I've come across an exercise in the Jazzology "jazz theory" book, where the chord should be identified, given the notes below:

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I identified it as a B7#5#9, but the answer was B7#9b13. I'm guessing that to be a #5 the g should strictly be a double sharp f. That is a quite cumbersome notation though. My question is if I'm correct in my reasoning. I'm also interested in if the b13 is the interpretation the venerable people of this SE would make. I understand that there are voicings without the fifth, but I find it a bit strange to leave it out in an exercise.

Also, what are the implications regarding the (mis)interpretation as a #5? If it's interpreted as a #5, that would mean that the g sharp (6th) is present, while if it's a b13, f sharp (5th) is there instead. Which should have implications regarding which scales to choose to play over it.

I haven't played the chord and tried the different added tones to see what sounds good, I'm interested in understanding the exercise fully.

  • I think that you should add to your post that the context is jazz (right now it's a bit misleading). For example, in jazz there would be a bass note somewhere down that would justify the G natural being b13 instead of just b6.
    – dtldarek
    Apr 4, 2014 at 7:30
  • @dtldarek: Good point, I've added this. Apr 4, 2014 at 9:23

7 Answers 7


That's a valid voicing of both a B7#9#5 and a B7#9b13 as long as we aren't concerned with the spelling. Jazz musicians often are less concerned with spelling and more concerned with things being easy to sight read at the gig.

I (and others, but not everyone) often think of the chord nomenclature as implying things about appropriate scale choices:

 #5 implies a #4 (but #4 doesn't necessarily imply #5)
 b5 implies a natural 4
 b13 implies a natural 5 
 #9 implies a b9

Note that Jamey Aebersold takes the #9 implications further, and says that a #9 also implies a #4 and #5. I think that's true a lot of the time, but not always. http://www.jazzbooks.com/mm5/download/FREE-scale-syllabus.pdf

  • I like your answer but I would argue that b13 certainly does not imply natural 5. b13 seems to be the standard way of describing what would classically be known as #5. I find that b13 tends to imply #11 and no 5. Apr 9, 2014 at 17:55

Chord nomenclature is dependent on context.

Without knowing the context, that chord could have different (and possibly equally correct labels) such as Eb+maj7(#11) (if respelled) or Gadd9(b13) to give a couple of examples.

I do not think you are correct in your reasoning - read on!

I disagree that interpreting the chord with an F## would imply a G# in any overlaid scale. There are no G#'s in the chord, and the harmony is clearly illustrating a G natural. Diatonically speaking, a B major (or even B melodic minor ascending) scale wouldn't make sense here.

Notationally, I'm not sure of your confusion as there is no F# in the chord. It is a b13 (technically speaking, a b6 by the way) because the chord has been spelled with a G natural. The only reason why you would use F## as a substitute would be if the pitch is serving a specific inner-voice voice-leading function to the next chord. Otherwise, it's just unnecessary.

To summarize, chord nomenclature does not determine what pitches are implied in scales to improvise over the chord. Chord nomenclature should articulate the sounding pitches of the chord as clearly as possible. In other words, you can't assign an enharmonic chord label to a chord because it implies other pitches / scales. If a particular notation is used, it must be used to show a specific function. If you can make a case for F## having a specific function over G natural, then great, use that notation. Otherwise, chord names are for documentation.

Regarding the "#9", the notation is incorrect. It should be spelled as a C##, not as a D natural. Otherwise you have a split third, in which case you'd need compelling reasoning for spelling it as such.

  • 1
    Why I brought in the F# at all is due to that I interpreted the G as the fifth, and thus slipped into the track on how to voice the chord with just the name of the chord, and not the given tones. The exercise is from the Jazzology book from Hal Leonard. I thought it was a trustworthy source. The B#9b13 is in the answer key. Maybe they are trying to show that "jazz theory" isn't necessarily so strict... Apr 3, 2014 at 18:12
  • 1
    I agree with you completely especially on the last paragraph. If you want a 9th spell it like a 9th not a 10th.
    – Dom
    Apr 3, 2014 at 18:15
  • @MeaningfulUsername - how / why would you ever interpret "G" as a fifth above "B"? It is always a sixth (a minor one in this case.) Apr 4, 2014 at 0:34
  • 5
    To be honest, to most jazz musicians the "compelling reason" you suggest in the last paragraph amounts to "That note's a sharp 9; this is jazz, don't make me read double-sharps if you don't have to." Common Practice rules of chord notation only apply up to a point in jazz, especially with a gnarly chord such as this one. (To a similar point, a jazz musician would NOT expect to see this called a b6 over a b13 -- it's just not the language.)
    – NReilingh
    Apr 4, 2014 at 3:17
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    @NReilingh - If I were writing a jazz tune, I wouldn't write the chord with a b6 for the same reason you outlined. That said, it should be noted that it was never explicitly stated that we were talking about jazz - it merely appeared that way given the context of the OP's question. My comments about "compelling reasons" and nomenclature are intended for a broader interpretation of the question, which I thought was fair given ambiguity of the question. Apr 4, 2014 at 3:28

B=root. D# =maj.3rd. G = b6. A = m7. D = m10. There is no b13, as G natural is too soon in the rising note list.Had the G been an F##, then B7#5 is a starter. Then the D on top, which could have been a C##, making #9, could have been B7#5#9. BUT it isn't.As is, it may be called B7b6b10, but that's hardly a common chord name.Someone goofed.

