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RE: vertical string pull on the soundboard (torque)   You are logged in as Guest
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TonyGonzales84

 

Posts: 78
Joined: Apr. 23 2020
From: San Diego, CA

RE: vertical string pull on the soun... (in reply to Tom Blackshear

Armando,

It just occurred to me that you may be too nervous about actually breaking something, seeing that you feel your current tops are too stiff. If you build a top that "breaks," what's likely to happen is that you can then come back to the Foro, and I'll bet a year's worth of COVID-19 haircuts that you'll have many great, experienced Luthiers answer ways to learn from your experience, and even salvage many parts!

What if you built two tops for one guitar, one with a thinner top and wider or deeper braces/struts, and the other with a slightly thicker top and narrower or shallower braces/struts? I'll bet there's a lot you can learn in this...

Tony

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 22 2020 22:06:30
 
Ricardo

Posts: 12668
Joined: Dec. 14 2004
From: Washington DC

RE: vertical string pull on the soun... (in reply to Armando

quote:

That is maybe the right way to do it but very hard in my opinion, unless you are Tom Blackshear.


After reading one of Blackshear posts years ago, I think it was Sr martins that took a file into his own guitar, not one he made but the finished product, and went to town filing certain braces...until finally his guitar was tuned “better”. He did a before and after audio and indeed it sounded better. So, why not try it on your already “stiff” guitars?

http://www.foroflamenco.com/tm.asp?m=229925&mpage=3&p=&tmode=1&smode=1&key=sanding%2Cbraces

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 23 2020 17:16:23
 
estebanana

Posts: 7999
Joined: Oct. 16 2009
 

RE: vertical string pull on the soun... (in reply to TonyGonzales84

Or instead of doing it randomly one could get Trevor Gores book out and study the ways different modes express certain frequencies that effect the timbre of the guitar. I’d put the pages up from my very expensive edition, but Trevor might not like that.

There’s a madness to the method.

If you search on the Delcamp classical guitar forum there are several discussions which include Gore chiming in un which they discuss a great deal of the information about which modes effect what.

Trevor helped me troubleshoot a problem about a year and a half ago and I asked him if I could pay him for the help, he said pay me by buying my book. What he shared with me during the troubleshooting was interesting because it convinced me that random sanding around was a crap shoot. In the end the problem was not shifting a frequency because it was too square on a fundamental tone, but that the guitar was so finicky spot on that the compensation needed micro management to make it play correctly. Otherwise without knowing how to diagnose the intonation issue it would have led to unnecessary sanding under the top.

In addition probably the stiffness and weight of the bridge means as much as top, because the bridge moderates the top so much.



Btw I wrote to find out the exact permissions I need to share the tap plate article but have not heard back yet.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 24 2020 5:23:51
 
Richard Jernigan

Posts: 3012
Joined: Jan. 20 2004
From: Austin, Texas USA

RE: vertical string pull on the soun... (in reply to TonyGonzales84

Finally got around to looking at TonyGonzales84's analysis of forces and torques on the top. I agree with his approach. His diagrams make it clear. My diagrams were just in my head

RNJ
  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 29 2020 0:47:34
 
estebanana

Posts: 7999
Joined: Oct. 16 2009
 

RE: vertical string pull on the soun... (in reply to Richard Jernigan

quote:


RE: vertical string pull on the soun... (in reply to TonyGonzales84) 

Finally got around to looking at TonyGonzales84's analysis of forces and torques on the top. I agree with his approach. His diagrams make it clear. My diagrams were just in my head


It looks fun, but if you do all that and you don’t get a main air resonance around F# with a back res that’s at least a half step apart, usually higher, them it’s academic. It’s crucial to be in the correct main Air Res zone. And it’s possible to get there by subtle adjustments of a top that’s thicker or strong enough to be resilient to the pull of the string. Or eventually you just make them right in the pocket.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 29 2020 2:31:19
 
Ricardo

Posts: 12668
Joined: Dec. 14 2004
From: Washington DC

RE: vertical string pull on the soun... (in reply to estebanana

quote:

ORIGINAL: estebanana

quote:


RE: vertical string pull on the soun... (in reply to TonyGonzales84) 

Finally got around to looking at TonyGonzales84's analysis of forces and torques on the top. I agree with his approach. His diagrams make it clear. My diagrams were just in my head


It looks fun, but if you do all that and you don’t get a main air resonance around F# with a back res that’s at least a half step apart, usually higher, them it’s academic. It’s crucial to be in the correct main Air Res zone. And it’s possible to get there by subtle adjustments of a top that’s thicker or strong enough to be resilient to the pull of the string. Or eventually you just make them right in the pocket.


What about all the guitars that produce G#-A when you tap the box or close mic the soundhole?

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 29 2020 16:47:26
 
estebanana

Posts: 7999
Joined: Oct. 16 2009
 

RE: vertical string pull on the soun... (in reply to Ricardo

Guitars that have a main air res of A usually have, or could have coupling issues with the A string. It’s not impossible to make one, but most people try not to hit that A - 110 Hz it’s asking for trouble with high partials and coupling issues.

