Theory & Impro Blues Question - combining major and minor 3rd

[AlanB]

I know there is a really obvious answer to this question, but I am a little confused.

In a book called "Progressive Rock Saxophone" Peter Gelling writes

"The Dominant 7th chord, combined with the use of the minor 3rd is the real heart of Blues harmony."

Now if you play a Dominant 7th chord with a minor 3rd - isn\t that a minor 7th where you use the Dorian. So instead of

E7-E7-E7-E7
A7-A7-E7-E7
B7-A7-E7-B7

why wouldn't you play

Em7-Em7-Em7-Em7
Am7-Am7-Em7-Em7
Bm7-Am7-Em7-Bm7

Puzzled,
Alan

 

[Pete Thomas]

It's not a really obvious answer. The word "combined" is the important one here. Often the ♭3rd is used along with the major 3rd of the chord. So it's not just a minor chord (which would be minor 3rd instead of major 3rd in the chord.

 

[AndyB]

Hi Alan. I have that book too. I think he's talking about 2 different things at the same time: 1) using dom7 arpeggios to outline chordal figures, and 2) substituting the ♭3 for 3 in melodic lines based on pentatonic minor.

Dom7 Arp: 1 3 5 ♭7
Min Pent : 1 ♭3 4 5 ♭7

Probably, the bebop mixolydian should be included in the thought. It all works over that dom7 blues based harmony. Even if the guitar isnt playing 7th chords, it is implied in the tone.

If I understand Pete's interpretation of "combined" then think of a blues/rock line that uses both elements of a dom7 arp and minor pentatonic scale in the same phrase.