Triad Chord Theory

Hello @JanWartenberg and welcome to the community.
See if this helps.

If you look at the major scale formula, with C major below as an example, you can see that some notes are two semitones apart (a whole tone) and some just one semitone apart.
Between the 2nd and 3rd scale degrees there is a two semitone distance. Thus, the 3rd can be lowered (flattened) by a semitone and it does not encroach on the note below.
Between the 3rd and 4th scale degree is just one semitone. If the 3rd was raised (sharpened) it would occupy the same space as the note above it, the 4th. You could forcibly call it a #3 and view it as an enharmonic equivalent to the 4th scale degree. But that is not what happens. Instead, if the 4th scale degree is played within a chord because the 3rd has been raised, we call it the 4th and the chord becomes a sus4.
No such limitation applies to the 5th scale degree as there are two semitones either side of it so it can be flattened or sharpened.

Plus, as @Jozsef says, it is also the internal intervals that make up any chord. An augmented triad must contain two major 3rd intervals by definition.
I hope that helps.

Cheers :smiley:

| Richard_close2u | JustinGuitar Official Guide, Approved Teacher & Moderator

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Do you mean all notes in the chromatic scale? You are exploring triads for all 12 notes?

The D note should be D#, not D natural.

For augmented triads, start with the major triad and raise the 5th scale degree note by one semitone BUT keep the alphabetical letter name. You cannot call it by the next alphabetical letter name even if it has that as an enharmonic equivalent.

B major: 1, 3, 5 → B, D#, F#

B augmented: 1, 3, #5 → B, D#, F##

The double sharp symbol resembles a bold letter x if you see that written.

6 posts were merged into an existing topic: Theory course videos not working

When learning about the triads, I realised only the notes in the major tried fully belongs to the major scale. For the minor, augmented and diminished triads, some of the notes are not from the major scale. I would assume that the notes in the minor triad belong to the minor scale, but what about the augmented and diminished triads? Is it ok if the notes do not belong to any scale? Or do the notes belong to some other scale that’s neither major nor minor?

I had the impression that notes making up a chord should belong to the same scale.

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Hey Zach,

Yep there are scales like various diminished and augmented scales that feature these types of triads and beyond. Not really on my radar at present - perhaps @Richard_close2u will be along at some point to illuminate.

Re your thinking on the triad/ scale relationship etc, remember that every major scale produces 3 major, 3 minor, and one diminished triad. All the notes from all these chords are in the relevant scale, including the minors and diminished. They have to be, as their whole existence derives from these notes.
A triads membership of a scale however is not exclusive though. It can be a member of many scales, and chord families. Eg You’ll find every triad of C Major in A minor, cos they share exact same notes. They just function differently.

Cheers, Shane


Shane is correct on Major, minor and diminished chords, in the Parent Major and relative minor ssales. Augmented are a Major chord with a raised 5th so in theory you could find a mode that the chord fits into but it’s easier just to raise the 5th of the chord. Also augmented chords have a specific use and are not used very often in music.

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Hi everyone!

Just beginning to wrap my head around triads and I have a question of triads in a key. I was building major triads by first writing up the major scale for that note and then taking, the tonic, the third and the fifth.

But I was looking into harmonising the major scale and it seems cumbersome to build the major triad, then turn into a minor, or a diminished. Is it possible to build the correct triad from only the notes in the major scale?

Say: C D E F G A B C
C major= C E G
D minor= D F A???
E minor = E G B
F major = F A C
G major = G B D
A minor = A C E
B diminished = B D F

Are the above correct?

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Hey Gustavo,

Yes, the triads you have there are 100% correct. :+1:Thats how you ‘build’ the basic triads/ chords in a particular key.
Built from stacking 3rds together, as you’ve done. ie alternate notes.
Triads are always built from their parent scale. By definition, that is what triads/ chords are.
So, in any Major scale you always have;

Major triads - 1st, 4th, 5th
Minor triads - 2nd, 3rd, 6th
Diminished triad - 7th

Cheers, Shane


It would be incredibly helpful if you’d get some kind of camera on your fretting had, or at least diagrams of what you’re doing there. The majority of the time I cant tell and it takes a lot of time to figure it out.

