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Thread: A fun bridge experiment

  1. #1
    Registered User SBrady's Avatar
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    Default A fun bridge experiment

    Hello all!

    I have learned and gained so much from this forum, so as a way of saying thank you, I'm posting a picture and a bit of info about a ridiculous bridge I made recently. Hopefully some of you will get a kick out of it. I really can't wait to see what Mr. Perry comes up with for his new bridge design. It will be obvious to you that my bridge is at the opposite end of the quality spectrum from Mr. Perry's work.

    There have been several interesting discussions on the topic of bridges in the past months, and I have been especially interested to read Dr. Cohen's comments about the short, squat, thick shape of mandolin bridges perhaps limiting them from displaying the twisting modes of motion you would normally find with a tall, thin violin bridge (please excuse this simplistic paraphrase). So I decided to try to build a mandolin bridge as much like a violin bridge as I could. I realized that I could get the same height/width ratio as a violin bridge if I split the mandolin bridge saddle in two. The shape is supposed to resemble two Joseph Curtin violin bridges next to each other (if the Curtin bridges were mauled by a bear). So here's my bridge:

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    And here's the Joseph Curtin bridge for reference:

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    The bridge is as thin as I dared to make it. The absolute miracle of it is the bridge doesn't sound half bad. It has roughly the same volume and sustain as my Cumberland Acoustics bridge, but it does make the trebles a bit more harsh (maybe just due to the lower mass), and it is not very balanced across the strings; the D course is particularly weak with this bridge. But if someone else with actual talent and experience in luthiery wanted to experiment with a similar design, I am surprised to say that I don't think it would be a complete waste of time.

    I'm sorry I don't have the time or resources to post a recording of this bridge, but I would be very happy to mail it to anyone who can weigh it, record it, and post the results to the forum. Just PM me.

    Thanks again to everyone, especially the moderators, for making such a fantastic forum. I'll finish by posting a picture of something you'll actually want to see: the truly incredible mandolin being made for me by the incomparable Steve Holst.

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  3. #2
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    Default Re: A fun bridge experiment

    Very interesting.

    1. The outer reaches of the feet seem to do nothing in this design. I suggest tapering them down from the leg and ending them closer in.
    2. Drill a hole in the middle of the big mass above the leg.
    3. Balance the D course by removing wood beneath the course if the hole in the big mass doesn't do it.
    4. Reduce harshness perhaps by removing wood from the sides of the new holes and from sides of the legs, if the holes themselves don't do it.

    Interesting design. Does eliminate the loaded beam issues across the middle courses.

    Thank you for posting.
    Stephen Perry
    www.giannaviolins.com - Primarily violin family
    mandovoodoo.com - Acoustic blueprinting
    South Side Chicagoland

  4. #3
    Registered User SBrady's Avatar
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    Default Re: A fun bridge experiment

    Thanks for your reply! I think it helps me understand a little more what you mean when you talk about tuning a violin bridge. Hopefully I'll get a chance to play with this little bridge a bit more. Thanks for all your help on the forum! The mandolin in the picture with my crazy bridge is a beater I use as a kind of Frankenstein's monster to perform cruel experiments. One of the things I did to it that did work well was to round the edges of the f-holes after I read one of your posts about your mandovoodoo process. I went way overboard with it just to see what would happen, but I thought the mando sounded a bit fuller and I could hear better dynamic range afterwards. Thanks again!

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    Default Re: A fun bridge experiment

    Interesting. Just a quik thought. Violin family bridges are intended for bowed instruments and tend to be weak for pizzicatto. The motion a bow induces in the string is very different. Thus I would not think making a mandolin bridge more like a violin would neccsarly be an improvement.

  6. #5

    Default Re: A fun bridge experiment

    Quote Originally Posted by Nevin View Post
    Interesting. Just a quik thought. Violin family bridges are intended for bowed instruments and tend to be weak for pizzicatto. The motion a bow induces in the string is very different. Thus I would not think making a mandolin bridge more like a violin would neccsarly be an improvement.
    Unless you like the sound of a violin being pizzicato'd. Personally I think it's one of the punchiest and richest sounds in stringdom, have recorded using it, really rings the bell.

  7. #6
    Mando-Accumulator Jim Garber's Avatar
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    Default Re: A fun bridge experiment

    I am curious... does splitting the bridge at the top makes any difference in the tone or volume?

    I checked Steve Holst's site and tho his design for mandolins is pretty modernized, it looks like he uses a pretty conventional bridge. Aside from Dave Cohen's mandolins, who else is building mandolins with their own proprietary bridges? I see quite a few tailpiece designs but few bridges.
    Jim

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    Resonate globally Pete Jenner's Avatar
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    Default Re: A fun bridge experiment

    I have a whacky bridge under development. I don't expect it to set the world on fire - just a bit of fun.
    More in a month or two.
    The more I learn, the less I know.

