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I am just curious about double x-braced tops and what the difference (any advantage/disadvantages) from the standard tone bars and finger braced style. It does not seem to be done a lot, is there a reason?

The reason it's not done more is probably the standard one: tradition.

The only advantage I can stand behind is that it's easier to Chladni tune a double-X top due to the symmetry. Al Carruth might have more as he's the one who taught me about the pattern.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I've built a few with double-X braced tops and they sounded great.

Cheers,

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Gwaltney Guitars

good timing on this post. i have an engleman top that i double x braced and am now faced with deciding where to scallop. anyone have pictures of a double x they had complete that we could check out?

When I got curious about this, I took an opportunity to build a 'matched pair' of Small Jumbos, one with 'double-X' and the other with 'standard' bracing. They were a commission from a jazz playing friend who wanted a nearly-identical pair for some duo work. When I got them strung up, I took the pair to an ASIA meeting, and passed them around for people to try, without, of course, telling them what the difference was. Afterward I did some objective measurements.

There was a slight but definite preference for the double-X top: about twice as many people preffered it by a little bit. The double-X was often said to have a more 'modern' sound, where the 'standard' pattern gave a more 'traditional' timbre. Some poeple thought the double-X had more treble, and some thought it had more bass.

When I got around to making the objective measurements, it turned out to have _both_ more treble and more bass, by a little bit. The 'bass reflex' part of the spectrum, below the pitch of the open G string, was a little more powerful, and there were a few more peaks in the output in the 500-1000 Hz range as well.

I'll note that these used my normal 'tapered' bracing. You could scallop the main bracing pretty easily if you wanted to, but the lower X would be a little more difficult, as you need some height at the X crossing for structural reasons. It's not an insoluble dilemma, just not something I've tried yet.

In short, double-X bracing _does_ work despite what one well-known builder said when told which guitar she preffered. The concept has been given a bad name by one large guitar company, which seems capable of messing up almost any good idea. If you do a better job than they did, which is not difficult, you should get pretty good results.

I've built a number of guitars with double X bracing and they came out great. I'm now experimenting with some other ideas, but more important than the actual bracing pattern is how they are carved and tuned along with the balance you achieve between the amount of top and the amount of bracing, and a thousand other factors. Having said that, I am a fan of symmetrical patterns.

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Randy Muth
RS Muth Guitars Website
RS Muth Guitars Blog
Facebook Fan Page

I didn't scallop my double-X braced guitars.

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Gwaltney Guitars

Gibson came out with the double X bracing system in the 60's. I think they did it because they were using INCREDIBLY BAD SPRUCE at that time.

I somehow stumbled upon the source they had for tops. They were nice,very fine grained Sitka spruce tops 1/8" thick,BUT THEY WERE SLICED like thick veneers. This broke every grain in the tops when the tops came off the veneer cutting knife rolled up like a big wide chip,just like regular veneers come off these machines. Ever seen veneers being cut? I have. We had a veneer factory near Old Dominion College in Norfolk,Va. in the 60's. I used to go there to buy veneer,and left over "backboards",which was the left over wood that the machine had to grasp. These leftovers were 3/4" thick. Nice,choice,often figured woods. I still have several sheets of Tamo,cut for the 1959 Cadillac interior trim.

You could take these tops and roll them around into a cylinder because the integrity of the wood had been ruined. KAY USED THE SAME TOPS !!!!! I was told that by the supplier!!!

These tops came book matched,glued together,and perfectly smooth and ready to use. THEY COST $1.00 EACH.

This was a long time ago,and I can't remember how I found out about these tops,or where they were sold. I tried a few,and was not impressed with their tone. I always looked for that top on Gibson guitars in stores,and saw it often. The grain was very close,and the grain lines were very thin. They had a certain look to them.

Fascinating story George!

Thanks,
Joe

Thanks,Joe. Maybe if I bump this to the top others will have a chance to read it.

When I have been using double x braces I have been making the angle very tight and pulling it up close to the bridge plate (not yet installed on this guitar). It has been working very well so far but I don't use it all the time. I usually put some sort of bracing behind it in the big open spot also. I left it out on one and the guitar is fine but that area distorts with temp/humidity swings. Here is a photo. This guitar also has the buttress bracing, that is why the UTB is so small. It is a 14 inch lower bout and tapers from .105 in the middle to almost .07 at the extreme upper and lower points. Most of the middle is in the .095-.105 range.

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Burton
http://www.legeytinstruments.com
Brookline, MA.

That is not the type of double X bracing that Gibson came out with,which I was thinking of. Theirs was the use of 2 of the main X's. I think theirs was to enable use of the very flabby spruce that I described.

Thanks for the replies everyone.

Alan- Interesting that so many preferred the double-x, might have something to do with the symmetry?

George- Great story, thanks!

Burton- Thats some interesting looking bracing

Burtons example gave me a new question. to tuck or not to tuck on the double x? who is taking their braces right down to nothing or leaving them a little high so they are inlet into the kerf? and which ones?

I inlet the main X, and taper the back X to nothing.

Great story, it sounds like Gibson was over building the crap out of their guitars to compensate for crappy tops!
I can't even imagine a guitar having double X braces, thats a lot of wood, heavy!
I have seen that type of double X brace in the pic built by another Texas builder for many years. I've heard many of his guitars are small but very loud. The more sound you can get thats pretty the better.

I was a factory authorized Gibson repairman back in the 60's. When Colonial Williamsburg got hold of me in 1970,I was in a different world till 2009,when I retired. Jerome Zoeller was a Gibson rep back then,and asked me to serve in that capacity.

I remember seeing a Gibson Dove that had brash,unsanded thickness planer marks under the lacquer about 1965. Of course,I have also seen Martin guitars with circular saw cuts on their backs,under their smooth lacquer finishes!! These were on pretty old guitars,too. They looked like figured rosewood from several feet away!! And,these old,vintage Martins fetch high prices,too,with those circular marks sanded sort of half way out! Somehow enthusiasts accept them!! I wonder if somehow the wood got resawed too thin to begin with?

Have any of you seen those tuners they used in the 40's(?) that have spur gears that are just stamped out of sheet metal? I THINK they might have been Grovers,but can't remember.It's been quite a while since I have seen them. I'm not sure about the era when they were used. Maybe it was a wartime economy?