Building 7th Chords From Triads

Building 7th Chords Feature

This lesson is a follow up to the lesson on figuring out the seven chords in any key. In that lesson, we took the major scale and stacked 3rds on each degree of the scale, to produce seven chords that could be transposed in any key.

Here is a brief summary of the lesson.

The Major scale has seven notes. If we build triads on each note of the major scale, by stacking them in 3rds, we get the following seven chords:

Maj – min – min – Maj – Maj – min – dim

Here is an example in the key of C:

C Major Stacked Thirds

Adding The 7th

In the previous lesson, we focused on the Major and minor triads. The Major and minor triads are by far the two most common chords and the foundation for building all other chords. If we take the Major scale and play the 1st, 3rd and 5th notes (stacking 3rds), we get the Major triad:

1 – 3 – 5

But what happens if we continue stacking thirds and produce an extra note? Instead of stacking 3rds until we have three notes, what if we stacked 3rds until we have four notes? We would then have the following:

1 – 3 – 5 – 7

This is known as a ‘7th’ chord and is also very common. When we are only working with triads, there are two types that we see most often – Major and minor. There are others (i.e. augmented and diminished) but the Major and minor triads are by far the most common. With 7th chords, there are three types that we use most often:

  • Major 7 (1, 3, 5, 7)
  • Dominant 7 (1, 3, 5, b7)
  • Minor 7 (1, b3, 5, b7)

These three chord types are the most common 7th chords and are used extensively in jazz and pop (and many other styles as well).

They all occur naturally by stacking 3rds on each degree of the Major scale, like we did in the last lesson.

Here’s how it works. The C Major scale (for example) contains the following seven notes:

C – D – E – F – G – A – B

If we take the 1st, 3rd, 5th and 7th of the scale, we get the following:

C – E – G – B

This is the C Major 7 chord. It is made up of 1, 3, 5 and 7 of the major scale.

If we then take the second note of the scale (D), and stack four notes (in 3rds) from there, we get the following:

D – F – A – C

This is the D minor 7 chord. In the key of D major, the 3rd of the scale is F# and the 7th of the scale is C#. Therefor, by playing D, F, A and C, we are producing the 1, b3, 5 and b7, which gives us the D minor 7 chord.

Just like in the lesson on triads, we can continue stacking 3rds on each note of the scale. Sticking to the C major scale, if we stack 3rds on each note of the scale, to produce four-note chords, we get the following:

Stacked 3rds Cmajor (7thchords)annotated

In summary, we have:

C Maj 7 – D min 7 – E min 7 – F Maj 7 – G Dom 7 – A min 7 – B min 7b5

Stacked 3rds Cmajor Different Voicings

You should play through the above chord sequence on the guitar to get a feel for how the chords sound when played as a sequence. Playing the chords using the exact voicings above is a little impractical, as the layout of the guitar makes it difficult to play chords that are strictly stacked in 3rds. What we can do, however, is change the order of notes within each chord by simply playing whichever version of each chord we are familiar with. For example, we could play the above sequence like this: 

Stacked 3rds Cmajor Different Voicings

As you can see, we are using chord voicings that are different from the original example. While the specific voicings may be different, the chords themselves are theoretically the same, so you should still hear a sense of movement and purpose from one chord to the next.

As you may have guessed, the seven chords are a pattern that can be transposed into different keys:

  1. Maj 7
  2. min 7
  3. min 7
  4. Maj 7
  5. Dom 7
  6. min 7
  7. min 7b5

We used the key of C and stacked 3rds to produce the 7-chord pattern listed above. Of course, now that we know what the pattern is, we can simply apply it to any key we like.

Let’s take the key of G.

