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I have only built three CBGs so I'm no expert, the following are just opinions of someone trying to figure it out. My main objective is to build the best sounding acoustic CBG that I can. I have just run into my first hurdle. My second CGB started out with a brilliant sound and then went flat. My conclusion is it suffers from "box crush" where the pressure of the strings on the bridge made the box cover (soundboard) sag.

I tried to do the research here and did some experimentation. Here is what I find from my experiments...

1. Thin lids make the best sounds.

2. Making sure the lid is not touching the neck vastly improves the sound.

3. The bridge transfers sound to the lid.

4. Sound holes will produce a much rounder sound.

So that second CGB (and my third) have lids about 1/8" thick. They both had brilliant treble sounds and nice bass tones. Once I realized I had box crush (and muffled sound), I set about trying to figure out how to brace the top.

I tried putting a support between, the neck and the lid. I tried putting a sound rod from lid to back. I moved that rod around to many different places and found that putting it below the bridge (closer to the tail), the less it dampened the sound but of course that gives it less support (the sag in in the middle of the box, not directly under the bridge as I would have expected.

Of course, either of these bracing methods are better than that flat sound that the sag eventually brings but I really hate giving up those bass tones. I'm thinking I need to abandon the neck though design, go to a bolt-on neck, and brace the cover with ladder braces.

Now to the apple and oranges... Because there are so many of you who have so much more experience than I do yet there is such a huge disagreement on what makes a great sound to these things, I'm thinking we are talking about different things. What makes an electrified guitar sound good is probably different than what makes an acoustic guitar sound good. What makes high (pitched) strings sound good is probably different than what makes low strings sound good. What may sound good on a box with a thick cedar lid will be different than a thin plywood lid or a composite lid.

One test I did was to build a CBG with no sound holes, played it to see how it sounded then added one round sound hole to see if that made a difference. Then after playing it that way I added a second round hole. My conclusion is with no sound holes, the treble strings sounded great but adding a sound hole really brought out the bass tones. The second hole added to that sound but not by much.

People swear by the "Glue the neck to the lid" option but that goes against every experiment I've tried so there has to be something that is not translating to what I'm doing.

I know these topics have been hashed out and re-hashed out so I apologize for bringing it up again but like I said, I'm just trying to figure this stuff out.