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Is vibrato easier to do on a cello than a violin???? Opinions please
Speaking as a violinist who took up the cello at the age of 22, yes, I would say that the more natural position of the hand encourages vibrato to develop very easily. Having said that, my violin vibrato wasn't taught to me, it just developed naturally.
The types of vibrato are also very different; violin vibrato comes from a to-and-fro movement of the hand and/or arm, while cello vibrato uses a rotational movement mainly from the forearm.
Those who play with a more relaxed left hand and arm develop vibrato quicker and without hinderance or the 'weak tremble' that often pervades those who are literally trying to force it into their playing.
Tension in the left hand (particularly gripping the violin neck between the forefinger and thumb; which in turn creates wrist tension) becomes a vicious circle - the more you try to force the vibrato the more the tension develops, so the vibrato is forced a bit more and so on...
ad nauseum.
Relax, is the best advice I can give.