Transition Chords: The Diminished 7th Chord

Diminished 7th Chord – Root, flat 3rd, flat 5th, double-flat 7th

Good morning, this is Duane. We’ve been talking about various kinds of 7th chords. First I took up the dominant 7th chord, which is root 3rd, 5th and the flat 7th of any scale. We went through all the dominant 7th chords. Then we covered the minor 7th chord, which is a minor triad plus that dominant 7th chord, dominant 7th note, the flat 7th, in other words. We call this the pregnant chord because it wants to move, and we call this the mellow chord because it is so mellow. Then we covered major 7th chords. I don’t remember what I called that. Sometimes it’s a sleepy feeling or a contemporary feeling. We said that you can find that in songs like Misty, that kind of sound. Today I’d like to take up a diminished 7th chord. A diminished 7th chord is made out of a diminished triad. In other words, lower the 3rd and the 5th, but you double flat the 7th. If I flat the 7th [inaudible 00:01:11] scale I get that, but I’ve got to double flat.

If I wrote it on paper I’d put 2 flats in front of that B. That would take me down a whole step, not a half step but a whole step to what looks like A, but I couldn’t call it an A. I’d have to call it a B double flat for rules of theory. Now some musicians do call it an A, but for proper theory definition that would be a B double flat. Let’s go through the dominant 7th chords. Let’s go through all the dominant 7th chords and make them diminished 7th. If I start out with a dominant 7th chord I change the 3rd and 5th a half step lower, and I change the 7th to a half step lower, actually a whole step lower than where the 7th degree of the scale is. Now there’s something unique about that chord. There’s only 3 chords like that. That chord and go up a half a step, that chord, another half step, that chord. When I get there that’s simply an inversion of the first chord, isn’t it? In other words, if I take the C off the top, guess what I have? I’ve got the original chord.

By learning 3 chords that are each a half step apart you’ve covered all the diminished 7th chords, that, that, that, that’s all because that diminished 7th chord is C diminished 7th, but it’s also E flat diminished 7th. It’s also G flat diminished 7th. It’s also if you want to call it A diminished 7th, that will work too. Any note that’s in the chord could function as the root of the chord. In other words, if I put in the bottom, that would clearly be A diminished 7th chord. If I put E flat on the bottom, that would be E flat diminished 7th chord. If I put G flat on the bottom, that would be G flat diminished 7th chord. If I put C on the bottom, of course, that would be C diminished 7th chord. If we go up a half a step, that’s the D flat diminished 7th chord. It’s also the E diminished 7th chord. It’s also the G diminished 7th chord and the B flat diminished 7th chord because every note of the chord can function as the root.

Now if I go up another half step, guess what that is? Sure, it’s a D diminished 7th chord, and the F diminished 7th chord, and the A flat diminished 7th chord and the B diminished 7th chord. That chord, by the way, is a very tension-filled chord. At least in old movies they used to use this a lot to create tension before the hero shows up and rescues the damsel or whatever. Those are diminished 7th chords. They are also transition chords. You don’t live with that chord. In other words, you can live with a major chord or a minor chord, but you don’t live with a diminished 7th chord. It wants to go somewhere. It wants to move. There are several places it wants to move, but I won’t talk about that today. So far we’ve covered 4 kinds of 7th chords, a dominant 7th chord, a minor 7th chord, a major 7th chord and a diminished 7th chord. Tomorrow we’ll cover a half diminished 7th chord, which is like that. We’ll see you tomorrow as we take up that. If you haven’t signed up for a series of videos and lessons on piano chords, come over to playpiano.com and sign up for that. They’re free, so hope to see you there. Bye-bye for now.

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