The G Major scale contains the following notes:

G – A – B – C – D – E – F#

Therefor, the chords (using 7th chords) in the key of G are:

G Maj 7 – A min 7B min 7  – C Maj 7 – D Dom 7 – E min 7 – F# min 7b5

The Bb Major scale contains the following notes:

Bb – C – D – Eb – F – G – A

Therefor, the chords (using 7th chords) in the key of Bb are:

Bb Maj 7 – C min 7 – D min 7 – Eb Maj 7 – F Dom 7 – G min 7 – A min7b5

Roman Numerals and Chords

In the last lesson, we looked at chord types (using triads) and how each degree of the scale is given a number, expressed as a roman numeral. The upper case roman numerals represent Major chords, while the lower case roman numerals represent minor chords. By assigning roman numerals to each degree of the scale, we can identify with chords based on their function or purpose, regardless of what key they’re in. As a recap, if we stick to triads, we get the following

  • I – Maj
  • ii – min
  • iii – min
  • IV – Maj
  • V – Maj
  • vi – min
  • vii – dim

We can do the same, using our newly formed 7th chords:

  • I – Maj 7
  • ii – min 7
  • iii – min 7
  • IV – Maj 7
  • V – Dom 7
  • vi – min 7
  • vii – min 7b5

So Are They The Same Thing?

If chords have a function, or mood, and are represented by roman numerals, are triads and 7th chords interchangeable? In other words, can we substitute a triad with its corresponding 7th chord, or vice versa. Can we substitute a IV triad with a IV 7th chord, or a ii 7th chord with a ii triad? Yes and no. The function of each chord does not change, regardless of whether it’s a triad or 7th chord, but the flavour changes. That might seem like an abstract way of describing chords, but it’s a good way to approach the topic. I like to think of 7th chords as more intense versions of triads. The I chord, when played as a 7th chord, has much more intensity than the I chord when simply played as a triad. Triads are used extensively in rock, pop and folk, because of their simple and stable sounds. 7th chords are used extensively in jazz.

Get Guitar Chords Galore eBook

The best way to really understand this is to put it into practice and experiment. Chords and functions express themselves when they are played in relation to other chords. The function of the IV chord (for example), can only really be experienced and observed when it is used in context, when played along side other chords (such as the I chord, or V etc.).

Practise taking two or more chords, and moving from one to the other, so as to hear and observe how they sound. For example, take the I and IV in the key of C, and practise playing the I chord for four beats, then the IV chord for four beats.

Start by using triads (C and F)

Chord Exercise 1 Chord Functions

This is a very common chord progression. The ‘I to IV’ and ‘IV to I’ movement are extremely common in almost every genre. It should sound comfortable and easy.

Now play the same chord progression, using major 7 chords

Chord Exercise 2 Chord Functions

It should feel like you’re playing the same thing, but the mood has changed slightly. The relationship between the two chords is still the same (because you’re still going from I to IV) but each chord has a slightly different flavour. Remember, understanding chord functions and relationships is more of an art than a science. You need to develop your own compass and reference points, to really begin to understand each chord and its functions. There are certain guidelines, such as ‘the I chord feels like the home chord’, but these guidelines should be a starting point for you to calibrate your own sense of appreciation with each chord. So experiment, compose, analyse and have fun!

Can We Stack More?

In the previous lesson, we stacked thirds on each degree of the major scale, to produce the seven triads that make up the chords in any given key. In this lesson, we stacked an extra note on the triad, to produce 4-note voicings, known as 7th chords. So what if we stacked another 3rd, to produce a 5-note voicing? Would that just be another, more extended version of the same thing? We technically could, but it doesn’t really work that way. When we get up to 5-note voicings, things can sound a bit too cluttered. There are only seven notes in the scale to begin with, so with 5-note chords, there are only two notes of the scale that aren’t being played, for every chord we do play. That being said, 5-note chords are used, but they don’t get treated in the same way as triads or 7th chords. They’re not treated like fundamental building blocks, in the same way that triads and 7th chords are. You can experiment with playing 5-note voicings on each degree of the major scale, just to hear what it sounds like.

Get Guitar Chords Galore eBook