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Top bracing on the little Stella build in the other post....



So... For reference - the bridge lands right in the middle of the spruce bridge plate. The lowest brace lands right under the top of the tailpiece.

The top flexed down about 1/10" under string tension. It's pretty obvious.
Removing the strings - it flexes right back up.... So it's not deformation/shifting of the structure.... More like a long term deflection test

I love the sound of the little guitar... But the top flex is probably a bit too much for me.

So... I am thinking of adding a 1/4 brace right in front of the bridge plate to stiffen things up a bit... But I am torn because I like the way it sounds.

Opinions?

I think if you are that skilled to add the brace, you re skilled enough to remove it if it backfires.

Are you using a tailpiece? If so can you raise it slightly to reduce the vertical component into the top (ie less break angle)?

I've only build one ladder braced guitar - a long scale 12 string basically following the hand drawn plans of Stefan Grossman's Stella. It has two fairly tall braces below the sound hole, roughly equidistant above and below the bridge plate and a moderately thick Adi top (0.120 if I recall). As far as I can tell, no significant flattening under string tension.

So.. My top was quite a bit thinner and I also used a fairly thin spruce bridge path.
The top runs in the 0.085 range and the spruce patch another 0.080 or so....

The quandary I am thinking about now.

I can double the stiffness of my top at the bridge patch area by adding a 0.190" tall x 0.25" wide "cross brace" under the bridge.

I could stiffen it up a bunch by adding a 1/2 x 1/4 cross brace directly in front of the bridge patch. This should cut the unbraced span about in half - which would also double the stiffness of the area....

Which way to go.... Is there a benefit of leaving the area directly under the bridge a little more flexible?

Just calculation wise....
My top + patch = 1 unit of stiffness.
Either the cross brace on top or in front of the bridge would take it to 2 units or double.

For reference - 0.125" top + 0.125" patch suggested = 3 units of stiffness....

I think that when the top is glued to the sides it will be much stiffer. I assume your testing it as shown, in which case the edges are free to move.

I recently built a tenor guitar, floating bridge, similar lower bout width, and similar bracing but no bridge patch. The top is yew and about 1/10 inch thickness. It's plenty stiff enough, no appreciable deflection.

Mind you, if mine had deflected 1/10 when strung up I'd have been content.

Fwiw, here is the bracing of my 12 string Stella clone. As I said before it has a tailpiece instead of pinned bridge and with the long scale length and fat strings that I use the calculated string tension is around 220 pounds (about the same as most 12 strings but certainly more that a sixer)



I've always felt that ladder bracing makes lots of sense for a guitar with a tailpiece but is asking for trouble with a pinned bridge, however I know that there are lots of them out there (Fraulini is a good example). And don't forget that as the height of a brace goes up its stiffness increases by the cube - double the height and its 8 times as stiff.

If it's the stella with the tailpiece, you could try lifting the tailpiece fixing a little to reduce the downforce on the bridge.

The little brace is in now. I gotta see if I can get a pic to show on here. Not going to be easy....

That was one royal PITA...

I am going to let everything sit overnight before I tempt myself by stringing it up again.

Thanks.

Most of the really good sounding ladder braced guitars I have encountered have scary looking tops. I own a 1965 Gibson J160-e ladder braced (J-45 size) guitar that has perfect action and relaxed even tone in spite of about 1/2 in top warp. Strange, isn't it? I've gotten used to people telling me my guitar needs fixing. They don't say that after they play it.

Leonard, that is a little reassuring i suppose. I guess I am just so used to seeing "pull up" that the sink just looks crazy to me.

So.... The brace is in. As planned - the top deflection is cut in half. I am playing it in while I dial in the setup.

Overall - I think this little ladder braced guitar is probably the loudest one I have made. For as quiet sounding as the old Harmony and Stella guitars were - this one is the opposite. It barks!

Thanks