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sound holes need advice

My last git had two sound holes on the front of the box but for my new one i want to put image on the box and no matter what way i put soundholes on the front counting the bridge pickup and holes its guna cover up too much of my image!

i have seen the soundholes on some gits not on the front of box but on the side mainly the side that points to your face! if i did it like that id have more room for image on front of box.

my question is will it take away from the sound acustically from the git?

any help appreciated in advance!

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Permalink Reply by gary sheldon on March 2, 2015 at 5:37am

I actually do measurements. I can measure volume, but tone is not all that measurable. You either like it or you don't. I bought a cheap digital decibelmeter from Amazon, around $20. I measure my instruments in a consistant way. Hold the pick up of the meter 1' from the soundhole and strum all the strings open using a pick. The meter has a "Max" position. Works well.

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Permalink Reply by Ron "Oily" Sprague on March 2, 2015 at 8:15am

Yep, I just requested that paper from the authors last week.

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Permalink Reply by gary sheldon on March 2, 2015 at 5:25am

Kid should be answering this, but since he is not around, I will put in my 2 cents worth. Assume the soundboard is a contiguous piece with no sound hole. Most of the vibration occurs at or near the bridge. It will decrease or stop altogether at hard spots, like corners and edges and where the neck enters/exits. Keep in mind that cigar boxes are relatively thick in comparison to acoustic guitars and violins. If you use long, thin f holes near the sides, like Kid's drawing, the top can vibrate freely inside the f holes, where it is hard at the edge due to the support of the sides. Thus one side of the f hole, the inside, nearest the bridge is free to vibrate, while the outside will vibrate very little. The f hole, or lighning decouples the soundboard to make the center part vibrate more freely. Very interesting thought.

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Permalink Reply by gary sheldon on March 2, 2015 at 7:25am

I think the "neck effect" is minor. On my builds I make the neck/top contact area small. Like around 1/4". It is a double edged sword. Large contact area dampens top vibration. When you think about it, neck effect can only come from the nut, almost 2 feet away and travelling down a relatively thin neck. This discussion can take us back to the other discussion "should the top contact the neck all the way through the body?" That is an individual builder's choice. I try to isolate my top as much as possible. I even leave a small space under the fretboard where it overlaps the top. I have tested it both ways and it doesn't seem to make any difference.

I realize that Martin and others glue the fretboard to the soundboard, but the large sound hole in the middle "decouples".

Just sayin'

My decibelmeter helps with the design and tweaking of my builds.

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Permalink Reply by Scruggy on March 2, 2015 at 9:56am

so basically sound holes on the white parts of diagram?

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Permalink Reply by Ron "Oily" Sprague on March 2, 2015 at 8:14am

Nope. The smaller holes enhance the lower frequencies. Larger holes enhance the higher frequencies. Think about it.

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Permalink Reply by gary sheldon on March 2, 2015 at 8:53am

I stand corrected. My logic was taken from speaker design. Tweeters are tiny, woofers are huge.

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Permalink Reply by Ron "Oily" Sprague on March 9, 2015 at 2:48pm

Yep. Tweeters are tiny to vibrate rapidly at relatively higher frequencies. Woofers are bigger because they gotta push a lotta air to get the thump going.

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Permalink Reply by gary sheldon on February 26, 2015 at 1:26pm

Wayfinder,
I like your "method". But I am not sure I like step 4 "plug holes" : )

Cheers

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Permalink Reply by Bill Baker on March 1, 2015 at 7:07am

The main result is just the direction that the sound is emitted. Directed out towards an audience or up towards you. Most acoustic CBG aren't going to overpower an audience, so it is pretty much a personal preference.