The Mudcat Café TM
Thread #124793 Message #2758456
Posted By: JohnInKansas
03-Nov-09 - 02:52 AM
Thread Name: Tech: Mandolin Bridges
Subject: RE: Tech: Mandolin Bridges
Because of their short length, mandolin strings are considerable "stiffer" against the fingers than is the case for longer strings. The stiffness is sufficient that single-course strings would literally slice the ends off your fingers. The double-course strings are to "spread the load" in the manner of a bed-of-nails. If one pound of pressure against one sharp edge would hurt, one pound against each of two identical closely spaced sharp edges may be "tolerable."
Because of the pain factor, mando players like to have much more precise adjustment of the clearance of the strings off the finger board, and - if they're really fussy - like to have some degree of adjustment across the strings, so that the "high" strings have a pressure requirement compatible with the pressure needed for the "low" strings.
Again primarily because of the short string length, the amount of "stretch" in the string when it's pressed down to a fret is relatively larger than for longer stringed instruments, so relatively large amounts of "compensation" are needed in the bridge. The open string length is actually different for each string so that mid-fingerboard tones will be close to pitch. The "staggered" blocks of the bridge* provide the required compensation.
Mando design is by now sufficiently "standardized" that it's seldom really necessary, but the sloped sides (notches) of the "block" for each string do provide a way to relatively easily tweak the compensation in the rare cases when that's needed - without making the bridge ugly (uglier?).
* An alternative design uses a curved/arched bridge similar to a fiddle to achieve somewhat similar compensation, but to my ear it doesn't do quite as well as the traditional "blocks" and especially "up the string" it requires some practice to accomodate the very slightly different string heights. Tried one once. Didn't much care for it.
Once again due to the short string length, the "down force" applied to the bridge by the strings is - relatively - very much higher than for longer-stringed instruments. Only the best (hardest) woods suffice, and a "sturdy" structure is necessary.
On one occasion when a bridge broke during a festival, and no replacement was available, a piece of a wooden clothespin was the only wood I could find that was hard enough to whittle (actually Dremel grind) a replacement that lasted more than a few minutes. That one did last me for about three years before I found a "real" bridge locally - although toward the end it also broke in a way quite similar to the fracture of the original. (Its hard to find a clothespin with "properly aligned grain.")