Replies to This Discussion

Permalink Reply by Jim Saraceno on August 11, 2015 at 12:05pm

I tried a dowelstick experiment and found that the sound was dampened considerably when I put a section of 3/8" dowel between the neck and lid right under the bridge.

Here's a video of my experiment... https://www.youtube.com/watch?v=F31SJo9Xd70&feature=youtu.be

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Permalink Reply by Tom T on August 11, 2015 at 12:28pm

Great experiment, Jim and the results are easy to hear.

One point to consider is that on violins, the dowel actually connects the top of the box to the bottom. This, I think, would transfer the vibration energy to a 2nd surface capable of vibrations (i e the bottom of the violin). I can understand how wedging the dowel between the neck and the box top would tend to prevent the top from freely vibrating as you demonstrated.

Shawn, in an earlier reply to this thread indicated that he had great improvement in volume when he installed the dowel, but he drilled a hole in the neck so the dowel could connect the box top to the box bottom without being dampened by the dense wood of the neck. That may be the difference between your two results.

Still, I think your experiment and video provides us with more information we can use to improve our builds.

Thanks!

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Permalink Reply by Richey Kay on August 11, 2015 at 7:48pm

When I use dowels underneath the bridge, I have two, one either side of the bridge. When I play the guitar the whole box seems to vibrate. My latest acoustic build uses this system and despite the tiny box it is loud enough to sing along to at home.

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Permalink Reply by Bluesheart on August 11, 2015 at 2:47pm

Thanks for sharing your experiment Jim. Your result is why I have always left a space between the neck and box. They start off sounding more like your no dowel sample and end up sounding more like your with dowell sound as the top collapses and touches the neck. I don't know if in this case the dowel being under enough pressure to lift the bridge a bit makes any difference or not but your test seems pretty convincing for a gap.

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Permalink Reply by Graeme L on August 12, 2015 at 2:32pm

Can someone put some pictures up of the dowels installed so us "non dowel" users can get a visual of what your doing? What sort of size dowels are you using and do you just leave the dowel end flat or do you shave it to some sort of a point? I'm keen to give this atry but just trying to get a better idea of the configuration!

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Permalink Reply by gary herget on August 13, 2015 at 3:56pm

The dowel talked about from the violin is called a sound post,and is placed under the treble foot of the bridge. It is placed there to transfer vibrations or resonation to the back of the instrument as well. This has been done for hundreds of years, so it's no suprise to find it working on CBG's as well.

There is also a rail called the bass bar that runs the length of the violin and is placed under the bass foot of the bridge. It would be interesting to see if the bass bar works in CBG's as well. A bass bar resembles a support brace from a guitar.

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Permalink Reply by Tom T on August 14, 2015 at 3:34am

Thanks for the clarification Gary. I thought it was to transfer vibration to the back of the violin, but didn't have any specific references. This could be a very good thing for CBG volume.

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Permalink Reply by Nathan Binns on August 14, 2015 at 6:37am

This seems to be an ongoing conversation on this forum popping up every month or two. I'm starting to think this is one of those whatever-works-for-you things. If you're having problems with having a space then I'd definitely try something else. 

From my experience (which is only 6 finished builds) the neck-glued-to-box works the best. I find it's an easier build method, better volume/sustain and I've had zero deformation of the lid. Saying that, my best build in terms of volume and sound quality was my tenor uke. That neck was fixed with dowels through the heel. The bridge-saddle was glued to the top and the top was braced. The BIG difference on this box is that I built the box from scratch and used 3mm cedar for the soundboard. I think the box itself makes the biggest difference. 

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Permalink Reply by Ronald Whitford on August 14, 2015 at 8:06am

I have built my cigarbox ukes and banjo using the bottom of the box as the top and that seems to give a better tone.  I think the bottom wood is a better grade than the top.

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Permalink Reply by Habanera Hal on August 17, 2015 at 11:40am

Are you using paper-covered boxes?  Most modern paper-covered box lids are actually masonite, not wood, ergo the bottom sounds better, even tho most of those are plywood.  Those masonite tops don't resonate so well.  Also, all the above (IMHO, YMMV) is moot if you're amplified.

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Permalink Reply by Blues Frog on August 17, 2015 at 2:28pm

I have recently built my first git that wasn't a neck through. Granted, the top was tin, not woood, but I think the process of pressure will still act the same. I needed to brace under the bridge to keep the face from bowing as I tightened the strings. The same goes for the neck through. I made mine so they glued to the face of the cigar box. So far they have given good sustain.

Brace the face along the neck and I think you will see the sustain you are looking for.

Just my opinion.....

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Permalink Reply by Bluesheart on August 19, 2015 at 5:07am

I think that sustain and volume are two completely different things, right? A banjo for example has very high volume but a very short sustain, or "rapid decay" of the note, but an electric guitar may have very long sustain of the note but almost no volume (until it is amplified). For an acoustic "guitar" to sound what is considered "good" it needs to have both high volume and long sustain, for the most part I think.

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