F#13#11

Construction

Built from these intervals: 1-3-5-b7-9-#11-13.

The 3 and b7 form a tritone (the interval of six half steps), maintaining dominant tension. The 9 adds brightness. The #11 (enharmonically the same pitch as the b5) is an alteration -- a chord tone raised a half step from its natural position -- replacing the natural 11 and eliminating the half-step clash between 3 and 11. The 13 adds warmth on top. This is dom7 (its parent chord) extended with 9, #11, and 13, containing every note of the Lydian dominant scale (fourth mode of melodic minor).

Harmonic Function

In Roman numeral analysis (uppercase = major, lowercase = minor):

• V13#11 -- Lydian dominant at full extension, resolving to I with maximum color. The #11 adds brightness that a plain V13 lacks. Derived from the melodic minor scale built a fifth below.
• IV13#11 in jazz -- on the fourth degree, the #11 is a half step below the tonic (the note that naturally wants to resolve upward to it), creating a bright subdominant with Lydian character.
• bII13#11 -- tritone substitution (a reharmonization technique where a dominant chord is replaced by another dominant chord whose root is a tritone away). The two chords share the same 3-b7 tritone, so the root descends by half step while the upper structure provides rich color.

Character

Rich and bright. As a member of the altered dominant family, 13#11 carries dominant tension but the #11 eliminates the subdominant gravity of the natural 11, replacing it with Lydian lift -- the raised 11 pulls the sound upward, away from the grounded quality of a standard thirteenth. The full stack of extensions creates lush color without any internal clash. Compare to 13: the standard dominant thirteenth uses a natural 11 (usually omitted because the 3 and natural 11 sit a half step apart). 13#11 raises that 11 a half step, solving the clash and adding Lydian brightness. That single alteration transforms functional dominant weight into something luminous.

Related Sounds

These chords are closely related -- each modifies one interval:

• 7 (1-3-5-b7) -- parent chord; lean dominant without extensions
• 13 (1-3-5-b7-9-13) -- natural 11 (usually omitted), standard dominant thirteenth without Lydian color
• maj13#11 (1-3-5-7-9-#11-13) -- major 7 instead of b7, pure Lydian rather than Lydian dominant
• maj9#11 (1-3-5-7-9-#11) -- shares the #11 but with major 7, leaner Lydian tonic rather than dominant
• Pairs with the Lydian dominant scale (fourth mode of melodic minor), which contains 1-2-3-#4-5-6-b7

Voice Leading

Voice leading tracks how individual notes move from one chord to the next. The #11 and 13 offer multiple voice-leading paths with bright character throughout. The Lydian quality means resolutions carry light rather than weight.

• V13#11 to Imaj9: The 13 of V holds as the 3 of Imaj9. The tritone resolves -- the 3 moves up a half step to the root of I, the b7 moves down a half step to the 3 of I. The #11 steps down to the 7 of Imaj9.
• bII13#11 to I: The root descends by half step to the root of I. The 3 and b7 of bII are enharmonically the b7 and 3 of V -- this shared tritone provides the harmonic glue. Tritone substitution with maximum color.
• IV13#11 to V7 to I: The #11 of IV holds through to V7 where it becomes the 3, then resolves up a half step to the root of I. Melodic continuity through the entire cadence.

These movements apply in any key -- the intervals are the same regardless of root.

Practice Seeds

Lydian dominant scale. Play 13#11, then play the Lydian dominant scale (fourth mode of melodic minor) from the same root. Every scale tone lives inside the chord -- this connection is the foundation of Lydian dominant harmony.

13 vs. 13#11. Play a standard 13 (omitting the 11), then 13#11. Hear how the #11 transforms the character from functional to floating -- this single alteration is what makes the chord Lydian.

Tritone sub. Use bII13#11 resolving to I in several keys. The half-step root descent with full extensions creates one of the richest cadences in jazz -- practice it until the resolution feels inevitable.

IV context. Play IV13#11 to V7 to I. Track the #11 of IV as it holds into the 3 of V7 and resolves to the tonic root. This melodic thread through the cadence reveals why 13#11 works so naturally on IV.