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Thread: Improper bridge placement and muted tone.

  1. #1

    Default Improper bridge placement and muted tone.

    Greetings cafe members! I have been the owner of a Carlson signed Gibson F5L for several months. After a few weeks I started to feel like it just wasn’t very loud and the sustain just wasn’t there. I was very happy with playability but had some issues with tone. I felt defeated to say the least. I loved the playability, feel, and look of the mandolin but it just seemed like it wasn’t “one of the good ones”. After several string changes and months now, I recently went to check the Intonation and noticed it off. I ended up making some adjustments that brought the bridge forwarded towards the neck more so than where it was and DEAR GAWD, did this thing open up. All the tone , sustain , and volume you could ever expect or want out of a high quality mandolin. I’m shocked really, the difference is incredible and I really can’t see myself ever parting with this instrument now. It makes me wonder, how does one know the correct spot for the bridge ? How far forward or back? I understand making adjustments once it’s close to the right spot, to ensure correct intonation but, what is a good rule of thumb for initial placement to allow proper movement of the the top and relative closeness for fine tuned intonation adjustments. If there are any tips to help me with that I’d much appreciate them. Not sure if there’s some trick with the f holes or some measurement that’s good to know. Thank you for taking the time to read this all who check it out and thanks in advance for the insight.

  2. #2
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    Default Re: Improper bridge placement and muted tone.

    I have found that as the instrument changes with seasonal humidity and heating the action will change. You have a couple choices. Don't worry about it and play it. Move the bridge to re intonate. I choose to carry a gauge for string height and adjust the string height often to keep everything sounding and playing good. I have a very low action so I feel when it is higher, and when it gets lower it buzzes. By keeping an eye on the string height I don't have to move the bridge. Intonation has a huge effect on sound, IMHO. I also make a light mark on the bridge and the top with a pencil, it will rub off easily but I can tell if I bumped my bridge and line up the marks. It's quicker when I am out playing and it is too loud to try and intonate. Use a soft pencil and don't press hard. I have not left a mark on the finish in decades of doing this.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

  3. #3
    Registered User Charles E.'s Avatar
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    Default Re: Improper bridge placement and muted tone.

    Rob Meldrum offers a free mandolin set up guide that is very popular here. You can request it from Rob here...

    https://mail.google.com/mail/u/0/?fs...drum@gmail.com

    Previous thread about it...

    https://www.mandolincafe.com/forum/t...in-Users/page6
    Charley

    A bunch of stuff with four strings

  4. #4
    Confused... or?
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    Default Re: Improper bridge placement and muted tone.

    Quote Originally Posted by MashMeister View Post
    ... how does one know the correct spot for the bridge?
    Don't be thrown by the elecric guitar; he's still talking archtops:
    http://www.frets.com/FretsPages/Musi...p/atsetup.html

    The underlying logic is:
    - The 12th fret is an octave up from the open string; that should give twice as many vibrations per second.
    - The 12th fret "should" be at half the length of the string, to double the vibration, BUT...
    - There must be room for the string to vibrate, so the string sits above the 12th fret by a bit.
    - Pushing the string down to the 12th, or any other, fret stretches the string, thus raising the pitch; not good!
    - "Compensation" is the art of leaving slightly more room between the 12th fret and the bridge than between the 12th fret and the nut, allowing the proper note to sound even after the string is fretted & stretched.

    Interestingly, the "stated" scale length is TWICE the distance from the 12th fret to the nut, even though the actual vibrating length of the string is longer by maybe 1/10 inch. And, different composition metal strings (thickness, windings, etc.) react differently to stretching, so we have saddles that are "stepped" (or just angled on guitar) to accomodate the different strings.

    Aside: Nylon reacts differently, so nylon-string guitars generally have the same compensation for all strings, meaning the saddle is not angled.

    But DO get Rob Meldrum's book!
    - Ed

    "Then one day we weren't as young as before
    Our mistakes weren't quite so easy to undo
    But by all those roads, my friend, we've travelled down
    I'm a better man for just the knowin' of you."
    - Ian Tyson

  5. #5

    Default Re: Improper bridge placement and muted tone.

