Using 6th intervals is a staple of classic R&B/Soul music, as well as in Blues music. An example might be a Robben Ford-type lick that could use the open 6th interval or the major 6th chord voicing:
Steve Cropper, most famous for being a member of Booker T. & The MGs, played on a myriad of R&B hits behind Wilson Pickett, Otis Redding, Eddie Floyd, and Sam & Dave. On their hit, “Soul Man,” Cropper’s guitar immediately identifies the song, similar to the example below.
Leo Nocentelli, of the pioneer New Orleans funk group The Meters, would use 6th intervals to outline 7th chord by also adding the root note of the chord with the first finger, similar to the example below.
Leo might use this type of example in his funk tunes such as Looka-Py-Py and Little Old Moneymaker. In this example, he would use his 3rd and 4th fingers for the 6th interval, on strings 2 and 4, while extending his first finger to grab the root of the chord on string 1, after which he slides the 6th interval down two frets to chord tones 7 and 5 (F and D notes, in this case).
Eric Clapton has been known to use 6th intervals in an unusual way, where he anticipates the coming chord change. In the example shown, he outlines the relative major/minor function of the Em and GMaj chords in a crafty way, using the same 6th intervals for both chords.
B.B. King used a 6th interval guitar riff for his Rock Me Baby, similar to this example:
The 6th interval used in this B.B. example is a minor 6th. It’s the interval between the Major 3rd of the chord and the root of the chord. This is the inversion of the Major 3rd interval. All of the other examples in this lesson use the Major 6th interval, which is the inversion of the Minor 3rd interval. The rule of thumb for inverting intervals is to use the number 9. Whenever we invert an interval, adding up the original interval with the resulting interval will result in the number 9.
In reference to the B.B. King example, the interval from A up to C# is a Major 3rd. If we raise the A up an octave, as in the example, we end up with a minor 6th. 6+3=9. When we invert a major interval, it inverts to a minor interval. Major 6th inverts to minor 3rd, and vice versa. Another example would be the interval between the A and G notes on beat 2 of the same example. A down to G is a Major 2nd. If we lower the A down an octave, the interval from G down to A is a 7th, which is a minor 7th. More 6th rhythms to come.
Keep practicing and have fun!