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jalalkun

Posts: 276
Joined: May 3 2017
From: Iraq, living in Cologne, Germany

Questions about braces 

is this board actually made for people who are not luthiers to ask questions?
I'm really interested in guitar building and was asking myself why some guitars have pointed braces and why some have parabolic braces. how do these different braces actually effect the top? not necessarily sonically but rather structurally.
And another thing, what difference does it make when a guitar has 3 back braces or 4? any answer would be highly appreciated

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My name is Jalal.
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 7 2017 7:51:51
 
estebanana

Posts: 8324
Joined: Oct. 16 2009
 

RE: Questions about braces (in reply to jalalkun

Hey, J, Prepare yourself for lot's of religious discourse.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 7 2017 9:22:05
 
jalalkun

Posts: 276
Joined: May 3 2017
From: Iraq, living in Cologne, Germany

RE: Questions about braces (in reply to jalalkun

Hey Steve (a buddy of mine actually calls me J, so it's okay ), I'm ready for anything and everything, let them bashers bash

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 7 2017 12:38:48
 
estebanana

Posts: 8324
Joined: Oct. 16 2009
 

RE: Questions about braces (in reply to jalalkun

Bracing is like religious talk. It's mostly anecdotal. But there are some general principles. Only they involve lots of variable circumstances, so if speak about one particular idea, there are many ways to modify that idea.

After lunch I'll see if I can outline some of it, and then you can watch others take swipes at my post.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 8 2017 3:55:55
 
jalalkun

Posts: 276
Joined: May 3 2017
From: Iraq, living in Cologne, Germany

RE: Questions about braces (in reply to jalalkun

that'd be great, thank you so much!

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 8 2017 10:47:05
 
constructordeguitarras

Posts: 1512
Joined: Jan. 29 2012
From: Seattle, Washington, USA

RE: Questions about braces (in reply to jalalkun

Impossible to say. Do what seems right. Hope for the best.

One thing about structural strength I do know: The method of attaching the sides to the soundboard using little glue blocks is AMAZINGLY strong. I had to remove sides after attaching them once, because a side was damaged* just as the back was ready to be glued on. It was a very difficult task.

*I was using a knife to mark where the back braces intersect with the sides and accidentally cut a side cross-grain. No more marking sides with a knife.

_____________________________

Ethan Deutsch
www.edluthier.com
www.facebook.com/ethandeutschguitars
www.youtube.com/marioamayaflamenco
I always have flamenco guitars available for sale.
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 8 2017 14:59:17
 
constructordeguitarras

Posts: 1512
Joined: Jan. 29 2012
From: Seattle, Washington, USA

RE: Questions about braces (in reply to jalalkun

Okay, maybe engineers really do know the answer:

http://cecs.wright.edu/~rsrin/Courses/ME474-674/Winter%202008/Slides-9-Full%20Size.pdf

"The strength of a tie rod depends only on the cross-sectional area and not on the shape."

So the idea is to make a pleasing shape while leaving enough material for it to work.

But of course guitars will magically sound better if one way over another.

_____________________________

Ethan Deutsch
www.edluthier.com
www.facebook.com/ethandeutschguitars
www.youtube.com/marioamayaflamenco
I always have flamenco guitars available for sale.
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 8 2017 15:07:56
 
jshelton5040

Posts: 1500
Joined: Jan. 17 2005
 

RE: Questions about braces (in reply to constructordeguitarras

quote:

ORIGINAL: constructordeguitarras

Okay, maybe engineers really do know the answer:

http://cecs.wright.edu/~rsrin/Courses/ME474-674/Winter%202008/Slides-9-Full%20Size.pdf

"The strength of a tie rod depends only on the cross-sectional area and not on the shape."


Ethan,
On the first page of that link are these two statements:

"Different shapes are more or less efficient for carrying a particular type of loading"

"An efficient shape is one that uses the least amount of material for a given strength or stiffness"

It strikes me that the implication is that shape does have an effect since we all know that a tall narrow brace is more stiff than a flat wide one even thought they have the same mass (cross sectional area?).

