Open C (CGCG) Tuning
Tune your viola to Open C (CGCG) — C3, G3, C4, G4
About Open C (CGCG) Tuning
Open C tuning (C3-G3-C4-G4) transforms the viola into a droning, resonant instrument by retuning the upper two strings to create paired octaves of C and G. When all four strings are played open, the result is a C5 power chord — a bare fifth with no third, giving it a stark, open quality that is neither major nor minor. This ambiguity makes Open C a favorite among composers and performers working in experimental, minimalist, and contemporary idioms.
The paired-octave structure of Open C creates extraordinary sympathetic resonance. The two C strings (C3 and C4) vibrate in sympathy with each other, as do the two G strings (G3 and G4), producing a shimmering, harp-like sustain that standard tuning cannot achieve. This effect is particularly pronounced on the viola, whose larger body amplifies low-frequency resonance. Composers like George Crumb and Helmut Lachenmann have explored similar scordatura effects in their works for strings, using altered tunings to unlock new timbral possibilities.
Playing in Open C requires a complete rethinking of the fingerboard. The D string is raised to a C4 (down a whole step from D4... actually, the standard D4 is lowered to C4), and the A string is lowered from A4 to G4. This means the upper two strings now mirror the pitches of the lower two strings one octave higher. Familiar scale patterns no longer apply, and violists must develop new fingering maps. However, the symmetry of the tuning — two pairs of the same notes — simplifies certain techniques, particularly drone-based playing, open-string harmonics, and bariolage patterns that alternate rapidly between strings.
String Notes
Recommended Strings
Open C tuning changes the tension profile of the instrument. The D string is tuned down a whole step to C4, which reduces its tension, while the A string drops a whole step to G4, also reducing tension. Standard medium-tension strings generally handle these changes adequately, but if the upper strings feel too slack or produce a weak tone, consider using heavy-gauge strings for the top two positions. The lower two strings (C3 and G3) remain at standard pitch and require no special consideration.
How to Tune to Open C (CGCG)
- 1.Start from standard CGDA tuning. The lower two strings (C and G) remain unchanged — only the upper two strings need adjustment.
- 2.Tune the D string (third string) down from D4 to C4 (261.63 Hz). Lower it one whole step. You can verify by checking that it sounds exactly one octave above the open C string.
- 3.Tune the A string (first string) down from A4 to G4 (392.00 Hz). Lower it one whole step. Verify by checking that it sounds exactly one octave above the open G string.
- 4.Play all four strings open — you should hear a resonant C5 power chord: C3-G3-C4-G4. The octave pairs should ring cleanly with no beating.
- 5.Check the intervals: C3 to G3 is a perfect fifth, G3 to C4 is a perfect fourth, and C4 to G4 is a perfect fifth. If any interval sounds impure, retune that string carefully.
Best Keys for Open C (CGCG)
C Major
The natural home key. The open C strings provide a powerful tonic drone, and simple first-position fingerings yield a full C major scale. Melodies in C sit naturally over the open-string resonance.
C Minor
Easily achieved by playing an Eb on the C4 string. The open fifth (C-G) is harmonically neutral, supporting both major and minor tonalities equally well.
G Major
The dominant key, with the open G strings providing the tonic. The paired G strings create a bright, ringing foundation for melodies and arpeggios in G.
F Major
The subdominant key. Accessible through first-position fingering on the lower strings, with the open C functioning as the fifth of the chord for a naturally resonant sound.