When you apply the pentatonic scale to music on the guitar, the general rule is to match the scale to the tonic. If the tonic is a major chord, then play the same corresponding major pentatonic scale. For example, use A major pentatonic over a song that centers on an A major chord (as in “Amie” by Pure Prairie League).
If the tonic is a minor chord, then play the same corresponding minor pentatonic scale. For example, use A minor pentatonic over a song that centers on an Am chord (as in “Stairway to Heaven” by Led Zeppelin).
What if you’re not sure what the tonic chord is in a piece of music? Here’s one way to figure it out:
Put on a piece of music and let it play.
Play notes on your guitar along the 6th string.
Begin with the open string and then climb chromatically from the 1st fret to the 2nd fret and so on until you reach a pitch that sounds like the tonal center of the music.
After you find the right tonic, put your first finger on it and play pentatonic pattern 1.
This will produce the minor pentatonic.
Now put your 4th finger on the same tonic and play the major pentatonic.
This means that you begin pattern 1 three frets below the tonic with your 1st finger.
Determine whether the minor or major pentatonic is the better fit for the music.
After you get oriented in the right key, you’re free to move about the fretboard and use any positions and patterns in that key.
Melt some faces.
Generally, minor pentatonic is played over minor chords and major pentatonic over major chords. Keep in mind, however, that rules are meant to be broken. Many popular styles of music, such as blues, country, and rock ’n’ roll, use the minor pentatonic over a major chord.
Perfect examples of this include “Hey Joe” by Jimi Hendrix, “When Love Comes to Town” by U2, and “Sundown” by Gordon Lightfoot. The tonic chord in all three of these songs is major, yet the guitar solos use mainly the minor pentatonic. In these cases, using a minor pentatonic over a major chord works and fits the bluesy style of the music.