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 8 2017 18:41:19
 
Echi

 

Posts: 968
Joined: Jan. 11 2013
 

RE: Questions about braces (in reply to jalalkun

Your question entails a too wide answer to be exhaustive enough.
I guess an answer with a lot of approximation.
The point is that, given a certain shape (or plantilla) of the guitar, you need to support the soundboard with a certain strutting system underneath otherwise the string tension (beyond 50 kg) would make the top collapse.
The pattern (how the bars are placed, shaped etc.) have a certain influence on the final result.
There are makers (I think to Felix Manzanero now) who made a guitar without any bracing but this entails a guitar with a too thick top and generally speaking poorly sounding.
Richard Bruné owns a small Torres guitar without fan bracing (the bracing pattern under the lower bout in he Spanish tradition) but that guitar shows at least the typical 2 transverse bars before and after the soundboard.
Generally speaking the 2 transverse bars are considered structurally essential and have a long tradition in guitarmaking since the times of Gennaro fabbricatore.

The bracing pattern underneath the lower bout works together with other features (like the top thickness, the top shape the top doming etc. ) in determining the right flexibility and stiffness of the top according to the maker.
You can find guitars with a thin top, quite heavily braced or domed and guitars with a thick top which can be tricked here and there.
Every maker has his own receipt.
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 8 2017 18:53:25
 
constructordeguitarras

Posts: 1512
Joined: Jan. 29 2012
From: Seattle, Washington, USA

RE: Questions about braces (in reply to jshelton5040

What you say sounds reasonable to me, John. Maybe I picked the wrong analysis. It was for tie rods.

_____________________________

Ethan Deutsch
www.edluthier.com
www.facebook.com/ethandeutschguitars
www.youtube.com/marioamayaflamenco
I always have flamenco guitars available for sale.
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 8 2017 20:07:11
 
Richard Jernigan

Posts: 3194
Joined: Jan. 20 2004
From: Austin, Texas USA

RE: Questions about braces (in reply to constructordeguitarras

Yes, shape matters. Going to extremes, an I-beam with the same cross sectional area as a flat strip is much more resistant to bending.

But to reply to Jalal, a parabolic brace of the same width and height as a pointed one will be stiffer, but it will also be heavier. Both stiffness and weight of braces will affect the response of the top. How to balance them depends on how you want the guitar to sound and respond to the player's touch.

I ran across this today:

http://www.guitarmasterworks.com/about-guitar-acoustics-101.html

The author makes classical guitars, designed and developed the successful Rainsong line of carbon composite guitars, has degrees in aeronautical engineering from MIT and a PhD in physics from the University of Cambridge in England.

Here's his opinion about whether physics is useful for predicting or determining the quality of a guitar:

"Guitar Acoustics theory is complex to the point of being unsolvable – the theoretical description of the vibrations of a guitar soundboard leads typically to a set of a thousand simultaneous nonlinear partial differential equations; and

Measurements tell one almost nothing useful – what one hears when a guitar is being played -- and measures on an oscilloscope or frequency analyzer – is usually dominated by the excitation mechanism, and the frequencies used by the human brain to determine “quality” look like white noise to laboratory instruments."

My own training and experience is in mathematics, physics and engineering. I agree with the author quoted above.

The development of guitar designs seems to me to be more akin to evolution by natural selection than to engineering design.

The guitar maker is an artist. He typically begins his career building fairly close copies of established famous makers, or of his teacher's design. There are exceptions. One well known one was Richard Schneider starting off on his own with a radical bracing design suggested by the physical chemist Michael Kasha, after being taught traditional methods by the great Mexican luthier Juan Pimentel Ramirez.

In either case, the luthier's design develops by evolution. It is unlikely that his first few guitars sound and respond the way he or she would like. The luthier makes design changes based largely on intuition, though there may be some valid physical reasoning that goes into it. The change either makes the instrument better, or it doesn't. If it makes it better, the luthier is likely to retain the change in future instruments.

Even invalid reasoning can lead to improvement in design. Jose Ramirez III used to enjoy expounding his mathematical "analysis" of guitar design. To me, as a person who made his living in engineering, mathematics and physics, Ramirez's exercises looked like numerology and superstition--but he still made great guitars.

Another factor that seems important to me is whether the luthier has contact with good players, whose feedback can influence design progress. And if the luthier gets a strong recommendation from a famous player, it's the best possible advertising, so the taste of famous players is an important component in guitar design.

But Jose Ramirez III was fond of pointing out that from a group of six of his best quality instruments, two different famous players would likely choose different instruments.

So in questions about guitar design there are a very few objective answers, based on physics and the properties of materials, and a very large number of subjective answers, depending upon the personal experience of luthiers and the tastes of players.

Personally, I enjoy the differences among my guitars, and enjoy meeting and talking to luthiers. Successful guitar makers have succeeded largely by relying on their own judgment. They generally turn out to be interesting individuals, with a range of opinions on other subjects. I may not agree with all their opinions, but they are usually interesting.

RNJ
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 8 2017 23:56:35
 
estebanana

Posts: 8324
Joined: Oct. 16 2009
 

RE: Questions about braces (in reply to jalalkun

quote:

I'm really interested in guitar building


Poor boy. Hopefully this interest will soon pass.



quote:

and was asking myself why some guitars have pointed braces and why some have parabolic braces. How do these different braces actually effect the top? Not necessarily sonically but rather structurally.


The sonic part and the structural part are married. The bridge is being moved by the string, which does not output a heck of a lot of energy. The bridge moves multidirectionally, and transmits that energy and movement to the top. The top has to be made so that it can receive as much of that energy without wasting it or damping it.

The energy is low, bridge/string output is low. The hard part is making the top thin, enough so it does not damp the low output of the bridge/string yet strong enough to withstand the tension of the strings. ( as an aside one of odd paradoxes of string tension is that high tension strings put out more energy, but it is also possible in some cases that they choke back the ability of the top to receive energy- a lower tension string will allow the top to move more openly of freely, but provide less energy. It's an interesting situation, but a separate topic.) Mass, density, and weight all play a part in damping of the top-

Once all that is settled out the size a placement of the braces come into play - The tall and thin profile braces, like parabolic braces tend to favor higher frequency transmission, the lower flatter triangular braces not as much. Higher profile braces stiffen the top more microgram for microgram than a lower flatter brace. But there is not grand chart of reciprocity between lower braces and taller braces. So it might take more lower flatter braces to stiffen the top as much as one tall parabolic brace, and if weight is your concern, one slightly heavier brace might be better than three lighter less stiff braces.

Parabolic shaped braces also concentrate the stiffness at the center of the brace, where as the lower profile braces tend to be more like archery bows, they flex evenly along the length. Parabolic braces are designed to more of less be rigid and function to stiffen the center area of the top. Lower flatter braces in general are easier to work with for flamenco designs, although one could brace a flamenco guitar with parabolic braces. Most of the time however parabolic braces work well for designs that are more about clear singing voice than the flamenco growl.

The brace placement is fairly important, there are a couple basic understandings about placement if you want to speak of flamenco voice vs. other kinds of voices. Although this is not set in stone, it's just general theory, feel free to run with it in actual building:

The Torres 'kite' set up is a design that is created to make low flat braces cross the grain at a steep angle, it provides a lot of cross grain support. If you put a pin point in the middle of the 12th or 13th fret and use that as a point to run diagonal lines through the top, (go look at a Torres drawing online ) you see the braces land on those diagonals and distribute stiffness and possibly some arch, to the top. The braces run at an oblique angle to the long grain of the top. That angle tends to stiffen the top across the grain, that is side to side across top. It also stiffens the top with or along the grain, but not as much. Using parabolic braces in that same way would render the top VERY stiff and probably take two fewer braces to do the same job, but the focus of the most stiffness would be more centrally located under the bridge area. The centrally located stiffness will make a different kind of voice, than the lower flatter braces with the triangular section.

The next placement idea is effecting cross grain stiffness - If you move the pin point at the 12th fret up to fret 1 or 2 and draw the same diagonal lines down the face the oblique angle that the braces placed on those lines will be much less. Placing the braces more parallel to the long grain direction generally, important to say generally, makes the cross grain stiffness drop a bit. That is important to pay attention to because making that cross grain stiffness looser will really effect the voice. Looser cross grain stiffness favors the cross di pole modes of the top. Meaning the side to side action of the bridge has less tension to pin in down and make it move more equally in all directions. Less cross grain stiffness allows the bridge to move more like a 'See - Saw' on a kids playground. The bridge swings said to side and that emphasizes the 'growly' qualities in voice. There are reasons why, but it's a long diversion to get into why. Moving the point that the braces shoot down from diagonally creates a more open movement cross grain wise.

Add flatter or parabolic braces to that scenario and then the predictable things happen. Parabolic braces bolster up the center stiffness, Because they are usually inflexible in their own center and flatter braces distribute stiffness more evenly and with more 'inherent spring' like the bow. Both braces placed more parallel to the long grain will allow for more open movement across the grain. And braces placed more parallel to the grain stiffen the top along the grain more directly than steeply angled braces. Stiffness along the grain is important because the strings are under tension of course which is using the saddle like a tiny levering device to push and pull the top into a distorted posture. If you choose parabolic braces with all the strength in the center area, you can make the most distortable area very impervious to distortion, that area is the top between the sound hole and bridge. Provided the lateral brace under the sound hole lower edge is bearing the load.

