Like F7b9 to B7+5 ; F7alt to B7+11? I meant any kind of different altered dominant seven, not only some particular ones like F7alt to B7 , F7b9 to B7b9, etc

2 Answers 2


Tritone substitution relies on two factors - the 3rd and the 7th. Let's take C7>F. C7 = C E G Bb. The tts is F#7, = F# A# (Bb) C# E. The 3rd of C7 becomes the b7th of F#7, while the b7th of C7 takes the place of the 3rd of F#7. Simple substitution - hence the name. Other notes may or may not feature in each chord, but those two need to. So, as far as I know, 7b9 won't make a lot of difference to tts, as any other altered chord, as long as 3 and b7 become b7 and 3.

Bottom line as always is try it, if it sounds good in the context, then use it.


Short answer: you can make almost any alterations you want.

Let's say the progression is | Cm | F7 | B♭∆ |. Let's also say that we don't have to worry about whether the chord substitution will clash with the melody or will clash with another soloist. It's extremely common to alter the F7. For example, you could add a ♭13, a ♭5, a ♭9, or a ♯9. You can combine two of these together, and you can do things like play a ♭9 with a ♮13, or play a ♮9 with a ♭13. There are many possible ways to alter the 5, 9, and 13 of the F7 chord.

Each of the altered F7 chords will sound great with a B in the bass. When performing the tritone substitution, it's not necessary to think in terms of the B7 chord at all--each alteration to the 5, 9, or 13 of F7 will correspond to a note in the B7 chord. For example:

F7 chord B7 chord ♭9 → 5 ♯9 → 13 ♭13 → 9 ♭5 → 1

And non-altered tones from the F7 chord will become alterations of a B7 chord.

F7 chord B7 chord ♮9 → ♭13 ♮5 → ♭9 ♮13 → ♯9

In addition to making alterations (or not making alterations) to the 5, 13, or 9, it's also possible to use a ♯11 chord. F7(♯11) implies a natural 9th and 13th, not an altered 9th or 13th. One common voicing for F7(♯11) involves using a G maj upper structure triad. For example, on piano, one could play the A-E♭ with the left hand and G-B-D with the right hand. The natural 9th and 13th of F7 will produce a B7(♯9♭13) chord when the base plays a B instead of an F. And equivalently, if you're thinking in terms of B7, playing B7(♯11)--played with a C♯ maj upper structure triad--would be the same as playing F7(♯9♭13) if the root were an F instead of a B.

Personally, when playing a tritone substitution, I usually think in terms of the original F7 equivalent chord. This is mostly a personal preference. But whichever way you think about it, if your alterations sound good with a normal F in the bass, then it will also sound good over the tritone sub.

  • I'm not sure what you mean by "F7(#11) will become B7(#9,b13)" and vice versa. The #9 of B7 is a 'D' which is the 13 of F. Maybe you mean B7(b9,b13), even though the 'C' (b9 of B7) would usually be avoided in an F7(#11).
    – Matt L.
    Commented Aug 23, 2017 at 21:32
  • @MattL., the #11 chord implies a natural 9th and 13th as opposed to a altered 9th or 13th. An extremely common voicing uses a G maj upper structure triad. These upper structure notes (G-B-D) are the b13, 1, and #9 (respectively) of B7. Similarly, if one were to play B7(#11), the C# maj upper structure triad would produce the b13, 1, and #9 of F7. I will edit to clarify. Also, I'll fix the auto-formatting guitar tab.
    – jdjazz
    Commented Aug 23, 2017 at 23:03

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