B♭ Added 9th Chord
Chord Tones: B♭ Added 9th Chord
Symbol: add9, add2 — Formula: 1-3-5-9
| Degree | Note | Frequency (A=440, Equal) |
|---|---|---|
| 1 | B♭4 | 466.164 Hz |
| 3 | D4 | 293.665 Hz |
| 5 | F4 | 349.228 Hz |
| 9 | C4 | 261.626 Hz |
Chord Notation
| Notation Type | Symbol / Value |
|---|---|
| Lead Sheet Symbol | B♭add9 |
| All Common Symbols | add9, add2 |
| Interval Formula | 1-3-5-9 |
| Harmonic Category | bright |
Roman numeral (e.g. I, IV, V) and Nashville Number notation are key-dependent. See Keys pages for chord function within specific keys.
Inversions
| Inversion | Notes (low to high) | Bass Note | Slash Notation |
|---|---|---|---|
| Root Position | B♭4 – D4 – F4 – C4 | B♭ | B♭ Added 9th Chord |
| First Inversion | D4 – F4 – C4 – B♭4 | D | B♭ Added 9th Chord/D |
| Second Inversion | F4 – C4 – B♭4 – D4 | F | B♭ Added 9th Chord/F |
| Third Inversion | C4 – B♭4 – D4 – F4 | C | B♭ Added 9th Chord/C |
Harmonic Function
The B♭ add9 chord commonly functions as the subtonic (♭VII) in C major or subdominant in F major. Its harmonic role varies by key — in major keys it provides stable harmonic grounding.
The add9 chord adds a ninth (octave + second) to a major triad without including the seventh. It has a bright, open sound, richer than a plain major chord but less complex than a major ninth.
Common Progressions
The B♭ Added 9th Chord frequently appears in these progression patterns (shown in Roman numeral notation relative to key):
Songs Featuring the Added 9th Chord
Well-known songs where the B♭ Added 9th Chord — or this chord type — plays a prominent role:
- Every Breath You Take – The Police
- With or Without You – U2
- Right Here Waiting – Richard Marx
Tuning Frequencies Across Temperaments
Frequencies shown at A=440 Hz. View full temperament data for any note.
| Note | Equal Temp. | Pythagorean | Just Intonation |
|---|---|---|---|
| B♭4 | 466.164 Hz | 463.538 Hz | 470.926 Hz |
| D4 | 293.665 Hz | 293.332 Hz | 294.329 Hz |
| F4 | 349.228 Hz | 347.654 Hz | 348.834 Hz |
| C4 | 261.626 Hz | 260.740 Hz | 261.626 Hz |
Scales Containing the B♭ Added 9th Chord
These scales include the B♭ Added 9th Chord as a diatonic or characteristic chord: