The dominant seventh chord

A famous opera critic once said “The only two elements essential for grand opera are sex and the dominant seventh chord.” Which makes a lot of sense if you think about it.

I confess I am completely fascinated by the dominant seventh chord. Without that seventh, the dominant chord is pretty wimpy. For example, when you play a G chord on the piano (G B D) there is only a mild feeling that the chord “wants” to go to a C chord (C E G).

But if you play a G dominant seventh chord — by adding the F, to get (G B D F) — then the sense that the chord “wants” to go to the C chord increases enormously. Why is this? What is causing the supercharging effect when you add that F note?

I wonder whether it’s because the C chord is pretty much defined by that E note in the middle. Each of the notes of the G chord create a pull toward one of the notes of the C chord, but the effect is only mild:

G → G
B → C
D →E

But once you add that F note, suddenly two notes are both pulling toward the E:

G → G
B → C
D → E
F → E

And that extra force creates a sense of inevitability. Suddenly the G dominant seventh chord wants to transition to the C, with a real sense of urgency.

I’m convinced its all about those two notes (the D and the F) both wanting to go to the E. Call it a hunch.

5 Responses to “The dominant seventh chord”

  1. Mari says:

    Since I’m a crook, I tend to hear G and F pulling outward, to two F# :) (“Neapolitan 7th”) But like yours, two pitches pulling arriving to the same pitch (octave different)

  2. x says:

    and all you need to make a movie is a girl and a gun…

  3. James Dering says:

    That’s certainly a unique perspective! The “textbook” explanation is that it’s the _B_ and the F that create the pull. B really wants to go to C, and F really wants to go to E. Although the D and F both “surround” the E, the D is also just as close to C as it is to E, and it will, more often than not, actually fall down to C. Of course this varies from style to style. You can really hear the effect of the B and F if you play them alone: play only B and F, and then resolve them to C and E. Then, if you want to mess with your ears, play the B and F again, but then resolve them _outward_ to B flat and G flat! But that’s another story…

  4. Kevin says:

    G7 pulls toward c for the simple reason that it can only be in the key of c or c minor and you live in a country where you have heard western music all your life. As a mathematician you probably know that people almost always resolve to majors with their ear because of this. I wonder if eastern cultures would do the same thing?

  5. Kevin says:

    When I teach theory I always say big chords are easier for this reason.

    Small chords have to be tonally centered based on who they hang out with.

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