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7th? and blues

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Reputable Member
Joined: 20 years ago
Posts: 301
Topic starter  

how come the 7th of any root note is always different then the added (or taken away note played in the chord) it always seems to be off by a semi tone. does this have to do with diminished and non deminished 7th's....if so wat is the difference, and which is used in blues, and which scales are used for which 7th chord?

sorry if this is confusing. but if u dont understand is try to just touch on 7ths in general maybe it would hlep me get a better understanding of it all.

thanks peeps


Illustrious Member
Joined: 21 years ago
Posts: 7833

The seventh chord used in blues is the dominant seventh, with a flatted seventh. That note's not found in the underlying major scale, but then neither are several notes in the minor blues scale we play over those chords. The dissonant tension of the seventh chord just sounds good.

"A cheerful heart is good medicine."

Illustrious Member
Joined: 21 years ago
Posts: 5349

Exactly. And if you don't like how it sounds, play another chord. Theoretic understanding won't explain musical taste nor is it supposed to do that. In general dissonant notes are universally considered to be cool in blues. Why? Who knows...

Illustrious Member
Joined: 21 years ago
Posts: 4921

The 'blues scale' is 1-b3-4-b5-5-b7, so the b7 of a dominant 7th chord is present in the scale.

It also means there's always conflict between the natural 3rd in a chord, and the b3 in the scale. That sets up the tension that Ricochet mentioned.

When you use 7ths for all chords (I7-IV7-V7) in a progression, it's normal to use just a major chord (or a 6/9 chord) for the very end, though - it kind of resolves the whole ball of wax.

Guitar teacher offering lessons in Plainfield IL

Noble Member
Joined: 21 years ago
Posts: 2337

BY dropping notes down in the scale alter the feeling of the scale gives it musical color from with some call Blue Notes and can make you tone darker or sad sounding. The third is the middle note in the I chord. By dropping this note ½ of a step, which makes the A minor chord is sad sounding. The flat third of the V is also the flat VII when you count up from the I chord. The flat VII is a very,important for color as a transition note. Learn the Diminished 7 chords, these are the Blues chords.

The flat 7 should be the starting point or ending point of many of your riffs. Here's some great informationn on the subject.

Blue Tone and Passing Notes


Illustrious Member
Joined: 20 years ago
Posts: 5038

Not to confuse things, but a diminished 7th is a flatted dominant 7th, which makes it a double flatted major scale 7th (same note as the major scale 6th).

-=tension & release=-