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Thread: Intonation - Bridge Placement

  1. #1
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    Default Intonation - Bridge Placement

    Hello - I just acquired a 2004 MT. It is aesthetically perfect, as the original owner took excellent care of the instrument. It will need the fist 5 or 6 frets replaced, so it is not perfect, but it looks and sounds outstanding.

    I found the intonation was + 10 cents sharp across the all strings. I had to move the bridge towards to tailpiece appx 1/8" to dial in intonation at the 12th fret. Brand new EXP J74's. I used 2 different quality tuners to verify my findings.

    The bridge has never been moved per the seller and he stated that it came set up that way from Collings. Assuming it was correct when set up originally by Collings 8 years ago, is it uncommon to need this much adjustment over time?

    My adjustment is nearly centered with the F hole points, which is ballpark on a fiddle. Either the bridge placement was never correct, or something has occurred over time to require this much adjustment.

    Thoughts?

  2. #2

    Default Re: Intonation - Bridge Placement

    Lots of perfectly normal setup issues can cause bridge position to need a slight nudge. String choice and bridge height can really affect this, for example. A refretting means you will get a setup automatically if you use any quality luthier, so I'd just ask whoever was going to do that for an opinion if you are worried. Personally I wouldn't lose any sleep.

  3. #3
    Registered User Steve Sorensen's Avatar
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    Default Re: Intonation - Bridge Placement

    Putting on new strings will also often pull (or tip) the bridge towards the nut as you tighten the strings. Normal to adjust until the intonation is correct including making sure the bridge is seated fully on the top.

    Steve
    Steve Sorensen
    Sorensen Mandolin & Guitar Co.
    www.sorensenstrings.com

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    Default Re: Intonation - Bridge Placement

    Steve - I visited your website and noticed a number of photos illustrating your compensated saddles. Very impressive. I should have added in my OP that I found using the the G and E strings to measure and set intonation caused the A and D strings to be noticeably sharp. I also noticed the bridge had slight angle and didn't look right. I ended up using the E and D strings for the my best overall result. The G ended up a few cents flat, but not terribly so. I can live with it for now. I'll likely be looking into finding a bridge/saddle with a little more forward comp on the G.

    As mentioned, lots of set up variables to observe and consider regarding this matter. I appreciate the feedback, as I've much to learn.

    Thanks

  5. #5
    Registered User sunburst's Avatar
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    Default Re: Intonation - Bridge Placement

    First, it is normal for the bridge to work it's way toward the neck from tuning and re-stringing. Second, your bridge top can be cut for better intonation by someone who knows how... that could be you if you learn how.

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    Default Re: Intonation - Bridge Placement

    If I understand you correctly, and your strings are in tune when open and then are sharp when fretted, I think you may need to check the nut as well. Make sure to file the nut slots andgled back down towards the tuning pegs. Email me at rob.meldrum@gmail.com for my free book on how to set up a mandolin (free to all mandolincafe.com members).

    Common setup issues are addressed and you'll learn how to use automotive feeler gauges (five to ten dollars for a full set at any car parts store, Wa!Mart or H@rborFreight) to measure your string heights at the nut and the 12th fret, make custom-width nut saws from the feeler gauges, and how to intonate the mandolin.

    You'll learn a lot and either learn to set up your own mandolin or take it to a shop and then verify the quality of the set up.

    Rob

  7. The following members say thank you to Rob Meldrum for this post:


  8. #7
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    Default Re: Intonation - Bridge Placement

    Rob - To clarify, once I set the intonation at the 12th fret (was +10 cents sharp) all notes sound in tune when fretted with the exception a couple of notes on the second fret (deeply grooved) which needs replacement from normal string wear over time. I have your book (thanks BTW) and have looked it over a couple of times. Very helpful for someone new to the instrument as myself. I've been around guitars for years, so I've a pretty good feel for the minor adjustments I'm making. I got a quote today from Dusty Strings for a partial re-fret and setup that I thought was reasonable. They've got a pretty long waiting list, but I trust their work from personal experience. So I'll wait my turn.

    I'll look into compensating the G String portion of the bridge and see if I can figure it out. I've got one on the way from ebay to start the experiment.

  9. #8
    lonewolf
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    Default Re: Intonation - Bridge Placement

    "sunburst has it exactly right.

    The one thing I do beyond that, is to mark the position of the back edge of the bridge base, so I can easily reposition it, when it moves, and it will. I use two very tiny strips of clear scotch tape (maybe 1/8' by 1/4"), laid in place carefully, with a pair of tweezers. They almost disappear after contact with the finish, and can always be removed if you change set-up parameters, which will change your intonation points.
    Gene Warner
    retired repairman

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    Default Re: Intonation - Bridge Placement

    Good tip on marking the bridge with clear tape. I'll do so. Finding the bridge off by an 1/8" clearly supports what has been discussed here about bridge movement over time.

