F#add9 Chord
The F#add9 chord is F sharp, A sharp, C sharp, G sharp played together. It starts with an F# major triad and adds G sharp as the ninth. The third stays in the chord and there is no seventh; those two details separate add9 from sus2 and a plain 9 chord.
- Notes: F sharp-A sharp-C sharp-G sharp
- Formula: 1-3-5-9
- No seventh
Which notes are in F#add9?
The major triad is F sharp-A sharp-C sharp. Add G sharp to make F sharp-A sharp-C sharp-G sharp. A ninth is the same pitch class as a second, counted an octave higher from the root. In the displayed chord, that higher placement leaves the triad clearly audible underneath.
G sharp is the ninth and A sharp is the major third. Both are black keys, but they play different roles.
How do its three inversions work?
The root position and three inversions contain the same four note names:
- Root position: F sharp-A sharp-C sharp-G sharp, F sharp lowest.
- First inversion: A sharp-C sharp-G sharp-F sharp, A sharp lowest.
- Second inversion: C sharp-G sharp-F sharp-A sharp, C sharp lowest.
- Third inversion: G sharp-F sharp-A sharp-C sharp, G sharp lowest.
Move the lowest note up an octave to hear each change. The order and bass shift, but the chord remains F#add9. If another instrument supplies the bass, its note determines the full ensemble's lowest note; Chord Inversions explains how to write that.
Is F#add9 the same as F#9?
No. F#add9 has the four notes above and no seventh. F#9 includes a minor seventh as well as the ninth. You can hear the difference by adding that seventh to F#add9 while the other notes stay put. The plain 9 symbol implies a seventh; “add9” explicitly asks for the ninth without it. Add9 Chord compares the formulas across roots.
Is it the same as sus2?
A sus2 chord replaces the third with a second. In F#add9, the third A sharp remains. Play the triad, add G sharp, and then remove A sharp. That last change moves you toward the suspended sound; it does not merely change the octave. The Suspended Second Chord explains the replacement.
Play it as a short phrase
Play the F# major triad, add G sharp, then return to the triad. Repeat with the added note an octave lower. The notes have the same names, but their spacing changes which part catches your ear. Keep the third present so the exercise remains about add9.