This is a truly unique and expansive tuning designed for a Guitar, specifically optimized for a Fretless Harp Guitar as demonstrated by Tim Donahue. Known in its original form as Amaj13 (all 5ths), it creates a rich, full A major 13th chord across its open strings, offering a wide harmonic palette. The tuning was inspired by the Quintar project and Hans' experimentation with all-fifths tunings, especially on guitars with heavier gauge bass strings. The original description also notes that the instrument itself is often tuned a whole tone lower to Gmaj13, showcasing the flexibility of this intervallic structure.

Technical Analysis

The open strings are tuned to A1 E2 B2 F#4 C#5 G#5. When reordered and analyzed harmonically, these notes (A, B, C#, E, F#, G#) perfectly spell out an A major 13th chord (A as the root, B as the 9th, C# as the major 3rd, E as the perfect 5th, F# as the major 13th/6th, and G# as the major 7th). This provides an incredibly rich and harmonically sophisticated open chord, ready for complex voicings and arpeggios.

The tuning predominantly features perfect fifth intervals between adjacent strings, creating a strong harmonic foundation:

• String 6 (A1) to String 5 (E2): Perfect 5th (7 semitones)
• String 5 (E2) to String 4 (B2): Perfect 5th (7 semitones)
• String 3 (F#4) to String 2 (C#5): Perfect 5th (7 semitones)
• String 2 (C#5) to String 1 (G#5): Perfect 5th (7 semitones)

A notable characteristic of this tuning, likely due to its Harp Guitar application, is a significant intervallic jump between String 4 (B2) and String 3 (F#4). This gap spans a perfect fifth plus an octave (19 semitones), allowing for an enormous overall range from a very low A1 to a high G#5. This extensive range offers unique melodic and harmonic possibilities far beyond what is typically achievable on a standard six-string guitar.

Chords and Playability

The open Amaj13 chord is the cornerstone of this tuning, perfect for lush arpeggios, ambient textures, and modal explorations. While traditional guitar chord shapes will largely not translate due to the unique intervals, the consistent perfect fifths across most string pairs facilitate the creation of powerful two or three-note chords and allow for easy transposition of certain harmonic ideas. The extreme range of this tuning encourages exploration of extended voicings and melodic lines that utilize the full breadth of the instrument. Given its origin on a fretless instrument, slides and microtonal inflections would sound particularly expressive within this tuning.

How to Tune

To achieve the Harp Guitar Ascending Fifths A13 Tuning, start from standard guitar tuning (E2 A3 D4 G4 B4 E5) and adjust each string according to the provided instructions:

• String 6 (Low E string, standard E2): Tune down 7 semitones to A1. A heavier gauge string is strongly advised due to this significant drop, which exceeds 4 semitones.
• String 5 (A string, standard A3): Tune down 5 semitones to E2. A heavier gauge string is advised due to this significant drop, which exceeds 4 semitones.
• String 4 (D string, standard D4): Tune down 3 semitones to B2.
• String 3 (G string, standard G4): Tune down 1 semitone to F#4.
• String 2 (B string, standard B4): Tune up 2 semitones to C#5.
• String 1 (High E string, standard E5): Tune up 4 semitones to G#5. A lighter gauge string might be considered due to this significant rise, which is 4 semitones or more.

You can see the guitar here: http://www.unfretted.com/reviews/gear-reviews/tim-donahue-fretless-harp-guitar/