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Thread: The so-called "compensated" bridge

  1. #1

    Default The so-called "compensated" bridge

    New strings on my mandolin, with the typical back-and-forth string saddle arrangement on its bridge. I'm moving the bridge and comparing fret-12 to harmonic-12 for best intonation.

    Jeez, when the Es line up OK, the 12th fret A is slightly flat and the 12th fret D is minutely sharp! So it goes - I gotta sdjust the bridge for a reasonable compromise between errors. Change to a new string brand or gauge, and there's a new set of errors to be compensated for.

    A fortune, or at least a couple bucks, awaits the luthier who invents a lightweight mandolin bridge with FULLY ADJUSTABLE SADDLE PIECES. We sent a man to the moon...

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    Orrig Onion HonketyHank's Avatar
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    Default Re: The so-called "compensated" bridge

    Oh boy!

    FWIW, I shoot for a bridge position that yields the best intonation at the 7th fret because good intonation up above that is the least of my worries when I make the rare foray into neverneverland. At least for now.

    It is still a compromise.
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    Default Re: The so-called "compensated" bridge

    Somewhere some time ago someone posted a picture on here of a bridge with each string being adjustable...I have always wondered why no one has mass produced these myself...I have seen them on electric guitars and I think they would be a huge help with the intonation on a mandolin...It is my opinion that a lot of builders think that if Lloyd Loar didn`t use it then it has no place, earlier mandolins didn`t have a compensated bridge saddle so what made the builders think that those with compensation was the correct way to go? It seems that most think that "Close enough is OK"

    Willie

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    Registered User foldedpath's Avatar
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    Default Re: The so-called "compensated" bridge

    If someone made a bridge with individually-adjustable saddles, I'd buy it. But it would have to weigh no more than my current non-adjustable bridge, and it would have to transfer acoustic energy with the same efficiency. Otherwise the tone would probably suffer. Or at least sound different.

    Keeping the same degree of acoustic transfer is probably the hard part, and the reason we don't see this kind of bridge for mandolin. On an electric guitar, there isn't the same need to milk every bit of acoustic energy from the strings to drive the top.

    Anyway, I can get my mandolin in near-as-dammit perfect intonation with my non-adjustable saddle. The key is to get the action as low as you possibly can (if you like that sort of thing, and because high action makes intonation more difficult). And don't be afraid to angle the bridge a tiny bit, if that gets you closer. My bridge doesn't like up exactly with the F-hole points, it's shifted down towards the tailpiece just a hair. There is also a very slight angle away from dead straight across the top. Always set up the bridge with fresh strings too, because it doesn't take long for intonation to go out with string wear. It can happen long before the strings start to sound dull.

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    Default Re: The so-called "compensated" bridge

    Intonation changes up and down the fingerboard. It is common to check and set it at the 12th fret, but to get the full picture, you actually need to check it at each fret. There are a lot of variables at work.
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    Default Re: The so-called "compensated" bridge

    I would set the bridge so than no string is flat, then take off wood on the sharp strings so they all are fairly close at several places on the neck.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

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    Registered User sblock's Avatar
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    Default Re: The so-called "compensated" bridge

    First off, exact compensation is simply not possible with a fretted instrument, because the amount of compensation required varies us you move up the neck to ever-higher frets. Furthermore, it changes with the string type/diameter and with the action height. Folks who want this to be perfect may be barking up the wrong tree. But it certainly can be made a bit better or worse.

    The engineering challenge with producing a mandolin bridge with individual compensation adjustments (for each string) is that is is not acoustically equivalent to a conventional mandolin bridge, which we all like the sound of. First and foremost, the individual mechanisms involve adding a LOT more mass (including extra metal) to the saddle area. This mutes the instrument, and the mandolin is quiet enough already, thank you! Second, they mechanically decouple the adjacent strings from one another, and this dramatically affects how the string vibrational energy gets propagated through the bridge to the top. In short, the sound will be very different.

    Individual string compensation adjustments are quite feasible on an electric guitar, where the issues of weight and string-decoupling don't apply, are they are widespread among electric fretted instruments (pedal steel, bass, etc.) But they tend not to adopted for acoustic guitars, either, for the reasons stated. And they would be even worse for an acoustic mandolin!

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    Middle-Aged Old-Timer Tobin's Avatar
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    Default Re: The so-called "compensated" bridge

    Chasing perfect intonation on a mandolin is like hunting for the Abominable Snowman. You'll never find it. And even if you think you have found it, it will disappear shortly.

    Fretted instruments are an exercise in compromise. Get it close enough to where the music doesn't suffer too badly, and move on. None of your mandolin heroes have perfect intonation on their mandolins, but you still enjoy their music, right?

