Robert Estrin - piano expert

What is a diminished 7th chord?

Learn one of the most intriguing chords in music

In this video, Robert approaches the diminished 7th chord, used rather frequently in old movie soundtracks - perhaps even overused!

Released on March 26, 2014

  
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DISCLAIMER: The views and the opinions expressed in this video are those of the author and do not necessarily reflect the views of Virtual Sheet Music and its employees.

Video Transcription

Hi. I'm Robert Estrin here at livingpianos.com and virtualsheetmusic.com with a special show, "What is a Diminished 7th Chord?" You may have noticed something is different. It's in the air. You have heard it in the theme. You hear it so much in old movies when there's a scary part.

In Liszt's Hungarian Rhapsodies and lots of music, the diminished seventh chord, well, what is it? Well, we're gonna have to discover that today and these are two-part series. Next time, we're gonna talk about the deception of the diminished seventh chord. But today, we're gonna just define what it is.

That was interesting how I made a progression from explaining what half steps are. Basically, two keys together or no keys between, to the whole step which is two keys together with one key between. Now, a diminished seventh chord is minor third which is a step and a half. It's one half step bigger than the whole step.

Now, just as there was only one chromatic scale and there are two whole-tone scales. There are only three possible diminished seventh chords. Let me show you.

First of all, building a diminished seventh chord you count one, two, three, one, two, three, one, two, three. If you count one more, one, two, three, you're back to the same note. So there is your diminished seventh chord.

So the first thing you discover is unlike all other seventh chords, you can't really invert a diminished seventh chord because it's still a diminished seventh chord. If you take, for example, a dominant seventh and you invert it, you end up with a second at some point, and it will always be there until you get back to the root position. But the diminished seventh chord? No. It's all diminished sevenths. It remains minor thirds no matter what you do.

So, there are only three of them. Watch. You start with one, go up a half step, go up a half step again, go up one more half step, and you're back to the first one.

That's all there is to a diminished seventh chord, but there are such amazing possibilities with the diminished seventh chord because of this. They can go virtually anywhere, fabulous way to modulate to other keys, and there are many different ways to resolve a diminished seventh chord. We're gonna cover it in the next of this series, the deception of the diminished seventh chord.

Thank you so much for joining me. Robert Estrin here at livingpianos.com and virtualsheetmusic.com.
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simflynn * VSM MEMBER * on December 28, 2016 @6:10 am PST
Hi Robert, In the Dim 7th chord. Why is it termed a 7th?
reply
Robert Estrin - host, on December 28, 2016 @1:35 pm PST
Diminished 7th chords are called 7th chords for the same reason all 7th chords are identified that way: they contain 4 notes arranged in thirds: a root, 3rd, 5th and 7th - basically, every other note of a scale. 7th chords can be built on any scale degree. The diminished 7th chord is built on the 7th degree of the harmonic minor scale. It does not occur without accidentals in any major or minor key.

If you build a 7th chord on the 7th note of a major key, you end up with a half-diminished 7th chord. So, in C-major that would be B-D-F-A. They are all minor thirds except between the F and the A. If you lower the A to A-flat, you have a diminished 7th chord.
Ms Susan * VSM MEMBER * on April 3, 2014 @5:19 am PST
Adult piano student! LOL!
Ms Susan * VSM MEMBER * on April 3, 2014 @5:19 am PST
Thanks for great explanation of Dim 7th chords! I've sent link to video to an adult piano studio after we came across it in a Bach piece!

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