Sunday, December 16, 2007
The humidity indicator card that came with my dampits is a perfect tool for checking to see if the bridge is square to the face of the cello. The tailpiece face of the bridge should be exactly perpendicular to the cello, (the fingerboard face of the bridge is beveled). The side of the card against the face of the bridge shows that the A/D half of the bridge is almost exactly perpendicular...
At the G/C part of the bridge, there is a noticeable gap along the upper edge of the card, showing that this part at least, is somewhat out of square. I'll have to (carefully) pull the top of the bridge towards the tailpiece. (Notice that my humidity is in the "Danger" zone, despite a room humidifier adding gallons of water into the air each day.)
Rechecking with the card shows the bridge is now properly aligned. I also rechecked the A/D half to make sure it didn't slip during this procedure (it was OK).
Now, I check to see if the bridge remains properly aligned to the strings. (Actually, this step ought to be done first). The "fingerboard" side of the feet should line up with the center point of upper notch in the "f-holes". If it's not aligned it will make intonation more difficult and it might be harder to tune to perfect 5ths. Mine has only shifted once, when I first changed strings (teaching me to do them one at a time and bring each new string almost up to full tension before doing the next one). Today, the alignment is perfect.
And the alignment is also perfect at the other "f-hole".
Now, if I could only apply this same basic geometry to my bow placement and arm/hand/finger angles....
I wonder if the f-hole notches don't vary from cello to cello, or at least maker to maker, though. Based on the varnish, my bridge has not moved, but the inside notch points to the middle of the foot, and if I align a card across both notches the line isn't parallel to the bridge, and the edge of the card extends to the tailpiece side of the bridge. Sounds like a good thing to ask the maker, since I can.
What's more important, though, is establishing the correct string length [or "stop"] between the nut and the bridge [on modern cellos, this distance should be 27.36" or 695mm]. It may be that the final bridge placement by the luthier might have to be slightly in front of or behind this "line" between the outer notches in order to ensure proper string lengths.
What is most important, though, is that the front of the bridge's feet should be perfectly parallel to that line between the outer notches.
Dealers must think I'm a little nuts, as I measure the instruments before I even try them. It's worth it, though. I'm convinced that limiting my instruments to the shorter string length is a major component of my ability to play pain-free now.
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