    With that said, I set intonation at my bridge based on the G and A strings. It's always the A string intonation that bothers me when it's off. The D and E strings end up where they end up, and it sounds fine.
    Keep that skillet good and greasy all the time!

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    NY Naturalist BradKlein's Avatar
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    Default Re: The so-called "compensated" bridge

    Quote Originally Posted by T-E-F View Post
    A fortune, or at least a couple bucks, awaits the luthier who invents a lightweight mandolin bridge with FULLY ADJUSTABLE SADDLE PIECES. We sent a man to the moon...
    Your wish is granted! It was designed, patented, and manufactured by or for Albert Shutt of Topeka, Kansas at the very beginning of the 20th century. Here is one. A century old, and working fine.

    Click image for larger version. 

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    Just ebony construction as far as I know. No metal. The saddles are small asymmetrical triangles held in place by string tension. I'm not saying, by the way, that this is a 'good' design. Just that it's basically workable and was patented a century ago. When this important instrument is fully restored (Shutt #1001, likely the first of this model), it will probably be with a simple one piece bridge, and the original will be preserved.
    Last edited by BradKlein; Jun-23-2017 at 3:02pm. Reason: added construction details and patent link
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    Default Re: The so-called "compensated" bridge

    Quote Originally Posted by BradKlein View Post
    Your wish is granted! It was designed, patented, and manufactured by or for Albert Shutt of Topeka, Kansas at the very beginning of the 20th century. Here is one. A century old, and working fine.

    Click image for larger version. 

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    Interesting! I note that the height of that Shutt bridge is not adjustable. Writing for myself, I would vastly prefer height adjustment over individual string compensation. Also, the four tilting slot components almost certainly communicate vibrations to the remainder of the bridge via some internal metal pivots, or hinges (which I'm inferring exist, allowing them to tilt about the axis of this pivot, but cannot see in the photo), and not through sideways interactions in the slotted bridge base. This arrangement will almost certainly change the sound (for better or worse, I can't say!). Those pivots also make the bridge a bit more massive that it otherwise might be (but then again, it's missing the metal used for height adjustment), and that will change the sound, too (for better or worse, I can't say).

    It looks like the only thing that might be holding the individual compensators in place is the string tension, or perhaps friction in the pivots? If so, do you have to set it (or worry about it getting accidentally re-set?) every time you change strings?

    Anyway, it's a promising start. All bridges will sound a bit different. Maybe there's room for some modernized version of this bridge design, but with full-up height adjustments? It may alter the sound a bit, but folks might like it even more. Who can say? I note that Vern Brekke introduced a height-adjustable bridge on early Weber mandolins that was lightweight and could be adjusted under full string tension (but had fixed compensation), and had a lot less metal in it. Some folks really liked that design, and the way it sounded. Other didn't like the way it changed the sound compared with traditional Gibson thumbwheel-style bridges. In the long run, the Brekke bridge design has not been widely adopted, but it does have some niche applications. Change is hard.

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    Default Re: The so-called "compensated" bridge

    I used to worry myself as well, but then after thinking about it a little (with a beer in hand) I realized it didn't seem to concern my favorite artist John Reischman or even todays players like Chris Thile playing Bach. They sound wonderful, so at my playing level the small inconsistencies in intonation are not going to make me sound worse (or better).
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    Default Re: The so-called "compensated" bridge

    IMO, the single most valuable modification I can imagine to the common adjustable bridge would be to have wider saddles, therefore allowing for more adjustment (by hand-filing) to the separation from string to string.

    In my experience, most bridges have too large of a difference between the E and A saddles (causing the issue you describe).
    Or, you can flip the saddle around, but this often sets the G string too far back and makes it flat.
    And all this doesn't even begin to consider the intonation perfecting and correction that (if you do it) should be done at the nut......
    Jeff Rohrbough
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    Registered User foldedpath's Avatar
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    Default Re: The so-called "compensated" bridge

    If a material close enough to ebony density and acoustic properties could be run through a 3D printer, then it would be possible to make our own saddles with custom offsets, sneaking up on the correct settings by trial and error (and re-printing).

    I guess you could do that now if you had a fancy CNC rig, set up to mill ebony blanks.

