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When does a Flat 5 become a Sharp 11?

dmkz

Member
Messages
1,180
I know the two tones are enharmonic, but I'm just trying to better understand extended harmony.

Is it a major/minor thing? Like if I'm playing over Cmaj7 and hit an F#/Gb is that a #11 or a b5?

Is there a rule for this?

Thanks in advance.
 

RyanM

Member
Messages
344
If there's already a 5th in the chord/scale. C major 7th has a G, so it would be an F# which is a #11.

Same reason why a #9 chord isn't just called a minor 3rd. You already have a major third in a C#9 chord, so the added note is a D# on top, not an Eb (which would be b10).

Although there are some chord/scales or melody lines where you have no choice but to have duplicate letter names, e.g. a chromatic run, or the 8 note diminished scale, or the altered scale (which has both b9 and #9).

Another guideline, for more chromatic type of lines, is # ascending and b descending.


This is related to why you'll occasionally see Cb or Fb instead of B or E, or E# and B# instead of F and C.
e.g if you wanted a G# Major or Dominant chord (leading to C# minor, for example), It would be spelled G# B# D#. It wouldn't be G# C D#, because C is four letters from G.... it would be a diminished 4th! Of course, you could call the chord Ab, but that wouldn't be a 5th above C#...

It might seem complicated but it actually simplifies things. For example it's easier to memorize chords if you know that some kind of F is always the 3rd of some kind of D, etc.
 
Last edited:

dmkz

Member
Messages
1,180
If there's already a 5th in the chord/scale. C major 7th has a G, so it would be an F# which is a #11.

Same reason why a #9 chord isn't just called a minor 3rd. You already have a major third in a C#9 chord, so the added note is a D# on top, not an Eb (which would be b10).

Although there are some chord/scales or melody lines where you have no choice but to have duplicate letter names, e.g. a chromatic run, or the 8 note diminished scale, or the altered scale (which has both b9 and #9).

Another guideline, for more chromatic type of lines, is # ascending and b descending.


This is related to why you'll occasionally see Cb or Fb instead of B or E, or E# and B# instead of F and C.
e.g if you wanted a G# Major or Dominant chord (leading to C# minor, for example), It would be spelled G# B# D#. It wouldn't be G# C D#, because C is four letters from G.... it would be a diminished 4th! Of course, you could call the chord Ab, but that wouldn't be a 5th above C#...

It might seem complicated but it actually simplifies things. For example it's easier to memorize chords if you know that some kind of F is always the 3rd of some kind of D, etc.
Thanks this is helpful
 

guitarjazz

Gold Supporting Member
Messages
23,102
No practical difference. A jazz player would add a 9 or 13 or #9 or b9 if he 'heard' it. Chord symbols are barely suggestions.
 
Messages
1,811
b5 is part of the triad and helps in determining the quality (major minor augmented diminished) the chord. 7ths, 9ths, 11ths and 13ths are added on top of the triad to color.

I generally spell from the root up (even when something else in the bass). This way you're just stacking color.

Start with the root 3rd and 5th. Then add your color out beyond this. There are obvious exceptions to this thinking and methodology but it's a really good way to get started with extended chords.
 

guitarjazz

Gold Supporting Member
Messages
23,102
I know the two tones are enharmonic, but I'm just trying to better understand extended harmony.

Is it a major/minor thing? Like if I'm playing over Cmaj7 and hit an F#/Gb is that a #11 or a b5?

Is there a rule for this?

Thanks in advance.
#4
 






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