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cornfedgroove
11-20-2009, 03:16 AM
sooooooo...whats the theory on sound holes. Obviously a big circular hole in the center is pretty standard...McPhereson has there fancy hole in the top, upper bout. Aside from that you have f-holes on mandolins and violins etc, but you also have an instrument like the tambouritza with several tiny holes to open it up for sound.

I've had some cool cigar boxes that has a nice design in the wood that I dont wanna jack up with a central hole...an off-center hole in the corner wont do it justice, its too late to scroll f-holes (I'm impatient..sue me), so I was considering multiple small holes...not too many but enough for sweet, functional simplicity.

whats the theory on this

RevWill
11-20-2009, 04:01 AM
I don't think there is one single theory. Two corner holes might look good rather than one. Ovation-Adamas style holes might be a good starting place for ideas, especially if you decorate the space surrounding them in some way.

Ukeffect
11-20-2009, 05:29 AM
Try something like this...
http://i653.photobucket.com/albums/uu257/bruce_2009_01/CBUtabac.jpg

Dibblet
11-20-2009, 05:34 AM
Well one thing it does is the the helmholtz frequency of the body cavity. Here's some basic theory. http://www.phys.unsw.edu.au/jw/Helmholtz.html

But I guess there is more to it than just that. The hole or holes remove a chunk of soundboard that would otherwise be vibrating. Removing a chunk presumably affects the distribution of nodes on the soundboard.

I'd have thought that putting the hole(s) in a part of the soundboard that doesn't vibrate much would be ideal. That would suggest near where the neck joins. Of course that isn't normal practice so I'm probably wrong. I'd love to know why.

cornfedgroove
11-20-2009, 06:07 AM
Well one thing it does is the the helmholtz frequency of the body cavity. Here's some basic theory. http://www.phys.unsw.edu.au/jw/Helmholtz.html

But I guess there is more to it than just that. The hole or holes remove a chunk of soundboard that would otherwise be vibrating. Removing a chunk presumably affects the distribution of nodes on the soundboard.

I'd have thought that putting the hole(s) in a part of the soundboard that doesn't vibrate much would be ideal. That would suggest near where the neck joins. Of course that isn't normal practice so I'm probably wrong. I'd love to know why.

great point...I've thought the same thing

Matt Clara
11-20-2009, 06:39 AM
Well one thing it does is the the helmholtz frequency of the body cavity. Here's some basic theory. http://www.phys.unsw.edu.au/jw/Helmholtz.html

But I guess there is more to it than just that. The hole or holes remove a chunk of soundboard that would otherwise be vibrating. Removing a chunk presumably affects the distribution of nodes on the soundboard.

I'd have thought that putting the hole(s) in a part of the soundboard that doesn't vibrate much would be ideal. That would suggest near where the neck joins. Of course that isn't normal practice so I'm probably wrong. I'd love to know why.

That's exactly what the Kasha designed instruments do, and that design is based on scientific principles. However, the fact that it hasn't been universally embraced would indicate a grain of salt should be taken along with those scientific principles.

Dave Higham
11-20-2009, 08:13 AM
Put the hole in the side?