Is it really necessary to learn about guitar modes? Well, you don’t need to learn anything. In fact, you don’t even need to learn to play the guitar. But we study things because they are interesting, they bring pleasure and they help us to develop. Guitar mods are a confusing subject, but once gamers figure out how they actually work, they’re pretty glad they did.

Many guitarists have their own complicated way of thinking about musical concepts. As a result, their explanations of what they’re playing seem inconsistent with certain terminology. To say that Slash and Joe Pass don’t know anything about modal scales is inaccurate. Everything is in a mode. They couldn’t play music without them.

“My sweet child” from Guns and Roses is a great example of mixolydian fashion. The two musical interludes that occur at 1:31 and 2:32 are based on the chords D, C and G which are VI IV I (5 4 1) in the G major scale (guitars tuned 1/2 step). Although the major major scale is G, it is actually the D chord that functions as the root.

Many guitarists make the mistake of basing the scale on the root chord. But the D major scale won’t work quite right in this example because the C# note collides with the C natural note in the C chord. The correct way to reproduce this progression is to recognize that it is a mode of the G major scale based on the fifth degree, D. This is called the “Mixolydian D mode” (also known as the Dominant scale).

So the correct major scale to play is G. However, if you want to apply the pentatonic, you have to follow the root chord, D. What you end up with is a combination of the G major scale and D major pentatonic.

Most guitarists prefer pentatonic boxes. So you could target the D major pentatonic first (pattern 1 starts at fret 7) and then blend the G major scale notes (G major scale pattern 3 overlaps the major pentatonic pattern of D1). And this is exactly what Slash plays!

Now Slash may explain guitar theory differently, but it’s still mods he’s playing independently.