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In your opinion or experience, what are the effects of different back bracing patterns on tone? For instance, x-brace verses Ladder?

Also, is there a structural reason to use one or the other?

Thank you for your imput, it is appreciated.

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Joe Beaver
Maker of Sawdust

This is just a blatant attempt to keep the post on the first page. It is so easy for it to slip into obscurity... guess it's just a Sunday morning thing.

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Joe Beaver
Maker of Sawdust

Ladder braces work well for stiffening a back laterally, but do very little to stiffen a back longitudinally. X-braces will add stiffness in both directions.

To me, the primary purpose of back braces (in this case, ladder) is to maintain a lateral back arch. I prefer braces that are somewhat taller than typical, rather sharply peaked, and thin. This configuration allows me to get by with a bit less mass glued to the back.

As a player, I like to play guitars that have responsive backs. That is, I like to feel the back vibrating as I play. This is why I am not fond of thick backs or heavily braced backs, because such do not respond as well when played. However, I know also that guitars with thicker or more heavily braced backs usually project quite well. That is, they often sound louder to the listener than they do to the player. I'm not much of a fan of guitars built this way, though. Many responsive guitars also project well, and it is much more fun to play one of them than it is to play a guitar that feels dead but sounds nice to the audience.

I realize that 'tone' and 'responsiveness' are different concepts, but I thought I'd toss it in there anyway, since this also something to consider.

Bottom line, I'm sticking with ladder bracing because I would rather have a back with some give than one that has been stiffened up, perhaps too much.

Best,

Michael

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Live to Play, Play to Live

I've used several different 'X' brace schemes on backs over the years, trying to get one I can 'tune' when it's off the guitar and have it work well when it's on. Each one sounds a very little bit different from the others. Ladder bracing has it's own, slightly different tone. When they're done right each works about as well as the others structurally, IMO. It's so hard to describe tone.....

Thanks for the feedback guys. The only thing I'm almost sure of is that the back has an influence on sound. I don't have a clue as to what that influence is.

Loose top, tight back... amplifling each other? Loose back, loose top...in phase with each other cancelling sound? Neither of the above? And how about wood choices? I guess I should stay with ladder bracing until I get a firm handle on it....

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Joe Beaver
Maker of Sawdust

Joe, on my experimental first, i had the same plywood veneer on the back and top, my bracing was ladder for the back and x brace scalloped bracing for the top, my kerfed lining was very thick and so were my braces and it just beats whatever guitar i've owned so far, so my newb question here would be why not experiment, i for one would be curious to hear about your results!

Serge

I was visiting a members page and now I forget who it was - I end up at many many luthiers pages everyday,
Anyhow - This ingenious luthier drilled structural holes into the side of his braces to reduce mass, he dd this on top and back braces unless I am off the mark. Appearantly it increases the resonance and sustain while maintaining the structural integrity, in the vein of girders{tressels?} on bridges?
This could technically enable a luthier to use larger braces with less mass, but still as much or nearly the same amount of strength, with a higher strtength to mass ratio.
Or someone could build with very small profile braces and have them feather light.
I wish I wasnt on my first build because Id love to be experimenting with this idea.
But Im definitely going to be playing it safe for the first few.
I know Im not getting the idea across in the best way but it made me think of it in conjunction with the current discussion, which intruiges me.
Cheers
Charlie

Actually that is exactly what I did on my first guitar, it sounds fabulous. I'm trying something different on the second and third, I already hear a difference with the closed box on #2 over #1, #2 seemingly more vibrant, with no holes drilled in #2 braces, so who knows.

Greg

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Gwaltney Guitars

The effect of the back on the sound is a little hard to describe briefly. As usual, you really have to look at the whole guitar to get it.

Most of the power output from the guita is due to the 'bass reflex' action of the 'main top' and main air' resonant modes working together. If that was all there was going on (the back and sides were rigid, and the the shape was simple) the output spectrum would have a peak for the 'main air' resonance, another, taller, one for the top about an octave higher, and then the curve would fall off more or less smoothly at something like 6 dB/octave. This would be about the most powerful guitar you could make, but all the notes above the 'main top' pitch (say, the open G string) would sound exactly the same: boring.

If you 'tune' the 'main back' resonant pitch so that it's close to that of the top the two will work together to move more air through the soundhole at the 'main air' pitch. That pitch will drop a bit, and the peak will broaden out, so that you'll have a more powerful bass sound. The is likely to be more output near the 'main top' pitch as well, since the back will be reinforcing that. You don't want these two to be at the same pitch though, or even too close together, as that will tend to give you a 'wolf' note at that frequency. It will be loud and 'thuddy', with no sustain. I feel that the 'best' place for the 'main back' resonance is about a semitone higher than the 'main top', but since the top tends to play down a bit when you first string it up, you can make them a little closer to begin with.

Most of the higher back resonances are 'losers': they actually cost you some output. What they do give you, though, is 'tone color', so you don't exactly want to get rid of them. I think it's best if they are not too strong, and fairly restricted in pitch bandwidth, which implies a fairly heavy back with low damping. Gosh, isn't that a description of Brazilian rosewood? Funny....

You had to ask.

Charlie,

re: holes in the top braces. You're probably talking about Jamie Kinscherff. Jamie has been doing this for several years and he builds a beautiful guitar. As for "playing it safe on your first few guitars", how come? Now's the time to experiment. Most likely, your first few guitars will be made for your own enjoyment. You can use these first few to develop your own style and give your guitars their own identity. You'll learn a lot on your early guitars and a little experimentation will only help the learning process. I'm not saying that you should try to "reinvent the wheel" as the wheel really doesn't need reinventing. But you'll learn that there is not necessarily a "right" way to do anything. I'm sure there were plenty of detractors when C.F. Martin came up with that wacky x-brace thing.

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Jimmy Caldwell
http://www.caldwellguitars.com

JimmyC
Yeah mabye your right, I did say I was intruiged with that design - but not convinced.
Most of the people who are walking me thru the luthiery process somewhat are advocates of the "light and strong" guitar philosophy so who knows where I will end up?
Im definitely ruling anything out yet.
Also I am considering building a concert and a parlor, eh hem......in concert.
So one could be designated for more of an experimental unit.
Cheers
Charliewood