The Octar Tuning is a unique 9-string guitar setup, originally conceived by Bernard "Senchant™" Birgenheier, with a stated purpose of bridging the gap between bass and guitar playing. This tuning offers a versatile sonic landscape, ranging from deep bass registers to bright, guitar-like tones.

Technical Analysis:

This is a 9-string guitar tuning, ordered from lowest (string 9) to highest (string 1) pitch as: E1-A1-D2-G2-C3-F3-A#4-D4-G4. A distinguishing feature is its largely consistent perfect fourth (P4) intervals across the lower and middle strings:

• String 9 (E1) to String 4 (F3) are all tuned in Perfect Fourths (E1-A1-D2-G2-C3-F3). This section provides a foundation akin to a bass or baritone guitar, excellent for deep, resonant power chords and bass lines.
• The interval from String 4 (F3) to String 3 (A#4/Bb4) is also a Perfect Fourth.
• A notable break in the P4 pattern occurs between String 3 (A#4/Bb4) and String 2 (D4), which is a Major Third (Bb to D).
• Finally, String 2 (D4) to String 1 (G4) returns to a Perfect Fourth.

The wide range, spanning from E1 to G4, offers immense harmonic possibilities, blending deep growls with shimmering trebles.

Open Chords and Playability:

While the full open tuning E1-A1-D2-G2-C3-F3-A#4-D4-G4 is a complex, extended voicing, it presents several interesting harmonic opportunities:

• Bass/Power Chords: The consistent Perfect Fourth intervals across the first seven strings (E1 through A#4) mean that power chords and movable shapes will be incredibly intuitive and consistent across this large portion of the neck, mirroring bass guitar fingering.
• Open G Minor Triad: The highest three strings (A#4, D4, G4) form an open G minor triad (G-Bb-D) in second inversion (Bb-D-G). This provides an immediate melancholic or bluesy harmonic texture that can be strummed openly or used as a high-register melodic cluster.
• Extended Voicings: Combining elements of the lower P4 section with the upper G minor triad allows for very rich, extended chords with wide intervallic leaps, suitable for jazz, progressive, or experimental music. The transition from bass-like intervals to a guitar-like triad in the higher register creates a unique blend of textures.

How to Tune:

To achieve the Octar tuning from a standard starting point, all strings must be tuned up by 3 semitones. Please exercise caution when tuning up multiple strings, especially by this amount, as it increases string tension. Always tune slowly and carefully to avoid string breakage or potential neck damage. While tuning up 3 semitones is significant, it does not exceed the threshold (4 semitones) at which a different string gauge is typically advised, but care should still be taken.

• String 9 (Lowest Gauge): Tune up 3 semitones.
• String 8: Tune up 3 semitones.
• String 7: Tune up 3 semitones.
• String 6: Tune up 3 semitones.
• String 5: Tune up 3 semitones.
• String 4: Tune up 3 semitones.
• String 3: Tune up 3 semitones.
• String 2: Tune up 3 semitones.
• String 1 (Highest Gauge): Tune up 3 semitones.

String 9 (Lowest Pitch): E1

String 8: A1

String 7: D2

String 6: G2

String 5: C3

String 4: F3

String 3: A4# (A sharp in the fourth octave)

String 2: D4 (D in the fourth octave)

String 1 (Highest Pitch): G4