Open C Tuning

Open C is one of the less commonly used open tunings. However, it is an interesting tuning as it expands the tonal range on the guitar more than the most common tunings of standard tuning, Open G, and Open D.

It is often used in blues and folk music and like all the open tunings it is well suited to fingerstyle guitar and playing with a slide.

How to tune to Open C

Open C tuning tunes the strings of the guitar so that when all the strings are played open it forms a C Major chord. The C Major chord is formed from the three notes which make up the C Major triad, these are the 1st, 3rd and 5th notes of the C Major scale, which are C, E and G respectively. Thus, each of the guitar strings in open D tuning will be tuned to one of these three notes.



As I have said, this tuning expands the tonal range of the guitar beyond standard tuning, and most other common tunings. As such, it involves considerable detuning of the lower strings, whereas the higher strings are left mostly as they are. If we take a guitar with standard tuning of E-A-D-G-B-E we can look at the changes to be made to reach open d tuning. Starting from the 6th string which is the thickest string:

The lowest E string is tuned down four semitones to C

The A string is tuned down two semitones to G

The D string is tuned down four semitones to C

The G string is not retuned and remains at G

The B String gets tuned up one semitone to C

The highest E string is not retuned and remains at E


Here it is in an easier to read table: 

Guitar String	Standard Tuning	tuning alteration	Open C Tuning
6th	E	Down 4 semitones	C
5th	A	Down 2 semitones	G
4th	D	Down 2 semitones	C
3rd	G	No Change	G
2nd	B	Up 1 semitone	C
1st	E	No Change	E

 

 

Chords in Open C

 

One of the good things about playing blues in Open C is you can easily access many of the most common chords used in blues music. Diatonic functions I IV and V, which are C, F and G respectively in the C Major scale, form the standard '3 chord trick' which is the basis for many blues tunes and these are very easily accessed and transitioned between in this tuning. Diatonic functions I7, IV7 and V7, which are C7, F7and G7 are also easily accessible and are commonly used in this style of music.

In addition, diatonic function vi, which is Am in the C Major scale, is also easy to get to and this forms the 4th chord in the standard 50's sequence along with I, IV and V. Although this chord isn't commonly used in blues its handy to know where it is.

Another chord that sometimes appears in Open C music is G6. It has a similar fingering pattern and shape to the other, more commonly used chords, so it is easy to access and transition to and from.

The good thing about this tuning is that most of these chords all have a very similar fingering shape, meaning that you can transition easily between them.

I have put together a list of the most common chords used when playing blues music in open C. For a more comprehensive list of chords you can easily find them by doing an internet search or, as I do, use powertab editor which has an excellent chord generator built in.

Slide Guitar and Fingerstyle Playing

 

Like the other open tunings, Open C is well suited to playing with a slide. In this tuning, because the major chords are formed with a barre across all six strings, you can access these chords using the slide which isn't possible in standard tuning. In addition, it allows you to use various thumb picking patterns on the open lower strings whilst still allowing you to slide around on the upper strings. Again this is tricky in standard tuning because of the need to fret the underlying chords for the bass picking patterns.

Thanks for Reading,
Neil