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I haven’t built a classical guitar in many years now but I am thinking I will. The plan I have been using calls for a typical fan bracing scheme. It works out well producing a nice guitar. That being said, I have been considering drawing a new plan and trying for a little more bass and perhaps more volume while maintaining balance.

So, I was wondering what it would do if I added a little more air space to the lower bout (slightly wider lower bout with a little more heel depth) and braced the top with light x-bracing?

I sure many of you have strayed from the traditional Torres/Hauser/Ramirez plans. Tried x-bracing? Any luck?

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Joe Beaver
Maker of Sawdust

i´m still learning, so keep that in mind... anyway,

larger body will mean a lower air (or A0 as people call it, IIRC) resonance, so maybe a little more "weight" in the lower register is indeed to be expected.

as for x-bracing on a classical, it has been done before (as everything else, it seems: Paulino Bernabe, deJonge, even Martin used it on their early nylon guitars - i´m shure there are many others), so maybe you can try to search those. I believe Mr.Alan Carruth has done it, maybe he´ll chime in.
You got me curious now... i suppose x-bracing will reinforce cross-grain stiffness when compared with traditional fan bracing. maybe you can shoot for a thinner soundboard? how large (wide) is your plantilla?

good luck with the build!

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member of the guild of professional dilettantes

My perception would be that you would get a boomy, bassy classical with limited treble response. Just a guess, but you don't have much energy from the strings to drive an X bracing system, which tends to rock a larger portion of the top, and also, in my opinion, will kill some of the hottest treble response areas on the top, between the bridge and the side of the guitar in the area just below the soundhole.

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Waddy

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Sound Clips of most of my guitars

Miguel

My current plan calls for a 365 mm lower bout, 492mm body length, and a 108mm heal depth.
I am thinking of a 375mm lower bout and 114mm heal depth and maybe a little more body length.

Waddy,

You might be right. It may be a waste of time and wood.

I would be interested to hear how this kind of experiment went.

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Joe Beaver
Maker of Sawdust

What I’m pondering is this.

Bracing came about as a means of stabilizing a top against string tension. When tension changed new, innovative bracing patterns emerged. As far as I can tell it was never because of the sound. It was always done for utilitarian reasons. Look at how archtops are braced. Since the string tension is being carried by the tailpiece and not the top, braces are only needed to support the down pressure of the strings. So what immerged is a modified fan brace scheme. What other bracing schemes could be and have been used? What other sounds is the archtop capable of?

The same question for the classical.

I am aware that people have spent lifetimes studying the effects guitar construction has on sound production and amplification and yes, tone.

What I don’t know about sound (musical and otherwise) could fill a book, actually it fills several.
None of this is new so I know you guys have the answers.

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Joe Beaver
Maker of Sawdust

X-bracing was originally developed for classical guitars, it didn't catch on. It was later applied successfully to steel stringed guitars.

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Old growth, shmold growth!

Don't do it. Because of the much lower string tension you simply don't need the stiffness that an X brace imparts to a top. You'll end up with a top that is too stiff and too heavy for optimal sound production.

The X brace will really restrict the cross dipole vibrations in the top, and I think you'll be disappointed. Also, bigger lower bout will certainly make it boomy, but also, most probably quieter, unless you are able to optimize the bracing. Heck, people have put nylon strings on a dreadnaught, and thought they had something great. My guess is they never heard a good classical. There's a whole world of people playing junk out there.

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Waddy

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Sound Clips of most of my guitars

Joe, lattice style bracing has gained some acceptance in classical guitars, kind of a derivative of an X brace. You might want to research that a little bit.
Also I agree with Waddy that a larger top will more than likely hurt you, not help you and if you go too deep I think it'll get a little muddy (not sure on that though). Think of a small transistor radio trying to drive a large speaker.

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Jim Watts
http://jameswattsguitars.com

Very interesting comments, thanks guys.

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Joe Beaver
Maker of Sawdust

I would try and do it (provided you have the time), even if the prospects are not overwhelmingly shiny.
As Jim said, lattice braced guitars have quite a following in the classical guitar concert scene (and, helas, a lot of detractors as well - you know the drill) and are somehow related to x-bracing; their focus is mainly on the main top (monopole) mode and the consensus seems to be they are, in fact, "loud". Paulino Bernabé had at least one flamenco guitar with x-bracing, he´s good pedigree. Talking of derivatives, you can also try to check out Byers´ double fan bracing - apparently he´s easy to reach and helpful.
Maybe you won´t get away with more "bass and volume while maintaining balance", but maybe you can still get two out of the three... but, then again, maybe you shouldn´t listen to me - i lack experience and finesse and am just thinking out loud...

