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Acoustic Double neck design
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=15669
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Author:  K.O. [ Sat Feb 02, 2008 4:48 am ]
Post subject:  Acoustic Double neck design

When Dave White stated his plans to build a double neck instrument today I realized the closest I came to knowing anything at all about how they should be braced was from seeing pictures of harp guitars bracing.

I have built one double neck instrument about 30 years ago I was about 15 and it was a present for a girl that I wanted to get to know, the seating position when playing one is quite intimate.
I am talking about a Courting Dulcimer,

an example about half way down this page
http://members.cox.net/keithyoungdulcimers/appdul.htm#COURTING

Off the top of my head I can only think of three builders of double neck mostly conventional shape guitar. Taylor made one for Ritchie Sambora (6-12 string) , Mike Doolin made a 6-6 with close set necks meant to be tuned dadgad on both and Fred Carlson made a nylon string that had a bit of a v between the necks. I looked but could not find any details on their construction. Does anyone have any info or links pertaining to double neck acoustics to share.

Author:  Sam Price [ Sat Feb 02, 2008 6:22 am ]
Post subject:  Re: Acoustic Double neck design

I believe Martin Edwards has actually built two and they are both now in the hands of the clients who commissioned them.

Can't remember if he documented the builds in any great detail, but why not contact him and see if he'll give you some advice. :)

Author:  K.O. [ Sat Feb 02, 2008 7:50 am ]
Post subject:  Re: Acoustic Double neck design

Thanks :)

Author:  TonyKarol [ Sat Feb 02, 2008 8:20 am ]
Post subject:  Re: Acoustic Double neck design

I built one a few years back ala Taylors RS model .. for a friend in a BonJovi tribute band. I think there should be a pic of the bracing in the archives somewhere, if not here, then on the MIMF for sure. I used a modifed X brace design, symetrical, and the X had a 20 thou CF piece laminated into the middle of each half. the bridges were separate, but they touch looking like one piece. Lastly, you will find that tuning one neck's strings affects the tuning of the other - especially the 6 then the 12 - the 6 will then again be slightly out of tune - the top moves and the bridges torque. And thats with the top likely overbuilt some - I wanted it to stay together first, sound great acoustically second - seeing as its mainly used live onstage pretty loud, this idea works very well.

Author:  TonyKarol [ Sat Feb 02, 2008 8:23 am ]
Post subject:  Re: Acoustic Double neck design

And here it is all said and done ....

Author:  martinedwards [ Sat Feb 02, 2008 10:46 am ]
Post subject:  Re: Acoustic Double neck design

Tony's is definitely prettier than mine, but then I bet the Koa on that beauty is worth more than ALL the parts of BOTH the doubles I built!!

here's one of my school pupils strumming at my second double.......
Image

I did a single bridge sprawled across the whole top of the instrument. the 12 neck has two strings per pin. all Dave White & Sam Prices fault......
Image

and this is the only bracing pic I have.
there are a few other fingers in there and then a LOT of shaving before the top went on. I really have to tidy up inside there, that soundhole patch is a MESS!!!
Image

Like Tony, the requirement was a reasonable amped sound and structural integrity. a piezo under each saddle sorted the pickup solution. unplugged it's surprisingly good!!

This one's now in Co Cork

Author:  K.O. [ Sat Feb 02, 2008 3:00 pm ]
Post subject:  Re: Acoustic Double neck design

Tony, Martin thanks guys.

I'm a cowboy..... on a steel horse I ride....... I'm waaannnned......

Oops :oops: had a Bon Jovi moment.

Hope you guys don't mind a question or few?

Did you notice any sympathetic string movement? If so could you detect any volume/sustain differences?

Nose heavy is a given for these; just noticeable, or crap I'm tired of holding this thing up(after playing for a while)?

OK the biggest challenge handling string tension without having to brace so heavy as to have a permanently tight sound.

Tony I notice a slight V to the necks is that in an effort to change the vectors of the string tension to allow the bracing to be slightly lighter?

What is between the U.T.B. and neck block? It is there to help spread the load to the bracing like the A frame scheme does?

Martin there is a simple elegance to your bracing it looks to be original.
my main question for you is how deeply did you tie into the neck blocks?

Last night I stayed up late thinking about an approach of my own before I saw any bracing examples,

What I came up with is to make one neck a 12 fret and the other a 14 fret or a
long-scale/short-scale scheme moving one bridge forward to provide the ability to divide the stress and treat the bracing a little more as if it was two separate guitars using what I would call lumpy lattice bracing. This in effort to be able to lighten the bracing and improve responsiveness. A little V to the necks might be a good thing.

Right now though I need a nap(only slept four hours). I think I will let my mind contemplate the implications of crossing the X in the middle of the bridges and putting the bridges between the legs of the X.

I have over time realized that I have an affinity for lap instruments and that will be the main focus in my future(not a huge jump from Dulcimers). I think multi neck instrument have a strong place there. Once again thanks. Anything that anyone can share probably has application to lap instruments.

Author:  martinedwards [ Sat Feb 02, 2008 3:14 pm ]
Post subject:  Re: Acoustic Double neck design

sympathetic strings?

yup, some.

neck heavy? well I deliberately made mine 12 fret join to help but it's still there.....

Neck block ties about 15mm

good luck!!

Author:  K.O. [ Sun Feb 03, 2008 2:18 pm ]
Post subject:  Re: Acoustic Double neck design

Hey guys once again thanks a double neck is definitely in my future but is a ways off. Right now I am doing my home-work and trying to come up with a way of thinking about the way these things behave.

Just seeing how the two of you tackled the job of bracing these things helps a lot.

Any way If anyone runs across any bracing examples (other than Ovation's) please pm me a link or if this tread is active post it.

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