Open D Forensics
Learning to see your own writing in functional terms — for the first time.
- Time
- 90 minutes of study + 30–45 minutes of homework
- You need
- Your guitar in open D, a tuner, a notebook, and audio of two or three of your own songs
- By the end
- You can name every chord you play in open D and identify the key of your own songs
What Open D Actually Is
Standard tuning is E-A-D-G-B-E. Open D is D-A-D-F#-A-D (low to high).
The math:
- Strings 6, 4, and 1 are all D — three octaves of the same note.
- Strings 5 and 2 are A — the fifth of D.
- String 3 is F# — the major third of D.
Strum all six open strings and you are playing a D major chord: root, fifth, third. The "magic" of open D is that the tuning is a D chord that doesn't need fingers.
There's nothing mystical here — just a tuning optimized for major and modal sounds.
Three reasons it feels different to write in:
- Drone. Two D's ring at all times. Everything pulls toward D whether you want it to or not.
- Movable barres. One finger across all six strings gives you a full major chord at any fret.
- Freed left hand. With shape memorization off the table, melodic fingerings come easier.
- What note is the 6th string in open D?
- What is the interval between the 6th and 5th strings?
- Which string carries the major third of the D chord?
- How many D notes ring when you strum all six open strings?
- What chord do you get when you strum every string open?
Reveal Answers
1. D. 2. Perfect fifth. 3. 3rd string (F#). 4. Three. 5. D major.
The Movable Barre Map
Bar all six strings at any fret. The chord you get is the major chord rooted at whatever note sits on the 6th string at that fret.
| Fret | 6th-String Note | Chord |
|---|---|---|
| 0 | D | D |
| 2 | E | E |
| 3 | F | F |
| 4 | F# | F# |
| 5 | G | G (IV in D) |
| 7 | A | A (V in D) |
| 9 | B | B (vi root; Bm needs a different shape) |
| 10 | C | C (bVII in D Mixolydian) |
| 12 | D | D (octave) |
Three frets do most of the work in your writing: 0, 5, and 7. That's I, IV, V in D major. Fret 10 is the wildcard — it gives you C major, which doesn't belong to D major at all. It belongs to D Mixolydian.
Common open D moves, decoded:
- Open → fret 5 → fret 7 → open = I-IV-V-I in D
- Open → fret 7 → fret 5 → open = I-V-IV-I in D
- Open → fret 10 → fret 7 → open = I-bVII-V-I (the indie move)
- Open → fret 9 → fret 5 → fret 7 = I-vi-IV-V
You have been writing modal music without knowing it.
That bVII (C major in D) is the single biggest reason open D feels indie. It is the Mixolydian flat-seven, and it appears constantly in Bon Iver, Big Thief, Fleet Foxes, early Iron & Wine, and most acoustic-leaning indie of the last fifteen years.
- A full barre at fret 3 gives you what chord?
- A full barre at fret 9 gives you what chord?
- The progression open → 5 → 7 → open in D is what Roman numerals?
- What is the V chord in the key of D major?
- Why does fret 10 sound "indie"?
Reveal Answers
1. F. 2. B major. 3. I-IV-V-I. 4. A major. 5. It is the bVII — the Mixolydian flat-seven — which creates a modal, unresolved color instead of pulling back to I the way V does.
Finding the Key of Your Songs
If your song lives in open D and resolves to the open strum, it is almost certainly in D major or D Mixolydian — or, more likely, a blend of both.
D Major scale: D E F# G A B C# D
Chords in D major: D (I), Em (ii), F#m (iii), G (IV), A (V), Bm (vi), C#dim (vii°)
D Mixolydian scale: D E F# G A B C D (flat seven)
Chords in D Mixolydian: D (I), Em (ii), F#dim (iii°), G (IV), Am (v — minor), Bm (vi), C (bVII)
The single tell: C# or C natural?
If your song uses C major (fret 10 barre), you are in Mixolydian or mixing modes. If it uses C#m or C#dim, you are in straight D major. Most indie open D writing is mixed: D major chords plus the occasional borrowed C. That's why your songs feel "modal." They are.
- A song uses D, G, A, and Bm. What key?
- A song uses D, G, A, and C. What mode?
- What is the vi chord in D major?
- What is the bVII chord in D Mixolydian?
- Why does Mixolydian feel less "resolved" than major?
Reveal Answers
1. D major. 2. D Mixolydian (or mixed). 3. Bm. 4. C major. 5. Because the bVII (C) does not contain the leading tone C#, so it does not pull strongly back to D. No leading tone = no resolution pressure.
Catalog Forensics — The Real Work
Pick three of your own songs. For each one, do all four steps:
- Chord names. Play through the song and write down every chord by fret position, then translate to chord name using the barre map.
- Key. Major, Mixolydian, or mixed? Look for the C/C# tell.
- Roman numerals. Write out the verse and chorus as Roman numerals. Forget the chord names for a moment — just the function.
- Drone audit. Where are you relying on the ringing open D strings to do work? Are there spots where, in standard tuning, you would need a chord change but in open D the drone covers for you?
This homework is the point of Week 1. The theory is just the language. The deliverable is seeing your own writing in functional terms for the first time.
Reflection Questions
- Did all three songs turn out to be in the same key?
- Did you use the same Roman numeral progression in more than one song?
