The "Open Bm9" tuning is a rich and resonant setup, inspired by the innovative English guitarist Mike Dawes, particularly from his work on songs such as "Encomium (Reverie)" and "The Old Room." This tuning is designed to provide a dark, full low end, often characteristic of modern fingerstyle and percussive guitar techniques.

Technical Analysis:

The open strings are tuned to B1-F#3-C#4-D3-A3-D4 (low to high). When strummed open, these notes form a beautiful and complex B minor 9 (Bm9) chord. Let's break down its components:

• 6th String (B1): The fundamental root, providing a deep, resonant bass. This extreme drop to B1 (an octave and a half below standard E) gives the tuning its characteristic "drop B" feel and requires special attention to string gauge.
• 5th String (F#3): The perfect fifth of B, adding harmonic stability.
• 4th String (C#4): The major ninth (2nd) of B, giving the chord its extended, jazzy character.
• 3rd String (D3): The minor third of B, establishing the minor tonality.
• 2nd String (A3): The minor seventh of B, further enhancing the chord's richness and color.
• 1st String (D4): An octave of the minor third, reinforcing the minor quality and adding brightness.

The wide range from B1 to D4 (a span of three octaves and a minor third) offers incredible sonic depth and versatility. The presence of two D notes (D3 and D4) creates a pleasant resonance, while the B, F#, D, A, C# stack clearly outlines the Bm9 chord.

Playing Potential & Chords:

This tuning is exceptionally well-suited for intricate fingerstyle arrangements, allowing for lush harmonic voicings and percussive techniques. The open Bm9 provides a rich foundation. Due to the consistent intervals, you can easily shift this Bm9 shape up the neck to create other minor 9 chords by barring across a single fret (e.g., barring at the 1st fret yields Cm9, at the 2nd fret C#m9, etc.).

The low B string lends itself beautifully to powerful, resonant bass lines and modern, heavy acoustic sounds. Melodic lines can be played across the higher strings while maintaining a droning bass. Experimentation with partial chords and open string drones will reveal a wealth of sonic possibilities for composition and improvisation.

Important Note: To achieve the darker low end of the drop B (B1) and ensure proper string tension without excessive floppiness, you may require heavier gauge strings, especially for the 6th string.

How to Tune Your Guitar to Open Bm9

This section details how to adjust each string from standard E-A-D-G-B-E tuning to achieve the Open Bm9 tuning (B1-F#3-C#4-D3-A3-D4). Please note that significant tuning adjustments may affect string tension and intonation, and for extreme drops, heavier gauge strings are advised.

• 6th String (Low E): From standard E2, tune down 5 semitones to B1. This is a substantial drop from standard E2; a heavier gauge string is strongly recommended to maintain playability and intonation, as this movement exceeds -4 semitones.
• 5th String (A): From standard A2, tune down 3 semitones. This movement would result in F#2. However, the target note for this string is F#3. This indicates an octave difference between the tuning instruction's implied result and the final target note from the tuning definition. You should aim for F#3.
• 4th String (D): From standard D3, tune down 1 semitone. This movement would result in C#3. However, the target note for this string is C#4. This indicates an octave difference between the tuning instruction's implied result and the final target note from the tuning definition. You should aim for C#4.
• 3rd String (G): From standard G3, tune down 5 semitones. This movement would result in C3. However, the target note for this string is D3. This indicates a whole step note difference between the tuning instruction's implied result and the final target note from the tuning definition. A heavier gauge string is strongly recommended due to this significant drop, as this movement exceeds -4 semitones.
• 2nd String (B): From standard B3, tune down 2 semitones to A3.
• 1st String (High E): From standard E4, tune down 2 semitones to D4.

Important String Gauge Advisory: Tuning down 5 semitones (as required for the 6th and 3rd strings) is a significant change. When tuning exceeds negative 4 or positive 4 semitones from standard, it often benefits from or necessitates the use of a different gauge string to maintain proper tension, intonation, and to prevent string damage or breakage. Please exercise caution when performing these adjustments.