This entry comes from Dimebag Darrell's classic Guitar World column, "Riffer Madness"
Hey, Dad! What's shaking? This month we're gonna rap about a few ways you can pump maximum heaviness into a riff.
One of the simplest ways to get some extra low-end grind happening is to use what a lot of guys call dropped-D tuning. It can definitely inspire you to jam out some bad-assed riffs. Just drop your low-E string down to D and leave the rest of your strings where they are. Your axe'll by tuned, from low to high, D, A, D, G, B and E.
Check it out: hitting the three low strings open gives you a nasty D5 chord (Figure 1), and you can play any power chord you want just using one left-hand finger (Figure 2)! Pantera uses this tuning on the likes of "Primal Concrete Sledge" (Cowboys From Hell) and "No Good (Attack The Radical)" (Vulgar Display Of Power).
If the dropped-D tuning ain't heavy enough for ya, you can always tune you whole guitar down a tone-so your strings go, from low to high, D, G, C, F, A, D.
Doing this can make a riff sound heavier than shit, which is why we used it for "Walk" (Vulgar Display Of Power). I'll tell ya, if Phil (Anselmo, Pantera singer) had his way, I would play all our shit in this tuning! To me, though, it's much more effective when used once in a while-if we did it on every song, it'd get old real quick! So, whenever Phil gets on me about it, I just go, "Hey, Dad! Cut it!"
Using string bends instead of just playing regular, unbent notes can definitely help give certain riffs a cooler, heavier edge. Take the opening riff of "Walk" (Figure 3).
If I played it without the string bend and release, it'd become figure 4.
I don't know about you, but the "real way" sounds far better to me, man! It's much heavier and nastier and that's what we're looking for, bud-weak riffs are out!
You can do the same thing with power chords, too. Take a fairly mediocre riff-FIGURE 5A, for example.
To make it more interesting and evil-sounding, try this: instead of using a regular G5 power chord, bend an F#5 shape up to a G5, as in FIGURE 5B. Bending two different notes up exactly half-a-step at exactly the same time is kind of difficult, but stick with it 'cause it sounds great when you get it down. You can hear me doing this kind of thing at the end of "Hollow" (Vulgar Display Of Power).
Sliding from one power chord to another can also help a riff sound more sinister. I got the idea from listening to Tony Iommi in Black Sabbath, and I do it a lot-check out "Mouth For War" (Vulgar Display...), for instance. So, if I wanted to make a riff like FIGURE 6A nastier, I'd throw in a chord-slide and probably a chord-bend as well (Figure 6B).
Which version sounds better? C'mon, there's no contest! figure 6B kicks figure 6A's sorry ass!
I hope these few ideas help you jam out a few crushing riffs of your own. See ya next time, bud-Timbale!