A more open way of playing intervals is by using sixths.  The mixolydian scale is harmonised by adding a second note that is a sixth higher then the original note.
The Bb mixolydian scale has these notes:
Bb   C    D    Eb   F    G    Ab   Bb (1-8)

When you add a sixth, you get these intervals:
Bb-G, C-Ab, D-Bb, Eb-C, F-D, G-Eb & Ab-F.

Hey, you’ll never remember this if you’re life depended on it.
Look at these examples to help you out.
Focus your riffs on these positions and vary them to your liking.

The tonic of the chord is the first note you play.
Move the riff (audio on Bb) up 5 frets to get the Eb riff (the IV chord) and another 2 to get the F riff (V chord).

Or play the IV chord Eb riff like the 2nd audio example.

Examples 1 and 2 are in the Swing- and Jump Blues Guitar e-book.
The tab gives you the two riffs combined.

Here we’re using the sixth-pattern on string 1 and 3.

For the IV and V chords we’re keeping the pattern the same, but movin it up to the corresponding positions for Eb and F.

(Example 4 is in the Swing- and Jump Blues Guitar e-book)



We’ve added a little bass line to the riff and expanded it with a new position.
The IV and V position that we’ve used up the neck can also be found a lot closer.
It sounds more like an accompaniment in this position and stays out of the way of the soloist or vocalist.

The first note in bar 5 is the tonic of the IV chord.
Position all other notes on the IV riff based on that note.
Do the same thing with bar 9 and the V chord.

Note the progression in bar 4.
It leads you smoothly from the I to the IV chord (inner logic again).
The pattern of the riff is continued through bars 9 and 10, all through the chord changes. In the last bar, we’re using a chromatic walk up to the V chord.

By now you’ve figured out that there are at least two positions for playing sixths: tonic on the E string and tonic on the A string.
This means that if you move the IV position riff from the last example up 7 frets (or 5 frets up from the V riff), you’ll get a new position for riffs on the I chord. The tonic Bb can be found on the 13th fret of the A string.
All riffs are played relative to that tonic.



Note: Inner Logic

As with tritone intervals, there is an inner logic to playing third intervals over these chords.
First listen to this example. What’s goin’ on?

Whenever you use a riff with notes from the mixolydian scale and you change chords (for instance from G7 to C7), you’ve got to change scales.
The first pattern on G7 uses notes from G mixolydian. On C7 you use notes from C mixolydian.

These scales look a lot alike (see Scales / Chords). By changing only one note of the first G7 riff, you can use it on a C7 chord. Move this one up two frets and you’re set for D7.
Whenever you play a riff with intervals or broken chords, there is a good chance you can play the same riff on the IV and V chord.

If it contains the third of the I chord (B in G7), move that note down one fret. Bingo! Move the riff up two frets from there to get the V chord version.

If the riff contains the seventh of the I chord (F in G7), you’ve also got to change the riff when you land on the V chord. Look at bar 9 of example 5. On beat two you’re playing an F# on the B string, not an F!

On the C7 the F sounds hunky dory because it’s part of the C mixolydian scale. These kinds of riffs are used a lot by experienced players.
Instead of moving all over the neck to play these riffs, they change one note and look way cool while giving the girls (or boys …) in the first row the eye.