Learn the function of notes within a chord part 2

​In the last blog, I gave a taster that knowing a little bit of the theory of chords helps us change and create chords we have not learned by applying the theory to shapes we already know. I didn’t cover what that knowledge was. I will cover some of it today.
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Firstly, we need to understand how chords are built a little more in a fashion that suits us as guitarists.

We will build the chord using “Stacked thirds”, which means starting at a note and going up in steps of three to add each note to the chord. In music theory, there is no zero; the note we are on is one, the following note is two, the following three.

These steps are illustrated with the boxes above, and in each box, there can be only one note. As guitarists, that works well as we can translate that to each box to a string on the guitar for the chord shape. The box for the root note only contains the root note (For now), so today, we will look at the box for the 3rd.

Six notes can be used in this box. However, only one can be used at a time. There are two very common, two common and two rarely used. The very common are Major 3rd (3) or Minor 3rd (b3), the common is the sus2 (2nd) or sus4 (4th), rarely used are the susb2 (b2) or the sus#4 (#4).

​Using the open D chord first, the chord’s notes are in red. The 1st string is the “box” that is for the 3rd. The note on the 1st string can be 2nd, b3, 3, or 4.
This gives us the Dsus2, Dm, D and Dsus4 chords.
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Next, we will do the same for the A chord. The chord’s notes are in red. The 2nd string is the “box” for the 3rd this time. The note on the 2nd string can be 2nd, b3, 3, or 4.
This gives us the Asus2, Am, A and Asus4 chords.

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Next, we will do the same for the E chord. The 3rd string is the “box”, this time for the 3rd. The note on the 3rd string can be b3, 3, or 4. There is no practical option for the 2nd on this string.
This gives us the Em, E and Esus4 chords.

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The four-finger version of the open G chord works best here. The 5th string is the “box”, this time for the 3rd. The b3 note on the 5th string produces a complex chord for our fingers, so we usually ignore this chord form. The note on the 5th string can be a 2,3, or 4.
This gives us the Gsus2, G and Gsus4 chords.

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​The Open C chord is slightly more complicated as there are two 3rds used in the open chord shape. The b3 note on the 4th string produces a complex chord like the G chord, so we usually ignore this chord form, leaving us the 2nd, 3rd, or the 4th.
With the 1st string muted, we get Csus2, C, Csus4.

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With this C chord shape, if we play the 3rd on the 1st string, we have two notes in the box for the 3rd. At the start, I mentioned it is one note per box. With the box already filled with a 3rd on the 1st string, we are forming a Cadd9 and a Cadd11 chord when changing the note on this string to the 2nd or 4th. More on add9 and add11 chords next time