3rds & Thirds Part C : the concept of 3rds as partial chords

3rds in the key of D … reprise

It is worth repeating … there are only two shapes for 3rds on any given set of two adjacent strings.

At the very outset of this topic, in Part A, 3rds in the key of D were introduced step by step. Firstly on the B & E strings. Then on the G & B strings. And lastly on the D & G strings. I deliberately chose to miss any 3rds that use the Low E & A strings.

For ease of reference, here are those 3rds in TAB format again.

At the time, they were simply presented as nothing more than shapes to explore musically as the fancy took. They were not ‘rooted’ (excuse the pun) in any knowledge or theory. They were not connected to scales or chords. They seemed to have their own independent existence separate of anything else. They sound good and they are fairly easy to play. What’s not to like? Why bother any further?

Well …

Having explored a fair chunk of the theory that can explain how these 3rds are derived, and having already seen the seven chords that come from stacking thirds in the process of harmonising the D Major scale in Part B here in Part B, it is time to root those 3rds within the context of the D Major scale and the diatonic chords that it gives rise to.

It is time to root those 3rds within the context of CAGED shapes.

CAGED shapes that become triad shapes.

Triad shapes that contain the magic intervals of thirds.

Thirds that we view as note pairs.

Note pairs that we call 3rds.

And because we are rooting the 3rds within the context of chords, we will see that they can be thought of as partial chords.

The character and name given to these partial chords will, hopefully, be completely obvious in the first instance. But, beyond the obvious lie some hidden facets that may surprise. The 3rds can be very ambiguous, fluid, lead double-lives in their make-up. They can take the character of more than one chord.

3rds as ‘partial chords’

We are going to see our, by now familiar, 3rds following the sequence of chords from the harmonised D Major scale

As we saw earlier, harmonising the D Major scale gives these chords:

D Major, E minor, F# minor, G Major, A Major, B minor, C# diminished.

We are going to see these chords charted only using the D-shape triad forms on the G, B and E strings for now.





Let’s remove one note from each triad and see what we have …

1] C# diminished triad → 3rd … … … … … … 2] D Major triad → 3rd


3] E minor triad → 3rd … … … … … … … … 4] F# minor triad → 3rd


5] G Major triad → 3rd … … … … … … … … 6] A Major triad → 3rd


7] B minor triad → 3rd … … … … … … … … 8] C# diminished triad → 3rd


9] D Major triad → 3rd



Wow. Oh boy. Those shapes are familiar!

See how by simply ‘removing’ the notes on the G string, we have laid out the 3rds that we began exploring way back at the start of the topic?

The note ‘removed’ is the 5 of each chord so we can look at these 3rds as a sequence of partial chords, containing just the root and 3, that track exactly the sequence of chords in the harmonised D Major scale.

Play these 3rds from the ‘tonic’ D at frets 2 & 3 to its octave and you will hear the do-re-mi-fa-so-la-ti-do with a harmony voice of thirds singing above.

:sunglasses:

Our original TAB of 3rds could be labelled:

Where the chord names are really partial chords, intervals between Root and 3, where the sound of the 3rd is suggestive of the chord.

This exact process of converting triads to 3rds labelled as partial chords (by removing a note on just one string for each) can be done for the sets of 3rds on the G & B strings, using A-shape triads.

Here are those triads as seen earlier.

Once again, by always removing the 5 from each triad (which we find on the D string), we will move from triad shape to 3rd shape.

1] G Major triad → 3rd … … … … … … … … 2] A Major triad → 3rd


3] B minor triad → 3rd … … … … … … … … 4] C# diminished triad → 3rd


5] D Major triad → 3rd … … … … … … … … 6] E minor triad → 3rd


5] F# minor triad → 3rd … … … … … … … … 6] G Major triad → 3rd


9] A Major triad → 3rd


Wow. Oh boy. Those shapes are familiar. Again!

The original TAB of 3rds could be labelled:

Where the chord names are really partial chords, intervals between first and third, where the sound of the 3rd is suggestive of the chord.

This exact process of converting triads to 3rds labelled as partial chords, by removing a note on just one string for each, can be done once again for the sets of 3rds on the D & G strings, using E-shape triads.

Here are those triads as seen earlier.




Once again, by always removing the fifth from each triad which this time is always found on the B string, we will move to 3rd shapes.

1] E minor triad → 3rd … … … … … … … … 2] F# minor triad → 3rd


3] G Major triad → 3rd … … … … … … … … 4] A Major triad → 3rd


5] B minor triad → 3rd … … … … … … … … 6] C# diminished triad → 3rd


7] D Major triad → 3rd … … … … … … … … 8] E minor triad → 3rd


So, so familiar. :wink:

The original TAB of 3rds could be labelled:

Where the chord names are really partial chords, intervals between first and third, where the sound of the 3rd is suggestive of the chord.

Putting all three sets of TABs together, with each 3rd labelled as a partial chord, we have:

B and E strings:

G and B strings:

D and G strings:

More on this concept of 3rds as partial chords to follow in part D.

Cheers :slight_smile:
Richard

Questions / comments?

OMG my brain hurts, this is really good stuff to learn about!

2 Likes

Crystal clear… :sweat_smile: :sunglasses:

2 Likes

Hi Richard,
Am enjoying doing this with my guitar,
Quick Q about the C# diminished E shaped triads here .
It looks like got a perfect fifth - second string 9th fret instead of the flat fifth.
Is that just a typo?

1 Like

@Eccleshall
Thanks - you’re right …
I have now edited.
:slight_smile:

1 Like

Phew,
I’m glad it’s the simple explanation.
And not an harmonic existential crisis :sweat_smile:

1 Like

A couple of paracetamol should see you back in the game Darrell! Glad you’re enjoying it. :slight_smile:

Like mountain-streams! Thanks Roger.

Nobody needs that sort of thing in their life! haha :wink: