Power Chords, Perfect Fifths and the Consonant Interval
So, going with the G5 power chord:
Root Note on the Sixth String and Third Fret
• Consonant Note: 5th String and Fifth Fret
• Octave Note: 4th String and Fifth Fret
This gives you a bit of a skeleton to build your improvising off of, so the best way to get that anchored in your mind is to go through a few basic exercises that utilize the perfect fifth at several different spots on the fretboard:
Exercise 1: Perfect Fifths Power Chords (Sixth String Root)
Exercise 2: Dyad Chords (Fifth String)
Exercise 3: Perfect Fifths Power Chords (Fifth String Root)
Exercise 4: Combination
Exercise 5: Combination
Hearing the Consonant Notes and Octaves
Once you understand the concept, the challenge is to start to be able to hear the consonant and octave notes that correspond to your root note. As you develop familiarity with that system, your instincts as a guitar player will start to improve, and your ear will be able to pick up on more subtleties of the instrument.
You’ll know what a consonant and octave note sound like, even if you might not be thinking in those terms as it’s happening.
So in a sense, it’s really more about your ear than it is about what you see on a piece of paper. If you can hear what’s going on in these patterns and replicate it in other musical situations, then you’ve built a crucial foundational tool to help you become better at improvising and playing by ear.