Tops distort in ways that are very complex, and it would take a lot of time to explain how and why, and how it makes guitar sound. Most makers tend to agree a wee bit of distortion is going to happen and it is ok, some others think distortion is a mortal sin. That is how it becomes religious, because most of the information is anecdotal. I tried to show a little bit abut why structure and sound are married - if they were not then you could over build the guitar and any old structure would make it work. See the structure of a Smallman type guitar. It's over built like a super stiff speaker cabinet, and it has a delicate membrane that the bridge/string unit moves. The Torres guitar is based on an integration of structure and sound. The Smallman design is also, but in a radically different way.


The engineering only matters to a certain extent, and engineers hate this (Richard and the fellow he quoted are two notable exceptions LOL and have read the Foro's own Kevin Richards express similar ideas.) . There is a genre of architecture called 'vernacular architecture' it means regional conditions call for special solutions to buildings and structures, and are old traditions that were not designed by architects or engineers. In Morocco a vernacular treatment of a house would be a special hole cut in the roof with panels of wood that direct the afternoon breeze down into the house to cool it. It is learned by trial and error over hundreds of years. A system is worked out, it becomes a regional practice. The guitar was developed the same way, there was a problem between the structure being to fragile and folding up under string tension, and of being built too heavily built and not picking up as much energy input from the bridge as it could gather. The guitar makers worked as 'vernacular engineers' to solve those problems and what we get today is a zone or parameters of size and strength of braces and structure that we know works. But it gets too weird really for striaght up engineering to solve problems after a certain point.

One example is that we know that there is a difference between the concept of stiff heavy ribs that don't move or allow the perimeter of the rim of the too to move in anyway thus creating a perfect torque free attachment point for the top. Tis means the top will not syphon energy into the ribs and bounce around on top of this perfeclty hard structure.

vs.

The ribs are very thin and attached to the top by glue blocks, which anecdotally are supposed to make the rim less stiff than robust solid liners, and the ribs being thin absorb or filter some energy form the top thus stealing some energy and making the top less efficient.

The problem is that the thin ribs do transmit some sound, and in fact do filter the sound and have a lot of bearing on voice for complex acoustical reasons. But measuring these things empirically is almost impossible. Just the solid liner vs. glue block issue is a mind bender to test, and to my knowledge it's not been done. But I can say anecdotally glue blocks once they are put in place and held in two directions by the rib and top make the structure REALLY F-ING stiff.

So the braces whether they are parabolic or flatter and wider both work. The deal is that you get a style of guitar or you design a guitar that has the structural qualities that fit the kind of sound you want to make and you work in that zone. Flamenco guitars are a particular zone, there are established standards for what works and you dive an work with those parameters, You can use engineering or acoustical programs or methods to thin the top or tune the top, but you're still working is a vernacular zone. I call the process vernacular engineering.

Square beams, rectangular beams, I beams are all interesting to analyze in section for strength, but modulating the beam for stiffness or flexibility and placement is a vernacular activity done by feel.

Now, that should start a grand religious war!

( I have a little typo fixing to do and some tweaking to the language, but I'll fix it later.)



quote:

And another thing, what difference does it make when a guitar has 3 back braces or 4?


Not too damned much.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 9 2017 2:31:05
 
constructordeguitarras

Posts: 1512
Joined: Jan. 29 2012
From: Seattle, Washington, USA

RE: Questions about braces (in reply to estebanana

Stephen--

You seem to be comparing tall and flat braces, whereas the question was about pointed vs parabolic braces, wasn't it? There seems to me to be little difference between the two: A pointed brace (which could be tall) could have its top rounded over a little and thus become a parabolic brace.

My fan braces are generally parabolic shaped in cross section. But I have had students emulate my work and end up with cross sections that were triangular. Nevertheless, the general graduation of thickness of the soundboard and the general placement and size of braces was like my work, and their guitars came out sounding like mine.

From what you've said about flat braces, I get the impression that soundboard graduation can substitute for their effect which you describe.

