DADGAD is a wicked, folky tuning for guitar.
The name comes from the notes that the six strings are tuned to, from lowest to highest.
Orginally invented by Davey Graham in the early 60s, this tuning on a well-played guitar can invoke all the traditional folk instruments like bagpipes, banjo and fiddle. The main reason for this great range of sounds being the sweet "drone" achieved by the tuning - almost without exception, whatever chord you choose to play will have a D-drone. But unlike a bagpipe or banjo drone, depending on the chord the DADGAD drone shifts octave, leading to an awesome range of possible effects.
As of this writing, DADGAD is enjoying unprecedented popularity, with most of the new generation of acoustic guitarists having a DADGAD tune or two in their set. Musicians like Al Petteway, Ani DiFranco, Art Edelstein and Pat Kirtley are all doing amazing things with this tuning. Pierre Bensusan has made a career playing DADGAD exclusively.
Here's a list of artists that contribute to Pierre Bensusan Presents DADGAD Guitar, which is an excellent book/cd resource for really getting to grips with the possibilities of this tuning: James Earp, Laurence Juber, Doug Smith, Bill Mize, David Surette, Eileen Niehouse, Brook Williams, Peppino D' Agostino, Adrian Legg, Phil Keaggy, and Pete Huttlinger.
So you've been enthused enough by the description above to pull out your acoustic guitar and give DADGAD a try? Excellent! Below are the basic three DADGAD open chords, look on the web or simply work the others out for yourself - it's not hard, especially if you have some experience with any of the D based tunings, like Open D.
1||---|---|---|---|---|--
2||---|---|---|---|---|--
3||---|-X-|---|---|---|--
4||---|---|---|---|---|--
5||---|---|---|---|---|--
6||---|---|---|---|---|--
That's the one (I) chord of the I IV V chord pattern in D. Next is G major, or the IV chord:
1||---|---|---|---|---|--
2||---|---|---|---|---|--
3||---|---|---|---|---|--
4||---|---|---|---|---|--
5||---|-X-|---|---|---|--
6||---|---|---|---|---|--
Finally the "V", in this case A major:
1||---|---|---|---|---|--
2||---|---|---|---|---|--
3||---|---|---|---|---|--
4||---|-X-|---|---|---|--
5||---|---|---|---|---|--
6||---|---|---|---|---|--
Sweet! Note you can use a "second finger" in the same fret for both G (two strings above)
and A (two strings below) for a "clearer" chord, killing one of your drone strings. Like I said, plenty of options...
Try anything Celtic at all in this tuning, and it will sound awesome. Or, for even more fun, try fingerpicking an old hymn or even a rock and roll tune. If you've never heard this done before, it will really knock your socks off!
http://www.strummeronline.com/dadgad.html
http://guitar.about.com/library/bltuningdadgad.htm