In Ex. 1, we take some ideas from our polymeters lesson for a hip single-string riff in dropped-D tuning. Each measure follows a 7-7-2 grouping to give the riff an odd-time feel without actually leaving 4/4. Not too much thought went into the note choices here, but in essence it's using notes from the D Phrygian dominant scale (D–Eb–F#–G–A–Bb–C).

Ex. 1

Ex. 2 uses notes of the D Phrygian mode (D–Eb–F–G–A–Bb–C), mostly against the low open D. To execute this cleanly, use the tip of the fretting-hand first finger to mute the 5th string. This allows you to strum the low three strings and get an aggressive sound. The riff is a repeating idea in 5/4, so spend some time listening and counting along before trying to play the idea. Also, for the sliding power chords at the end, I slide up on the third finger, and down on the first. This feels comfortable, but the jump back to the start of the riff will still be tricky, so heads-up!

Ex. 2

Our next riff (Ex. 3) takes inspiration from one of Tool's most famous jams, and is a fun little idea that alternates between 5/8 and 7/8. Tool are no strangers to multiple time signature changes like this, and there are songs of theirs where I still can't work out what the time signatures change between as they're so frequent and well masked by the groove. This idea could be seen as an eighth-note motif with a 16-note triplet played as an informal turnaround. In the first measure, it's a four-note idea, and in the second this is extended to six notes. This sounds very unexpected the first time you hear it, but after a few plays you'll get in the groove.

Ex. 3

In the next few examples, we'll explore how Adam layers different rhythmic parts on top of each other. Our first piece is Ex. 4, which also hovers around the D Phrygian dominant scale we touched on earlier. The minor third between Eb and F# gives this scale its distinctive sound. Also, you might have noticed how the open string creates an almost drone-like quality. That's another signature part of Tool's music.

Ex. 4

Now, we create a simple melodic idea to go over what we played in Ex. 4. As you can see in Ex. 5, the Gtr. 2 part is our low-end riff and Gtr. 1 is a rather syncopated riff that combines eighth- and 16th-note patterns. Especially prevalent in Danny Carey's drumming, these complex rhythms are at the core of the band's ethos.

Ex. 5

Ex. 6 uses bigger chord voicings to get a huge sound. In essence, a big D5 chord is played over five strings, and then one note is changed (Bb) on the 3rd string to create a moving inner voice. As in previous examples, the sound has a lot more to do with the driving rhythm than the notes being played.

Ex. 6

Not all the band's riffs are based around thick, saturated distortion. In Ex. 7 we use a clean tone with some effects to create a moody riff in 5/8. You want to let the notes ring out as much as possible, so be careful with your finger placement as the bass notes start moving from D to F, and finally to G. In terms of sonics, I've put different delays on the left and right channel, plus a phaser on one side and a flanger on the other. The concept here is to create a richly textured part that could support a vocalist.

Ex. 7

The final example (Ex. 8) mixes arpeggiated notes with bigger chord stabs for some drama. I made sure everything rang out because this gives the biggest sound and is perfect for a full-band setting. The idea is based around D minor, but the Ab (b5) adds a darker, bluesy sound.

Ex. 8