  20. #14

    Default Re: The so-called "compensated" bridge

    All of the mass produced mandolin bridge tops that I have seen are poorly compensated for today's popular string gauges. As has been noted by others in this thread, the A - string is the worst culprit but not the only problematic string. Getting your intonation perfect at the 12th fret will not solve all intonation issues up and down the fingerboard but it will get you closer than what the majority of folks are putting up with.
    Years ago, I made a bridge top with no filed in compensation notches. I then strung it up with J74s, the brand I use as standard. Using a spark-plug gapping, feeler gauge, the wire type that are shaped like a hockey stick, or "L", I inserted the wire under the strings, one pair at a time. I then moved the wire back and forth until the string pair intonated perfectly at the 12th fret. Once done, I carefully measured the string length and subtracted my scale length to get the amount of compensation required for each string. From that time on, I have made my own bridges that are well compensated for J74 (or similar) strings.
    If we make a traditional bridge top where the E - string comes off of the very front edge of the bridge, then the rest of the "set-backs" will be as follows. 1.9mm back from edge for the "A", 1.5mm back from the edge for the "D" and 2.3mm back from the edge for the "G". (assuming J74 or similar gauges)
    As mentioned, this won't solve all of the various intonation problems inherent in fretted instruments but it will be a big improvement. Other things that will help are, nut slots as low as possible, action height low, not using excessive down force while fretting a string and of course, a bit of tolerance and resignation on the musician's part.
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    Registered User sblock's Avatar
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    Default Re: The so-called "compensated" bridge

    Quote Originally Posted by foldedpath View Post
    If a material close enough to ebony density and acoustic properties could be run through a 3D printer, then it would be possible to make our own saddles with custom offsets, sneaking up on the correct settings by trial and error (and re-printing).

    I guess you could do that now if you had a fancy CNC rig, set up to mill ebony blanks.
    Well, probably a better way to do this same thing would be to produce a "jig" bridge saddle with screw-adjustable compensation for each individual string. The jig saddle would sound terrible, but that's not the point. You would adjust the jig saddle to the desired action height, then tweak the individual string compensations until you had these right where you wanted them. You would then remove the jig saddle and use it to record the desired offsets set for each string. You would then carve a real ebony (or bone, or other) saddle with these custom values. No need for a 3D printer, and no need for awkward trial and error with multiple saddles. You might even be able to convince an existing company (Steve at Cumberland?) to modify their CNC saddle instructions to use your custom offset values, for a price, or get a luthier to carve you one to your specs.

    Or maybe you could convince Steve at Cumberland to try making a new line of bridge saddles with the "modern" compensations for J74 strings worked out by Oliver Apitius, which he generously just shared?! You would probably need to convince him that there's a market. How many MC players would want one?

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    two t's and one hyphen fatt-dad's Avatar
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    Default Re: The so-called "compensated" bridge

    I too have much bigger worries (e.g., dynamic range, clams, etc.)!

    That said, I adjust intonation according to the fretted note. Fretting elongates the string, etc. and influences the pitch - or so, I'd imagine?

    Is the most informed intonation adjustment made on the harmonics? I just never thought that?

    (I do have a compensated nut on my A3 and that's really what it took for my ear.)

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    f-d
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    Default Re: The so-called "compensated" bridge

    I will presume you are talking about a typical Gibson-style bridge. But is it an Asian bridge or American made? There is a difference in the way they are compensated. (And no disagreement with previous comments about the difficulties of getting perfect compensation or the effects of string gauge or type.)

    In the diagram below the fingerboard and nut is UP, and the tailpiece is DOWN. The Asian-style compensation is designed so that the saddle can be flipped 180 degrees and it's the same. Therefore it's impossible to install it wrong, BUT it has less compensation. The Gibson-style saddle below is often installed backwards, 180 degrees from what is shown. But the diagram below is the correct orientation. You'll notice it has relatively larger difference in string length between the E and A string. I'm not going to claim that the standard Gibson bridge installed in the correct orientation will give you perfect compensation. But I want to point out that not all bridge saddles are the same.

    Steve

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    Default Re: The so-called "compensated" bridge

    When I intonate an electric guitar if the player is a rhythm player I intonate around the 7th fret so it is less off by the nut and still not bad at the 12th fret. A lead player that hangs around above and below the 12th fret a lot I would intonate so the 12th fret is on. I don't see why mandolins are any different. If you never play past the 7th fret or get to the 12th fret, why intonate there. I would move it down so it intonates where you spend most of your time playing. As I posted earlier, taking some wood off the saddle for sharp strings is not that hard and makes it play in tune better. I agree the A string is the worst and making sure that plays in tune is a great start.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

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    Default Re: The so-called "compensated" bridge

    Quote Originally Posted by pops1 View Post
    When I intonate an electric guitar if the player is a rhythm player I intonate around the 7th fret so it is less off by the nut and still not bad at the 12th fret. A lead player that hangs around above and below the 12th fret a lot I would intonate so the 12th fret is on. I don't see why mandolins are any different. If you never play past the 7th fret or get to the 12th fret, why intonate there. I would move it down so it intonates where you spend most of your time playing. As I posted earlier, taking some wood off the saddle for sharp strings is not that hard and makes it play in tune better. I agree the A string is the worst and making sure that plays in tune is a great start.
    I brought my first good mandolin back to the luthier a few weeks after I got it and told him I thought the intonation was off. I hit a few open chords and went up and down the neck a bit and explained where it was off a few cents here and there.

