The tritone got a very bad reputation among intervals. It's been called "the interval of the devil", it's been considered impossible to use or hard to sing, and in general seems to attract a lot of negative labels.
Overall, this is the interval your parents warned you about.
And yet, this reputation seems to be largely unmerited. The tritone is one of the most useful intervals out there and the source of great sounds.
Most of Blues music is based on the tritone (ok, ok, 'the music of the devil, I get it...) but in fact it's necessary to play Jazz, Metal, and even Classical music.
If you are a guitar player you totally need to understand the tritone and how it works, as you are going to meet it on your way (maybe at a crossroad), and it may change your musical life.
In this video we see how the tritone works and how it's used in music, and we go from the basics, up to the famed tritone substitution
And once you have seen how the tritone works, it's time to see some interesting tricks with it directly on the fretboard.
The video below shows you how you can do a tritone substitution "on the fly" directly on your guitar fretboard using a mechanics called "core tritones". There is no need to do any mental math to play a tritone substitution if you know how to do it on the fretboard:
See? Told you it was easy. Enjoy!
Tommaso Zillio is a professional prog rock/metal guitarist and composer based in Edmonton, AB, Canada.
Tommaso is currently working on an instrumental CD, and an instructional series on fretboard visualization and exotic scales. He is your go-to guy for any and all music theory-related questions.