x-braced mandolin with depressions under the bridge feet

[Primarilywoodcharlie]

Hello - This is my first post.
I recently purchased a "The Loar" LM-300 at a very reasonable price. This seems to be a very nice instrument and I think it sounds wonderful. The mandolin has X-bracing, and this is my first mandolin that is braced this way.
I have noticed that the carved top, though not flattened or crushed at all, has a dip under each of the feet of the adjustable bridge. On my other mandolins the bridge feet sit more or less over the inner tone bars so I do not notice such a depression.
So my question is; Do I need to worry about this? Is it normal to have a bit of a dip under the bridge feet on an x-braced mando? Should I consider using a different bridge, perhaps a solid one which will distribute the pressure more evenly across the top of the instrument?

Any guidance is appreciated.
thanks
Charlie

[sunburst]

Do the bridge feet sit over the arms of the X or between them? Sometimes they are done each way in X-braced mandolins, and the feet can sink into the top either way, but it's much more likely if the bridge feet sit over the unsupported area of the top between the arms of the X. A good fix is, as you surmised, is a 'full contact' bridge base. No need for a solid bridge (meaning non-adjustable), though that can be done too, just a new bridge base that contacts the top completely, without the cut-out in the center.

[Tavy]

When you say depressions - are these along the whole length of the bridge feet, or just part of it? I ask because if you have a badly fitted bridge (not uncommon on cheaper instruments) then the bridge "digs in" where it touches - effectively distorting the top to match the bridge feet. That's particularly bad and can lead to the top cracking where the bridge is digging in.

On the other hand, if you the bridge is properly fitted, and it's just a slight depression under each foot, then it should be fine. By all means try a monopod bridge, but the choice between the two may well come down to which tone you prefer as there's usually a difference.

[John Kelly]

When I build my cross-braced mandos and octaves, I arrange the bracing so that the bridge sits on the cross braces. Not carved tops but slightly curved via the cross braces being curved when I am shaping them. So far I have not had problems with dips/depressions/etc and I do use non-adjustable bridge with the middle cut away, generally. Mind you, my oldest build is only 7 years old.

[Primarilywoodcharlie]

Thank you all for your input.
The feet of the bridge do not touch any part of the top that is braced. These feet do sit very evenly on the tiop, admittedly in the little depressions that they create. This is a carved top and the depressions I saw were just about what you would expect if you push down on an unsupported portion of the thin wood.
I took the strings off the instrument and the top went back to a nice even curve.
I think I will at least try a "monopod" bridge or maybe make one like those found in the Murphy Method blog since I have the equipment and ability to do so. I can always go back to my adjustable ebony bridge if I don't like the new one.
Can anyone recommend a commercially made monopod bridge that I could try?

Again, thanks again for ll your great opinions.
Charlie

[sunburst]

Can anyone recommend a commercially made monopod bridge that I could try?

Not really, but you have to fit the bridge to the top anyway, so almost any bridge can be "monopoded" by simply not maintaining the little arch in the middle as you remove wood to fit the bridge.

[lenf12]

Steve at Cumberland Acoustic should be able to help you with the "monopod" bridge. I believe he calls them "full contact" bridges.

http:\\www.cumberlandacoustic.com

Len B.
Clearwater, FL

[Primarilywoodcharlie]

Thanks to All again
I am going to embark on some experimentation. I would love to get back with you in a few weeks to let you know what I found out.
take care all
Charlie

[Primarilywoodcharlie]

Well I did it!
I crafted an "almost full contact" bridge much along the lines of the Murphy Method blog bridges invented by Red Henry. I made mine out of rosewood as I had some around. I left only about 3/4 inch hollow at the center and fitted the rest of the foot on both sides to the top of my little mandolin.
Not only did the top not push down, but the mando is louder and has a much sweeter tone. Where the trebles were thin before, now it is nicely balanced. The whole instrument sounds and looks much better.
A little experimentation seems to have paid off.
Charlie