This is a rich and resonant tuning known as Open Bm tuning. As described in its origin, it's often employed for creating deep, atmospheric "doom drones" and is achieved by significantly dropping down from an Em lap steel tuning.

Technical Analysis:

The open strings of this tuning form a complete B minor chord (B-D-F#) distributed across multiple octaves, providing a full, dark, and harmonically rich foundation. The arrangement of notes creates a powerful and resonant sound:

• String 6 (B1): The foundational root note, providing a deep, impactful bass.
• String 5 (F3#): A perfect fifth above B, positioned two octaves higher than the root on string 6, adding a vibrant harmonic layer.
• String 4 (B2): An octave of the root, reinforcing the fundamental B and adding body to the lower register.
• String 3 (D3): The minor third of the chord, crucial for imparting the tuning's characteristic melancholic minor quality.
• String 2 (F4#): Another perfect fifth, three octaves above the low B, contributing to the open chord's overall brightness and sustain.
• String 1 (B3): The highest octave of the root, completing the chord and allowing for ringing, expansive harmonies.

The extensive use of the root (B) and its perfect fifth (F#) across various octaves creates a thick, enveloping sonic texture, making this tuning exceptionally well-suited for sustained, heavy, and atmospheric musical compositions.

Chords and Playability:

With Open Bm tuning, simply strumming all open strings produces a full and powerful B minor chord. This simplifies playing minor-key pieces considerably, as a single finger barre across all strings at any given fret will instantly yield the corresponding minor chord. For instance, barring at the 1st fret creates a C minor chord, at the 2nd fret a C# minor chord, and so forth. The wide interval spread, particularly between the low B and the higher F# and B notes, offers an expansive soundscape, making it excellent for crafting atmospheric textures, massive power chords, and deep, resonant drones. The consistent minor third and perfect fifth relationships throughout the tuning provide an intuitive framework for exploring melodic and harmonic ideas within the B minor scale.

How to Tune:

To achieve this Open Bm tuning from standard E Standard tuning (E-A-D-G-B-e), you will need to adjust your strings as follows. Please exercise extreme caution when making significant tuning adjustments, especially when lowering strings by many semitones. If you plan to keep your guitar in this tuning for extended periods, it is strongly advised to consider a heavier gauge string set, particularly for strings tuned down 5 semitones or more, as the significant reduction in string tension can affect playability and intonation.

• String 6 (Low E string): Tune down 5 semitones to B1. (Note: Tuning down 5 semitones is a very significant drop; a heavier gauge string is advised.)
• String 5 (A string): Tune down 3 semitones to F3#.
• String 4 (D string): Tune down 3 semitones to B2.
• String 3 (G string): Tune down 5 semitones to D3. (Note: Tuning down 5 semitones is a very significant drop; a heavier gauge string is advised.)
• String 2 (B string): Tune down 5 semitones to F4#. (Note: Tuning down 5 semitones is a very significant drop; a heavier gauge string is advised.)
• String 1 (High E string): Tune down 5 semitones to B3. (Note: Tuning down 5 semitones is a very significant drop; a heavier gauge string is advised.)

String 6 (Low E string): B1
String 5 (A string): F3#
String 4 (D string): B2
String 3 (G string): D3
String 2 (B string): F4#
String 1 (High E string): B3