, the major third of the chord) yearning to resolve to the octave, replacing the flat 7 in the 'correct' spelling of the cadence minor 5 1.

I just spent three months playing major 25's so as to get any tone into the cadence in a meaningful way. I now want to do this with the minor 251 - jazz style. Its a much more murk thing, it seems people have contradictory takes on things...


thanks for the input folks, hope its of interest to others..in an esoteric geeky kind of way...


Z


Last edited by ZeroZero; 07/09/14 12:29 PM.
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