Riffin’ is a free weekly video guitar lesson series by Nashville guitar guru Dave Isaacs focusing on the construction and development of killer guitar riffs. There’s a lot to learn in this series, so be sure to subscribe!

Video Guitar Lesson

We’ve explored the use of 4ths and 5ths in creating riffs both in open position and up the neck. We’ve also begun to include fragments of pentatonic and major scales to spice things up with melody. Next, I want to move on to a different set of related intervals, the 3rd and the 6th.

Like our 4ths and 5ths, these intervals are based off of scales and are simply the distance between notes 1 and 3 or notes 1 and 6. However, they have a very different sound. Thirds and sixths can be major or minor, depending on the scale we derive them from, and both the major and minor forms appear in the notes of a given key. (We can also manipulate the major and minor qualities, borrowing notes from other keys to create cool “mode-mixture” sounds).

The video shows the different fingering patterns across the neck for all four intervals: major and minor forms of the 3rd and the 6th. These patterns can be slid around the neck to create simple but very rich semi-chordal riffs. Remember that a two-note interval implies a chord but doesn’t complete it, so there’s room for other instruments to add color and dimension by varying the notes that surround or blend with your lick.

Thirds and sixths are also the primary intervals we use to add harmony to a melodic line. You may have even practiced exercises that made use of intervallic skips of a 3rd as you move up a scale, or harmonized the entire scale in 3rds or 6ths. You’ll hear the same thing in vocal harmony parts. Remember the openness and grind of 4ths and 5ths? Thirds and sixths blend in a different way, creating a richer, more harmonic sound.

We’re not limited to these intervals by any stretch – in fact, if you start combining the different interval shapes we’ve learned you’ll see very quickly how the possibilities multiply. Incorporate the concept of melody against chord and you’ll start to really see the big picture: how everything works together, and that all these small concepts can be combined in many ways. As we continue through this series, this big picture approach will become clearer and clearer.

Returning to scales for a moment: once again, if you don’t know your major scales up and down the neck you need to lock in that information. Everything else will be based off of this foundation. As you practice your scales, start incorporating interval patterns: rising thirds, rising fourths, harmonized scales in thirds and sixths, and any combination of the scale with interval patterns that you can think of. Don’t just use scale shapes that move across the neck in a single position, either…move along the fretboard and try to figure out the harmonized scale in a variety of keys, using both 3rds and 6ths.

One last bit of theory here. The 3rd and the 6th are actually inversions of each other. In other words, if you take a major 3rd – say, C to E – and then move the C to the top so the notes are E to C – you create a minor 6th. When we invert any interval, the sum of the two numbers will add up to 9, and the quality will flip (major becomes minor and vice versa). This is why we can say that 3rds and 6ths are directly related, and if you harmonize the same melody a third above or a sixth below the note names will be the same. Mastering this particular element is very useful in riff creation, working out harmonized guitar licks, or even vocal harmonies….so it’s a very useful musical tool.

As always, get to work, have fun, and keep on exploring!

Riffin’ is a free weekly video guitar lesson series by Nashville guitar guru Dave Isaacs focusing on the construction and development of killer guitar riffs. There’s a lot to learn in this series, so be sure to subscribe!