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member of the guild of professional dilettantes

I think Waddy is right on with his analysis. It's too easy to think that loosening the top up to the max will improve everything overall.
I've come to believe that the parts of the top which previously were just thought to be only structural are vital in the extreme high end response of the classical guitar (which by the way separates the excellent from the ho-hum ones).

I think your proposed biody size is too big, no matter what style of bracing you choose.
I'd consider staying within these maximum parameters:

360 mm lower bout
485 mm body length
95 mm heel depth
100 mm bottom depth

This is a clip of one of the nylon-string guitars Jimmy D'Aquisto built. It uses an X brace.
Joe... I should mention... a print of this guitar is available from the Guild.

http://www.youtube.com/watch?v=gmX2gM6H ... ce=message

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"No man ever steps in the same river twice, for it's not the same river and he's not the same man.” -Heraclitus of Ephesus

All the Humphrey Milleniums I've worked on were double x-braced (widely splayed above and below the sound hole) and lattice-braced. They all had a characteristically big bottom end and an ultra-live first string. Many people think the modern sound and power of the Millenium comes from the wedge shaped body, but it's pretty clear to me that it comes from the lattice.

My opinion of that, Gary, would be that the X was used, primarily, to restrict the vibrating area more than for stabilization. Seems, and you, surely, know more than I do, that many of the Lattice builders as well as Double Top builders are restricting the size of the vibrating plate for better control of the sound. I'll go back to Al Carruth's quote, "It's easier to make a loud small guitar than a loud large guitar." Forgive me if I didn't get it exactly right, but that's the general take.

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Waddy

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Sound Clips of most of my guitars

Waddy,
Far be it for me to say what the late master's design intent was. In this case I think it is difficult to separate structural contributions from tonal since both are at play. The X's are light by steel string standards and capped by carbon fiber. Interestingly, I looked back at my notes on the 1979 Humphrey Pre-Millenium that I worked on and that guitar has an X-fan pattern. There are seven fans where fans 2 and 3 are inlet through a treble-side arch in the lower leg of the X. The bottom of the soundboard has two cut-off bars. Recall that Tom Humphrey was trained in the Gurian workshop where classicals and steel strings were both abundant. This gives a fascinating glimpse into the evolution and influences on Mr. Humphrey's designs.

That's very cool, Gary. The loudest classical I've ever heard was a Millenium with the swooped wings, at Dream Guitars. It was amazing. It hurt your ears in a small room when you attacked it.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

I agree with the others: I wouldn't go that big for a classical. All of my favorites that I've played and built have tended to be on the smaller side and even the larger bodied classicals I've played haven't been as big as you're suggesting.

As to the X-bracing, It's been done and done relatively well (though I wouldn't brace it Martin style but rather more DeJonge style if I were going to try it) but I think you're going to have a lot harder time producing a good sounding instrument going this route and even if it is successful it is not going to have the Spanish sound (if that's what you're going for).

I'd also agree with others that if you want to try something different you might have a better chance of success building a lattice-braced instrument instead of X-braced. Check out Greg Byers' design. He does an all wood lattice that has a more traditional (and to me, more pleasing) sound than the Smallman style lattice-braced instruments that use carbon fiber, etc.



I think you're right here, Waddy. I build fan-braced instruments but use a relatively massive lower transverse to restrict the vibrating area (kind of the opposite approach as builders like Jeffrey Elliott). I find it easier to control the sound and get consistent results this way. I've also noticed slightly better sustain without sacrificing volume since I started doing this a few years ago. The sound is slightly different, though: it's no longer a purely Spanish sound but still closer to a Spanish sound than any of the non-fan-braced instruments that I've personally come across.

Martin's 12-fret 000 was originally designed for gut strings. It's about a centimeter bigger all around the the lower bout (15" wide instead of about 14" for most classicals), and uses X bracing. I've made a couple that way, and they work OK. You have to use a thinner top that you would on a steel string, and lighter bracing.