- Where are open strings doing work that a real chord change would do in standard tuning?
If you answered yes to 1 or 2, you have just found your rut on paper. That is the prize. You cannot break a pattern you cannot see.
Before Week 2 — You Should Be Able To
- Name the notes of all six strings in open D from memory.
- Identify any full-barre chord by fret.
- Write the Roman numeral function of any chord in D major and D Mixolydian.
- Name the key and progression of at least three of your own songs.
If any of those four feel shaky, repeat Part 2 or Part 3 before moving on. Week 2 builds directly on this — the diatonic engine won't make sense if the labels aren't solid.
The Test Bank
Take this after the homework is done. Score yourself. Answers and scoring at the bottom.
A · Tuning Mechanics (1–10)
- The 6th string in open D is tuned to ___.
- The 3rd string in open D is tuned to ___.
- Three strings in open D share the same letter name. Which letter?
- The interval between strings 6 and 5 in open D is a ___.
- To go from standard to open D, the 6th string is tuned down by a ___.
- To go from standard to open D, the 1st string is tuned down by a ___.
- To go from standard to open D, the 3rd string is tuned down by a ___.
- Strings 2 and 5 in open D are both tuned to ___.
- Strumming all six open strings produces what chord?
- True or false: standard tuning's 3rd string (G) is the same pitch as open D's 3rd string.
B · Movable Barre Map (11–20)
- A full barre at fret 2 = ___.
- A full barre at fret 3 = ___.
- A full barre at fret 4 = ___.
- A full barre at fret 5 = ___.
- A full barre at fret 7 = ___.
- A full barre at fret 9 = ___.
- A full barre at fret 10 = ___.
- A full barre at fret 12 = ___.
- Which fret gives you the IV chord in the key of D major?
- Which fret gives you the V chord in the key of D major?
C · D Major and D Mixolydian (21–30)
- The notes of D major are: D E ___ G A B C# D.
- The notes of D Mixolydian are: D E F# G A B ___ D.
- The single note that distinguishes D major from D Mixolydian is the ___.
- The vi chord in D major is ___.
- The IV chord in D major is ___.
- The V chord in D major is ___.
- The bVII chord in D Mixolydian is ___.
- The leading tone of D major is ___.
- The relative minor of D major is ___.
- A song using D, G, A, Bm, and C is most likely blending which two modes?
D · Roman Numerals and Function (31–40)
- In a major key, I, IV, and V are built on which scale degrees?
- A lowercase Roman numeral (e.g., vi) indicates a ___ chord.
- The primary function of the V chord is to ___.
- In D major, the iii chord is ___.
- In D major, the vii° chord is ___.
- The progression I-V-vi-IV in D is: ___ ___ ___ ___.
- The progression vi-IV-I-V in D is: ___ ___ ___ ___.
- A bVII-to-I move in D Mixolydian is: ___ to ___.
- Which Roman numeral represents the relative minor in any major key?
- Which Roman numeral is built on the 4th scale degree?
E · Applied Scenarios (41–50)
- Your song goes open → fret 7 → open. What Roman numerals?
- Your song uses only open, fret 5, and fret 7 barres. What three Roman numerals are you using?
- Your part goes open → fret 10 → fret 7 → open. Roman numerals in D Mixolydian?
- You strum the open chord and let it ring while you sing a full verse. You are using the chord as a ___.
- Two of your songs both center on D and use I-IV-V-vi. What does that pattern reveal?
- You want to write a song that does not resolve neatly. Which scale degree should you lean on?
- To translate an open D song into standard tuning, the first thing you need to know is ___.
- Your song lives in D major and you want a darker bridge. Modulating to which related chord adds moodiness without leaving the key?
- The "indie" sound of open D comes mainly from two things: ___ and ___.
- You write a song where every "chord change" is actually just lifting a barre and letting the open strings ring. What does this reveal about your reliance on the tuning?
Answer Key
A · Tuning Mechanics
1) D. 2) F#. 3) D. 4) Perfect fifth. 5) Whole step. 6) Whole step. 7) Half step. 8) A. 9) D major. 10) False — standard is G, open D is F#.
B · Movable Barre Map
11) E. 12) F. 13) F#. 14) G. 15) A. 16) B. 17) C. 18) D (octave). 19) Fret 5. 20) Fret 7.
C · D Major and D Mixolydian
21) F#. 22) C (natural). 23) Seventh scale degree (C# vs. C natural). 24) Bm. 25) G. 26) A. 27) C major. 28) C#. 29) Bm. 30) D major and D Mixolydian.
D · Roman Numerals and Function
31) 1st, 4th, 5th. 32) Minor. 33) Resolve to I / create dominant tension. 34) F#m. 35) C#dim. 36) D-A-Bm-G. 37) Bm-G-D-A. 38) C to D. 39) vi. 40) IV.
E · Applied Scenarios
41) I-V-I. 42) I, IV, V. 43) I-bVII-V-I. 44) Drone or pedal. 45) You are returning to the same harmonic engine — a rut to address. 46) The flat-seven (bVII). 47) The chord names and Roman numeral function, not the shapes. 48) Bm (the relative minor, vi). 49) The droning open strings and the Mixolydian bVII. 50) The tuning is doing the songwriting; you are leaning on sonic gravity instead of harmonic motion.