chord extensions -- everything up to the top?

[Bob]

If you've got a 13th chord, does that mean it automatically includes the notes leading up to that -- the 9th, the 11th, etc.?

I'm thinking in terms of a 7th chord with extension. 

If it didn't, then it would be some sort of added 6 chord, if it was a 13th...
If it was only adding the 11th or 9th, that might be some type of suspension...

I've always thought if it was an extended chord, it included the tones below it.  If 13th, then that includes 9 and 11.  But then I read something that mentions you can just add those upper tones by themselves.

[coca cola veins]

Just as you wrote, if the extended chord don't include the notes "below" it (like the 7th and 9th in a 11th) it becomes an 'add' chord (Cadd9 = CDEG, Cadd11 = CEFG, etc). However, an added 13th just turns it into a 6th chord.

[earl]

Hi Bob,

In my experience these extended chords beyond the 9th are only used in jazz or jazz oriented music. In pop music you may see a triad with an added 9th for example. In this case the 7th should not be added. Or you may see it for example: G9. This implies the 7th (in this case a dominent 7th chord with a 9th added.)

Jazz theory says that the 7th is always in a chord unless it is specifically a plain triad or one with an added 6th.

Therefore, a 9th, 11th, or 13th will always include a 7th. A 13th chord without the 7th is just a triad with an added 6th, so there is no reason to have two names for the same chord.

There are also chords with multiple extended notes and some of the extensions can be altered (that is raised or lowered). This allows for a fair amount of possible combinations.

Hope this helps.

Earl