Intervals – String/ Frets
Above figure shows intervals for roots on 2nd string and 5th string. It also shows additional roots at the extremes on the 4th string and 3rd string.
In the below figure, we take a small part of the interval possibilities.
Here we have roots on the 4th and 2nd strings, and the corresponding 3rd and 7th interval options which are physically possible and easy to play.
The 4 sevenths
We get 4 seventh chords by using combinations of minor and major 3rds and 7ths.
The below figure is an exact representation of the above, on the guitar.
Keep the Root and 5th in place. Then change the thirds and the sevenths by just one fret shifting, and you get all the 4 seventh chords, played comfortably and efficiently.
Playing the 4 sevenths on the guitar
Any of the above patterns can be used for any note on the 4th string.
For example: If you want to play the 7th with E as the root, find E on the 4th string 2nd fret and arrange the rest of the pattern depending on which 7th you want.