The Murphy Method Blog

I was recently talking with one of our students about my mandolin bridge experiments, and thought that others might like to see some examples of how I found out which bridge woods sounded the best. Here’s a detailed experiment in which I compared mandolin bridges made from ten different woods other than maple, and some of the woods were rather exotic (each bridge is about 4 inches long):

Here are the 10 woods, with the weights when the bridges were finished and tried:

In the left column:

Bridge #83. Ebony, 10.5 grams

Bridge #85. East Indian rosewood, 7.5 g.

Bridge #84. Brazilian rosewood, 8.9 g.

Bridge #67. Bloodwood, 10.4 g.

Bridge #66. African Blackwood, 8.7 g.

In the right column:

Bridge #89. Extra-heavy maple, 7.1 g.

Bridge #90. Teak, 7.6 g.

Bridge #88. Satinwood, 10.1 g.

Bridge #91. Persimmon (American Ebony), 8.7 g.

Bridge #92. Honduras mahogany, 6.4 g.

…and here were the results:

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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:

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If some of you are members of the Mandolin Cafe discussion site, you’ve seen that mandolin bridges have generated a couple of good discussions lately. One topic has to do with a subject of many experiments I’ve done, and that is mandolin bridge weight.

Most folks may never think much about the bridge that comes on their mandolin—it’s only a bridge, right?—but finding the right bridge is possibly the easiest (and sometimes the cheapest) way to give your mandolin a big improvement in sound.

One well-proven possibility is to put a maple bridge on your mandolin. Maple bridges are easy to make, and the material is cheap. I also offer bridges that I make (check out my bridge page), but I recommend that you make your own, starting with designs that I’ve developed and going on to test your own ideas.

One of the most remarkable things about maple bridges is that they weigh so much less than conventional, two-piece ebony ones. For example, a maple bridge will typically weigh from 6 to 10 grams installed, and a two-piece ebony bridge might weigh from 13 to 22 grams! —that’s a lot of extra bridge-weight for the mandolin to try to overcome.

So how did I find this out? By making over a hundred experimental bridges. First, I tried to make lighter and lighter bridges. Here’s a photo of Bridge #2:

This bridge was fairly thin and weighed only 4/5 grams, which I soon found out was pushing the low end of the bridge-weight range. My next bridge, #3, was even thinner and lighter, coming in at about 4 grams:

–and not only was the bridge thinner than the last one, but the sound was thinner too, with less volume as well. So now I had a lower limit on bridge weight. I made a much heavier bridge, almost 1/2″ thick, and reduced the thickness gradually while playing it to see how the sound was changing. It turned out the best sound came into the bridge at about 10g., and then there was very little variation until the weight came down to 4g. or so. After another 15 or so bridges, experimenting with the design as well as the weight, I developed a standard model:

This “winged” bridge was my standard for a couple of years. These have all weighed about 7g. to 10g. installed (on bluegrass mandolins), and their sound is very rich, clear, and consistent.

So that’s how I found out the best weight for a mandolin bridge. Don’t believe it? Try making one for yourself!

When I first began making maple mandolin bridges I got a good bit of flak from folks who were wedded to the conventional bridge stereotype—the idea that because the Gibson company had used ebony for its adjustable bridges (and for the one-piece bridges before that), there was no way to improve on the conventional mandolin bridge. But I believe that the Gibson company, restricted by its requirement for profitability, may never have experimented much with mandolin bridges. It takes some time and imagination to do a lot of bridge experiments, and all that would have gotten in the way of producing mandolins. So now, it’s up to us!

For centuries, the violin world has known that maple is the best wood for bridges. Now, the Gibson company boasted that they took many of their F-5 mandolin design aspects from fine violins: the arched, finely “graduated” top and back; the f-holes; and the elevated fingerboard and tailpiece, for example. But they seemed to stop when it came to the bridge. So I thought I’d make a one-piece maple bridge for one of my mandolins (Randy Wood #3) and see how it sounded. Here’s a photo of Bridge #1. The bridge was really crude, but it sounded great!

…with this bridge, the tone was smoother and the treble was clearer, and the volume took a jump. I could see that I was onto something. So I kept on trying more and more bridge designs until I found my three favorites, the ones I talked about a few days ago.

While I developed the one-piece bridge designs, I also tried out new woods. If maple worked so well, I thought, shouldn’t I try out a lot more woods including the traditional bridge woods, ebony and rosewood? So I started making bridges from lots of wood, and you might think I got carried away. I eventually tried out about 30 or 35 kinds of wood. Here are eighteen of them, with their sound compared and described:

… you can see that while there were quite a few woods that approached the sound of maple, none of them were better. So that’s why I settled on maple as the best wood for mandolin bridges. Since then some mandolin builders I was in touch with, including Peter Coombe, Bill Bussman, and Randy Wood, have started providing one-piece bridges of maple (or ebony, in Peter’s case) on the mandolins they make, either as standard equipment or by the customer’s request.

I do sell maple bridges on our website but I recommend that you make your own. If you play mandolin and you’d like to do some light woodworking, check out the bridgemaking page, where the steps to making a bridge are listed and described. It’s fun, and it’s by far the cheapest way to upgrade your mandolin’s sound! Try out some different designs and let me know how they do. Good luck!

OK. In my first article about bridges, you got an idea of the experiments I’ve done in finding out what kind of bridge sounds best. Now, let’s go over some choices in bridge types, which you can use to bring out one part or another of your mandolin’s sound. These three are the very best of the 25 or 30 designs I have tried:

a. The 11-hole bridge

This design is my favorite, and offers exceptional volume along with excellent richness, giving a pleasing bass/treble balance with remarkable clarity and sustain. This is a first choice for bridges 5/8″ inches high or more, and it sounds very good in a variety of woods including maple, cherry, yew, and mahogany. (My current regular-height bridges, and some low-profile bridges also, are of this type.)

b. The 6-hole bridge

Comments: Developed after more experiments, this design yields not only volume but also exceptionally clear highs and excellent sustain, with a satisfying “fullness” of sound. For oval-hole instruments, there seems to be little difference between the 6-hole and 11-hole designs. This design can also be used where there is insufficient vertical space for an 11-hole pattern. (Some of my low-profile bridges, and all my bridges below 1/2″, are of this type.)

c. The winged bridge:

Comments: This design was the first one I developed, and was my standard for two years. The sound typically features very good volume, a resonant low end, very good sustain and clarity, and excellent projection. Overall volume may not be quite as good as with the 6-hole and 11-hole bridges, but these winged bridges have an advantage over the 6 hole type in richness.

—so there you have three excellent designs for one-piece bridges, developed by sheer experimentation from a lot of other types. For a history of bridge experiments, take a look at these early bridges. And I urge anyone with the interest to make your own maple bridge. It’s the cheapest way I know to make a mandolin sound better!