That said, Waddy's right about the cross dipole mode, and that affects the sound in an interesting way. On most classical guitars the cross dipole resonance is something like 3-4 semitones above the pitch of the 'main top' resonance. This is close enough for the dipole to 'steal' energy from the top resonance, and cut into the width of the output peak in the spectrum. It's been observed that guitars with a narrow 'main top' peak tend to have a more 'cutting' timbre. On a classical, where the strings don't have nearly as much high frequency energy as steel strings do, that narrow main top peak can help the instrument to cut'. I'll note that Flamenco guitar makers often omit the outer two fans, which makes the cross dipole even lower in pitch on Flamenco guitars, and helps to give them their characteristic timbre.

Steel string guitars have the opposite problem: there's so much high-end energy in the strings that you have to think of ways to get enough bass and fullness to balance it. X-bracing tends to give the pitch of the cross dipole up; often to seven or eight semitones above the 'main top' resonance peak. This gives a much broader peak in the spectrum at the 'main top' frequency, which seems to me to help in getting a 'full' or 'solid' sound out of a steel string.

If you do make an X-braced classical, I'd say go for something at the size of a 12-fret 000. Use the lowest density top you can find, to help keep the mass down. Use a tieblock bridge, as most classicals do these days: if you use a pin bridge it's almost assured that some idiot will try to string it with medium gauge steel strings and rip the top off. Besides, using a tieblock bridge means you can leave out the bridge plate, which will save a few more grams. Use narrow (1/4" wide) bracing, and lighten up on the tone bars: you might even leave the lower one out entirely. You'll only need one finger brace on each side, too. Don't use a scalloped brace profile. That tends to shift the cross dipole pitch up and the 'main top' pitch down: good for steel strings, but not so good for classicals. I used 'tapered' bracing, tallest at the bridge, on both of my 000 classicals, and they came out pretty well. Use a 'normal' steel string size soundhole; you don't really need to shift the 'main air' resonance down below the usual F#-G .

My first tendency is to trust those of you who build primarily classical guitars, in regard to this matter. That said, this subject aroused my curiosity since I'm preparing to build a classical. In doing some research I ran across a fellow in the UK, Rohan Lowe, who has been building classical's professionally since the mid 90's. As you can see from his link, he makes at the very least, an interesting case in favor of X Bracing in classical's. I listened to some recordings of his guitars and they're OK. But nothing IMHO like many of the other hand crafted units I've heard in today's market with various forms of fan and lattice bracing. Just thought I'd put this into the mix since the discussion is interesting to me.

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Bill Hodge


One does not simply, own enough guitars!

Very informative post from all.

Thank you Alan for the details of an x braced classical. It is a big help and may verywell save me from a disaster.

So much information now I'm wondering if a Humphrey Millennium style bracing pattern would be something to consider? But then the sound clip of the x braced Jimmy D'Aquisto classical did sound pretty good to my ears.

Anyone know where I might be able to glimpse some x-braced tops?

Regarding the Millennium, it is my understanding that Humphrey was constantly evolving his top bracing. Is this in the ballpark as to what one of his later day guitars would look like?


Of course he used many other factors that influenced sound, not the least of which was a raised fingerboard.

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Joe Beaver
Maker of Sawdust

Just for the record, Juan Pages of the Pages family of guitar makers in Cadiz used an "X" brace under the fretboard extension (a' la Humphrey) way back in 1792:

Yes Martin did make 000 12 fret guitars for gut starting in 1902 and nylon up through the mid 1960s. They weren't very good though compared to the smaller sizes and even Martin switched to the smaller 00 size for the style 28C guitar in 1966.

Curiously, Martin's latest attempt at a nylon string was also a 000 12 fret but with a cutaway. They built it with a cedar top in a rosewood and mahogany version and yes it uses a very light X brace. The mahogany versions are just ok (rosewood not so much) and bought mostly by steel string players crossing over who find the narrower neck (1 7/8") and arched board familiar. They are also mostly used with the decent on'board electronics built into this model.

David,

So the x brace that Juan Pages and Humphreys used were in the upper transverse area?

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Joe Beaver
Maker of Sawdust

There's some good information on Humphrey's development of the
Millennium model in the February 1996 issue of Acoustic Guitar
magazine, including several photos.

Thanks Carey

I'll check my old issues. I just might have it.

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Joe Beaver
Maker of Sawdust