Saddle placement diagram |
Zero frets and saddle placement: an inquiry Martin Koch wrote: > > William, certainly I will check your pages frequently. > > By the way I have two questions too: > > 1) I like to use a zero-fret. What do you think about that? That's a very "European" thing to do. Almost nobody does that over here. With a zero-fret you need two things: a zero fret and a spacer nut behind it. The zero-nut is just a zero-nut. Simplicity would militate against a zero-fret. Then there's the argument that since the zero-nut is made of bone and the first fret is made of metal, logically there should be a difference in the sound of the open string versus the sound of the fretted string. But in practice, it never has been considered a flaw in the guitar's design except for those few people who think that, logically, there should be a difference. There may be an argument for it in that a zero nut must be cut more carefully, and thus requires somewhat more skill and time to execute. That would be a good argument for its use in mass production, but not a very good one in luthierie. > 2) I'm not very certain on how to place the saddle on an acoustic guitar. > I believe that the best way is to mount an temporary extra tailpiece and > to find the individual saddle-locations for a given set of strings like > described in Don Teeters book. I don't think that's a very good method. > But when I don't want to do it this way: > You write in THE book that the exact scalelength should be in the middle > and in front of the slanted saddle-slot. (And that's the way I always > did it. But I can't explain it) > It means that the string-length for the treblestrings is shorter then > the scale-length. No, its not. >I understand that the bass-strings have to be longer > to make up for the increase in pitch when the string is pressed down. That's true. > But isn't the same true for the treble strings? Absolutely. >The treble strings must > be way too high this way. No, the compensation ends up just right. >I believe that all strings have a higher pitch > when pressed down. Am I right? Yes. The pitch increases when you press down because you increase the tension slightly when you do so. The compensation balances it out. > Why? I don't understand that completely. The saddle slopes 3.17 mm over its 7.62 cm length. If you pivot the saddle at it's centerpoint, the treble saddle-end travels 1.58 mm towards the nut. The bass saddle-end travels 1.58 mm away from the nut. Now when you locate the bridge when you glue it down you must a) locate the front edge of the bridge parallel to the frets b) locate the centerline of the bridge to lie along the centerline of the fingerboard c) locate the center point of the saddle (that is, the central pivot-point of the sloped line of the saddle) so that, when measured down the extended centerline of the fingerboard, the saddle's central pivot point lies at the end of the scale length PLUS 3.81 mm (the compensation of the saddle measured at the center pivot point). Now, if the center of the saddle is 3.81 mm beyond the scale length, how can the treble saddle end, which has pivoted only 1.58 mm towards the nut, result in the string length of the treble string being shorter than the scale length? Besides, the treble string isn't located at the end of the saddle! Indeed, it's located about two-thirds down the length of the saddle portion between the pivot point and the saddle-end. Thus the actual compensation of the treble string is two thirds of the distance that the saddle end has rotated towards the nut. Two thirds of 1.58 mm is 1.05 mm. The same occurs viceversa with the bass string. So we can say that the treble string is compensated 3.81 minus 1.05 mm which equals 2.76 mm; and the bass string is compensated 3.81 mm PLUS 1.05 mm which equals 4.86 mm. Schwerverstaendlich? Cordially yours, William R. Cumpiano
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