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JD, I got a lot of flack from someone on another board about it until Kevin stepped in, made some comments and several others pointed out the differences in our ideas. I had all but scrapped the idea and started to remove the plate when the pallet knife took a wrong turn and pushed through the top. Sad to say the whole top is waste. I was quite soured on the whole idea, but proceeded to join a new top, make the rosette and put in the X brace and fingers while thinking the whole situation over. Late yesterday I decided to proceed with the idea, and made a new plate for the top.
I'm actually glad I went this route because in the end, my idea ended up a little more refined and the X braces were made thinner, and I lost 30 grams on the top so far. I will probably lose another 7-10 grams from final tuning and sanding.
My idea (after making a test honeycomb plate and discarding that idea) was to use a solid spruce patch and set the grain at 45 rather than 90 to the top. It is quite different than Kevin's plate. Apparently, he says the idea of the honeycomb plate is to make the area very stiff and light, while my idea is to make the area more flexible than stiff. He says that there is no belly in his tops and I prefer just a bit of belly. I can't say for sure, but my plate looks quite a bit larger than his and has much more recurve.
So far, after drying overnite, the sound of the top is more lively than the other and I haven't even started to work it yet. I have regained some of the excitement that I had lost in the last couple of days. My only regret so far is that I destroyed a beautifully grained red spruce top. I'll get a photo up later.
The braces are rosewood/red spruce ala Larson Bros. The UTB is maple.

JD, I got a lot of flack from someone on another board about it until Kevin stepped in, made some comments and several others pointed out the differences in our ideas. I had all but scrapped the idea and started to remove the plate when the pallet knife took a wrong turn and pushed through the top. Sad to say the whole top is waste. I was quite soured on the whole idea, but proceeded to join a new top, make the rosette and put in the X brace and fingers while thinking the whole situation over. Late yesterday I decided to proceed with the idea, and made a new plate for the top.
I'm actually glad I went this route because in the end, my idea ended up a little more refined and the X braces were made thinner, and I lost 30 grams on the top so far. I will probably lose another 7-10 grams from final tuning and sanding.
My idea (after making a test honeycomb plate and discarding that idea) was to use a solid spruce patch and set the grain at 45 rather than 90 to the top. It is quite different than Kevin's plate. Apparently, he says the idea of the honeycomb plate is to make the area very stiff and light, while my idea is to make the area more flexible than stiff. He says that there is no belly in his tops and I prefer just a bit of belly. I can't say for sure, but my plate looks quite a bit larger than his and has much more recurve.
So far, after drying overnite, the sound of the top is more lively than the other and I haven't even started to work it yet. I have regained some of the excitement that I had lost in the last couple of days. My only regret so far is that I destroyed a beautifully grained red spruce top. I'll get a photo up later.

Looking forward to the results!

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Expectation is the source of all misery; comparison the thief of joy.
http://redrivercanoe.ca/

If I may throw in my opinion, it looks slightly unbalanced in terms of how the bracing covers the top. I'd still add one small tonebar close to the bottom if I was trying this.

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Build log

Haans,

I do think you are on to something with this. I too have been trying to figure out how to eliminate the tone bars. My approach was using carbon to get a very light plate, but always have problems at the edge. If i extend the carbon to the lining the top is too stiff, but if I stop the carbon before the lining strange stuff happens and the boundry between the stiff plate the the much lower modulus spruce top. I also tried a zig-zag edge since I really couldn't thin the carbon effectively to ease the transition.

By using a spruce plate at a bias to the top you eliminate the abrupt transition in stiffness at the edge of the plate.

-jd

OK, here's a photo of the completed, ready to glue on top, but not fully worked yet. Plate is a bit larger and there is more recurve at the rear. Here is the a recent GC with Larson X bracing, the "dead" top and the new top.







