In the beginning, I built the repertoire of the open major tunings that the old black blues guys came up with... The simplest one is D modal: D A D G B D; Neil Young uses that a lot. And then open G: D G D G B D, with the fifth string removed, which is all Keith Richards plays in. And open D D A D F# A D. Then going between them I started to get more ‘modern’ chords, for lack of a better word."
- Joni Mitchell
Many
great guitarists have experimented with alternative tunings, but it's hard to imagine anyone in popular music experimenting more than Joni Mitchell. Indeed, in
the article where I found the above quote Mitchell says she has used 51 different tunings. She explains that her reasoning for this is that each new tuning forces her to approach the guitar, and her compositions, in a different way. Artists of all types can understand
this line of thinking: put yourself in a foreign situation, with contrived
restrictions, and you will have a better chance at stumbling across something
new. This is even more important with guitar where the
muscle memory involved makes it far easier to play progressions you've played before. By retuning your guitar you can "reset" your fingers' memory and force yourself to avoid worn out patterns.
Another reason to play around with alternative tunings is that it makes your guitar sound different. I won't get into the physics of it, since it is beyond me to explain them, but a guitar is designed to be tuned in the standard way. The way the neck, strings, and bridge are calibrated are based around the six strings being set to EADGBE. When you use an alternate tuning it sounds unique not only because the inversions and chord progressions you will use are different, but also because there is an additional inharmonic element added. Or to put it another way, as you invent new chords across the fretboard they don't quite match up properly and create more dissonance. Despite the words negative connotation, dissonance can sound really good. The drawback of this calibration is that a guitar will fall out of tune easily in an alternate tuning, regardless of how expensive it is. Another drawback to alternate tunings is that they can warp the neck of your guitar. One way to prevent warping is by using a capo when you want to tune to a higher pitch.
Lastly, alternate tunings can be used to make a guitar much easier to play, allowing you to focus more on the rhythm than the fingering.
Open Tunings
When set in an open tuning, a guitar can produce a chord without any of the strings being pressed down on the fret board. For example, a basic Open C Tuning is CGCGCE and the C E and G form the triad known as the C chord. Normally, people use open tunings built from simple chords, but it needn't be so.
Open tuning is a common type of alternative tuning and is great for slide guitar (since you can bar all six strings on one fret), playing harmonics, and letting open bass strings drone while you play melodies or different chords on the higher strings. Here are the common open tunings:
A: E A C# E A E
Am: E A E A C E
B: B F# B D# F# B
Bm: B F# B D F# B
C: C G C G C E
Cm: C G C G C E
D: D A D F# A D
Dm: D A D F A D
E: E B E G# B E
Em: E B E G B E
F: F A C F C F
Fm: F G# C F C F
G: D G D G B D
Gm: D G D G Bb D
Modal Tunings
The word modal is one of those intimidating words in music theory. For right now it is enough to say that it refers to a series of notes found within a scale. It's like a scale in a scale. The tunings listed below are used when you want a tuning that is not distinctly major or minor. The most famous modal tuning is probably DADGAD aka "Dad Gad" aka D modal aka Open Dsus4 aka Celtic Tuning (it can make your guitar sound like a bagpipe!). While many open tunings are really only good for slide guitar and basic progressions (because they make some chords nearly impossible to play), Celtic Tuning actually has a lot of versatility and can be used much like a standard tuning, only it sounds more ethereal.
You might have noticed that Celtic Tuning is also known as D modal and that when Joni Mitchell referred to the D modal Neil Young likes, the tuning was different. That is because many types of tunings fall in the modal category. For the theory inclined guitarist, what unites these tunings is that they lack a 3rd.
A modes
Asus2: E A B E A E
Asus4: E A D E A E
B modes
B F♯ C♯ F♯ B D♯
C modes
Csus4: C G C G C F
C6: C A C G C E
D modes
D A D G B D
Dsus2: D A D E A D
Dsus4: D A D G A D
E modes
E B E E B E
Esus2: E A E F♯ B E
Esus4: E A E A B E
G modes
Gsus2: D G D G A D
Gsus4: D G D G C D
G6: D G D G B E
Drop Tuning
If you have only ever retuned your guitar in one other way, it was probably into drop D tuning. Drop D is the same as the standard tuning only the top E string is tuned down to a D. Because it is so easy to retune your guitar in Drop D it is by far the most popular alternative tuning choice. In drop tunings the top string is one step lower than in the standard tuning but every other string maintains the same relationship. Here are the basic drop tunings:
Drop A: A E A D F♯ B
Drop B: B F♯ B E G♯ C♯
Drop C: C G C F A D
Drop D: D A D G B E
Drop E: E B E A C F♯
Drop F: F C F B D G
Drop G: G D G C E A
There is also Double Drop Tuning which involves tuning both the top string and the bottom down one step.
Instrument Tuning
One of my favorite instruments is the ukulele. The way it is tuned is a great example of how alternate tunings can give a stringed instrument a unique character and also make them easy to play. The uke's four strings are normally tuned GCEA, with C as the lowest note. It is possible to tune your guitar in this way. In fact, if you are willing to make the effort, you can just restring your guitar and put what is normally the E bass string where the D normally sits and you have yourself a huge uke (of course the nylon strings and small body are also part of the uke's distinctive sound.) While we are on the topic of restringing, a popular tuning in some African pop music is to use a standard EADGBE tuning but to tune the D string one octave higher than normal. You just use a high E string instead of the standard D string.
I am not going to include a list of all the stringed instruments and their tunings because most of the tunings are small variations of the lists above. For instance, the standard Banjo tuning is an Open G with the top D string removed. To fully appreciate these tunings you will probably want to restring your guitar in a way that approximates that instrument. It sounds like work but hacking your guitar can produce some interesting results. Bill Sethares has posted a PDF document on his alternate tunings website that compiles 39 alternate tunings which include the tunings of different stringed instruments. He has a little spiel about each instrument he includes.
And on and on
As you can see, there are lots and lots of ways to retune a guitar. Far more than those I have listed above. But after a while all the lists just blur together anyway. The point is to try something new. Personally, I like to bang away at my guitar and hear the strings ring out, so I usually only use four strings, spaced as far apart as I can in a modal tuning. A little bit of music theory (I recommend Mark Levine's Jazz Theory book if you already know the basics) can help you figure out how to make chords, find scales and plan how you want to tune your guitar. Of course the theory is not really necessary if you have the time and inclination to experiment.
Sources:
Http://eceserv0.ece.wisc.edu/~sethares/alternatetunings
http://www.howtotuneaguitar.org/tuning/alternate-guitar-tuning-chart/
http://en.wikipedia.org/wiki/Guitar_tunings
http://library.thinkquest.org/3343/web-docs/muglossary.html#interval
http://www.acousticguitar.com/issues/ag44/CoverStory.shtm
the.web.hermit
Any corrections and advice are welcome. The author is not liable for any popped strings, bent necks, or wildly dissonant compositions suffered using the above information. Godspeed!