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Note identifier · Reference entry

What chord is C–E♭–F♯–A?

The notes C, E♭, F♯, and A spell C Diminished 7th (Cdim7) — C the root, E♭ the ♭3, G♭ the ♭5, and B♭♭ the ♭♭7.

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.

C Diminished 7thCdim7Confident

Every tone of Cdim7 is present, with C in the bass — the definitive reading.

DegreeNoteIn this set
1Csounding
♭3E♭sounding
♭5G♭sounding
♭♭7B♭♭sounding
E♭ Diminished 7thE♭dim7Confident

All tones of E♭dim7 are present; the D♭♭ note is lowest (3rd inversion).

DegreeNoteIn this set
1E♭sounding
♭3G♭sounding
♭5B♭♭sounding
♭♭7D♭♭sounding
F♯ Diminished 7thF♯dim7Confident

All tones of F♯dim7 are present; the C note is lowest (2nd inversion).

DegreeNoteIn this set
1F♯sounding
♭3Asounding
♭5Csounding
♭♭7E♭sounding
A Diminished 7thAdim7Confident

All tones of Adim7 are present; the C note is lowest (1st inversion).

DegreeNoteIn this set
1Asounding
♭3Csounding
♭5E♭sounding
♭♭7G♭sounding
D 7♭9D7♭9Likely

3rd, 5th, ♭7, and ♭9 of D7♭9 sound; it reads as D7♭9 with the D (1) omitted.

DegreeNoteIn this set
1Domitted
3F♯sounding
5Asounding
♭7Csounding
♭9E♭sounding
F 7♭9F7♭9Likely

3rd, 5th, ♭7, and ♭9 of F7♭9 sound; it reads as F7♭9 with the F (1) omitted.

DegreeNoteIn this set
1Fomitted
3Asounding
5Csounding
♭7E♭sounding
♭9G♭sounding

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 Am7♭5

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

Not Cm7♭5

Not Cm7♭5: a half diminished C chord needs B♭ as its ♭7 — B♭ is absent.

Not E♭m7♭5

Not E♭m7♭5: a half diminished E♭ chord needs D♭ as its ♭7 — D♭ is absent.

Not F♯m7♭5

Not F♯m7♭5: a half diminished F♯ chord needs E as its ♭7 — E is absent.

Not Adim(maj7)

Not Adim(maj7): a diminished major 7th A chord needs G♯ as its 7th — G♯ is absent.

How these notes relate

C, E♭, F♯, and A is a voicing of D7♭9 with the D (root) left out.

The same notes over E♭ in the bass spell E♭dim7.

Add G (its ♭7) and the set reads as Am7♭5.

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, 3, 6, 9}
Normal order
[0,3,6,9]
Prime form
[0,3,6,9]
Interval vector
<004002>
Forte set class
4-28

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