Major triad over dominant chord

Hello Folks!

I recently came across this exercise that uses triads over dominants. However, the exercise didn’t really go into the details of how that is supposed to work and why. I think the exercise is assuming that the user has this knowledge. Could someone please break this down for me? I would really appreciate it!

Have a great day!


Alright I’ll give it a try
As I understand it, the major triad (eg C) is contained in the dominant chord already (eg C7), that’s why it works.
The chord tones of the dominant chord (C7) are the major triad (1st, 3rd, 5th) plus the dominant (flat 7th)
So as long as you’re playing the triad it will sound good even if you are not playing the “dominant sound” it’s the same as playing root + 5th or simply roots, it works


Hey Matsumoto,

I gotta find my old piano and accordion material and upload it here if I find it. There it explains the triads well.

As far as I remember, the difference between only triads and additional dominant sevenths is that Dominant sevenths literally “urge” to solve into the next lover harmony on the circle of fifths.
I.e. if you have C-F-G-C , G may solve into C back again, but it doesn’t necessarily need to. We can go to the parallel minors like C-F-Am-C, or elsewhere. However if it is C-F-G7-C, G7 urges to solve back down into C. It doesn’t sound well if you’d go elsewhere on the circle of fifths, like C-F-G7-dm. Dominant 7 always urges to come back to the next bottom harmony. If you play on 7s, you give it a different touch and the song urges to solve into somewhere. That is why one should have a bit of caution there. But: Dominant 7s sound very nice if taking their rules into account, tho.

This :+1:

As an example, a C Major triad consists of the chord tones C-E-G.

A C Major 7 chord consists of C-E-G-B.

A C7 chord (Dominant) consists of C-E-G-Bb.

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So, I can’t be sure (because I don’t know the exercise you are referring to), but the case where you play a C-E-G triad over a C7 chord would have to be considered the trivial case.

I think what the exercise potentially was hinting at is that you can play another triad over a, e.g., C7 and make it sound cool, namely the triad that starts a whole tone below your root note. So, for a C7 chord, you’d play a Bb-D-F triad over it, which just happens to be the 7th, 9th, and 11th of the C7 chord (its extensions) and this adds more flavor to the whole thing.



Is it true that each interval of the C7 chord forms the ‘key center’ of an ‘allowed’ triad?

So C7 is C-E-G-Bb, which in turn are the possible triads I can play. C-E-G, E-Ab-B, G-B-D, and as you said Bb-D-F. Like that?


One thing that might confuse people here is that the key and the dominant are actually different things. For example, in the key of C major, the dominant seventh chord is G7 (G-B-D-F).

Well that used to confuse me anyway. But dominant chords are built from the dominant tone in a scale, i.e. the perfect fifth.

It’s also true that the dominant chord with the same root note as the key is useful (and sounds cool when used in certain ways) when used with that key, despite the dissonance.


Hm, Ok, we need to disentangle some concepts here first :smile:

If you take a major scale and then construct the diatonic 7th chords over each degree of the scale, you get the following types of chords (always the same type of chord for the same degree):

Let’s take the F major scale (key center is F): F - G - A - Bb - C - D - E (- F)

The 7th chord over the first degree is a major 7th chord: F-A-C-E
The 7th chord over the second degree is a minor 7th chord: G - Bb - D - F
The 7th chord over the third degree is a minor 7th chord: A - C - E - G
The 7th chord over the fourth degree is a major 7th chord: Bb - D - F - A
The 7th chord over the fifth degree is a dominant 7th chord: C - E - G - Bb
The 7th chord over the sixth degree is a minor 7th chord: D - F - A - C
The 7th chord over the seventh degree is a half-diminished 7th chord: E - G - Bb - D

As you can see, all the triads of all these chords (the first three notes of each of them) would “fit” to be played over a C7 chord as they are all of the same scale (diatonic to each other), in other words they are all scale tones (of the F major scale). However, it is often “better” (and that’s to some extent a personal preference) to use chord tones rather than scale tones.

But, you can also include extensions of 7th chords (the 9th, the 11th, the 13th) by further stacking thirds on top of each other, and you can actually “get” them by playing the neighboring triads to either side of the C7 chord (here, the Bb - D - F triad and the D - F - A triad).

Not quite (see my explanation above). You are on to something here, but note in particular that some of the triads you suggest are not diatonic (not from the same parent scale (here F major) where C7 is the dominant chord); in other words, Ab (should really be G# here) and B are not scale tones and hence can’t be chord or triad tones either. That is - as laid out further above - because not all these triads are major triads!!

Hope this clears things up a bit!?!


Dominant chords are like a fun trifecta of confusing.

  • They do not reside in the key of the root note of the chord
  • They can, however, often be substituted for the triad of that key and still sound great
  • Even for the key that they are enharmonic with, they contain a tritone and thus are dissonant (which is the primary reason they are used)

I guess you could say that for all of these chords (other than the one constructed over the 1st degree); i.e., D - F - A - C does not reside in the key of D (major) and so on…

Not sure I understand this entirely!? First, I assume you meant to say “diatonic” and not “enharmonic”. But, where is the tritone coming in? Could you give an example? :smile:


Dominant seventh chords contain a tritone between the seventh and third (F and B, for G7). It is what gives them their tension.

oops yes, sorry


Thanks @joergkutter, trying to digest the information. One thing I can see is that I constructed my triads off of the wrong notes. I didn’t adhere to a scale, my understanding was to, simply build a C7 chord and then for each interval of that C7 I built a triad (major). I now know that is not correct and I need to abide by a key.


Ah, yes, I see now - makes total sense (and I probably should have known/remembered that :wink:)


Well, most (popular) music does this because it “sounds better”. But, there is no law that says you have to do this. Things get quite a bit spicier, though, if you bring in non-diatonic notes :grin: