Which keys work in DADGAD?

(This section focuses on major and minor keys, i.e. Ionian and Aeolian modes. Other modes are discussed elsewhere.)

tl;dr

The keys that contain the notes D, G and A (the open strings of DADGAD) are:

Of these keys, D major/minor, G major/minor and A minor have a low-pitch tonic bass note (i.e. D, G and A, respectively) which is easily accessible from most positions on the fretboard in DADGAD.

What do I mean by ‘work’?

Technically, it's possible to play in all keys using any tuning.

In practice, however, some keys are trickier than others.

For any given tuning, the notes of the open strings are not found in all keys.

For example, DADGAD has open string notes D, G and A.

These notes are not found in the key of Db major (Db, Eb, F, Gb, Ab, Bb and C).

While you can play in Db major in DADGAD, any open string (played intentionally or accidentally) would sound dissonant.

So when I say that a key ‘works in DADGAD’, I mean only that it contains the notes D, G and A.

This limitation still leaves a lot of options.

Keys that do/don't work in DADGAD

The table below shows all keys organised according to the Circle of Fifths.

The notes in each key are listed (though spelled incorrectly with all flats shown as their enharmonic sharps).

The notes D, G and A are highlighted in green and the notes D#, G# and A# (meaning also their enharmonic equivalents Eb, Ab and Bb) are highlighted in red.

The keys of C major, G major, D major, Bb major and F major (and their relative minors) are compatible with DADGAD because they contain the notes D, G and A.

Note also that these keys are adjacent on the Circle of Fifths.

Circle of fifths deluxe 4 by Just plain Bill is licensed under CC BY-SA 3.0. / Green and red highlights added

Tonic bass notes

Though these five keys (and their relative minors) are all compatible with the open strings of DADGAD, there is a secondary issue.

For some of these keys, there is no low-pitch tonic bass note easily accessible on the neck.

For example, F major is compatible with DADGAD, but the only low F on the fretboard is the 3rd fret of the bottom string.

This note is accessible near the nut, but not if you're playing higher on the neck.

Likewise, there is a Bb at the 1st fret of the fifth string and the 8th fret of the bottom string, these are hard to reach from a position between those two frets.

Accessible tonic bass notes are available for the keys of D (bottom string, open), A (fifth string, open; bottom string, 7th fret) and G (bottom string, 5th fret).

Filtering compatible keys for accessible tonic bass notes leaves these keys:

Does this make a difference in the real world?

Hypothesis: Guitarists using DADGAD play almost exclusively in keys that are compatible with the open strings of DADGAD. Of these keys, pieces will be centered on tonalities of D, G and A.

Test case: Intuite by Pierre Bensusan

Pierre Bensusan is a world-renowned guitarist and undisputed master of DADGAD.

In interviews, he has said something along the following lines (unfortunately, I can’t seem to dig up a quote):

Many people who experiment with DADGAD play only in D (major, minor, Dorian, Mixolydian… etc.). But DADGAD is a versatile tuning. In my music, I play in different keys. The guitar and tuning should be a conduit for expressing musical ideas, not a limitation to expressing them.

(N.B. The above is not a quote.)

I agree 99% with the sentiment.*

However, it’s clear from a quick glance at Pierre’s music that he plays predominantly in the safe zones described above.

Take his album Intuite.

Only on two tracks on the album does he break away from tonic D, G and A (and those two exceptions are in DADGAD-compatible C major).

Occasionally, he uses a capo to play in other keys.

For example, Silent Passenger is played with a capo at the 2nd fret in A major. This is equivalent to playing without the capo in G major.

This observation is not a criticism of Pierre or his music in any way and I have no doubt that he’s perfectly comfortable playing outside these safe zones.

Rather, even someone with Pierre Bensusan’s undeniable proficiency in DADGAD stays largely within the most compatible keys.

Regarding DADGAD-compatible modes (Dorian, Mixolydian, etc.), see here.

(*Incidentally, my 1% disagreement is that technical aspects of an instrument can inform the music you play/create. But that’s not directly relevant to the issue of tuning-compatible keys.)