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Note identifier · Reference entry

What chord is C–D–E♭–A?

The notes C, D, E♭, and A do not complete a single standard chord in root position. They are commonly misread as D7♭9, but a dominant 7th ♭9 D chord needs F♯ (its 3rd), which is absent. Voiced as a rootless partial they fit B♭maj11, missing B♭ (root) and F (5th).

Ranked readings

Every chord these notes can spell, most complete first. The bass note anchors the root-position reading; each candidate maps every note to its scale degree.

B♭ Major 11thB♭maj11Partial

3rd, 7th, 9th, and 11th of B♭maj11 sound; it reads as B♭maj11 with the B♭ (1) and F (5) omitted.

DegreeNoteIn this set
1B♭omitted
3Dsounding
5Fomitted
7Asounding
9Csounding
11E♭sounding
F Dominant 13thF13Partial

3rd, 5th, ♭7, and 13th of F13 sound; it reads as F13 with the F (1), G (9), and B♭ (11) omitted.

DegreeNoteIn this set
1Fomitted
3Asounding
5Csounding
♭7E♭sounding
9Gomitted
11B♭omitted
13Dsounding

Not these chords

Names these notes are often mistaken for. Each is ruled out because a defining tone of that chord is missing — the note that would make the name true simply is not being played.

Not D7♭9

Not D7♭9: a dominant 7th ♭9 D chord needs F♯ as its 3rd — F♯ is absent.

Not Adim7

Not Adim7: a diminished 7th A chord needs G♭ as its ♭♭7 — G♭ is absent.

Not Cdim7

Not Cdim7: a diminished 7th C chord needs G♭ as its ♭5 — G♭ is absent.

Not E♭dim7

Not E♭dim7: a diminished 7th E♭ chord needs G♭ as its ♭3 — G♭ is absent.

Not Am7♭5

Not Am7♭5: a half diminished A chord needs G as its ♭7 — G is absent.

How these notes relate

C, D, E♭, and A is a voicing of B♭maj11 with the B♭ (root) and F (5th) left out.

Add F♯ (its 3rd) and the set reads as D7♭9.

Set-class analysis

The pitch-class set theory identity of these notes — order- and key-independent, computed from the set itself.

Pitch-class set
{0, 2, 3, 9}
Normal order
[9,0,2,3]
Prime form
[0,1,3,6]
Interval vector
<112011>
Forte set class
4-13

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