I like the insides of the picture that heads this forum. It seems that a real attempt has been made to get the best sound out of his box (that suits him!)

I was wondering if the guitar theory of bars and bracing really applies to CBGs?

Regarding bracing, then if we are to have more than 4 strings or use high tension strings then there does appear to be a need to construct bracing to keep the neck and the box in line and prevent warping.

Acoustic bars, depending on the thickness of the sound board wood, might not do much to "improve" the sound?
The same with the thin supporting bars that are traditionally put around the guitar rose sound hole. They are clearly needed for a wide thin sound board, but I doubt if of value to a cigar box.

Similarly the fan and cross bars carefully placed to accentuate the required sound for the guitar, I cant think that they will really change the sound produced except to the most discerning ear.

What do you think?

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vanity....vanity....putting sequines on a sow's ear doesn't make it a silk purse....

JMHO,

Wichita Sam
That's a good one! So putting an ear tag on a a silk purse likely doesn't make it a sow either?
On my guitars, I've found that I don't really need to do more than glue a strip of 1/4" red oak right under the bridge and line the sides of the box with 1/2" poplar (box lid is glued to this poplar frame). That's for an acoustic bridge. If I have something like a Gibson style bridge, I change the 1/4" strip to about 1/2". The lid (soundboard) is so small in our case that just a little bit of extra reinforcement around the sides is enough to bear the load.

As far as keeping the neck in line with the box, yeah, if I'm using a standard six string neck I'll usually run about a 3/4" inch piece of oak down the center of the body and either glue or bolt my neck to that. That's good enough to get me what I need in all cases.

I've never done it before and I tend more towards electric instruments anyway, but I have to imagine that you're not getting a whole lot of return on your investment of traditional bars and braces. Yeah it keeps the box more supple and light and preserves its ability to resonate but really, we're only talking about an 8 X 6.5 X 1.5 box here. You're never going to get this thing to sound like a classical Spanish guitar. An acoustic CBG sounds thin and tinny. Moreover, that's what they're supposed to sound like. That's that Delta Blues sound everyone keeps plugging. If you want it to sound like a dreadnought, get yourself a bending iron and make a dreadnought.
I have to say that in building a CBG there is no way that I "want" it to sound sweet. I use the term "twangy blues guitar" is what I want.

However the acoustics do interest me and I might try and make a "sweet psaltery-like" CBG one day!! :)

It is probably called a CB Dulcimer?????

Perhaps we should encase a CB into the body of a classical guitar and see how that sounds? !!!!!
I have tried all kinds of bracing to improve box stability, and to see what sound comes out. I made a six string dulci-mandolin with very thin all wood box, with an X brace, and it sounded very good. I also put an X brace on the bottom with a "sound post" on the bass string side. I was surprised at the nice tone. The box was Cedar. I put kerfing along the inside edges to strengthen the box, as it had six strings with lots of tension, tuned in the mandolin range. I took it to a jam and sold it. That was the best sounding CB mando to date. I now make them with the stick on the top, like a traditional dulcimer.
hey richard, can you throw up a picture of something similar? so those of us less experienced can see and understand what exactly you did.

Richard Sanabia said:
I have tried all kinds of bracing to improve box stability, and to see what sound comes out. I made a six string dulci-mandolin with very thin all wood box, with an X brace, and it sounded very good. I also put an X brace on the bottom with a "sound post" on the bass string side. I was surprised at the nice tone. The box was Cedar. I put kerfing along the inside edges to strengthen the box, as it had six strings with lots of tension, tuned in the mandolin range. I took it to a jam and sold it. That was the best sounding CB mando to date. I now make them with the stick on the top, like a traditional dulcimer.
Seems to me that for typical thru-neck CBGs with 3 or 4 strings there really isn't a need for any bracing. I haven't built an instrument with more strings than that yet so I can only theorise about what the situation would be with a 6-string guitar or something like a mandolin.

One significant factor in the question of bracing is the ratio of a soundboard's width to its thickness. Traditional guitar soundboards need bracing to stop them bowing because they're made of thin wood and they span a considerable width (even across the narrowest part of some guitar bodies and certainly across the part where the bridge sits). Most cigar boxes and biscuit tins are much smaller than the body of an average guitar - so the soundboard (typically the box lid) is spanning a much shorter width. And the cigar box lids I've encountered are a bit thicker than a guitar soundboard. So simple engineering says you already have a much more rigid soundboard, and so you're less likely to need bracing. The idea that bracing contributes to sound is a bit of a red herring - it's certainly important to design bracing so that it doesn't mess up the sound of an instrument, but the primary reason for bracing is surely to provide strength rather than to improve sound.

I've just built a 3-string CBG strung and tuned like Seasick Steve's guitar (ie. G-G-B using a low E-string tuned up 3 semitones, a D-string tuned up 5-semitones and a G-string tuned up 4-semitones) - that's a reasonably heavy load but there's no sign of even the slightest bow in either the box or the neck (which has no trussrod).

Probably silly to resurrect this thread (on nearly its 5-year anniversary :) )
but...

It occurs to me that one could achieve a thinner (and presumably higher resonance) CB soundboard if, rather than adding braces, one subtracted material (thickness) with a router and the material that you LEFT became (in effect) the bracing. I think this idea would work best if the lid is solid wood (not plywood). Would be interesting to compare two identically constructed CBGs with this "router reveal" of bracing being the only difference.

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