C Dominant ninth flat thirteenth

The dominant 9♭13 chord keeps the open width of a ninth while adding a lowered thirteenth for darker altered gravity. It is one of the most useful “half altered / half extended” dominant colors: still melodic-friendly because of the 9, but more serious than 9 or 13 alone. You will hear it across jazz, fusion, soul-jazz, and modern pop harmony whenever a dominant should feel rich without going fully into sharp-ninth crunch.

Construction

Practical formula: 1-3-5-♭7-9-♭13 (the fifth is often omitted). In C9♭13, a common working set is C-E-G-B♭-D-A♭. The ninth widens the chord above the seventh; the ♭13 adds shadow in the upper structure.

Usage

Use it on dominant approaches to minor tonics, on modal dominant areas, and in turnarounds where you want altered weight but still want to sing or comp lines that emphasize the ninth.

Examples

• Jazz standards: dominant bars with 9 in melody and ♭13 in harmony
• Fusion progressions that alternate 13 and ♭13 colors
• Neo-soul keys voicings with smooth upper extensions

Play

Keep 3-♭7 clear, place ♭13 above the ninth when possible, and resolve ♭13 by semitone when you want a strong cadential pull. If the voicing is muddy, omit the fifth before removing the ninth.

Ear-training cues

Hear the ninth’s openness with the ♭13’s downward pull—a classic modern dominant blend.