_____________________________

Ethan Deutsch
www.edluthier.com
www.facebook.com/ethandeutschguitars
www.youtube.com/marioamayaflamenco
I always have flamenco guitars available for sale.
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 9 2017 11:54:43
 
constructordeguitarras

Posts: 1512
Joined: Jan. 29 2012
From: Seattle, Washington, USA

RE: Questions about braces (in reply to Richard Jernigan

quote:

But to reply to Jalal, a parabolic brace of the same width and height as a pointed one will be stiffer, but it will also be heavier. Both stiffness and weight of braces will affect the response of the top. How to balance them depends on how you want the guitar to sound and respond to the player's touch.


Thanks for clarifying things, Richard.

_____________________________

Ethan Deutsch
www.edluthier.com
www.facebook.com/ethandeutschguitars
www.youtube.com/marioamayaflamenco
I always have flamenco guitars available for sale.
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 9 2017 12:00:55
 
estebanana

Posts: 8324
Joined: Oct. 16 2009
 

RE: Questions about braces (in reply to constructordeguitarras

quote:

You seem to be comparing tall and flat braces, whereas the question was about pointed vs parabolic braces, wasn't it? There seems to me to be little difference between the two: A pointed brace (which could be tall) could have its top rounded over a little and thus become a parabolic brace.


I think I'm calling the braces lower and flatter because they are like squares in cross section, - then the top of the brace gets cut into a point or rounded over. Vs. parabolic which means it looks like an airfoil profile and is tall.

I guess you can have low height parabolic braces, but true parabola have a constant curve on one side, so low parabola would not be very effective. I'm thinking of parabolic braces on Hauser and other makers where the brace height could be 7 or 8 mm and quite thin. In contrast to lower flatter braces. Flat meaning flat in comparison to a parabola.

I see parabola as curved and pointy top braces as "flat" because they are not curved on top. I think that is the confusion.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 9 2017 15:25:35
 
Njål Bendixen

 

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RE: Questions about braces (in reply to jalalkun

Hi Jalal



Make 2 guitars, one with tall thin braces and one with wide low braces. You will probably find that you like one of the guitars better than the other one. That is the only way to learn.



Njål
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 9 2017 15:52:52
 
jshelton5040

Posts: 1500
Joined: Jan. 17 2005
 

RE: Questions about braces (in reply to Njål Bendixen

quote:

ORIGINAL: Njål Bendixen
Make 2 guitars, one with tall thin braces and one with wide low braces. You will probably find that you like one of the guitars better than the other one. That is the only way to learn.
Njål

Two guitars will tell you almost nothing. If you make 5 of each type limiting all other variables as much as possible you MAY be able to make a guess as to the approximate affect of the brace shape.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 9 2017 18:04:59
 
NorCalluthier

 

Posts: 136
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RE: Questions about braces (in reply to jalalkun

Hello All,

The closest thing to a "Unified Field Theory of Guitar Tone" that I've come across is described in Trevor Gore's books:

http://www.goreguitars.com.au/main/page_the_book_overview.html

He is primarily a steel string builder, but works closely with the co-author, who is a classical and flamenco builder. He has a doctorate in mechanical engineering, but in spite of that makes excellent steel string guitars---the best I've ever heard.

Cheers,

Brian
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 9 2017 21:11:30
 
jalalkun

Posts: 276
Joined: May 3 2017
From: Iraq, living in Cologne, Germany

RE: Questions about braces (in reply to jalalkun

YAAAAS BOIIIII so many replies !! thank you all so much i've had gigs today and yesterday and I need to sleep, so I'll definitely get back to you tomorrow. have a good one.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 10 2017 1:37:50
 
Andy Culpepper

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From: NY, USA

RE: Questions about braces (in reply to jalalkun

I like Stephen's post. One thing to watch out for is that it's tempting to think that you can make the top *really* thin if you just use taller, stiffer braces to get to the same overall stiffness as a thicker top, but that can cause some nasty distortions of the top. If the braces don't flex at all but the top does, the top will pull up between the braces which can lead to the bridge eventually coming unglued.

