4ths and 5ths as Double Stops

Perfect 4ths and 5ths are the most open and powerful double stop intervals. The perfect 5th is the interval inside every power chord — two notes with a strong, stable resonance.

When played as ascending double stops through a scale, 5ths follow the familiar power-chord shape but move diatonically rather than staying parallel. This means some pairs will be diminished 5ths (on the 7th scale degree), which adds harmonic tension.

4ths are the inversion of 5ths and have a similarly open sound. They are common in modern rock, funk, and quartal harmony jazz voicings.

5ths in A — Power Interval Shape

5ths in A major follow the power-chord shape up the scale — strong, open intervals.

Play 4ths in D Major

Fret each 4th with two fingers on adjacent strings and strike both strings together
Walk the 4ths up through the D major scale, then reverse back down
Compare the sound of 4ths to the 5ths in the example — notice the slightly different character