    He basically told me what you just said, in different words, and told me that if I needed an instrument that had perfect intonation up and down the neck, he could make me a violin.
    A quarter tone flat and a half a beat behind.

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    Registered User Mandobart's Avatar
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    Default Re: The so-called "compensated" bridge

    I put one of these on my Eastman mandocello as part of its guitar conversion. Sounds and works great. I'm sure they could make one for a mandolin as well - probably not enough demand. I haven't had a lot of trouble with getting the intonation right on my mandos. If there is a problem its usually at the nut.

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    Default Re: The so-called "compensated" bridge

    The zig-zag compensation assumes certain string types and is not automatically correct. I get near-perfect pitch up to my highest fret with a simple slanted saddle. This is mainly due to using light strings which have less difference in flexibility.

    Instead of using packaged sets it is better to choose the right gauges for your mandolin. If the A plays flat to the D the answer is a thicker A or thinner D.

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    Default Re: The so-called "compensated" bridge

    Quote Originally Posted by Austin Bob View Post
    I brought my first good mandolin back to the luthier a few weeks after I got it and told him I thought the intonation was off. I hit a few open chords and went up and down the neck a bit and explained where it was off a few cents here and there.

    He basically told me what you just said, in different words, and told me that if I needed an instrument that had perfect intonation up and down the neck, he could make me a violin.
    I have normal gauge strings and low action and intonate up the neck just fine. You need not play a violin, but maybe you need a different luthier. I know nothing plays in tune perfectly, even a piano is tuned so the choruses of strings are not the same. My mandolin plays very well in tune and I play up the neck a lot. It takes some constant adjustments, but I carry a gauge for action adjustments and do it often. If I keep my string height above the frets the same and the instrument is intonated well it stays intoanted well. Humidity and temp changes may change your action and if you don't compensate regularly then you won't be intonated correctly. Once setup doesn't mean it will stay there, it is a constant thing checking and adjusting, but it is very much worth the effort.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

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    but that's just me Bertram Henze's Avatar
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    Default Re: The so-called "compensated" bridge

    Quote Originally Posted by T-E-F View Post
    ... We sent a man to the moon...
    If that is the budget range you have in mind, something might turn up
    But seeing how most of astronaut communication was about fixing this, tweaking that and never being sure that it worked, the moon missions were as close to mandolin tuning as you can get. The key to success is being grateful to return from the moon (or the stage) alive.
    the world is better off without bad ideas, good ideas are better off without the world

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    Default Re: The so-called "compensated" bridge

    Quote Originally Posted by acousticphd View Post
    IMO, the single most valuable modification I can imagine to the common adjustable bridge would be to have wider saddles, therefore allowing for more adjustment (by hand-filing) to the separation from string to string. ...And all this doesn't even begin to consider the intonation perfecting and correction that (if you do it) should be done at the nut.
    I've been considering getting extra fussy and cutting a new bridge for my main mandolin, putting on a Zero Glide nut to get the advantages of a zero fret, and making a solid bridge out of a piece of ebony, using wire to really dial in where the compensation should be.

    What's pretty funny though is that my mandolin already has excellent intonation and incredibly low action up and down the board, thanks to my instrument tech's amazing set-up work. Chord-melody playing is a dream.

    The reason I've been considering it off and on is to reduce the weight at the bridge *and* going with a solid bridge. Even so, i've been on the fence for a few years now, so it's clearly not urgent....
    ----

    Playing a funky oval-hole scroll-body mandolin, several mandolins retuned to CGDA, three CGDA-tuned Flatiron mandolas, two Flatiron mandolas tuned as octave mandolins,and a six-course 25.5" scale CGDAEB-tuned Ovation Mandophone.

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    Default Re: The so-called "compensated" bridge

    Most of us know that the fret positions on fretted instruments are not 100% accurate when it comes down to comparing note/note on different strings - they are a very good 'approximation' of the correct positions.

    On my mandolins,i usually set the bridge so that the "A" strings are as accurate as possible checked with my tuner on open/fretted & harmonics at the 12th fret. If i then tune up the G,D.A,E strings to my tuner,comparing one string pair to another produces differences so tiny they're not worth bothering about - in fact,it's possibly due more to 'string stretch' than inaccurate frets - except for the A to E strings. Fretting the A strings at the 7th fret,the E's are a tad 'flat',maybe 2 cents worth on my tuner.
    I tune the E's to the A's & i'm good to go.

    The only mandolin where i don't get a tiny error between the A's & E's,is my Ellis,which is spot on - but then Tom Ellis makes his own bridges,compensated for GHS A270 strings,which i use,
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