C Dominant Seventh Sharp Nine chord (C7#9) on the guitar fretboard

The C Dominant Seventh Sharp Nine chord (C7#9) is made of C (the root), E (major third), G (perfect fifth, optional), Bb (minor seventh) and D# (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.