In the last issue I showed you some of the more common ways to harmonize solos or riffs with a second guitar part. I explained that this was most commonly done using diatonic major and minor thirds – where you play the same melodic line only three scale steps higher and you stay within the scale. There are many other ways of harmonizing solos and I’d like to show you a few more.


Understanding how to harmonize two musical lines requires a good knowledge of intervals (the distance between two notes). Since there are 12 notes in Western music, this means there are 12 basic types of intervals (13 including a perfect unison). This is shown in Exercise 1. Try playing both notes at the same time (by playing the original E note on strings two or three) so you can hear how each sounds. Going through each different interval in detail is beyond the scope of this lesson. However as a general rule, any interval one or two frets apart will sound too dissonant (min/maj 2nds, min/maj 7ths). So too the tri-tone of the augmented fourth/diminished fifth (that’s not to say you can’t try these though!). All the other intervals will be reasonably pleasant to the ear.  

Hear Exercise 1


This is a fast alternated-picked lick using a hybrid Dorian/Blues scale in A. The original line is that played by Guitar 1. The Guitar 2 harmony part introduces the concept of parallel harmonies. As the name suggests, you play the exact same riff but starting an interval higher (or lower). In this example, parallel fourths are used.  The harmony lick is exactly the same, only played a fourth higher (5 frets on the guitar). Thus, every harmonized note is a perfect fourth apart. Since you are no longer staying within the scale, this can create some unusual (but also heavy and twisted!) sounds. For example, the intro to the Slayer classic ‘Raining Blood’ uses parallel fourths and it tends to work great with more chromatic riffs like this. Other parallel intervals that can sound good are minor thirds, major thirds, perfect fifths, maj/min sixths, and perfect octaves. 

Hear Exercise 2


Rather than the harmony part always following the same rhythmic/melodic outline as the original and using the same intervals throughout, you can select different intervals and mix them up. This means each guitar will be playing a different melody. Exercise 3 illustrates this using a very simple example in A Dorian (see if you can work out the different intervals used). In classical music terminology, when two musical lines are independent and moving in different directions, it is known as counterpoint.

Hear Exercise 3


This is a fast thrash/death metal riff that uses both parallel and contrapuntal harmonies. The basic riff is what’s played by Guitar 1. When the second guitar harmony kicks in, it first uses parallel minor thirds – the chromatic tremolo-picked notes of the riff are played exactly three frets higher. The next time through, the second guitar plays a more counterpoint style line for the tremolo picked notes. If we compared the notes of Guitar 1 to Guitar 2, the intervallic relationship is as follows: perfect 5th, min 3rd, maj 3rd (an 8ve higher), maj 3rd (an 8ve higher), maj 3rd. So, both guitars are moving in different directions and playing different notes, but still harmonizing together in a meaningful way. In essence, it’s two riffs becoming one!

Hear Exercise 4

Hopefully this gives you a few more ideas on how to harmonize solos and riffs. So grab your buddy – or your recording gear – and try coming up with some twin harmony parts of your own.