Thread: My Acoustic Guitar Design

Very innovative Mike.

So just for my understanding, the soundboard is actually inside the guitar body and only secured along the centre section leaving the "wings" to vibrate freely?

Amazing stuff Mike, yeah more pictures, assembled with strings on if you have it to, I get the strength for the neck bitt ,but dont get how the bridge works, cant see it, is the internal sound board a plywood or solid ? . Rob

The first guitar uses uses the internal soundboard only to produce sound acoustically, although the back is contributing some too. If I place my hand on the back and hit the strings I can feel the back vibrating. Mounting the pickups in that guitar wasn't the way I originally planned it. I decided to use the thick maple top and mount the pickups so that only the internal sound board would produce an acoustic sound, if it did'nt , at least I could use it as an electric guitar. Fortunately it worked, I was amazed at volume such a small soundbox produced. The saddle on this guitar passes through the top and rests against the internal sound board, I glued a piece of wood with a groove routed in it for the saddle to set in. That keeps it from moving around but the saddles not touching the top. The dreadnought that I'm working on now will have the saddle not only resting on the internal sound board but will be clamped to the top as well, in effect I will have two sound boards vibrating in this guitar, hope it works. The top and back of this guitar are very lightly braced to allow them to vibrate more freely, wasn't sure what pattern to use, just had to guess. I tried to come up with one that wood allow the wood to move with changes in humidity. Incidently, I gave no regard to humidity while building either one of these guitars, the first one was built when it was really hot and sticky. After completion I took it in the house, into the AC to try and get it to crack, but it did'nt. The internal sound board is anchored at both ends, I'm using a bolt on neck, like an electric, to firmly clamp that end, the other end I used cross bolt connecters to attach the board to the hinged block. This allows that end some movement and I felt it would allow the board to vibrate more. The board is not attached to the sides and is free to vibrate, as you pointed out Steve. Unlike a standard acoustic where the guitar resting against your body mutes some of it's vibrations, the internal sound board isn't affected. The internal board also keeps the saddle height uniform and is supporting the downward push of the strings. Because it's under tension not compression, it always wants to stay straight. It will never need a neck reset or have a lifted bridge. Did you notice the change in the direction of the grain in the sides of the guitar at it's ends. This allows the top, back, and the ends to move together with changes in humidity. Here's the rest of the pics I have of the first one and some more of the dreadnought.Mike

Nice stuff man, Ive been trying out the secondary soundboard idea out for a while too.
I've done 2 portotypes to get the whole idea worked out and have one serious build on the go now,,,, between every other build.

Good to see

Originally Posted by AussieOzBorn

Nice stuff man, Ive been trying out the secondary soundboard idea out for a while too.
I've done 2 portotypes to get the whole idea worked out and have one serious build on the go now,,,, between every other build.

Good to see

Do you have any photos of your build Aussie? I have to start all over again as I had a freak accident while working on mine, it was in so many pieces I had to scrap it. Is your internal board under tension like mine? I know the theory works because of the first one I built, I expected great things from the dreadnought I was working on as I was going to drive both the internal and top soundboard. Felt the larger size and different woods would boost the bass and increase the volume. From the sound it produced by tapping on the box I think it was really going to be something, but then disaster struck.I was ready to give up building altogether if it were'nt for some encouraging words from members of this forum. Wal made a really kind offer to help thats motivated me to try again. Trying to figure a way to get some more materials and keep my internet service going, if you have any imformation you can share on your experiments I'd sure like to see what you've done. Mike

I'll have to dig through my pile of un sorted pics, but yeah im sure i have a few.
And yes, mine is braced all round, including a "tounge" that comes off from the neck pocket and is the spine of the second soundbaord.
I would refer to my "second soundboard" more as a resinator, like a freak diversion from a Dobro. Theres a small block that rests under the bridge, under the soundboard and down onto the "tounge" of the resinator/ 2nd soundboard.
I also have 2.5 inch holes drilled in particular areas to deliver more bass on the trebel side and more trebel on the bass side. It also lets sound reflect back up to the front sound holes,,,,, i have 2 on the front soundboard.

Originally Posted by AussieOzBorn

I'll have to dig through my pile of un sorted pics, but yeah im sure i have a few.,,, blah, blah, blah.

Anyway, here are a few pics of my acoustic prototypes, to give you an idea of what I was talking about.
Btw, the first pic is from the 2nd build and the rest are from the 3rd build (still in progress).

Those are a couple of sharp looking guitars, nice design work there. Looks like your internal board is glued to the sides of the guitar, is that the case? I wondered about doing that but since the internal board in my guitar is tensioned by the strings I let it float free from the sides. I've been tyring to do a bit more research on how vibration travels through wood, came across some interesting stuff. Vibration or sound travels almost 3 times as fast with the grain as across it and it travels fastest through steel. It travels slowest through air. Don't know yet what I'll do with that info, have to think on that awhile, might try an internal board of thin steel plate. Going to put that on the back burner for now, just can't bring myself to start another right now, still stinging a bit after what happened to the last one, not to mention what the materials would cost. Got enough wood to build an electric, a little success at something would sure help brighten things up. Thanks for posting the photos, any chance you might put a video on U-Tube so we can hear what it sounds like? Mike