In last months post I covered playing a 12 bar blues in different keys, but this we'll turn all three chords in the key to dominant 7th chords. Usually you will only find a dominant 7th chord in a major chord and that is on the V chord.
A dominant 7th chord is one that is made using a 1 3 5 b7. For example, in the key of C the V chord is a G and making it a dominant 7th would yield the following notes: G B D F. When we see it written as a chord symbol it would be G7; hence, if we say play "G seven" we really mean G dominant 7th.
Of course a 12 bar blues does not always contain all dominant 7th chords, but applying them in this manner helps give our blues a bit more flavor and it will also help our students to expand their chord vocabulary.
I have attached a sample 12 bar blues in the of A - the choice of this key is purposeful as it will help students utilize open position dominant 7th chords which only use two and three finger chords. Try having your students try other keys that use all open position dominant 7th chords such as G, D and E.
