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Updated Mar. 15th, 2006


Some Frequently Asked Questions


1. Why are those little notches cut into the front of mandolin bridges?


Answer: Some of the strings are less flexible than others. The flexibility depends on the size of the solid wire in the string, which means that the G strings, with their big solid core, and the A strings, since they are a large plain solid wire, are the two least flexible strings.

These stiffer strings have a lot of tension on them, and they tend to "pull" out of tune when you press them down to fret them. If you set the bridge to where the E string plays in tune all the way up (the 12th fret note and 12th fret chime are the same), then the A and G strings will note a little sharp. The sharpness increases gradually as you go up the neck, until the 12th fret note is noticeably sharp compared to the chime. There is also usually a little extra sharpness on the D string too.

The best way to correct for this is to set the A and G strings (and to some extent the D strings) back a little on the bridge top. This effectively lengthens the scale a little for those strings, or you could regard it as shortening the frets a tiny amount, so that each fret makes a slightly flatter note than it did without the compensation.

If this is done just right, and the bridge is set in the right place, then all four strings will play in tune up the neck, and all four 12th fret notes will agree with the corresponding chime-- this is a good way to check it.


 

2. Will a straight bridge top work? How about a diagonal top?


Answer: You can use a diagonal bridge top such as Steve Tourtellotte recommends, and much of the time it will work just fine. Teri LaMarco made her maple bridges that way, and was very pleased with the results (her description is linked to the bridge development page). I have even used completely uncompensated bridges for months at a time. With a diagonal bridge top, though, if you play much up the neck, sometimes you may find a little sharping on the A strings and flatting on the D strings. This may or may not be noticeable on your mandolin, depending on several factors such as the height of action you use. So the diagonal bridge top can work fine.

Compensation notches are not difficult to make, however. There's nothing really critical about them. If I want full compensation on a bridge, I just put the bridge in a vise and use a file about 3/8" wide, and I notch the A and G strings back about 1/16" from the bridge front, and I also notch the D strings about 1/32" back. And of course, there's no real need to make notches on the back of the bridge.


 

3. My mandolin is old and fragile, and it came with a bridge which was in contact with the top of the whole width of the bridge, about 4 inches. I don't feel comfortable with very short bridge feet, since there will be so much pressure on the top.


Answer: As long as that top is stable it should do fine with a two-footed bridge. If you don't feel comfortable cutting short feet on the bridge, you might consider making the feet as long as 1 3/8". Each foot will be almost 1/3 the width of the bridge. You will get quite good response that way compared to an all-foot bridge, while still spreading out the pressure on the top much more than you would with 1" bridge feet.


Click here to email me with questions.

Red Henry.


 

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