Does a c11 chord have to span more than one octave?

[jancivil]

c, d, e, f and g

amounts to a diatonic cluster really, so who knows. C E F G in same octave might be deemed 'C add 4' instead of writing '11', for instance...
these words do not so much suggest to me any real '11th chord' type hence my interrogation of that bit in Mad's reply. TBH this software-reliant approach is not the really rewarding way to go.

[nordickvr]

amounts to a diatonic cluster really, so who knows. C E F G in same octave might be deemed 'C add 4' instead of writing '11', for instance...

You'r right, to my knowledge '11' belongs to the minor family chords.

[MadBrain]

amounts to a diatonic cluster really, so who knows. C E F G in same octave might be deemed 'C add 4' instead of writing '11', for instance...

You'r right, to my knowledge '11' belongs to the minor family chords.

Depends on the 11th chord:
C11: Dominant (same as C7) or suspended (same as Csus4)
Cm11: Minor (same as Cm7)
Cm7b5(11): Half-diminished (same as Cm7b5)
C7#11: Dominant (same as C7)
Cmaj7#11: Major (same as Cmaj7)

[Numanoid]

A beautiful chord

A major chord + a major chord transposed one octave up - 1

https://www.8notes.com/piano_chord_chart/c11.asp

Some excellent counter point, playing c major + B major and then a major + g major

[jancivil]

Again, (IME) in jazz praxis, dominant w. perfect 11 is about non-existent, it just don't sound right (I think there are reasons beyond conventionality or taste in dissonance for this.). I doubt this is where the OP is coming from, so this is for the wider world reading this: Pretty much always gwyne be #11.

[nordickvr]

amounts to a diatonic cluster really, so who knows. C E F G in same octave might be deemed 'C add 4' instead of writing '11', for instance...

You'r right, to my knowledge '11' belongs to the minor family chords.

Depends on the 11th chord:
C11: Dominant (same as C7) or suspended (same as Csus4)
Cm11: Minor (same as Cm7)
Cm7b5(11): Half-diminished (same as Cm7b5)
C7#11: Dominant (same as C7)
Cmaj7#11: Major (same as Cmaj7)

Was refering to OP.
If all you have is '11' to me it refers to minor family chord.
But it's all about conventions of course.
Different area different terminology?
I may be learned it wrong in the first place...

[MadBrain]

Again, (IME) in jazz praxis, dominant w. perfect 11 is about non-existent, it just don't sound right (I think there are reasons beyond conventionality or taste in dissonance for this.). I doubt this is where the OP is coming from, so this is for the wider world reading this: Pretty much always gwyne be #11.

Are we talking about perfect 11th without the major 3rd or with it? Without the major 3rd, I can give you about a million examples where it's used as a straight dominant chord on the V (though it's more a disco-80's era thing than Jazz, I guess). With the major 3rd, you're right, it's a rare chord and not used as a dominant.

[jancivil]

it ain't much of a dominant harmony lacking that 3rd really, so yeah, absolutely I mean with it.