jarrodmedrano Guitar Fretboard Mastery (Fret Science System)
A systematic approach to guitar theory emphasizing geometric patterns and understanding over rote memorization.
Core Concept: The Warp
The most important fretboard concept: the G-B string boundary shifts patterns by one fret.
- Standard tuning uses perfect 4ths (5 semitones) between strings, EXCEPT G-to-B which is a major 3rd (4 semitones)
- Any pattern crossing G↔B shifts one fret toward the bridge (G→B) or toward the nut (B→G)
- This explains why chord shapes change when moved across strings
Pentatonic Scale: Rectangle & Stack
The pentatonic scale is a 5-string repeating pattern with two geometric shapes:
The Rectangle (Red)
- Two notes on adjacent strings spanning 3 frets each
- Contains: 1, 5, b3, b7 (minor) or 6, 3, 1, 5 (major)
- Both right-hand notes can be bent a full step
The Stack (Blue)
- Three adjacent strings with 2-fret intervals
- Contains: b3, b7, 4, 1, 5 (minor) or 1, 5, 2, 6, 3 (major)
- Top-right corner bends full step; lower-right notes bend 1.5 steps
Navigation
- Rectangle and stack alternate vertically in each pentatonic form
- Rectangle and stack alternate horizontally with slight diagonal descent
- Stack connects diagonally to itself one octave higher (Clapton pathway)
Five Forms
All forms derive from shifting the 5-string repeating pattern up strings (accounting for warp): Form 1 → Form 4 → Form 2 → Form 5 → Form 3 → Form 1
Modes: Pentatonic + Fill-in Notes
Six modes are pentatonic scales with two notes added inside the rectangle:
| Mode | Type | Fill Position | Brightness |
|---|---|---|---|
| Lydian | Major | Both right | Brightest |
| Ionian | Major | Staggered | Medium |
| Mixolydian | Major | Both left | Darker |
| Dorian | Minor | Both right | Brightest |
| Aeolian | Minor | Staggered | Medium |
| Phrygian | Minor | Both left | Darkest |
Locrian (b5) doesn't fit this system—it's not built on major/minor pentatonic.
Brightness Order (each differs by one semitone)
Lydian (#4) → Ionian → Mixolydian (b7) → Dorian (b3,b7) → Aeolian (b3,b6,b7) → Phrygian (b2,b3,b6,b7) → Locrian
3nps (Three-Notes-Per-String)
A 7-string universal pattern with only 3 fingering shapes:
- 1-2-4 (half-whole): Scale degrees 7, 3
- 1-3-4 (whole-half): Scale degrees 6, 2
- 1-3-5 (whole-whole): Scale degrees 5, 1, 4
Phone Numbers for String Movement
- Going UP: 7-3-6-2-5-1-4
- Going DOWN: 4-1-5-2-6-3-7
Pattern 4→7 transition shifts one fret (can combine with warp for 2-fret shift).
String Pairs (for horizontal movement)
Memorize the 7 pairs—great for melodic sequences:
- Pair 1: 4/1 → 5/2 → 6/3 (same shape as Pair 5)
- Pairs 2-7 follow sequentially
CAGED System
Five open chord shapes (C-A-G-E-D) become a pegboard for the entire fretboard.
Root Locations
Memorize where roots fall in each CAGED shape—snap any pattern onto these positions.
Layered Hierarchy (for improvisation)
- Root — Home base, most stable
- Triad (1-3-5) — Always consonant, great phrase endings
- Pentatonic — Adds melodic options
- Mode — Full color palette
Triads
Four Types (stacked thirds)
| Triad | Formula | Lower 3rd | Upper 3rd |
|---|---|---|---|
| Major | 1-3-5 | Major (4) | Minor (3) |
| Minor | 1-b3-5 | Minor (3) | Major (4) |
| Diminished | 1-b3-b5 | Minor (3) | Minor (3) |
| Augmented | 1-3-#5 | Major (4) | Major (4) |
Inversions
- Root position: 1-3-5
- 1st inversion: 3-5-1
- 2nd inversion: 5-1-3
Nine closed-form shapes exist (3 inversions × 3 string groups, warped versions for G-B crossing).
Quick Modifications
From Major: lower 3rd → minor, raise 5th → augmented, lower root 1 fret → maj7, lower root 2 frets → dom7 From Minor: raise 3rd → major, lower 5th → diminished, lower root 2 frets → m7
Intervals
Counting System
- Horizontal: +1 fret toward bridge, -1 toward nut
- Vertical: +5 per string up (toward floor), -5 per string down
- Warp crossing: count diagonally
Reference Table
| Semitones | Interval | Semitones | Complement |
|---|---|---|---|
| 0 | Unison | 12 | Octave |
| 1 | m2 | 11 | M7 |
| 2 | M2 | 10 | m7 |
| 3 | m3 | 9 | M6 |
| 4 | M3 | 8 | m6 |
| 5 | P4 | 7 | P5 |
| 6 | #4/b5 | 6 | Tritone |
9th = 2nd, 11th = 4th, 13th = 6th (subtract 7)
Harmonization with Thirds
Which Scale Degrees Get Major/Minor Thirds
- Major thirds (4 frets): 1, 4, 5
- Minor thirds (3 frets): 2, 3, 6, 7
Technique
- Play melody on one string
- Add third on adjacent string (major or minor based on scale degree)
- Keep one finger anchored, shift other finger for major/minor
Spread Thirds with Pedal Tone
Capture open string as pedal, play thirds 2+ strings away. Assign scale degree to the note matching the open string to create any modal sound.
Circle of 4ths/5ths
Vertical Movement
Moving up a string = up a 4th (clockwise on circle) Moving down a string = down a 4th (counterclockwise)
The Sequence
4ths: B-E-A-D-G-C-F-Bb-Eb-Ab-Db-Gb 5ths: Reverse order with sharp names
Wraps diagonally around fretboard due to warp.
Fretboard Memorization Exercises
- Combine with pentatonic: Find note everywhere using octave jumps, build pentatonic each time
- Follow progressions: Find roots and build triads for each chord in a song
- Cycle of 4ths on one string: Play B-E-A-D-G-C-F-Bb-Eb-Ab-Db-Gb
- Chromatic one-note-per-string: Move chromatically while changing strings
Octave Shapes (CAGED Backbone)
Two "chess moves" for octave jumps:
- +2 strings, +2 frets (no warp) → +3, +2 with warp
- +2 strings, -3 frets (no warp) → +2, -3 with warp
These shapes connect CAGED positions.
For detailed diagrams, fingering charts, and visual references, consult the references/ folder.