  • Could you explain what you mean by "too soon in the rising note list" ? Apr 3, 2014 at 23:07
  • @microtherion - Tim means that if the G is considered a 13th, it should rightfully be on top of the chord, which it is not. Apr 4, 2014 at 0:35
  • 2
    @jjmusicnotes ah, thanks for the explanation, but I don’t think that’s how chord extensions work. What octave a note is played in is a matter of voicing and has nothing to do with the chord identity. Apr 4, 2014 at 16:17
  • 2
    @Tim let me ask you the converse question to explain my view: Do you think that a pianist, when encountering e.g. a C13, is obliged to hit a particular set of keys spanning more than one octave, but a bit less than two? That’s not exactly how it works. Apr 4, 2014 at 20:55
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    @Tim in my (limited) understanding, the difference between a 4 and an 11 is not what octave the note is played in relative to the root, but the context implication, i.e. that a 4 is usually a sus4, with the 3 omitted, while the 11 is not. Apr 4, 2014 at 20:57

A b13 voicing can be exactly the same in sound as a #5 voicing, but it depends on the notes you use in the construction of your voicings. The nomenclatures are different because each implies different notes which can be added to the chord. For example, in the case of a b13 voicing, you could use BOTH the natural fifth and the b13th, but in the case of a #5 voicing, the natural 5th, nor the 13th could be added but the b5 could be added.

In practice, sets of voicing such as the two mentioned above, are mixed, interchanged and blended according to aesthetic taste and the circumstances in the moment of playing.

As an aside, selecting notes for extensions of basic chord voicings (i.e. vanilla 7th chords) is intrinsically tied to scales-as scales are just horizontal representations of chords (i.e. vertical structures). Thus, #5 voicings can include notes from the wholetone scale, whilst the b13th voicings could include notes from the mixolydian (b13th) scale. Moreover, whether or not these scales were to be used for improvisation would also be an aesthetic decision.


I agree that writing a chord voicing that leaves out the 5 is a bit of a curveball.

The reason it's a b13 and not a #5 is basically because it IS a G in a B chord, and that's the "least gymnastics" way to annotate it.

Also, if there's any note you're going to leave out of a dominant chord voicing and still maintain the flavor, the 5th is the one that can go. Leaving the 5th out basically gives the chord a bit more air and stops it from turning into a tight cluster...which has it's own uses and flavor, appropriate sometimes, undesirable other times.


I bet we could identify 20 or so "valid" spellings of that chord. And herein lies the rub: enharmonic spellings are the bane of existence for musicians trying to understand harmony. A chord symbol has two purposes: to name a particular grouping of notes such that it can be communicated to others intact, and to identify its FUNCTION within the harmony. Enharmonic spellings can utterly obfuscate the chord's role in the harmony. we know little about the chord's context here, but we can discern that no other inversion will be any more "lucid" than the one we've got, so "B" it is.


That looks like a G augmented chord in first inversion with a ninth added and fifth doubled.

If you are wondering if that D# is a raised fifth then I will say yes that is a G chord with an augmented fifth. Also my question will be if the other D in the chord is raised or not?

  • Could downvoters please explain there votes in a comment? My answer may be short but it still answers the question.
    – Neil Meyer
    Aug 10, 2015 at 18:57
  • 2
    Read the whole question and the accepted answer. Note that OP writes, "My question is if I'm correct in my reasoning." Specifically, their reasoning about whether B7#5#9 is a reasonable name for the chord. Discussing a G chord does not in fact address the OP's question. The real implied question is "When do you say b13 and when do you say #5?". Again, your answer does not address this. PS: I am not the downvoter. Aug 10, 2015 at 19:21
  • Well if the holy jazz book says so whom am I to question it. That is clearly not a chord built on the B. The basis for the chord is G=B=D
    – Neil Meyer
    Aug 10, 2015 at 19:25
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    Again, not related to the OP's question. They didn't ask, "Is this a G or a B chord?" Notice every other answer addresses the idea of b13 or #5. Aug 10, 2015 at 19:26
  • Without going through the exercise personally, I bet we could identify 20 or so "valid" spellings of that chord. And herein lies the rub: enharmonic spellings are the bane of existence for musicians trying to understand harmony.
    – dwoz
    Aug 10, 2015 at 20:08

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