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Richard has a really useful diagram here: Vintage Club 6 with Richard | Triads

This is from his triad overview session in the Club. This opened my eyes to using these in a way that the official lesson missed. Worth a read.


Had a very theoritical question. If i were to sharpen the 5th note of the minor would that theorically be an Augmented minor? Does something like this exist in theory at least?


Good question. You don’t mix sharps and flats so in theory the #5 would be a b6 because the 3rd in a minor chord is flattened. So in theory to write the chord out it would be R b3 b6 but in reality it could be a #5 making a augmented minor chord.


In my opinion it will become a different chord altogether, not an “augmented minor” or something like that. For example:

Gm triad: G Bb D
With the 5th sharpened: G Bb Eb (enharmonic equivalent of D#). This is an Eb major triad.

Check out the respective shapes on strings 1-3, it will become more obvious.


Hmm. Not sure I entirely agree with this @Jozsef.

Based on the notes, in a vacuum, you could see your example as Eb major triad. You could equally call it a Cm7 ( rootless), and several others besides.

In reality, it all depends on the function of the notes, and by extension, the chord, in the overall melody and harmony.
It could very well be functioning as a Gm5+ rather an Eb Major.

Cheers, Shane


I have to agree with Shane, every chord can have multiple names depending on how and where it is used.
But by definition a triad is made up of stacked maj/min 3rds, so an augmented 5th wouldn’t follow this recipe and this question is in the triad chord section so the renaming of the chord to a Major triad fits the category of triads. On the other hand not all chords fall in the category of triads which brings us back to where we started.
I quess that’s way it’s called theory and not written in stone.


Hi Zach.
That is not accurate …

Using the C major scale for ease.

Three major, three minor and one diminished triad all fully derived from the notes of the C major scale.
The only triad that this does not work with is the augmented triad.

Augmented triad = 1, 3, #5

The augmented has a major 3rd. Using the three major triads above would give:

C+ = C, E, G#
F+ = F, A, C#
G+ = G, B, D#

Clearly, those #5ths do not belong in the C major scale. None of these augmented triads are diatonic to the key of C.

My advice would be not to get too hung up on augmented triads. They are rarely used.

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That is exactly what we do.
See my diagram in the post immediately prior to this one.

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Strictly speaking, no. The definition of an augmented triad is that it contains two major third intervals. Your triad does not.

Augmented triad = 1, 3, #5

1 → 3 is a major third

3 → #5 is a major third

Your ‘triad’ would be

unknown = 1, b3, #5

As @stitch correctly writes, that is awkward and contravenes the naming conventions so you would have to alter one or other so you do not have flat and sharp in the same triad formula.

unknown - 1, b3, b6


unknown = 1, #2, #6

The 1, b3, b6 looks a better option as it contains a 3rd.

Making a specific using a given root note.

C unknown = C (the 1), Eb (the b3), Ab (the b6)

These three notes match exactly those within Ab major triad.

Ab triad = Ab, C, Eb

The C unknown is actually a first inversion Ab major.


I have had this in my mind since posting and wanting to bring in two short examples of augmented chords (triads) in action.

Mamma Mia (Intro) by ABBA.

This uses the augmented of the tonic chord, simply moving from major tonic to augmented tonic and back again.

Just Like Starting Over (Intro) by John Lennon

This also uses the augmented of the tonic chord as a stepping stone to the relative minor vi chord and back to the tonic again. The movement on the high E string is a great example of voice leading.

There are other ways in which an augmented could be used would be used but I shall refrain from going too deeply down that hole. I just wanted to bring a little light rather than dismiss them altogether.



Richard @Richard_close2u
As you say the first is the intro to Mama Mia, with quick changes between D and Daug, not too difficult if you use your little finger which I mentioned recently in D Shape Explorer.


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