Andy Powers Replies to my V-bracing Question

[gitarro]

Trevor,

Thanks for your post. Does your explanation mean that Taylor can only succeed on fulfilling their better intonation promise if the v bracing actually suppresses the responsiveness of the guitar by overbuilding since their bracing does not rely on individualised shaving of the braces of each guitar in order to ensure better intonation ?

[rpnfan]

Originally Posted by TD2

I hope Taylor is paying attention to this thread and hires all those that know so much more about guitar design than their lead designer.

Assuming that the Taylor lead designers task is to come up with designs for guitars to be produced and sold with a profit I think you imply someone said they could make a better job in doing so. I think no one in those threads here stated that. Nor did someone question that the new guitars may sound "nice".

What was questioned is the validity of some statements -- also the implication made that all X-braced guitar must suffer from problems which only can be solved with the V-bracing. And also pure curiosity to try to understand was expressed!

I think it should be legitimate to ask (IMO well reasoned) questions like Eltjo and others have done here.

I find the following quote from Erwin Somogyi from 1993 very interesting in this context:

Bracing is a complicated and never-ending puzzle. I’m sure that throughout my lifetime, and maybe even my children and grandchildren’s lifetimes, controversy will rage about what is the best bracing system. The fact of the matter is that successful guitars have been built with just about every conceivable bracing system. Superb guitars are built with symmetrical bracing systems. Wonderful guitars are built with asymmetrical systems. I’m led to believe that a bracing system as a recipe approach has little virtue. It’s best when it’s part of a context, an thought-out process. To say only that I use X bracing, or Sitka spruce, is by itself relatively meaningless.

Source: http://www.esomogyi.com/principles.html

[KevWind]

Originally Posted by Herb Hunter

I have a suite of apps on my iPhone called AudioTools by Studio Six Digital. It contains sound level meters, a real time analyzer, Fast Fourier Transform, Dual Trace Audio Oscilloscope and Signal Generator among several other apps.

https://itunes.apple.com/us/app/audi...325307477?mt=8

Hey thanks Herb, I actually already have that app also (but with only the included free tools)

I was curious about the specific app Picker 2 was using

[KevWind]

Originally Posted by Picker2

I'm using an app called "Analyzer" You can find it in the AppStore. There are zillions of similar apps in the AppStore, but this one is very good. Simple and complete. The microphone of my iPhone X is surprisingly good (sound recordings are excellent), but you are right - if you want ultra-high precision you have to use calibrated microphones.

In the graph you referred to, L means 'loudest' indeed. And yes, my guitar was a little sharp at 331 Hz. I never use electronic tuners.

In the graph of the 12th fret pluck you are right: the first harmonic is louder than the fundamental. There are various reasons this can happen. It may have to do with where you pluck the string, but also in which direction. If you pluck sideways, the string's fundamental will reduce and a tone of twice the fundamental will become more dominant. This has to do with the longitudinal tension in the string. But that would be food for another thread. In any case the fundamental does not always need to be the loudest frequency - its the lowest frequency.

Thanks for the reply

[printer2]

Originally Posted by Trevor Gore

I was wondering how soon someone would mention "the book", which does explain what is going on using conventional scientific language and all the physics and maths to back it up.

Good thing Trevor showed up and saved me some reading and better yet thinking of how to explain what is going on. I was pretty sure it was the oscillators repelling (I usually think in electrical terms as it was my first dip into the engineering pool) but I only skimmed through the books when I got them and it was more than a year ago. I didn't want to just wing the explanation in case I was missing something. So that means I can go down and glue some wood together.

Oh yeah, Trevor's explanation reminded me on my viewing the Taylor bracing last night. I am doing an inverted fan style for nylon so not in the same ballpark of Taylor's but it struck me that the V brace is pretty substantial. For responsiveness not so good but for evening out the sound it is. Where they make up for this is their relief rout around the perimeter. So the top is more controlled and yet allowed to move. It also seemed to me (since the manufacturing end had been talked about recently) that the bracing was designed for ease of manufacturing with the parts placed and no further work need be done. I spent +25 years in manufacturing so I pretty much look at any product and think about how it was manufactured. Sometimes the simple and obvious way to do things start out not so simple and obvious. I can see this design would have on manufacturing over the X brace in the factory.

[KevWind]

Originally Posted by Trevor Gore

So bracing can effect intonation, either by making the bracing stiff enough that you avoid the problem (the usual factory method) or by modally tuning the top by brace shaving to pitch it (and other resonances) accurately. I don't for a minute think that Taylor are doing the latter, but it makes a for a good story if you tell it in an obscure enough way that nobody can figure out what it actually means and they can define what they say as they like.

One thing is true though. Guitars that are well intonated and play equal temperament accurately sound a whole lot better, but not many guitars are that well intonated.

Hey great post. For a bit more clarity. If bracing can effect intonation and can be done by "brace shaving" (assuming a hand method of subtracting a certain amount of wood in specific place ?) Then could it be possible that pre cutting the braces to "shaved" like state, and placing them in a specific pattern ( V) as per Taylors claim accomplish a similar goal ???

