You'll find Dominant 7th Chords more often than Major 7ths Chords. And they're super easy to construct!
View the full lesson at Dominant 7th Chords | JustinGuitar
I was playing Buffalo Soldier on Rocksmith, and they play a triad but call it an E7, which was played 4th fret of 3rd, 3rd fret of 2nd, and 4th fret of 1st. This would be the notes B, D, and G#. They hit all the notes of the E dominant chord except the Root note.
Is the game mislabeling the chord, or can you actually play quadad’s with only 3 notes?
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@Fncanuk There will have been some other instrument (bass likely) playing the root note, thus defining and grounding the chord.
Cheers 
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Ahhhhhhhh never would have thought of that lol. Thanks!
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Having a hard time understanding why in the Maj7 chord grips, we don’t play the 1st string, and play it on the Dominant grips?
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Hey Guillame,
Justins recommended grips are based on sound, fingering, and common usage.
For example try playing a full Root 6 Major 7 chord with the high e string fretted. Awkward fingering and it sounds a bit crappy. Also, Root 6 Dominant 7s are often played without the high e string. Technically, theres no right or wrong here. Its about the sound and playability.
In the end, as long as you have the correct intervals, you can play any chord however you like.
Cheers,
Shane
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Yeah, you can play the 1st string in those grips if you like. In root 6 Maj7 grips you would double the root note at the same fret, while in the case of root 5 Maj7 grips you would double the 5th. It’s all down to the sound you prefer and the grip you find more comfortable.
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Must the Dominant 7th Chord have 4 notes? I was looking at fingering for an A7 chord played at the 10th fret using a C7 shape, but it didn’t contain an E note. (The 6th and 1st strings were muted.)
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Hello Dana,
The defining notes are the 3rd and the b7th. You can drop the 5th anytime. Even the root. So depends on the context/ sound your going for.
I like alot of the triad type versions of the domininant 7
ie. R-3rd-b7
The rootless dominant 7 also sounds cool in certain contexts
ie. 3rd-5th-b7
All valid 7th voicings.
Cheers, Shane
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Good question.
As Shane explains, it must contain root, 3rd and b7th but the 5th is an optional note once you begin extending a chord beyond it basic major triad notes.
I was looking at the different keys and how the chords are constructed and how you would change those chords to 7th chords.What I’m finding is not all the chords can be changed to 7th chords without going outside of the key.I’ll use the key of C major for this example, a blues in C would consist of C7, G7, and D7 but in order to make a C7 chord you would have to add a Bb note to the chord and that note is not in the scale so you would have to add the B note which would make it a Maj7. So my question is where are we pulling the Bb for a C7 ?
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The Blues form of a 145 with 7th chords is not a diatonic chord progression. So its a ‘special’ case. The Blues ‘breaks’ diatonic theory. So, even though a C Blues is said to be in the key of C, technically it is not.
C7 is derived from the F Major scale
F7 is derived from the Bb Major scale
G7 is derived from the C Major scale
In normal diatonic harmony, the 7th chords are built by added another 3rd interval on top of the triad, so you always get that
M7,m7,m7, M7, dom7, m7, m7b5 structure.
Cheers, Shane
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Thank you that was very helpful.
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Shane has given a full reply.
For all cases, remember this.
The ‘rules’ specifically determine that in any major key, one, and only one, chord extends to take the form dominant 7. It is always the chord built on the 5th scale degree - hence called the five chord. It is commonly called dominant or V. When extended, as dominant 7 or V7.
If you restrict the scale numbering to use only digits 1 to 7 inclusive for the major scale, the chord built on the 5th scale degree, by stacking 3rds, must comprise (using scale degree numbering):
5th then 7th then 2nd then 4th
Example
Eb major scale
Eb --> F --> G --> Ab --> Bb --> C --> D
1st --> 2nd --> 3rd --> 4th --> 5th --> 6th --> 7th
5th scale degree = Bb
V chord = Bb and V7 chord = Bb7
V7 chord = 5th + 7th + 2nd + 4th scale degrees
V7 chord = Bb + D + F + Ab
Note … the formula for a V7 chord is given as 1, 3, 5, b7. That is in relation to the major scale arising when the root note of the V7 chord is shifted to become the root note of its major scale. The b7 of the Bb7 chord is the note Ab. In the Bb major scale the 7th scale degree is A, not Ab. Hence, it is seen as a b7 within the Bb7 chord. Bb7 does not belong in the Bb major key. But it would be the I chord in a 12-bar blues described as being a blues in B flat.
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