A colossal effort, Richard, that provides sufficient food for study, practice, and musical expression to keep a person interested in running down this road busy for a good while.
Right now I am not that person, but I expect somewhere further on down the road you have provided the key to the highway that will take me to new and wonderful places.
So Richard,
Now take a little vacation 
You earned it as far as I’m concerned…,brilliantly explained 
Greetings
Excellent Richard, I’d never really thought about this - it’s a bit of a revelation when I think about it!
This is great, thank you! I’ve spent much of today with this lesson
The concept of seeing two (or more, if you don’t stick to the chords in the key…) possible chords at once from the same third is really helping take my knowledge of the neck to another level, by seeing the triad shapes across the neck.
I’m having to be careful to really take one thing in properly, and resist jumping around with my ideas
Thanks David. It was your creativity that sparked the inspiration for this entire 3rds exploration. I am sure one day you will return to walk through the gateway you opened. 
Thanks Roger. I try.
Hi Darrell, I’m glad to be a revelator!
That is music to my ears - yours too I’m sure. Knowing that someone has taken these ideas and used them with guitar in hand to explore and develop and push their own musical boundaries is heartwarming. Good stuff.
3rds & Thirds Part E - 3rds as Partial maj7, min7 and dom7 Chords
We are now going to look at chords extended beyond the triads
So far all that we have focussed on in terms of chords are triads. Chords that are obtained by stacking three thirds in the process of harmonising the Major scale. That process can continue beyond just the first, third and fifth. If another step along the notes of the Major scale is taken, if the next interval of a third beyond the fifth is included, we start to create chords with a seventh in them. These seventh chords can be Major 7, minor 7 or dominant 7.
I do not intend going through the formulation of each and every chord in painstaking detail, so shall cut right to the chase here.
The D Major scale …
D - E - F# - G - A - B - C# - D - E - F# - G - A - B - C# - D
The chords resulting from stacking four lots of thirds together:
Now each harmonised chord comprises a new third pairing at the end of their respective formulae. But, importantly, none of these pairs are new, they have all appeared previously in different chords and different guises. Some as a pair of Root to 3 intervals. Some as a pair of 3 to 5 intervals. It was these two types that allowed us to reach the point previously where we could say that each 3rd can be ambiguous and suggestive of two chords, not just one.
The extension of that very same idea will allow us to see that each 3rd can also be seen / heard as suggestive of a type of seventh chord - if it is being played over that chord in the backing.
Previously the 3rd shown below was seen as suggestive of either a D Major or a B minor chord. We can now add to that. When played over a G Major chord, this 3rd will add the quality of G Major 7 to the sound.
G Major 7 = G - B - D – F#
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Previously the 3rd shown below was suggestive of either an E minor or a C# diminished chord. We can now add to that. When played over an A Major chord, this 3rd will add the quality of A7 to the sound.
A7 chord = A - C# - E - G
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Previously the 3rd below was suggestive of either an F# minor or a D Major chord. We can now add to that. When played over a B minor chord, this 3rd will add the quality of B minor 7 to the sound.
B minor 7 chord = B - D - F# - A
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Previously the 3rd shown below was suggestive of either a G Major or an E minor chord. We can now add to that. When played over a C# diminished chord, this 3rd will add the quality of C# m7b5 to the sound.
C# m7b5 chord = C# - E - G - B
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Previously the 3rd below was suggestive of either an A Major or a C# diminished chord. We can now add to that. When played over a D Major chord, this 3rd will add the quality of D Major 7 to the sound.
D Major 7 chord = D - F# - A - C#
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Previously the 3rd below was suggestive of either a G Major or a B minor chord. We can now add to that. When played over an E minor chord, this 3rd will add the quality of E minor 7 to the sound.
E minor 7 chord = E - G - B - D
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Previously the 3rd below was suggestive of either an A Major or a C# diminished chord. We can now add to that. When played over an F# minor chord, this 3rd will add the quality of F# minor 7 to the sound.
F# minor 7 chord = F# - A - C# - E
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- !
Now that we have seen all chords extended with sevenths, we can take stock and label one final time the TAB diagrams with their partial chords or suggestive sounds.
You may wish to cross reference those TABs with the chord formulae together.
Questions, comment, discussion etc.
Thanks for another great thread Richard, that sounds super cool by just adding two notes we get a feeling of a completely different chord played over a standard chord. I will look it up for sure!
Thanks Adrian exactly as you say. And if you pick any adjacent string pair you will find that for any twelve fret span there are four different double-stop 3rds to match whatever chord is being played. Yoh are never far away from playing just two notes of the triad or two notes where one of them extends the triad with its 7th.
Example:
B and E strings only.
If the underlying chord (triad) is D major you can play within the triad at frets 2 & 3 plus frets 5 & 7 plus frets 14 & 15 and you can suggest Dmaj7 at frets 9 & 10.
Looks like a typo as above the table its C# again
