The Guitar Lesson Review Blog

Guitar Chord Theory - Seventh Chords

In a previous post on the topic of guitar chord theory, I talked about how regular major chords are created from the 1, 3 & 5th notes of the major scale.

To recap, here are the C Major scale notes, with the 1, 3, 5 notes highlighted:

which leads to the regular C Major chord as played in open position on the guitar:

OK, so far so good, we have our basic C major chord, and can see where it came from.

Plain major chords are just the beginning however, which you will see if you look in any guitar chord book. There are loads of different variations on this basic chord.

In this post, we’re going to look at just one type of variation on the regular major chord, which are seventh chords.

We’ll start by taking our C Major scale, and in addition to the 1, 3, 5 notes that we already used for the basic major chord, also include the 7th note of the scale, which is the note ‘B’, the one ringed in dark blue here:

Just adding this 7th note of the scale to our existing 1, 3, 5 notes gives us a chord with 4 different sounding notes (remember that the number represents the scale degree of the note - that is, where that note comes in the scale). This chord is known as C Major Seventh, and is written in music/tab notation as:

where in the diagram on the left, we just show the 4 notes. In the diagram on the right, we’ve just added the 3rd note (E) on top of the others. In chord diagram terms, this is usually shown as:

You might also see it written as ‘C7M’ sometimes. Notice that since the top 3 strings are all open, this C Major seventh chord is even easier to play than the regular C Major chord!

To get the sound of adding this 7th note of the scale, try alternating between the regular C Major chord, and this C Maj 7th chord:

just by taking your first finger off the 2nd string to form C Maj 7th, then putting it back on to get regular C Major.

And that’s the reason why these chord variations exist - they give a slightly different sound to the plain old major chord, which can be useful in a particular setting.

A good example that comes to mind of a major 7th chord like this being used is in the RHCP song, ‘Under The Bridge‘. At the end of each of the main verse sections, there’s a chord that just seems to ‘hang there’ in the sound it creates. That’s a major 7th chord. Experiment with it, and incorporate it into your playing if it sounds right in a given situation.

So that was the major seventh chord. Quite often though, you’ll come across chords just written as C7 or G7. These are not major seventh chords, but ‘regular’ or ‘dominant’ seventh chords.

The difference between the major seventh chords we looked at above, and these ‘dominant’ seventh chords is that the 7th note that is included in the dominant 7th is a ‘flattened’ 7th. That means it’s the 7th note from the scale, but moved down by one semitone (one guitar fret).

Here are the notes from the C Major scale, but with the 7th note being ‘flattened’ like this, it’s the one in green, labelled ‘b7′ (note: a lower case ‘b’ indicates a note is flattened by one semitone/guitar fret):

This is the note ‘B flat’ (written Bb), which is found on the guitar at the 3rd fret on the 3rd string. Putting this flattened 7th note on top of our regular 1, 3, 5 scale tones gives us the following chord:

A word of warning - if you’re looking at the guitar tab in the above diagram, don’t try and play it - there’s too much of a stretch for your fingers! It’s just for illustration, to show that the chord is formed by adding the flattened 7th note on top of the other 3 notes.

This illustrates something that you run into on the guitar - due to the tunings of the strings in the regular guitar tuning, it’s sometimes not possible or convenient to play notes in a certain way.

With the major 7th chord, it was easy, just by playing the open 2nd string (B), we added the 7th note onto the regular major chord. However, flattening B by moving it down 1 fret (semitone) makes it become the 3rd fret note on the 3rd string. But the 3rd string is already being used for another note - the 5th, G - so we can’t play both.

The answer (at least for the open position chord), is to drop the 5th note from this chord, which leaves us with:

And, by just playing the top string, we add the 3rd note, E, to the chord again:

This is the usual form of the open C 7th chord, which you’ll see written in chord diagrams as:

and the fingering for this is much easier! So from this, you can see that this version of the C7 chord has no 5th note (G) present. This isn’t a big deal, as in this chord, it’s the flattened 7th note along with the root (1st) and 3rd notes that give it its distinctive sound.

As before, try alternating between playing the regular C Major chord and this C7th chord, listening for the difference in sound.

Switching between them is fairly easy, from the regular C Major chord, just drop your pinky finger in on the 3rd string to add the flattened 7th note (B flat - Bb) we saw above.

Knowing the difference between a C Maj 7th and C7 chord can also help when playing lead guitar. For example, if soloing over a C Maj 7th chord, any of the notes 1 (C), 3 (E), 5 (G) or 7 (B) are going to be useful for starting or ending lead licks.

Over a C7 chord though, the regular 7th note of the C major scale, B, isn’t going to sound so good, it would need to be B flat (Bb) to fit in with the chord’s sound.

In fact, the C major scale with the 7th note flattened to Bb is called C Mixolydian Mode, and is an important scale mode in rock lead guitar licks. But that’s a different post topic!

To get a much more in-depth understanding of how chords and scales relate, and how to take advantage of this in guitar solos, take a look at Guitar Scale Mastery, which covers this topic in much more detail.

Chris

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