When it comes to guitar riffs, they don't get much better than this! Just like Back In Black, AC/DC use the power of musical space and driving drums to create something truly magical. The song only consists of a few open chord shapes, but we'll also tackle the guitar solo so that you can really get your teeth sunk into it!
For this song, we are using open power chord shapes, which is where we get that very thick and rich sound. We are using them through the verse and chorus, alongside a fair bit of gain! Here are those chords:
For the main riff you really just need to listen to it, rather than count it! It's not often we say that, but in this case, it is counterproductive to count through the riff. When we get to the chorus, once again we can be quite loose with the rhythm as you are using so much gain. The main thing is that you put the chords in the correct place, so below we have written out when the chords change:
Thomas takes time to explain why this song is in the key of A mixolydian, rather than A major. The song really uses chords form teh key of D major (the D, G and A) but as the song revolves around A, this is the mixolydian mode of the D major scale. If this stuff blows your mind, you may want to check out this super cool theory course on modes: https://www.yourguitaracademy.com/courses/the-modes-part-one.
The first thing to bare mind is that the actual recording is slightly tuned down. This means that, even though we are in the key of A blues, on the track it sounds very much like somewhere between A and G#! Crazy, we know. Thomas is playing in A for our benefit. As for the actual scales, we are combining the A Minor pentatonic and A major pentatonic scale shapes together. Here are those 5 patterns across the neck:
As Thomas talks us through, Angus Young uses both the major and minor pentatonic. He is able to do this for a number of reasons, but mainly because the chords/bass being played underneath typically use powerchords. This means that we have just the root and the fifth, no mention of the 3rd. It is this 3rd or flat 3rd that defines major or minor, so without it, we can use both over the top. Amazing!