Altered Dominants

Does anyone have some good information on common usage and application of Altered Dominants?

Altered dominants are commonly used in jazz as the 5 chord in a minor 2-5-1 or as a 5th chord in general in a minor jazz progression

eg.


Am7b5 - D7alt - Gmin


An ''altered" dominant means that a dominant chord such as D7 has had it's 5th raised or lowered as well as the 9th raised or lowered.

The scale that the Altered chord comes from is the Super Locrian scale (or altered scale), which is the 7th mode of the melodic minor ascending.

eg. D7alt comes from the Eb melodic minor ascending scale

Thanks for the help. :) Is the main purpose of using an altered dominant to have different colors in the chords?

Originally Posted by: Dave CardwellThanks for the help. :) Is the main purpose of using an altered dominant to have different colors in the chords?

That's one reason. The other main reason is to do with tension and release. If you play a dominant chord (or 5th chord eg. D7), it naturally wants to go to the 1 chord (Gminor or Gmajor). Altering the 5th and 9th adds more tension and makes the transition from 5 to 1 even more satisfying.

Compare:

Dm7b5 - Gm7 - Cm

Dm7b5 - G7 - Cm

Dm7b5 - G7#5b9 - Cm

When you play those you should notice how the G7 wants to go to the Cm more than the Gm7 does. when you change the G7 to a G7#5b9 it enhances that effect even more.

I hope that made sense :)

Thanks again Julian. I've been playing those chords and I'm hearing the difference. :)