Hey music nerds of ACM

This is a quick blog about the famous 2-5-1 jazz progression and how to spice it up even more.

The 2-5-1 itself

the 2-5-1 progression is actually spelled ii-V-I, uppercase Roman numerals meaning a Major chord, and lowercase Roman numerals meaning a Minor chord. This progression is very popular in jazz, the most prominent example, in my opinion, being Autumn Leaves by Nat King Cole, where it is used multiple times in a row.

The V chord (usually a dominant chord, adding the flat 7th to the chord) acts as a "perfect cadence" to get to the I chord (the "tonic" or home chord). It sounds really nice, trust me.

What's a Tritone?

The "tritone" of a note means 6 semitones away from the note (halfway to the octave), the most dissonant and uncomfortable interval (pairing a note with another). Let's say we have the note G. Six semitones away from G is (Ab, A, Bb, B, C) Db. Therefore, the tritone of G is Db.

Tritone Subsition in a ii-V-I

Finally, the spice. Let's think of the C Major scale and its chords (I, ii, iii, IV, V, vi, vii°). The 5th chord of C Major is G7 (Dominant). Now we take that 5 and switch it out for G's tritone, the 5th's tritone, not the tonic. The chord name is still the same, so now we have Db7.

This makes our progression Dm ( ii ) - Db7 ( bII ) - C ( I ). Wow! It's just a walk down the chromatic scale! And it sounds great too. Now that you now it's just a chromatic walk down, it's so much easier to remember the progression, so you don't have to do the whole process again.

So yeah

This concept is better explained in only 5 minutes by Music With Myles. This was my first exposure to the concept, and it's really effective when using Modal Interchange (tell me if I should talk about that).

Have a good day yall -evan j 🥪