One of the most enjoyable things about making and trying mandolin bridges has been (sometimes) verifying old assumptions about bridges, but (more often) finding out new things. Last time we talked about bridge weights, and how conventional bridges can bee heavy enough to mute the mandolin. Today, let's talk about another dimension: bridge length.
The Gibson company, long ago, made one-piece ebony bridges for their mandolins. These bridges were about 4" long and a little less than 1/4" thick. But then after Gibson introduced adjustable bridges, they began making them 4 1/2" long. If the change was made gradually over several factory-sample bridges, probably no one there noticed a difference in the sound. And bridgemakers ever since have copied that Gibson bridge-length of 4 1/2".
But soon after I began making maple bridges, I wondered about how bridge length could affect the sound. My earliest bridges were about 4" long, but I decided to make an extra-short bridge, only 3 1/2" tip-to-tip. Here's a photo (this was a very early winged bridge):
The sound of this bridge was very disappointing, and I was at a loss to explain why. My previous bridges had almost all sounded fine. But after thinking about it for a while, I wondered if I'd made the bridge too short for good sound. So I made my next bridge #11, much longer, about 4 1/2" tip-to-tip:
--this bridge sounded better than #10, but I thought it could be improved. So I began shortening it and playing it, to find out where the best bridge-length was as far as the sound was concerned. Below about 4 1/4" length the tone and volume really improved, and it kept sounding good until I shortened the bridge below 4" in length.
I tried this experiment another time starting with an extra-long maple bridge, and then two additional times with regular 4 1/2"-long adjustable bridges, shortening their bases until the sound improved (at about 4 1/4" bridge-length), and then deteriorated (below 4" length). All these bridges confirmed the principle for both one-piece and two-piece mandolin bridges: the best sound, for most bridges and most mandolins, seems to come with a bridge length between 4" and 4 1/4".
So a mystery was solved, and some mandolin knowledge was gained: Bridge #10 sounded poor because it was too short, and conventional bridges may lose some sound because they're too long. So I've made all my bridges since then to be between 4" and 4 1/4" long.
Have I said that making maple bridges is easy? -- Well, it is. It's coming up with the design that was hard!