A while back I bought a violin with five strings, i.e. there in an extra low C on it. However, as the body of the violin is the same size as that of a normal violin, so whenever I play on the C-string with even moderate force, the note goes sour. If I play with low force, however, the note stays clean. I assume this is because the tension on the string is too low due to the shorter body of the instrument.
Spontaneously, I would guess using a thicker string would give the string the necessary tension to maintain the tone. So my question is, could this be a solution? If not, is there another way I could go about it?