I picked up this question because it was my photo that John linked in his answer. He's right that the bridge feet should be midway between the f-holes, on a line joining the inner notches (the ones that make the s into an f). But there's more. A bridge is not symmetrical but lower on one side than the other, and it should face the direction that allows the wire E string to fit the notch on the lower side, with the thick G string on the higher side. Normally, the bridge-maker's stamp will then face away from the player. Also, the feet of the bridge must be shaped to fit the curve of the belly, or they won't transmit the tone properly, and this curve varies between instruments. (It is possible to buy self-adjusting bridges with pivoting feet, which are OK for school-type instruments). The mass of the bridge (which depends on both height and thickness) must also be right for the instrument, in order to get the best tone (muted=too heavy; strident=too light) although the exact position of the soundpost has an important interaction here, too. Very importantly, the height and curvature of the top edge of the bridge must be shaped to give the correct clearance between the fingerboard and each of the strings (least for the E and most for the G). If the bridge is too high, giving too much clearance under the string, the pitch of the note will sharpen too much as you press the string down and playing in tune becomes difficult (it's hard enough for beginners anyway!!). If it is too low, the strings (especially the G string, which moves most) will buzz on the fingerboard when you play loudly, especially pizzicato (plucking). Again, the exact shape needed varies between instruments because of small variations in the angle and curvature of the fingerboard, so each bridge has to be cut for that instrument. Fitting a new one really is a job for an expert, because it is much tricker than putting back one that was originally properly fitted but has simply fallen down.
Jeremy, September 2006