The only other thing I would add is that if you're talking about braces being "pointy" as in having peaked tops, I believe that's to facilitate so-called fine-tuning of the guitar after it's been assembled. If you want to reduce the stiffness of a brace, the quickest way is to make it shorter (flatter) and when you have sharp peaks on the braces it's easy to take some height off with a small thumb plane through the sound hole.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 10 2017 2:16:31
 
jshelton5040

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RE: Questions about braces (in reply to Andy Culpepper

I've always assumed that triangular braces are made that way to have the maximum stiffness with the least weight. In other words the taller and more acute the triangle the stiffer the brace without increasing weight.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 10 2017 13:24:07
 
jalalkun

Posts: 276
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From: Iraq, living in Cologne, Germany

RE: Questions about braces (in reply to jalalkun

wow. thank you all so much for your posts. this is seriously an awful lot of information, especially stephen's post, and this didn't make my interest fade. it actually made me even more curious to dive into this topic. basically what I meant by 'pointed' was triangular in cross-section as opposed to round. though I didn't know the parabolic shape is only referred to a higher brace. i like to visualize it by imagining that a fan brace kind of works like an x-band equalizer (depending on how many struts), but now I believe it's much more complex than just assigning one brace to one frequency range. how accurate is this analogy of mine anyway?

this is some valuable information that I need to process. thank you all so much - and especially stephen for your great and informative text - for taking your time and explaining all these things to me!

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 10 2017 23:26:34
 
Ricardo

Posts: 13240
Joined: Dec. 14 2004
From: Washington DC

RE: Questions about braces (in reply to jalalkun

The hard science and engineering is quite clear. You follow some plan of glueing flat and bent wood and sticks together so the thing won't fall apart, then you proceed to sand the F out of it all until it sounds good. The more you sand the better it sounds.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 12 2017 14:58:03
 
Richard Jernigan

Posts: 3194
Joined: Jan. 20 2004
From: Austin, Texas USA

RE: Questions about braces (in reply to Ricardo

quote:

ORIGINAL: Ricardo
The more you sand the better it sounds.


...there is a sizable faction who believe that to achieve the ultimate in sound and playability, you have to paint it orange.

RNJ
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 12 2017 19:59:21
 
jalalkun

Posts: 276
Joined: May 3 2017
From: Iraq, living in Cologne, Germany

RE: Questions about braces (in reply to jalalkun

if you sand too much you end up with paper

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 13 2017 15:02:36
 
Ricardo

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Joined: Dec. 14 2004
From: Washington DC

RE: Questions about braces (in reply to jalalkun

quote:

ORIGINAL: jalalkun

if you sand too much you end up with paper


And best sounding guitars crack easy for this reason too. Although humidity change can bust any strength wood.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 14 2017 14:01:14
 
jalalkun

Posts: 276
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From: Iraq, living in Cologne, Germany

RE: Questions about braces (in reply to jalalkun

i mean ok you can drive the wood so far that it's almost collapsing, but still stucturally sound, but don't you lose "character" in the sound if you make the wood too thin? i haven't played a lot of good guitars so i'm just speculating.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 16 2017 18:10:02
 
constructordeguitarras

Posts: 1512
Joined: Jan. 29 2012
From: Seattle, Washington, USA

RE: Questions about braces (in reply to jalalkun

quote:

i mean ok you can drive the wood so far that it's almost collapsing, but still stucturally sound, but don't you lose "character" in the sound if you make the wood too thin? i haven't played a lot of good guitars so i'm just speculating.


Indeed, it is ridiculous to say that the thinner the better. I thought it was a joke.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 16 2017 18:23:11
 
estebanana

Posts: 8324
Joined: Oct. 16 2009
 

RE: Questions about braces (in reply to jalalkun

quote:


i mean ok you can drive the wood so far that it's almost collapsing, but still stucturally sound, but don't you lose "character" in the sound if you make the wood too thin? i haven't played a lot of good guitars so i'm just speculating.


It's very conceivable that making a top too thin can make the guitar sound unpretty. But again it's a structure problem, some guitar designs support thinner tops and some don't. And thinness is highly dependent on the density, cross grain and long grain stiffness of a particular top. One top graduated to 1.8 mm around the edges and 2.2 mm under the bridge might work with a certain design with a stiff top. But will be certain death with another design and another quality top.

Best to stick with the basics.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 17 2017 1:52:51
 
Echi

 

Posts: 968
Joined: Jan. 11 2013
 

RE: Questions about braces (in reply to jalalkun

I played a Felipe V Conde whose top was about 3 mm thick and an old Conde whose top was about 2 mm. My preference is for the design with a thinner top. I noticed that a thicker top often needs More time to warm up and to take out good overtones.
Again, they are all generalisations as it depends a lot from the density of the wood the young modulus, the doming, the bracing, the plantilla shape etc.

It's very interesting to compare the top thicknesses of historical guitars. A good reading is the last edition of "A collection of fine Spanish guitars" with the contribution of Richard Bruné
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 17 2017 7:53:45
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