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Tone bar questions....
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=24012		 Page 1 of 1
Author:  kburner1 [ Thu Oct 01, 2009 11:54 pm ]
Post subject:  Tone bar questions....
Let me preface this post by saying I am a new builder and it is very possible I am digging into things that are over my head at this point. That being said I will keep digging beehive. I was drawing out a bracing plan on a redwood top that my father and I are working on right now and I got to thinking...I have generally seen tone bars oriented as shown below, so that they are closer together as they run towards the bottom of the lower bout.
Image
I guess my questions is why? If you want the tone bars to act as pathways for vibrations is seems that you would want to spread them out more in order to activate more of the top. Also on a smaller body guitar like the one being built it seems that traditional placement of the tone bars would have the bottom tone bar relatively close to the rim of the guitar. It seems that placing it closer to the bridge would offer more transference of vibrations. I realize that they are a combination of both tonal and structural components, but why not do something like the picture below shows? or possibly even the double X system.
Image
It is very possible that I am missing an important component here, and please tell me if I am. I am just searching for the "why" in what I build.
Author:  P@uL [ Fri Oct 02, 2009 12:51 am ]
Post subject:  Re: Tone bar questions....
i am a new builder as well and thought in quite the same way. i dropped my lower tone bar a slight bit. not as much as in your demonstration picture. the stiffness of the top would be affected the more you move away from running across the grain. i would assume that changing the angle of your main X brace could do the same but affect the entire top. I personally don't even know if you can hear the difference, but i would say go for the experiment as long as your bars arent running under the bridge pins or into your butt block.
Author:  kburner1 [ Fri Oct 02, 2009 12:01 pm ]
Post subject:  Re: Tone bar questions....
that is true, you would lose some cross grain stiffness. It would be interesting to see how this would change the tone of the guitar. Might be worth bracing both ways and taping to see if you can hear a difference just from the tap tone.
Author:  Zach Ehley [ Fri Oct 02, 2009 4:31 pm ]
Post subject:  Re: Tone bar questions....
Having them spread out like in the second pic with stiffen up the top in the lower bout, given that the size and shape are the same. Think about how the string tension is pulling up on that portion of the top. If you angle one of those braces more in line with the strings, it will resist the pull of the strings more. Your theory of activating more of the top may have some validity if you compensate for this by making the brace thinner.
Author:  David Newton [ Sat Oct 03, 2009 10:10 am ]
Post subject:  Re: Tone bar questions....
Your lower tone bar would be running into the end block. Have you taken that into consideration?
It is valid to try all sorts of things with brace positioning, just keep in mind all the elements of the whole structure. I doubt you will find a layout that is "wrong" though you may find one that is particularly bad.
Author:  woody b [ Sat Oct 03, 2009 10:23 am ]
Post subject:  Re: Tone bar questions....
Keep in mind that Redwood likes to split along the grain. Lattice bracing (which I know nothing about) or a double X might be best.
Author:  kburner1 [ Sat Oct 03, 2009 3:37 pm ]
Post subject:  Re: Tone bar questions....
I had wondered about that woody. It seems like that would be an interesting thing to try. Basically I think that I just need to build a lot more guitars so I have more of a working knowledge of how moving these braces will alter the tone. Thanks for the replies.
Author:  gozierdt [ Sat Oct 03, 2009 8:02 pm ]
Post subject:  Re: Tone bar questions....
I've been reading my new Somogyi books, and looking at the Somogyi videos in another thread, and I think I would go with the second choice you show, together with appropriate tapering/peaks on the bars. The more I look, the better the original Martin bracing looks, as regards creating the best Chaladni patterns. There may be a more optimum pattern, but that original Martin work created a lot of great sounding guitars...

And you're right- it'll take you building a lot of guitars (I'm only at #7, and I'm still a novice), before you start to really internalize this stuff. But keep reading- search the archives for threads on bracing, look on MIMF as well, and research Chaladni patterns and how to create them.

It's a lifework if you really go after it- frustrating but rewarding, is how I feel...only sorry I started so late in life.
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