Twelve bars of dominant 7th chords on I, IV and V: the form of the blues. Major: I7 – I7 – I7 – I7 – IV7 – IV7 – I7 – I7 – V7 – IV7 – I7 – V7.
Twelve bars of dominant 7th chords on I, IV and V: the form of the blues. Major: I7 – I7 – I7 – I7 – IV7 – IV7 – I7 – I7 – V7 – IV7 – I7 – V7.