An Analysis of the San Casto Obispo Tuning

Verbal Analysis: A Harmonically Rich, Modern Landscape

The San Casto Obispo tuning, as its creator describes, is "based on Barry Harris and Bela Bartok, modified to be able to play two octaves." This immediately signals a sophisticated, harmonically driven approach. It's a tuning that steps far outside the conventional, offering a unique sonic palette. Verbally, this tuning presents a sound world that is at once dissonant and deeply resonant, suggesting modern jazz, fusion, or even contemporary classical applications. The influence of Barry Harris points to a focus on chord-scale relationships, symmetrical structures, and fluid voice-leading, while Bartok's presence implies an interest in modal exploration, tension, and release. The mention of "two octaves" suggests a wide melodic range and extensive possibilities for intricate musical phrases and expansive harmonic textures across the fretboard. This is not a tuning for the faint of heart, but for those seeking to unlock new harmonic dimensions on the guitar.

Technical Analysis: Unveiling Symmetrical Harmonies

The open strings of the San Casto Obispo tuning are set as follows (from 6th to 1st string): F#3, C3, D#4, F#4, A3, C4.

When these notes are ordered by pitch – C3, F#3, A3, C4, D#4, F#4 – a profound harmonic structure emerges. The core of this tuning's technical brilliance lies in the immediate availability of a C Fully Diminished 7th chord (C, D#/Eb, F#, A) across the open strings. Specifically, strings 5 (C3), 6 (F#3), 2 (A3), and 4 (D#4) form this highly symmetrical and versatile chord. This diminished harmony is a cornerstone of both Barry Harris's bebop concepts and Bartok's innovative compositional language.

Beyond this striking diminished chord, other interesting intervals and partial harmonies are present:

• The F# diminished triad (F#, A, C) is readily available across multiple string sets (e.g., strings 6, 2, 1 or 3, 2, 1).
• The intervals between adjacent strings are notably irregular and wide:
  • 6th to 5th (F#3 to C3): Descending Augmented 4th (or Diminished 5th)
  • 5th to 4th (C3 to D#4): Ascending Major 9th (Octave + minor 3rd)
  • 4th to 3rd (D#4 to F#4): Ascending Major 2nd
  • 3rd to 2nd (F#4 to A3): Descending Major 6th (Octave - minor 3rd)
  • 2nd to 1st (A3 to C4): Ascending Minor 3rd

Chords and Playability: The open string diminished 7th chord provides an immediate foundation for exploring diminished scales, altered dominant harmonies, and symmetrical melodic phrases. Due to its inherent symmetry, a single diminished 7th chord can function as four different diminished 7ths (e.g., Cdim7, Ebdim7, F#dim7, Adim7) depending on context and bass note. This vastly expands harmonic options. Players will find that certain arpeggios and linear ideas from jazz and modern classical music fall very naturally under the fingers, while standard "cowboy chords" will be virtually unusable. The tuning's wide range and deliberate intervallic choices will encourage horizontal (melodic) playing and inventive vertical (harmonic) stacking. It's a setup designed for deep harmonic exploration rather than casual strumming.

How to Tune Your Guitar for San Casto Obispo

Follow these steps to set up your guitar for the San Casto Obispo tuning. Always approach significant tuning changes carefully to protect your strings and instrument.

• 6th String: Tune up 2 semitones to reach F#3.

• 5th String: Tune up 3 semitones to reach C3.

• 4th String: Tune up 1 semitone to reach D#4.

• 3rd String: Tune down 1 semitone to reach F#4.

• 2nd String: Tune down 2 semitones to reach A3.

• 1st String: Tune down 4 semitones to reach C4.

Please be aware that while most individual string changes are moderate, the 1st string is tuned down 4 semitones. For tunings involving changes of 4 semitones or more (either up or down), considering a different string gauge might be advisable for optimal performance and to mitigate potential issues with string tension or playability.