Alternative to X/Parallel bracing

[Fernando Esteves]

Hello people!
I saw some comparatives of X bracing vs Parallel bracing and I found the 1st a bit stiff sounding and the 2nd a bit floppy.
Is there any alternatives to the 2 tradicional bracing styles? Never heard of it...
Thanks

[Mike Conner]

I'm building dreadnoughts (3 complete and one closing the box) using "V" bracing inspired by the Taylor offering. They sound fantastic. Just some partial photos of the Taylor version online, and of course no drawings. Created my own version with pen, paper and informed guesswork. The front plate and braces are both Engelmann Spruce. The bridge plate and ball-end reinforcing plate are Red Maple.

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For each build, the front plate goes to the recipients family to sign or write messages on the interior surface.

Here's another view, showing the last brace glued with gobars:

[Barry Daniels]

I have not seen anything on archtops except for parallel or X bracing. Don't let the descriptions you read turn you away from either pattern. Those were gross generalizations. Since you are making it, you can make either pattern to act like you want.

[Mike Conner]

oops! I guessed I missed that Fernando was asking about archtops. On my archtop builds I use X bracing, crossing ahead of the bridge line. Carving of the braces can help adjust the stiffness. Documented in my Archtop Journal posts.

[Freeman Keller]

I recently built my first (and probably last) carved arch top guitar and I debated for a long time which of the two standard bracing patterns to use. Both the archtop panel discussion at the GAL conference a few years ago and Benedetto's book indicated that "in general, a thinly carved top with parallel bracing will produce a louder voice with greater projection than a thicker top with "X" bracing, which will typically produce a softer, mellow sound" (Benedetto, page 51). Since projection is not an issue with me and I tend to prefer softer, mellow sounds, I went with X bracing.

After six months I'm still trying to come to grips with this guitar. At first I hated it, it was loud and brash sounding, but that has mellowed (there's that word again) and I'm learning how to play it somewhat better. Its definitely an archtop, but still a surprise.

[Alan Carruth]

On archtops you have some dials to turn that are not generally used on flat tops; in particular, arching and graduation. These provide a lot of the stiffness that a flat top gets from bracing. This can get quite subtle; arch shape and well as height can control the stiffness in different areas of the top. 'Parallel' braces usually are not really parallel, and you can vary the angles of the braces as well as the profile and length to get the stiffness you need.

In many respects, so far as I can tell, the bracing on an arch top guitar top is there to make up for the stiffness that is lost when the holes are cut. Either 'parallel' or 'X' bracing can do the trick in that respect. They may well sound different all else equal, but I don't have enough experience to sort that out for sure. After all, it's most likely impossible to make 'identical' guitars sound alike anyway. All else is really never equal.

[Mike Conner]

Here's a photo showing the X bracing I used, and also the pickup sensor placement. The sensors are JJB. The notes and signatures are from George's family and friends.

Here's how the carved braces end up. Also, the braces end well in from the edges, and these areas of the top plate are where I sand the recurve from the outside surface.

[John Tuttle]

I am in the middle of a build for a customer who asked for something a bit atypical.

This customer wants an acoustic archtop with a floating neck pickup but he wanted to know if there was a way to design the structure of the build to allow for the possibility of installed pickups at a later date if he decided he wanted to do that.

This brought up a number of structural questions and bracing challenges posed by both X and parallel designs.
So...I employed a little of each to achieve the space needed and did a vector analysis assuming various top and end loads at full string tension.
This idea "should" hold together with strength to spare.

For those of you who are envisioning a problem if/when a bridge pickup cavity is created, you're not alone but I'm throwing caution to the wind and doing it anyway.

Heck, the worst that can happen is a total collapse of the top and we learned something that can be shared with the community.

So far, the tap tone has lots of sustain and a high degree of compressional strength at the bridge location under load (lead weights).

Here is a design image and an image of the bracing after installation.

[Beate Ritzert]

Nice. Looks very interesting.

That kind of fan bracing also came out pretty well, also a bit more mellow, but still projecting:



The background of this structure was a different one: i wanted additional support on the previously delaminated top which i cured under heat and humidity. The top originally had two parallel braces witch were much higher thand they were previously (i reglued and lowered them).

[Barry Daniels]

Nice work there, Beate.

[Beate Ritzert]

THX

[Fernando Esteves]

Hello, me again!

I was thinking here, what do you think would happen of instead of the 2 soundbracing/double X bracing, do a tradicional X, but those 2 on the lower part beneath the bridge you do something alike the fan bracing of classical guitars?

Thx

[Carl Dickinson]

Check this out, Fernando. https://www.edwinsonguitar.com/Design_P ... sophy.html

[Fernando Esteves]

Awesome!

[Alan Carruth]

I've used X bracing on all but one of my arch top guitars. That one was an 'homage' to a Lloyd Loar L-5, and I used 'parallel' bracing (which is really more like an 'A'). On round hole arch tops I also use a cross brace/patch above the hole.

I've gravitated toward more or less uniform top thickness, or even 'reverse graduation', with a thinner area along the center line. This follows some of the recent work on Cremona violins, and it works well. Again, the Loar homage was an exception, where I went back to the older practice of making the center of the top thicker, and graduating it thinner toward the edges and lower end. This was based on Hacklinger gauge readings from the original.

I also used what's often called a 'flatter' arch on that one. It's not actually any lower in height than any other, but it has a more level (but not flat!) area in the center, which drops off faster at the edges. The flatter center needs to be thicker to avoid sinking under the bridge down load. That's really one of the keys to the whole thing.

Flat top guitars use largely uniform thickness on the top, generally thinner than you'd use on an archtop. They use bracing to add stiffness where it's needed for structure, and to a much lesser extent, tone. Arch top guitars use a combination of thickness, arch height, arch shape, and bracing, to work on both structural and acoustic aspects at the same time. You can't successfully 'mix and match' things freely. Work on mapping outline, arching and graduation on fine violins tend to show them falling into 'schools', with each combining particular features consistently. As I understand it the 'Cremona' school, from later Nicolo Amati onward, tended toward a combination of uniform or 'reverse' graduation on the tops with curtate cycloid cross arches. Other schools did things differently. They all 'work', but they produce different results, particularly in sound.

I've also found that it works well to scale the arch height with the thickness of the top. Making a high top arch for stiffness, and using thin graduations to reduce weight, works out structurally, but not acoustically. I did that on my first two arch top Classicals, and ended up with instruments that worked far better for Blues than the Classical repertoire. Since then I've used lower arches with heavier thickness, and used the lowest density wood I could find to keep the mass down for those.

So; if your 'parallel' braces tops are too 'floppy', and your 'X' braced ones are too stiff, it's not only, or even primarily, the bracing. You've got to learn to work with them as systems.

[Fernando Esteves]

I've posted on the wrong forum, the doubt is on flattop guitars