    Poking around in the achieves I found a comment by John regarding individual string compensation if needed. Now I can't find it... but the gest of it was to set the intonation at the 12 fret using the the flattest string. Set bridge placement for correct intonation for that string (all other strings would be equal to or sharper at the 12th fret harmonic) and then file the leading edge of the saddle slots on any strings that are sharp until the correct intonation is achieved. I think I've got that right.

    What's the minimum width of the saddle top surface before it breaks down? It's like 1/16" now, not much material there to remove at this point. I'm thinking less than half would be needed, leaving like +1/32". Perhaps a different bridge with a little more meat in that area would be a better approach. Thanks for the help thus far. If anyone has a favorite bridge for this specific purpose, please do tell.

  11. #10
    Registered User sunburst's Avatar
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    Default Re: Intonation - Bridge Placement

    That's the procedure. If the top of your bridge is too thin, you can replace it, or if there is plenty of adjustment, you can just cut some off the top so that what remains is wider at the top surface. I don't like to cut much wood off of bridge tops, though, because it weakens them.

  12. #11
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    Default Re: Intonation - Bridge Placement

    "you can just cut some off the top so that what remains is wider at the top surface"

    That seems so obvious now that you mention it, and there is adequate bridge height to do just that. I'll heed your advice to do so conservatively. Thanks John!

  13. #12
    Registered User Ivan Kelsall's Avatar
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    Default Re: Intonation - Bridge Placement

    It's amazing really what folk will put up with. A fellow 'cafe member recently e-mailed me re.a 'used' mandolin that he's just bought.
    He had to move the bridge back towards the t/piece by quite a bit to get the intonement right,leaving an imprint of the bridge foot where he believes the bridge has been sitting for the last 8 years - out of position !,
    Ivan
    Weber F-5 'Fern'.
    Lebeda F-5 "Special".
    Stelling Bellflower BANJO
    Tokai - 'Tele-alike'.
    Ellis DeLuxe "A" style.

  14. #13

    Default Re: Intonation - Bridge Placement

    I can affirm that this guide mentioned above by Rob Meldrum is a thoughtfully devised and exceptionally well written guide. I emailed Mr. Meldrum as I was about to start my setup and figured i would hear back in a few days, so I went ahead and got started with my very first setup. The setup went fairly well and my result was far better that what was achieved by the "professional" who I paid nearly $100 to do it when I first purchased my $400 mandolin. As far as I can see, all he did was tune it up. It even had two strings that weren't fully down into the grooves which he did nothing to address and this caused such ridiculous headaches in trying to learn to strum chords. I felt pretty dumb when I finally tried to force the strings down and they just popped right into place after causing me enough frustration I almost quit a couple times in those first 3 months. Duh! How did I not try that before??!!??!! Anyway, I wasn't quite finished when I received a response to my email with the guide included. I gave the guide the once-over and realized it was the most comprehensive, yet simply written setup guide I had seen anywhere. so I immediatly ran out and bought 2 sets of snew strings, a cheap set of feeler guages, and a couple other inexpensive and easily acquired supplies the author recommended and decided to do it all over again and even do it twice more if needed--just to learn and get comfy with the process. Lemme just say the third go round was not necessary. I had no idea how sweet this thing actually sounds. I already have plans to upgrade my "The Loar" with an eastman when reach the 6 months of practicing mark. But now I'm thinking I may be good with what ive got until I reach the one year mark; it sounds that much better. Thanks again! I highly recomend this guide.
    Last edited by Elliesdad; Feb-08-2023 at 1:42pm. Reason: messed up

  15. #14
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    Default Re: Intonation - Bridge Placement

    in my experience, there is no single bridge position that will make all strings happy at the same time. you could build a custom-compensated bridge and it will make *these strings* happy *today*. but if you use different strings, they will want different compensation. and as strings age, they will want different compensation.

    this is because what is being compensated are 2nd-order deviations from the theoretical ideal-string length-frequency curve.

    a non-ideal string is attached at the ends (so the slot shape and the material of nut and bridge matter). string flexibility at the attachment point matters (and it changes with time, metal fatigue). string density-along-it's-length distribution matters ("false string" affect) (and it changes with metal fatigue, with string material getting removed/worn out and sweat and elbow grease material getting added, non-uniformly along the string length).

    so bridge for new strings and bridge for old strings wants to be in different places.

    in my experience, for the music I play, I locate the bridge to have the A string intonate exactly (bridge position), I rotate the bridge to have the E or the D intonate well. I let the G string intonate "do what you can do" (which is quite well on my best instruments).

    the thing to remember, mandolins are tuned to equal-tempered intonation, which means it's "out of tune" equally in every key. if your friends play in just intonation, you will be out of tune with them and there is nothing you can do about it. (but note: some ouds have movable frets).

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