[Song]

https://youtu.be/J2SYPzKzD94

[printer2]

Originally Posted by KevWind

Hey great post. For a bit more clarity. If bracing can effect intonation and can be done by "brace shaving" (assuming a hand method of subtracting a certain amount of wood in specific place ?) Then could it be possible that pre cutting the braces to "shaved" like state, and placing them in a specific pattern ( V) as per Taylors claim accomplish a similar goal ???

The problem is, how much? Wood is different in weight and stiffness. The combination of these two things determine where the resonances fall. You have to take into account the top characteristics and brace it accordingly. Once you put it in a box the back and its bracing modifies the resonances. In a production setting it is more trouble than it is worth. That is why you have custom builds by luthiers. They are building one-offs and can take the time to adjust the braces and top and back thicknesses to get what they want.

[KevWind]

Originally Posted by printer2

The problem is, how much? Wood is different in weight and stiffness. The combination of these two things determine where the resonances fall. You have to take into account the top characteristics and brace it accordingly. Once you put it in a box the back and its bracing modifies the resonances. In a production setting it is more trouble than it is worth. That is why you have custom builds by luthiers. They are building one-offs and can take the time to adjust the braces and top and back thicknesses to get what they want.

Yes those things are kind of obvious ,and the thing is for production , you could do it one time (by hand if necessary ) for each model (specific shape, dimensions, type, wood, etc) determine the correct specs and then replicated it by computer cutting machine .

[Shuksan]

Originally Posted by KevWind

Yes those things are kind of obvious ,and the thing is for production , you could do it one time (by hand if necessary ) for each model (specific shape, dimensions, type, wood, etc) determine the correct specs and then replicated it by computer cutting machine .

Your suggestion for a production situation would only work if wood was consistent in its physical properties, which it is not. The physical properties vary not only within a species, but even between pieces cut from the same tree. That was the point printer2 was making above. You could do the production set up once as you suggest, but then the individual guitars would vary and not be optimized across the board. If you look at studies of physical properties of a specific wood such as spruce, you find that the ranges in values for properties like stiffness or density are very large. This is one place where the luthiers building one at a time have an advantage because they can optimize dimensions and such for the specific pieces of wood going into a specific guitar.

[KevWind]

Originally Posted by Shuksan

Your suggestion for a production situation would only work if wood was consistent in its physical properties, which it is not. The physical properties vary not only within a species, but even between pieces cut from the same tree. That was the point printer2 was making above. You could do the production set up once as you suggest, but then the individual guitars would vary and not be optimized across the board. If you look at studies of physical properties of a specific wood such as spruce, you find that the ranges in values for properties like stiffness or density are very large. This is one place where the luthiers building one at a time have an advantage because they can optimize dimensions and such for the specific pieces of wood going into a specific guitar.

I agree with the basics of yours and Printers post and of course wood is not 100% consistent . As a carpenter of 50 years experience , again kind of obvious. As is the difference between the ability of a luthier (provided they actually knows what they are doing) to bring more flexibility to the build......But I don't think that is really the applicable question, issue, or answer, as to why it might or might not be viable in a production situation . The question is -- are those variances actually significant enough to prevent a production situation from being a viable technique to address the problem. Maybe it is and maybe it isn't thus the question.
Not to mention, wood can be and is often, graded to account for significant variances of grain spacing etc. Again the question is are the minor variances enough actually dismiss it out of hand as invalid .

[Shuksan]

Originally Posted by KevWind

The question is -- are those variances actually significant enough to prevent a production situation from being a viable technique to address the problem. Maybe it is and maybe it isn't thus the question.
Not to mention, wood can be and is often, graded to account for significant variances of grain spacing etc. Again the question is are the minor variances enough actually dismiss it out of hand as invalid .

This is a great question (except for the assumption that the variances are minor).

Grain spacing isn't terribly important with regard to the physical properties, but I get the point. However, I find it hard to believe that companies that crank out the enormous numbers of guitars per year that Taylor and the other usual suspects do can possibly source massive numbers of spruce tops that don't have significant variation in the properties that do matter such as stiffness and density.

This relates to what I see as a black box quality of the claims for the v-bracing. It seems that for the v-bracing to work its magic on "intonation", the whole top/bracing system would have to be tuned for each guitar. And yet, the underlying assumption is that this can be accomplished in a mass production setting using a naturally inconsistent material to build the part of the guitar that does the magic. Maybe it can, but I doubt it because I know that the physical properties of wood vary significantly, I suspect that the window of physical properties of the top/bracing system in which this effect would supposedly work is small (could be wrong), and I haven't seen or read anything from Taylor that addresses this particular question one way or the other. So, I remain to be convinced that this is viable in mass production.

[KevWind]

Originally Posted by Shuksan

This is a great question (except for the assumption that the variances are minor).

