[Noodler]

What is at about a Chord that makes it Dominant?

eg in the Nashville system, the IV is called the sub-dominant, and the V chord is called the dominant chord of the key.

We also have "dominant" 7th chords, spelled 1,3,5,b7, as opposed to major 7th chords (1,3,5,7).

The V is often a V7, but I'm pretty sure that a III7 is still a dominant 7th, too, isn't it?


The reason I ask is that in Tritone Substution you can substitute a dominant chord for another chord a Tritone away hence the name. So instead of playing Gmaj7, Amin7, D7, back to G, you could play Gmaj7, A min7, G#7, G. (G#7 has substituted for D7).

So does that mean you can substitute any dominant 7th chord, or just any V chord?

Thanks in advance.