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Ok Gang...

I'm going to let the cat out of the bag on this one but I need some help....

Does anyone have pictures or information on bracing a two necked acoustic??

I'm doing a full 12 string on the top and a 6 on the bottom, both will have pickups and a small mixer that will allow you to flip between them or combine them...

I have some ideas how it should be braced but I want to see what others have done first to make sure I'm not totally off the deep end on this one....

Thanks

-Paul-

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-Paul-

Patriot Guitars

Mike Doolin Where are you?

id actually indeed reccomend you e mail Doolin.
he has some fine pics of his bracing designs.
he has always answered my questions and gave me some great ideas and insights.

Udi.

I'll email Mike and see what he has to say, I'm going for a more traditional design than what he has there so the bracing will be different by quit a bit..

Thanks

-Paul-

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-Paul-

Patriot Guitars

Here is the innards of the one I built ....

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

And here is the top view once completed.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

So Tony, How does she sound? She sure is beutiful, that is nice lookin Koa (?). I am also using this brace system (Larrivee symetrical) but man you did a nice job! Is your cross laminated with carbon fibre or something?

Shane

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Canada

[QUOTE=Sprockett] both will have pickups and a small mixer that will allow you to flip between them or combine them...[/QUOTE]

Gee Paul is that for that 3 armed person you know.

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Hi All,

It was jsut over for a visit last night, to show one of my students. He thought is was amazing. A lot of folks arent amazed by the sound, but by the playability of the 12 side - its like butter.

IMO it is a good sounding guitar, but in designing and building it, the first priority was for it not to explode once strung at concert pitch. We took the sound for what it was - I designed the whole thing myself, as far as the innards went, and I must way it turned out great. Its got PUs in her as well, the side mount Baggs with a neck selector switch (or is that a bridge selector switch !!) Baggs under saddles, the coax cable type. They were a bear to get sounding even across the strings compared to others I have used. The guitar is certainly not bass heavy, even though its a 16 3/4 lower bout. Its crisp and clear though, and he loves it to death.

The owner is in a BonJovi tribute band, and always wants whatever Ritchie is getting his hands on ( yeah and her too !!) to keep the band looing up to date. He only has 24 guitars, so hes halfway there !!!

The main X is 10x18 mm with 20 thou Cf in the midlle. Even with all that mite in there, the necks still affect each other when tuning up. Its kinda like a floating FloydRose type bridge without the whammy.

But one thing is for sure - you learn alot doing one. I thought I had the necks all set up, and then the client points out that the two headstocks arent quite even, one was a tad lower than the other. So I say, no prob, watch this. I do a few sandpaper pulls, and there it is, dead on. You could lay a ruler across one headstock face, and it just lays on its brother - beautiful.

Cheers, Tony.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

I see CF in those braces Tony, am I right?...

I was thinking of something with two actual seperate bridges and X braces that crossed over at the center (Kind of like gibson did with some of their ealier acoustics), the necks would be parallel and a little wider apart than yours. I would not need any lower finger braces with a pattern like that, the 12 string side would have taller bracing and the 6 shorter but it would all be CF lams as I normally do.

The two scales would be identical and the guitar symetrical, I'm doing some layouts tonight to see if I can get the basic measurements down, since I still don't have a shop I'm using some my older ones to lay things out...

Thanks..

-Paul-

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-Paul-

Patriot Guitars

Speaking of carbon fiber in the braces - how does it effect the sound? Does it make the guitar brighter?

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tim...
http://www.mcknightguitars.com

Hi Paul,

I see where you are going with the 2 X's and the somewhat separate X heights. I would think that you may need a touch more height at the 12 , but I would nt put too much. The top is still going to work as a whole, and I think you might actually end up overbracing with the double X. Not sure how to figure out what sizes to use either. But you could always get in there and shave a bit post stringing up, and see how that gets the sound to open up.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Thanks Tony...

I went down and bought some paper and supplies last night and will draw up some ideas today, I wonder if anyone knows how much more force a 12 string puts on the bridge than a 6 string, that would be useful info.

for the braces where they cross over they would be tapered and shaped so it would not be all that much wood....

Tim...

I have not done any tests, Mario would be able to speak to it better than I but I don't think it makes all that much difference, I'm only use .010 thickness in my braces and I only use it in the X braces, then I keep them pretty thin and carve their height. I tune the top to my ear which likes a clear crystal type of sound, on my next couple I'm trying something new and going for a more bassy response but still using the CF braces...

Cheers

-Paul-

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-Paul-

Patriot Guitars

Forces ... check the back of any Daddario pack, they list the tensions for the given guage, with a certain scale length and tuning (differnet, because on hteir baritone set, its B to B, but at 29 3/4 inch scale, and most bari's are more in the 28 range).

So anyway, a 12 light gauge is pretty much double a six string - I thnink I had 450 or 460 Lbs of pull to work with there on mine.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Paul, if you know the tuning frequency (Hz)of the extra strings on a 12 string, the gauge of string and the scale length, I can provide you with the string tension.

If you also provide me with the break angle on your bridge saddle I can also provide you with the downward force on the top.

From your post above I am not sure whether you want string tension, downward pressure on the bridge or both.

Tony those sound like fairly heavy gauge strings to have that much tension.Anthony Z38695.7963425926

Hey Anthony,

Nice of you to make it out last night !!! The string pull I mention above is right off the Daddario packs, both are light gauge sets. I was a bit off, just found my notes - 80/20 bronze lights are 159 lbs, the 12 string is 249 - so about 410 lbs. Meds would add another 30 or so on the six, more on the 12.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Hey Tony,

Hey thanks for having us -- what a great bunch of people that were there ... wish I could have stayed later but my youngest ran out of gas. I was great meeting the owner of that double necked Koa (next hopefully next time he'll bring it).Anthony Z38697.7051736111