Grain spacing isn't terribly important with regard to the physical properties, but I get the point. However, I find it hard to believe that companies that crank out the enormous numbers of guitars per year that Taylor and the other usual suspects do can possibly source massive numbers of spruce tops that don't have significant variation in the properties that do matter such as stiffness and density.

This relates to what I see as a black box quality of the claims for the v-bracing. It seems that for the v-bracing to work its magic on "intonation", the whole top/bracing system would have to be tuned for each guitar. And yet, the underlying assumption is that this can be accomplished in a mass production setting using a naturally inconsistent material to build the part of the guitar that does the magic. Maybe it can, but I doubt it because I know that the physical properties of wood vary significantly, I suspect that the window of physical properties of the top/bracing system in which this effect would supposedly work is small (could be wrong), and I haven't seen or read anything from Taylor that addresses this particular question one way or the other. So, I remain to be convinced that this is viable in mass production.

You may be correct or not ...........
Your "doubt" is not surprising given type of rhetoric you use "a black box quality" and "v-bracing to work its magic" etc. The words we use are a window into what we really feel, which often directs how we think . Just something to ponder.

While stiffness and density make a fair amount difference in load bearing and varies from specie to specie and why for example fir is considered structural framing wood and pine isn't. But within a given species, load bearing differences (which has stiffness/rigity as major a component ) is much more dependant on thickness


I am not convinced the pertinent question does not then become, what is the actual (as opposed assumed) amount difference in stiffness and density that manifests itself in the vibrational characteristics a piece of wood as thin as a guitar top ? Or put differently how much actual difference in stiffness and density of the same species and grade, is actually possible in two different pieces Ady. spruce Top wood say an 1/8 in thick ?? I don't know but would be surprised if were even 10%

[Shuksan]

Originally Posted by KevWind

You may be correct or not ...........
Your "doubt" is not surprising given type of rhetoric you use "a black box quality" and "v-bracing to work its magic" etc. The words we use are a window into what we really feel, which often directs how we think . Just something to ponder.

While stiffness and density make a fair amount difference in load bearing and varies from specie to specie and why for example fir is considered structural framing wood and pine isn't. But within a given species, load bearing differences (which has stiffness/rigity as major a component ) is much more dependant on thickness


I am not convinced the pertinent question does not then become, what is the actual (as opposed assumed) amount difference in stiffness and density that manifests itself in the vibrational characteristics a piece of wood as thin as a guitar top ? Or put differently how much actual difference in stiffness and density of the same species and grade, is actually possible in two different pieces Ady. spruce Top wood say an 1/8 in thick ?? I don't know but would be surprised if were even 10%

"The words we use are a window into what we really feel, which often directs how we think . Just something to ponder."

Yes, and how I feel is skeptical. Compelling evidence is the only answer to my skepticism.

As far as how much variation there can be in one species, I will cite one example from a study in issue 128 of American Lutherie. The author collected stiffness data for a variety of hardwood and softwood species which included Sitka spruce. He had 80 Sitka spruce samples that came from guitar top sets, so pre-selected for qualities relevant to luthiers. As you can see, the variation in vertical grain stiffness was more than twofold in this population.

[IMG][/IMG]

[KevWind]

Originally Posted by Shuksan

"The words we use are a window into what we really feel, which often directs how we think . Just something to ponder."

Yes, and how I feel is skeptical. Compelling evidence is the only answer to my skepticism.

As far as how much variation there can be in one species, I will cite one example from a study in issue 128 of American Lutherie. The author collected stiffness data for a variety of hardwood and softwood species which included Sitka spruce. He had 80 Sitka spruce samples that came from guitar top sets, so pre-selected for qualities relevant to luthiers. As you can see, the variation in vertical grain stiffness was more than twofold in this population.

[IMG][/IMG]

For starters you could be right and I certainly could be wrong or vice versa
Which is why I have avoided categorical statements .


OK interesting graph ... Question what is it actually measuring and actually showing ?

Side note First: after some Googling and reading of links. While I found info on Youngs Modulus" per se, I could not find anything under the term "Youngs Modulus Vertical Grain .." So the designation seems to have been applied by whom ever produced the graph, suggesting the numbers apply to vertical and horizontal grain stiffness ( would not grain spacing then also play a factor ?) .

So assuming for now Youngs modulus numbers are actually being correctly used.
The next question are what was the test methodology ???
What do the numbers mean in terms of, how do the numbers actually relate what can or can't be addressed sufficiently or adequately with a standardized bracing spec. What does 7000 variation in Youngs Modulus numbers actually mean ??? 7000 what ? 7000 or 8000 arbitrary units of measure does not mean that amount of variation cannot be addressed by a standardized mean bracing spec.

The next question and the biggy is ??????? What stress factor was used in the test to arrive at the numbers . How much force was being applied
The amount of force applied by a vibrating guitar string ?

I could go on but you catch my drift.

More importantly for me , It seems as if I have ventured far from my consistent position being, until I actually play one I really have no opinion. So thanks for the replies people, I have posted my questions and run my race so cheers.