Hi, I am making my first guitar box out of local timber, 250 x 200, and wondering what depth it should be as a starting point? Our acoustic guitar is 110mm deep, by comparison.
The local hardwood timber for the neck is 40 x 19 ( +/-1mm), but I can plane that to a different dimension if necessary.
Do you recommend a rebate on the top and bottom of the box for the 5mm thick base and lid to fit in? Might look neat, but takes up space inside the box.
Nothing is set in concrete, will to have a go as long as it sounds nice and looks nice :)
Some people like the sound of certain size boxes, but it doesn’t matter much as long as they’re at least 50mm -60mm deep, you’ll get good volume/acoustics? The macanudo box that Shane uses for his signature build isn’t very big in length, but it’s a little over 63.5mm deep, so it’s plenty loud? Check out these non cigar box boxes, there’s even a video demo of an actual build?
fyi, if you go all the way to the top of the page, on the far right, there’s the “Search” box, you can easily find tons of info from past topics & discussions? Maybe you’ll find answers to some of your questions?
Hi BrianQ, many thanks for the advice and the links, they were very informative. I think the thing I have learnt already is that there are no rules, other than the Scale Length if doing frets.
Of course muggins here wants to build a very nice sounding CBG with excellent bass first off :) Not going to happen, lots of experimenting to be done to get it right.
Possibly could, if you follow a proven recipe.
There are a number of builders that demo their CBGs acoustically & plugged in. Find one that sounds pleasing to you (as best you can from listening to a video), then try to duplicate it as best you can. Decorate to suit.
Hi, JillB, in the photo this CBG has a box size of 200 x 200 the ID is 60mm. The scale is 24’’. I built two of them as experimental.
It sounded so lacking that I didn’t even give it away. The first one I did sell after changing sound hole capacity, made it sound more pleasing and louder.
It’s important, I think, to first place the bridge where it works best on the top and then see what scale length is most suitable. In the photo, you can see the footprint left by the bridge when in its original position, when I moved it to a more responsive area of the top the volume increased three-fold, but the intonation is crap. Haha.
However, the same box built using better timbers and a more suitable soundhole area sounded great of the bat. So, what I learned is that it’s a combination of elements that gives a box a better tone and/or output, and size is only part of it.
In case you missed it, below is a list of guidelines I have compiled and have in my workshop for reference. You may be helpful.
TaffFrom the above list, you can see what design guidelines you would need to incorporate for the bass response you are looking for.
Many thank Taff, a real eye opener, and very timely too. Having decided on a box 300 x 200 x 60 OD based on available timber, bigger the better for sound, I then went looking for an F-note, and found one as per attached, and drew up a template for my router with a 10mm guide bush and a 3mm router bit to cut it out.
Your problem with sound holes alerted me, and I found the total area of this f-note was equivalent to one hole 38mm diameter.
Based on your experience, would two of these f-notes, either side of the neck, be adequate? I can make it bigger
Yea Taff, that’s not the greatest place for a bridge, not much balance between volume & acoustics.
hi Brian, what do you think is a good position for a bridge please? How do you find it?
Hi Brian Q, yes dead right. These were built to see what others were getting when no or small soundholes are used - bridge placed near tail - small box - budget materials - low action.I gradually changed these features to observe improvements.
Taff’s pic & post from the earlier post is a good example of bridge placement?
Hi, I’m no physics type I work it out by experiment and experience and suspect you will do the same over time.
When I was asked to build a CBG for a guy I had never heard of one let alone seen one. The customer explained what it was, and I thought oh, a box with strings on it. Even though I had built many guitars over many years I still made three cbgs before I was happy with the one I would sell, changing each one as I went along.
Anyway, the size box and soundhole you mention will work fine. It will give you a baseline from which to work if you are going to build others. One would have to be very lucky to nail it the first time, I reckon.
The finished item is a great thing to behold and enjoy, but I think so is the mystery in the journey, which will be full of highs and lows and great light bulb moments.
I may be wrong, and this may be a case of too much info too soon… but it’s not just the size of the box that is the basis for the desired hole size, but the responsiveness of the top and the air it moves. Sorry.
People often say that the bridge is a third of the way up from the butt end on an acoustic guitar, which is correct. However, the bridge is where it is due to it being in the Centre of the effective vibrating area of the top. From the soundhole or waist area to the heal/neck end, the top contributes very little.
Jill, can you please stop asking such interesting questions. Haha
"Jill, can you please stop asking such interesting questions"
Sorry, Taff, but it is such an interesting subject, and I am on a really steep learning curve. And being a perfectionist, I thought I would just read up on it, master the concepts and theory, and then draw it up and and then make the perfect CBG, without ever having seen one. I need to get real !! :)
And it is a classic case of the more information I get, raises even more questions.
I really appreciate you and others like BrinQ sharing your knowledge and experience, What a great Forum !!
Just keep asking the questions Jill.
Really interesting answers and advice, so helping me tons and saves me having to ask ‘em.