Alexandru, the plate worries me too, which is why I made it larger. I will see what it works out to as far as deflection when It's glued on to the ribs, and make a decision at that point as to whether to add anything else as far as bracing (wouldn't be my first choice).
JD, just as Kevin was put off by non-organic honeycoymb, so am I, so I figured that a plate of spruce might be just the ticket. It has a very lively tap.
My only problem now is deciding on the B & S material. I'm inclined to go with my favorite, white oak, but my wife says I should go with something more mainstream like IRW.

Ohh, who listens to their wife anyway...and stays married?!


...I do. She's a smart cookie.


But sometimes you just know in your gut what you gotta do regardless of the opinions of those around.

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Expectation is the source of all misery; comparison the thief of joy.
http://redrivercanoe.ca/

I don't know, Filippo, some people call the transverse braces tone bars, on a classical, when it's the fan braces that control the tone.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Man, that is so cool, I'd put that on the outside!

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Under Compensated Nut!

Hanns, is your soundhole / rosette backing-plate grain going across that of the soundboard (I have done this on my latest for strength), It was pointed out to me that this may cause the soundboard to split.
Any thoughts on this?
Geordie

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some tunes on acoustic and guitar synth.
http://www.youtube.com/user/TheGeordieAdams
http://www.myspace.com/geordieadams

Haans, it is commonplace on the internet forums for someone who knows very little about the subject to jump in and defend somebody else against some imagined slight or infringement. And person supposedly being defended isn't there and doesn't care. Comments about intellectual property on the forums are about the worst examples of this. They are wrong 99% of the time. Don't worry about it.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Haans,

I admire what you are doing here with the carbon. May I ask the format of the carbon? I'd guess you are buying pre-cured uni-directional strips and gluing them up as a sandwich.

It's a bit awkward for me to offer any advise to an acoustic builder, not having done it myself, but I do have a pretty good sense of the load capabilty of the braces you made here and it seems to me that there is quite a bit more carbon than is necessary to carry those loads....perhaps rendering the braces a good deal more rigid and heavier than you need. Just taking a cursory look at it, I expect my first attempt to do something like this would involve a strip of uni-directional fiber down the middle no thicker than 02". Working with carbon in aerospace applications, the objective was always to build the part to the minimum strength requirement, plus a little margin, in order to achieve the lightest part possible. My thinking is that one is trying to accomplish the same thing with top braces. If you were able to suspend that main brace such that it would not buckle sideways...I expect you could stand on it.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Hey Stuart, that's rosewood he's laminating into his braces, not carbon. Following the Larson brothers laminated bracing. Hard to tell from the pics.

Joe

haha....then he should use carbon there! So much for my reading skills as well.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Not before I thoroughly read a few thousand more threads around here.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Zlurgh, I'm not too much on CF except for the tone tubes. I like an organic top. I use RW, maple and African blackwood for brace lams.
Howard, problem was the "defender" was another builder. Kevin finally showed up and saw the difference in what I was doing and made some positive comments about innovation. I thought about it a long time and decided to proceed with the thought.
I'm into a 2nd top, slightly thicker, as a comparative, and we'll see how it deflects when braced. Thinking is that possibly it may be a little more like ladder bracing requiring a thicker top. This may end up a long term undertaking to find the right combination. I might even have to make a regular Larson X to compare...fortunately I have an order for an oak GC.

Geordie, missed your question/comment. Yes, it is cross grain, and I don't know/hadn't thought about it. I may change grain direction or not. Same could be said, I suppose about bridge plates and all bracing...
Most every crack I have ever run into has been due to neglect in terms of keeping the instrument properly humidified.
Filippo, IMHO, I surely would call the "tone bars" structural.

"Tone tubes?" I like the sound of that. Kind of reminds me of Bohmann. But what are we talking about? CF struts running from the headblock to the waist? I used to make them hollow, but I've gone solid. I guess they could be tone bars, but that's already taken.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Howard, look up third photo back. Can't miss 'em. That's what Prairie State (Larson) called the single metal tube running down the center from neck block to tail. I ran two because I didn't want to be hated by every repair-person in the universe. They are like yours and others, but run full length.