B Dominant Seventh Sharp Nine chord (B7#9) on the guitar fretboard

The B Dominant Seventh Sharp Nine chord (B7#9) is made of B (the root), D# (major third), F# (perfect fifth, optional), A (minor seventh) and C## (augmented ninth). The fretboard shows every one of them across the neck in standard tuning (E A D G B E), and plays them back so you can hear the chord.

The seventh sharp nine takes the dominant seventh and adds a raised ninth, which sits right beside the major third. That close pair gives it a gritty sound, and the map shows the two notes next to each other. The fifth is optional.