Posted: July 7, 2013
Michael, thanks for that video. It was extremely informative. In fact, based on your previous post, I had pictured a much different vibrato.
First off, let me say that I think your bow hand is GORGEOUS! Your whole set up is exceptional. I see no red flags in regards to tension.
Here are my thoughts about your vibrato. You have a wrist vibrato, not an arm vibrato. You are initiating movement from the wrist. The problem I see is the angle of your wrist (like Eileen mentioned). Because it's a bit pronated, it's limiting your range of motion. Another words, you are vibrating from a vertical position of the arm to a pronated position, which means you are not getting the benefit a full rocking motion. Your knuckles are plenty flexible, but without the supination of the wrist involved in the vibrato motion, you are getting a fraction of the whole movement, and therefore a fraction of the pitch modulation.
Practice with the mirror. Start with a perfectly straight wrist and arm, then rock the hand back as far as you can and then forward to where there is a slight pronation in the wrist. That should be the range of motion for slow practice. Obviously it will be minimized when you increase tempo.
I also think you should practice vibrato exercises with a metronome if you're not doing so already. It's obvious your a quick learner, and you've already done amazing work in just six weeks. The metronome will help you build in evenness. It takes several months to a year to really get a nice functioning vibrato. You are off to a fantastic start. But the left arm/wrist angle issue will be an impediment if you don't fix it.
Thanks for the video!