    You did not say how far you had to move it. If it was a significant distance then the bridge may have been moved away from the place where it was fit to. Poor fit of the bridge to the top will have all of the symptoms you talk about with muted tone, poor sustain and so forth. The bridge base being slightly tipped so it does not contact the top properly will also cause those things. If you can slip a piece of paper under the bridge then it is not fitting to the top. Correct fit of the bridge will make a night and day difference in a mandolin.

  6. #6

    Default Re: Improper bridge placement and muted tone.

    I can slip a piece of just barely in on the back side of the bridge towards to tail piece but not all the way through at any point. I can’t slip a piece through the front at all. Mostly the outer edges of both sides towards their respective f holes.

  7. #7

    Default Re: Improper bridge placement and muted tone.

    The first rule beat into me in my shop days was "don't fix what ain't broke". If it sounds great now I would leave it alone.

    Ideally the paper does not slip underneath at all. When I have fit bridges if it slips under 1/8 inch anywhere I work on it some more. If there is a tiny bit on a corner I leave it.

    But again if it sounds great play it and do not worry.

  8. #8

    Default Re: Improper bridge placement and muted tone.

    Quote Originally Posted by MashMeister View Post
    I can slip a piece of just barely in on the back side of the bridge towards to tail piece but not all the way through at any point. I can’t slip a piece through the front at all. Mostly the outer edges of both sides towards their respective f holes.
    Carl was right on about the bridge not making solid contact at it's old position. The fitting in it's present position needs to be fine tuned, paper should not be able to fit under it. The process involves laying fine sandpaper on the top and rubbing the bridge feet across it until the two are perfectly mated. There are some threads on here about the process.

  9. #9
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    Default Re: Improper bridge placement and muted tone.

    Quote Originally Posted by MashMeister View Post
    I can slip a piece of just barely in on the back side of the bridge towards to tail piece ... can’t slip a piece through the front at all.
    I've mentioned this previously (and never ever by anyone else) but once more can't hurt ...

    That happened to me once and the sound went all to heck. I DID IT TO MYSELF, while experimenting w/ altered tunings over a several-week period.

    I continually loosened two or three courses, played a bit, then tightened 'em back up, bringing them up to pitch more-or-less at once. I eventually realized that:
    - loosening 2 or 3 courses greatly reduces the downward stabilizing pressure on the bridge, while,
    - tightening 2 or 3 courses, together, tends to put a bit of neck-ward pressure on the bridge, just as the stabilizing force is reduced.
    Repeated loosening & tightening (especially of other courses) just adds to the neck-ward pressure, slowly building to a neckward lean.

    Since then, I make sure to tighten JUST ONE course at a time up to pitch, followed by re-tightening prior courses that may have come loose(er) under the added pressure on the arch. (Arch-tops, IMHO, tend to compress/expand under varied string pressure, even if just a tiny amount, more than we might expect).

    By having -only one- course at a time exerting sideways pressure as the others exert only downward pressure, that "currently-in-tuning" course tends to not overpower the others, and the string more easily slides across the bridge, with reduced pulling on the bridge.

    Yes, this is just one amateur's opinion. It may be theoretical, unproven, and just in my head, and the true experts may disagree, but it is my experience.
    Last edited by EdHanrahan; Jan-24-2023 at 11:18am.
    - Ed

    "Then one day we weren't as young as before
    Our mistakes weren't quite so easy to undo
    But by all those roads, my friend, we've travelled down
    I'm a better man for just the knowin' of you."
    - Ian Tyson

  10. #10

    Default Re: Improper bridge placement and muted tone.

    Many people are afraid of doing damage, whether to mandolins, car engines, or toasters. Straightening, or moving a bridge for best contact, especially under string pressure, probably qualifies as scary. Doing the sandpaper fitment thing would also seem dangerous. Even replacing strings can defeat otherwise competent adults. Nothing to be done about it, except that the supply of good instrument techs is limited, and many instruments will go for years sounding poor.
    It is true that, unlike a violin bridge, a leaning mandolin bridge isn’t going to come crashing down, but it won’t work either, so checking its stance should really be a player’s responsibility, even if fearful of putting it right.

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