The Octage Fmaj9 tuning is a deeply resonant and sophisticated configuration designed for extended-range guitars such as baritones or bass VIs. As its name suggests, it is built around an F major ninth chord (F-A-C-E-G), but with several notes tuned an octave lower than might be expected in a standard six-string guitar context. This creates a rich, expansive sound ideal for jazz, ambient, or progressive styles where a full, dark harmonic foundation is desired. The unique string intervals provide both challenges and creative opportunities for voicings and melodic lines.

Technical Analysis

This tuning sets the open strings to F1-A1-C3-G3-C4-E4, which are the root, major third, perfect fifth, major ninth, an octave higher perfect fifth, and major seventh of an Fmaj9 chord, respectively. When played open, the instrument delivers a complete F major ninth chord, providing a rich, jazzy, and full-bodied sonority. The low F1 and A1 strings lay a powerful bass foundation. The intervals between strings are quite wide in some places:

• String 6 (F1) to String 5 (A1): Major 3rd (4 semitones)
• String 5 (A1) to String 4 (C3): Compound Minor 3rd (15 semitones - A to C is 3 semitones + 1 octave)
• String 4 (C3) to String 3 (G3): Perfect 5th (7 semitones)
• String 3 (G3) to String 2 (C4): Perfect 4th (5 semitones)
• String 2 (C4) to String 1 (E4): Major 3rd (4 semitones)

The wide interval between the 5th and 4th strings (15 semitones) is particularly notable, departing significantly from standard guitar intervals and suggesting unique chord shapes and melodic approaches.

Chords and Playability

With the open strings forming an Fmaj9, this tuning naturally lends itself to compositions in F major or minor. Open chord voicings are readily available for Fmaj9, F major (by muting or altering the E and G), and F minor (by fretting the A string to Ab). Due to the powerful F-A-C base, inversions of F, C, and even G chords can be explored by selectively fretting and muting. The repeating C notes (C3 and C4) and the F-A-C-E relationship provide a strong harmonic framework that encourages exploration of jazz extensions and contemporary harmonies. Common chord shapes will need significant adaptation due to the non-standard intervals, but this also unlocks unique voicings unreachable in standard tuning.

How to Tune

To achieve the Octage Fmaj9 tuning from standard EADGBe:

• String 6 (Low E string): Tune down 11 semitones from E2 to F1.
• String 5 (A string): Tune down 12 semitones from A2 to A1.
• String 4 (D string): Tune down 2 semitones from D3 to C3.
• String 3 (G string): Keep as is; no change (0 semitones) from G3 to G3.
• String 2 (B string): Tune up 1 semitone from B3 to C4.
• String 1 (High E string): Keep as is; no change (0 semitones) from E4 to E4.

Important Note on String Gauges: For strings 6 and 5, which require significant tuning down (11 and 12 semitones respectively), it is highly recommended to use heavier gauge strings. Tuning down this drastically with standard gauge strings can lead to insufficient tension, floppy strings, poor intonation, and potential string breakage if tuned back up. Conversely, tuning up more than 4 semitones (not applicable here, but generally) also suggests using a lighter gauge to prevent excessive tension.

String 6: F1 (The lowest string, tuned to F in the first octave, providing a deep, fundamental bass note for the Fmaj9 chord.)

String 5: A1 (Tuned to A in the first octave, forming the major third of the Fmaj9 chord and creating a powerful low-end harmony.)

String 4: C3 (Tuned to C in the third octave, establishing the perfect fifth of the Fmaj9 chord. This note is significantly higher than the preceding A1.)

String 3: G3 (Tuned to G in the third octave, this string introduces the major ninth to the F chord, giving it its characteristic jazzy extension.)

String 2: C4 (Tuned to C in the fourth octave, this string doubles the perfect fifth, adding brilliance and reinforcing the chord's core harmony.)

String 1: E4 (The highest string, tuned to E in the fourth octave, completing the Fmaj9 chord with its essential major seventh.)