The "Quadruple Drop-D 'My Two DAD-GADs'" tuning for an 8-string guitar is a rich and expansive soundscape, building upon a modified Double Drop-D concept. It's designed for deep resonance, extensive octave layering, and percussive tapping techniques. It allows you to reach into D1 and A1, an octave lower than typical, for truly massive layering capabilities.

Verbal Analysis:

This tuning immediately strikes with its deep, resonant character, particularly with the lowest strings reaching into D1 and A1. It creates an almost orchestral depth, perfect for sustained drones reminiscent of instruments like the tanpura or sitar. The abundance of D notes across multiple octaves (D1, D2, D3, D4) makes it ideal for "five octave taps" across these strings (e.g., a 12th fret tap on D4 yields D5), allowing for rapid, percussive melodic lines that span a vast range. The tuning feels very open and encourages ringing chords and arpeggios, with a natural inclination towards D-centric tonalities. Its name, "My Two DAD-GADs," hints at a derivation from the DADGAD structure but expanded and deepened across an 8-string instrument, offering a unique blend of familiar and novel voicings with enhanced low-end power.

Technical Analysis:

The full open tuning is D1 A1 D2 A2 D3 G3 B3 D4.

• The foundational structure is heavily rooted in D, with D notes appearing on the 8th, 6th, 4th, and 1st strings. This provides a powerful, multi-octave D unison or D5 power chord when strummed openly, creating immense depth and sustain.
• The sequence D1-A1-D2-A2-D3 forms a robust D5 power chord across five strings, offering a colossal low-end.
• The upper strings (D3, G3, B3, D4) create an interesting harmonic cluster. Played open, these notes (D-G-B-D) form a G major triad (G-B-D) with an octave D as a low root. This implies an open sound that can be interpreted as a Dsus4add9 chord or G major over a D bass. This provides a sweet, resonant quality, offering harmonic contrast to the lower D5.
• The intervals from the lowest D1 are:
  • String 8 (D1): Root
  • String 7 (A1): Perfect 5th
  • String 6 (D2): Octave
  • String 5 (A2): Perfect 5th (one octave up)
  • String 4 (D3): Octave (two octaves up)
  • String 3 (G3): Perfect 4th (two octaves up)
  • String 2 (B3): Major 6th (two octaves up)
  • String 1 (D4): Octave (three octaves up)
• This arrangement makes D minor, D major, Dsus2, and Dsus4 chords particularly accessible and resonant in open positions or with simple barre shapes. The G3-B3-D4 cluster makes G major and related chords very natural, enhancing the versatility for both rhythmic and melodic playing. Sliding chord shapes built on the D5 power chord foundation will sound huge and harmonically rich.

Tuning Notes:

String 8: D1
String 7: A1
String 6: D2
String 5: A2
String 4: D3
String 3: G3
String 2: B3
String 1: D4

How to Tune:

To achieve the "Quadruple Drop-D 'My Two DAD-GADs'" tuning, follow these specific string adjustments. The instructions assume a starting point where changes are relative to some standard 8-string setup, but are precise as to the target note and semitone movement.

• String 8: Tune down 4 semitones to D1.
  Note: Tuning down 4 semitones is a significant change. For optimal tone, tension, and to prevent potential fret buzz, a heavier gauge string is advised for the 8th string.
• String 7: Tune down 2 semitones to A1.
• String 6: Tune down 2 semitones to D2.
• String 5: Keep as is; no change (0 semitones) for A2.
• String 4: Keep as is; no change (0 semitones) for D3.
• String 3: Keep as is; no change (0 semitones) for G3.
• String 2: Keep as is; no change (0 semitones) for B3.
• String 1: Tune down 2 semitones to D4.