    Peter Jenner
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    Registered User SBrady's Avatar
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    Default Re: A fun bridge experiment

    Hi everyone!

    Nevin, I think you're absolutely right. I really didn't have any expectations for this little bridge (except maybe that it would most likely make my mando sound terrible). The idea was just to see if trying to coax out those twisting modes that Dr. Cohen sometimes talks about might make any noticeable difference in sound. (Of course, Dr. Cohen also points out, as you do, that bowing a violin is also a part of those twisting modes.) Another reason a mandolin bridge can't be like a violin bridge is that the mando bridge will always have to be much thicker so it doesn't snap under the heavy string tension. I think what Stephen Perry is talking about in his current thread on violin style bridges makes a lot more sense than the goofy experiment I did; he seems to be talking about making a bridge that he can easily fine tune, not to make a mandolin sound or function like a violin, but to make a mandolin sound the best it possibly can. I really am looking forward to seeing what he comes up with.

    High Lonesome Valley, that's a really cool thought! It gives another excuse to try finger style mandolin.

    Jim Garber, I'm not sure I've ever seen anyone else split the bridge like this. In my n-of-1 experiment, the biggest difference was noticeably less balance across the strings (compared to a Steve Smith bridge). When I initially put this weird bridge on, I was so surprised that it didn't sound horrible that I started to convince myself that it sounded a little better than the CA bridge. Then when I put the CA bridge back on a couple weeks later, it was immediately obvious that I preferred the sound of the CA bridge. Volume and sustain did seem to me to be genuinely about the same as the CA bridge. The short version of this is that it was a fun way to pass a bit of time, but there's no reason for anyone to rush to build bridges this way.

    I actually sent a picture of my bridge to Steve Holst about a week ago. He got a good chuckle out of it, and he mentioned that he has tried different bridge designs in the past, but he always comes back to the usual thumb wheel design. My silly bridge will absolutely not be going on the new Holst mandolin. The only builders I can think of who consistently use atypical bridge designs are Weber and Peter Coombe. Of course Marty Jacobson made some cool tweaks to the usual design.

    Pete Jenner, that was exactly my goal as well! The difference between the two of us being that you actually make mandolins, whereas I just waste time, so there's hope that your wacky bridge will result in something useful.

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    Default Re: A fun bridge experiment

    Without modeling or otherwise doing any analysis, I am not going to separate the strings by a middle split. By my way of thinking, each course needs to blend across the remainder of the courses to some extent. Much of my thinking focuses on how to build in places to focus the adjustments. I have wheels on screw threads for height, differential cuts for intonation, pendulums or pendulum equivalents for controlling response up the frequency range of each course, and a puzzling opportunity for beam strength manipulation, all of the above blurring together. I can do a good deal with surface working on the individual pieces, but this is out of the equation for a production type item. That was the issue with my maple violin bridge translation - the tuning took real puzzling out.

    For another tack at your bridge, I would:

    1. Join the top pieces together
    2. Put holes in each of the upper large masses
    3. Have the two struts come down onto a beam supported by two feet, if you can squeeze that in.

    Were I making one like this, I would do the shaping by tapping, listening, and removing wood until I got what I think the instrument would like. There's a good deal of intuition involved, and probably experience. I'd also rough out a bunch and modify in various ways. Looks like a whole day's work to me to get this a little more focused. I like it, though.
    Stephen Perry
    www.giannaviolins.com - Primarily violin family
    mandovoodoo.com - Acoustic blueprinting
    South Side Chicagoland

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    but that's just me Bertram Henze's Avatar
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    Default Re: A fun bridge experiment

    This reminds me very much of Red Henry's experiments with maple bridges and bridges on two feet. For some reason, the link that leads there from his website is now defunct. I could make good use of his results, though, by replacing the one-footed bridge on my OM by a two-footed one.
    the world is better off without bad ideas, good ideas are better off without the world

  12. #11
    Mando-Accumulator Jim Garber's Avatar
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    Default Re: A fun bridge experiment

    Quote Originally Posted by Jim Garber View Post
    I checked Steve Holst's site and tho his design for mandolins is pretty modernized, it looks like he uses a pretty conventional bridge.
    Quote Originally Posted by SBrady View Post
    I actually sent a picture of my bridge to Steve Holst about a week ago. He got a good chuckle out of it, and he mentioned that he has tried different bridge designs in the past, but he always comes back to the usual thumb wheel design. My silly bridge will absolutely not be going on the new Holst mandolin.
    Actually, I take back (sort of) what I said. I was just looking at Steve Holst's gallery page and found this sort of D'Aquisto-style bridge on it. I wonder if that was a one-time experiment.
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    Jim

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