A 7th chord consists of 4 notes: Root, 3rd, 5th & 7th.
Any note but the Root can be altered to create a different type of 7th chord:
There is only one note different between adjacent types:
Know the differences between types!
Major:
Dominant: flat 7
Minor: flat 3 (plus the flat 7 from the previous type)
Half-Diminished: flat 5 (plus flat 7 & flat 3)
Full-Diminished: double flat 7 (plus flat 5 & flat 3)
7th chords can also be thought of as a triad with a 7th added:
Major 7: Major Triad with a 7 added
Dominant 7: Major Triad with a flat 7 added
Minor 7: Minor Triad with a flat 7 added
Half-Diminished: Diminished Triad with a flat 7 added
Full-Diminished: Diminished Triad with a double-flat 7 added
Note on the Full-Diminished: A double-flat 7 is the same thing as a 6th. So why not call it some kind of 6th chord? You could call it a C-6(b5), right? I suppose so, but no one ever has that I know of. There is a conceptual difference between a 6th and a double-flat 7. It has to do with how you got there, and we're getting there from a 7th chord, not a 6th chord.
Nomenclature
C Major 7 is written as: C∆7, CM7, Cma7 or Cmaj7.
C Dominant 7 is written as: Cx or C7.
Note: I've only seen the “x” symbol to denote a Dominant chord in theory textbooks. I have never seen it in actual sheet music or chord charts. My teacher, John Elliott, sometimes used it in the lessons he wrote out but never in an arrangement or a tune.
C Minor 7 is written as: C-7, Cm7, Cmi7 or Cmin7.
C Half-Diminished is written as: Cø or Cmi7(b5).
Note: The circle is a diminished symbol. If you draw a line through it, you have halved it – thus Half-Diminished. It is not necessary to say, “Half-Diminished 7.” There is no Half-Diminished Triad, there is only a Diminished Triad. A seventh must be present for something to be Half-Diminished. However, “Half-Diminished 7” is not incorrect, merely redundant.
C Full-Diminished is written as Cº7
Note: “Full-Diminished” is to be distinguished from “Diminished.” “Diminished” is a triad. “Full-Diminished” requires a 7th. You can also call it, “C Diminished 7.”
We're going to use the Key Circle (Circle of 4ths) as a mechanism to drill these 5 types of 7th chords in every key. Therefore there will be the 5 types on 6th-string roots as well as 5th-string roots.
If you don't understand what the Key Circle is and how I apply it to the guitar, see the demonstration video below or go through the 5-Lesson Foundational Series. It can be downloaded for free here.
Voicing
The voicing for the 6th-string roots is Root, 7, 3, 5 from low to high:
This voicing is covered in Unit 6 of Vertical Truth: Chordal Mechanisms for the Guitar (not yet released as a download).
The voicing for the 5th-string roots is Root, 5, 7, 3 from low to high:
This voicing is covered in Unit 4: 7th Chords.
Note concerning fretboard diagrams: The intervals designated (root, 3rd, 5th, 7th) are relative to the chord type; for instance, I don't put "b7" in the Dominant fretboard diagram because the b7 is the 7th of the Dominant chord. "b7" is in relation to a Major 7 chord. For an in-depth discussion on my reasoning, see Arguing Over Fretboard Diagrams.
The above chords should be drilled two different ways:
Go through each of the 5 types on each root of the Key Circle. Recite the difference from each type to the next thusly; "Major. Flat the 7th to make it Dominant. Flat the 3rd to make it Minor. Flat the 5th to make it Half-Diminished. Flat the 7th again to make it Full-Diminished."
Play each type separately around the Key Circle - recite the key names as you play them.
How to Drill: Demonstration Video
Examples of how to use Quick & Dirty 7th Chords in tunes:
This approach to using 7th chords is very incomplete - thus, "Quick and Dirty." For a complete method for learning and using 7th chords, become a MasterGuitarSchool.com site member and use your site member discount to download Unit 4: 7th Chords, Unit 5: 7th Inversions and Unit 6: 7th Voicing.
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