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Summary: Seventh chords have four notes because the 7th note in the scale is added to the normal triad. Learn how to form and play a dominant 7th guitar chord from an experienced musician in this free music theory video.
Thomas Marchevsky is a professional guitarist/composer and college professor. He has an M.M. in guitar from the New England Conservatory in Boston. He teaches private lessons at his...read more
"Now, let me give you the basic instruction for the dominant seventh chord so that you have the theoretical basis for this chord. In the dominant seventh chord, of course since we're dealing with the seventh chord, there are four notes within the chord. So, we're taking a major triad, three notes, and adding a seventh to the triad to create a seventh type chord. So, the starting place is the major triad so we need, of course, the roots, we need the third, which is a major third. We need a fifth, which is a perfect fifth and we need a seventh, which is a minor seventh. So, let's look at an example here of this type of chord. Again, we can use these notes in any arrangement. The important thing is that we have those notes within the chord. In this case I'll play a C dominant seventh and the notes are C, the root, G the fifth, B flat the minor seventh, and E the third."