Why do we use Dominant 7th alt term. Because the dominant 7th alt is basically the tritone sub but with a natural and flat nine and flat five with the flat 5 in bass. I mean i guess g7alt is better than reading Db7(nat.9,b9,b5)/G

  • Sorry, I don’t understand your question. Could it be that some words got lost? Would you please reread and eventually make some corrections or precisions? Apr 24, 2020 at 19:18
  • I think the question is about the terminology used to name the chord, rather than when to use the chord itself.
    – mkorman
    Apr 24, 2020 at 19:56

2 Answers 2


You are right in that a ♭II7 tritone sub chord with a ♭V in the bass sounds essentially like a V7alt chord but your analysis of “Db7(nat.9,b9,b5)/G” being a G7alt is not quite right. In the keys you referenced a G7alt contains ♭9, #9, ♭5 and ♭13. This is basically the same as a D♭13#11 Which has 9, #11, 13. They have the same notes but they have different roots.

The root largely defines the chord and the way it functions in a chord progression so it’s better to spell a chord from the root when possible. That’s why we use the term “alt”. I’m sure I’m not alone in saying that I would rather see G7alt over a D♭13#11/G on a chart. As a musician, bass player and improviser I even approach the two differently when creating walking lines or improvising. Hope this answers your question.

  • Yeah most people at least myself still voice the 5th of the g7 in the g7 alt giving essentially a Db13,9,b9/G because you have to take in account the actual g7 your playing under extensions i mean i know you dont have to voice 5th but it adds more tension
    – beastmode
    May 17, 2020 at 18:18
  • It’s true that the natural 5 will add even more tension to an already tension filled chord. I however think of the 7alt chord as having a b5 because the scale that is often used to play over it, the 7th mode of the melodic minor (R b9 #9 3 b5 b13 b7) has no natural 5. May 17, 2020 at 19:10

We can use V7(b5b9)or its triton substitution when ever we want, just the way we like it.

There’s no rule, no law or principle why we should choose the one or the other.

Sometimes it is comfortable to progress chromatically down steps walking through the circle of fifths, especially the bass line.

  • 1
    The question is asking: "what's the point in describing a chord as an altered dominant if we could more simply just describe it as a tritone substitution? After all, the two chords (altered dominant and tritone sub) share the same notes."
    – jdjazz
    Apr 24, 2020 at 21:39

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