semicord

Bbadd9 Bb major add nine chord

Notes
Bb D F C
Formula
1 3 5 9
Semitones
0 4 7 14 above the root
Also written
A#add9 (A# C## E# B#)
Other symbols
Bb(add9), Bbadd2

Bb to D is a major third (4 semitones), D to F is a minor third (3 semitones), F to C is a perfect fifth (7 semitones). A major triad with the ninth, C, added and no seventh. The ninth is the second of the scale an octave up, so with C played right next to the root the same chord is often written Bbadd2. It is not Bbsus2: the third D is still there.

Bbadd9 on the piano

C4D4E4F4G4A4B4C5D5E5F5G5A5B5C6D6E6F6G6A6B6C#4Eb4F#4Ab4Bb4C#5Eb5F#5Ab5Bb5C#6Eb6F#6Ab6Bb6C4BbC5DFCC6

Root position from Bb4: Bb4, D5, F5, C6. Middle C is C4.

Bbadd9 on the guitar

Standard tuning (E A D G B E). Strings run low E on the left to high e on the right, frets downwards; × is a muted string, ○ an open string, and each dot shows the note it sounds, with the root in blue-green. Every shape below has Bb as its lowest note.

×BbBbD×CCFF
A-shape, root on the A string at fret 1
x 1 0 x 1 1 (low E to high e)
Sounds Bb2 D3 C4 F4
5frBbBbDD×CCFF×
E-shape, root on the E string at fret 6
6 5 x 5 6 x (low E to high e)
Sounds Bb2 D3 C4 F4

The E-shape and A-shape grips are movable: an E-shape chord's root is the note under your first finger on the low E string, an A-shape chord's root is the note on the A string. Slide the same grip up or down to play major add nine chords on other roots.

Inversions of Bbadd9

An inversion puts a note other than the root in the bass. The name is what semicord's chord finder calls those notes played bottom to top; a slash name like C/E means a C chord with E in the bass.

PositionNotes, bass firstNamedListen
Root positionBb D F CBbadd9
1st inversionD F C BbBbadd9/D
2nd inversionF C Bb DBbadd9/F
3rd inversionC Bb D FBb/C (also read as Bbadd9/C)

Where Bbadd9 fits

Bbadd9 is I in Bb major, IV in F major, V in Eb major. The added C belongs to all three of those keys, so Bbadd9 can stand in for Bb wherever it appears; it keeps the major sound but softens it. It is not a substitute for Bb9, which also has the seventh Ab.