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Sound Hole or No Sound hole?

So my most recent build seems fine without a sound hole. After I put it together I gave it a play, and I just don't hear a need for the addition of a hole in the body. The body is 1/4" ply, which seems to resonate just fine and produce plenty of sound. Has anyone else opted out of cutting a sound hole? Cutting a sound hole has been a standard practice for me up to this point.

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Permalink Reply by JL on February 26, 2016 at 2:20am

Like the Thiele/Small calculations for a speaker/amp cabinet size for closed/ported/open-back, lots of fiddley little bits having a big impact on the response.

Depending on the size/material/thickness of the box and the attachment of the neck & bridge, & the frequencies imparted, the air inside the closed box can act like the bumper/cushion on a pool table and strongly rebound the compressions inside the box back to the soundboard to reinforce its transmission to the room, or with a sound hole allow the vibrations from the inside face of the soundboard to reflect outside and join the vibrations from the outside face of the soundboard to reinforce

or dampen and cancel if the physics line up the wrong way....

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Permalink Reply by Fomhorach on February 26, 2016 at 11:51am

Loosen it off a little and try strumming it with a shim of wood holding it open just a tad.. Listen to it closed and slightly open, it's best to make a judgement with more information without having to change anything.

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Permalink Reply by Ron "Oily" Sprague on February 26, 2016 at 10:23pm

You can also, if you have a smartphone or tablet, download sound measuring apps like dB meter, or suchlike, and actually measure the difference. I have experimented a bit with this on things like my plywood versions of the Sound Enhancer for guitar amps, and there are measurable differences. I've done the same with a couple of my boxes, and found, as JL says above, the results are highly dependent upon much more than just the presence or absence of a soundhole.

On this one, I'm with Wayfinder. If you like the tone already, don't dick with it. However, if you want to get outrageously scientific, and spare no expense, you'll have to build your own boxes, with varying thicknesses of sound board, varying sizes and shapes of soundholes, varying types of tonewood, various box sizes, neck-through versus neck-to versus bolt on, blah blah blah. Lots of variables to attempt to control. Antonio de Torres Jurado, arguably Spain's most famous luthier of the 19th century, attempted to zero in on these variables in this same way; it is thought that his experiments led to the development of fan bracing. That said, standardish 9" X 7" X 1-1/2 or 2" cigar box simply doesn't have a lot of air volume to push around.