What is the difference between b10 and #9?

In answer to the question Why does E7 sharp 9 have a G?

Matt L. writes:

I think the real question is whether that chord should be called E7(#9) - as is very common, at least in the English speaking part of the world -, or if it should be called E7(b10), which is also used, and definitely not only by people who don't understand the issue. If you accept the b10 notation, then that note is indeed a G.

and later:

I always use #9 (because everybody does, and for me it's about communicating chord symbols efficiently), but if you ask me what I hear, I'd probably say that I hear a b10. One important argument for me is that that note virtually never resolves upwards

I remember I've seen many sheet music of Blues and Boogies where the minor third (= blue note!) was notated both ways.

Very often it was meant as a chromatic approach to the major 3rd #9 - but it was notated as b10: In this case I would say b10 is wrong.

When the minor 3rd was dropping to the root note (ma-do), or eventually passing the ninth (ma-re-do) I would say it a blue note and a b10.

Would you say it is only a blue note when it is leading downwards?

Is it correct to notate the popular ri-mi do-ri-mi otherwise than #9?


  • may be related to: music.stackexchange.com/questions/32918/… Nov 27, 2019 at 17:53
  • This is brought up a lot. The duplicate question covers all points in the question and answers. If there's something specific you want to cover outside of it, we can make this question solely focus on that.
    – Dom
    Nov 27, 2019 at 18:01
  • I forgot to mention that Matt’s answer was downvoted. (Not by me!) I wonder what could be the reason why ... Nov 27, 2019 at 19:17
  • I believe that my answer was downvoted because somebody thought I was saying that b10 is correct and #9 isn't. That's of course non-sense (as the contrary statement would be). I just wanted to point out that b10 is used by some people for some good reasons, and the people who keep repeating that "chords are built in thirds, so b10 must be wrong" miss the point of the discussion.
    – Matt L.
    Nov 28, 2019 at 9:15
  • I could understand that someone downvoted you for this sentence: One important argument for me is that that note virtually never resolves upwards. Nov 28, 2019 at 10:20


Browse other questions tagged or ask your own question.