Discover Game-Changing Chord Progressions for Guitarists - Jazz R&b Chord Progression And Tricks
► Watch the full lesson on YouTube
One small change to a familiar chord opens up a game-changing sound — and understanding why is the key to soloing over it. Here's the I to IV7 move (G major 7 to C9) and the scale that actually fits it.
What you'll learn
- A dominant chord isn't always the V chord — understand it through "home-based tonality"
- I → IV7 (e.g., G major 7 → C9) shows up everywhere in pop, jazz, and soul
- Over the IV7, lower the 3rd of the key's major scale — that's melodic minor
- From the chord's root that scale is C Lydian dominant (1 2 3 ♯4 5 6 ♭7), a bright ♯11 sound
The progression
In the key of G, Adam plays G major 7 to a C9 — the I chord to the IV. Normally the IV would be C major 7, but he changes the B in that chord to B♭, turning it into a dominant 7th, and adds a D for a C9 color. You'll hear this I-to-IV7 move in countless pop songs, jazz standards, and soul and R&B tunes.
Why a dominant chord isn't always the V
A lot of players assume any dominant chord must be the V of the key, but that's not how chord-scale relationships work. Your ear uses "home-based tonality" — it likes to group the seven notes that fit the key. Over G major 7, the G major scale fits perfectly.
When you hit that C9, though, one note in the chord — the B♭ — isn't in the key of G. Even without naming anything, your ear hears the G scale shift to accommodate it: you lower the 3rd, B to B♭. That scale (1, 2, ♭3, 4, 5, 6, 7) is G melodic minor.
Ready to take this further? The Academy
Go deeper with monthly live workshops, study guides and a community of serious players.
Lydian dominant over the IV7
Take those same notes but start from C — the root of the C9 chord — and you get C, D, E, F♯, G, A, B♭, or 1, 2, 3, ♯4, 5, 6, ♭7. That's C Lydian dominant. The F♯ is the ♯4 (♯11), a bright, cool-sounding note against the C root.
So in practice: over the G chord play G major, and when you switch to the C9, play C Lydian dominant — which is the very same set of notes as G melodic minor. It's a simple major-to-melodic-minor switch that instantly sounds more sophisticated.