G# is ok, but kind of where a lot of classical guitars end up. Something a
within few Hz above or below F# works better for flamencos in general. Lower than that close to F can be ok too, but E and A are frequencies you want to stay away from. G isn’t great either, but can work.

When people are “intuitively” sanding the inside what they are in part doing us lowering the main air mode, but they might not know that. Flamenco guitars that are up at G# main air can settle down a lot and get more juicy by dropping the main air mode to around F#, it’s not that hard. I figure that’s mostly what they’re actually doing, because you can’t mess with the modes in any realistic way without employing a tone generator and some thinking about frequencies on mostly the treble E

I use Spectrum Analyzer and a mic and take main air res reading, but I don’t obsess over it. I just check to make sure it’s not sitting directly over the frequency of a fretted note. And I’ve always from the very beginning tried for F# because Chris Berkov a great but under-known maker told me that in 1997. Turns out all the real vetted literature points there too.

Getting a bearing on the main back mode is a little more tricky, but as long as you have a separation and don’t couple the top and back air modes ( sonic muddle) the distance between top and back us forgiving. A back turned quite a bit higher than the top can make a good guitar. But again flamenco sound in part comes from slightly more lower pitched backs. Not a hard rule, but in general.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 29 2020 17:27:40
 
TonyGonzales84

 

Posts: 78
Joined: Apr. 23 2020
From: San Diego, CA

RE: vertical string pull on the soun... (in reply to TonyGonzales84

quote:

quote:


RE: vertical string pull on the soun... (in reply to TonyGonzales84) 

Finally got around to looking at TonyGonzales84's analysis of forces and torques on the top. I agree with his approach. His diagrams make it clear. My diagrams were just in my head


It looks fun, but if you do all that and you don’t get a main air resonance around F# with a back res that’s at least a half step apart, usually higher, them it’s academic. It’s crucial to be in the correct main Air Res zone. And it’s possible to get there by subtle adjustments of a top that’s thicker or strong enough to be resilient to the pull of the string. Or eventually you just make them right in the pocket.



It's interesting to see your nicely detailed discussion of actions required to empirically separate potentially resonating frequencies, yet not understanding that Armando's original question was explicitly about the relatively simple vertical pull on the top, and that that is the only point of the analyses, upthread. The force and moment analyses discussed upthread are extremely simple, yet, as required with any physical analysis, include all the important phenomena (as even "academic" analyses would hopefully show). Here, it might be time to point out that, one performs analyses to gain insight, not answers. The insight, here, is that there is no vertical load on the top, in the static, unplayed condition. This is very important in the Luthier setting up any test to gain insight (there's that word, again) in "how close am I?"

I applaud your mentioning that you do not "obsess over" your testing with "Spectrum Analyzer and a mic." Your description tells me that you do get it, just that the analyses, upthread, are at such a basic, fundamental level, that, maybe you're not seeing the forest for the trees? -- these analyses would result only in the static loads to, at the next stage of analyses, apply to the guitar structure, to ensure it does not "break" when it's just sitting there. The guitar-strings-air system is so complicated that, I would be absolutely surprised to see anyone claim to be able to perform any level of hand analyses predicting any level of testable frequency response -- what you're actually discussing.

Finally, I am curious if you have a list of "the real vetted literature," and how much of such literature would originate in the world of academia?

Now, go enjoy a sifter of nice Suntori Hibiki, as will I!

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 29 2020 22:12:38
 
Richard Jernigan

Posts: 3012
Joined: Jan. 20 2004
From: Austin, Texas USA

RE: vertical string pull on the soun... (in reply to estebanana

Estebanana-

An anecdote, a question and an opinion.

While Bernabe, Sr.'s shop was still just off the Plaza Mayor on Arcos de Cuchilleros I stopped by one afternoon. I was the only one there. Paulino Jr. was behind the counter. I asked if they had any "primera clase" classicals on hand. They never did when I was there, but Paulino Jr. came out with an "experimental model" whose fit and finish corresponded to their best instruments. I played a few scales. The note "A" was louder than all the rest, no matter which string or which position. I played a couple more "A's", said nothing and handed the instrument back. Paulino apologized for not having any "primera clases" on hand, and I went on my way.

Question: I have read that some of Torres' instruments have a main air resonance down as low as E-flat. Of course standard pitch was lower--and not nessarily the same everywhere--in Torres's day. I've played one with a tornavoz, which seemed to have a low main air resonance, but I didn't measure it, and I've heard recordings that I liked. What do you think Torres was up to?

Opinion: Analyses that can be written up in a short internet post will seldom give much insight into the sound quality of a guitar. (Main air resonance may be an exception.)

RNJ
  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 30 2020 0:35:47
 
estebanana

Posts: 7999
Joined: Oct. 16 2009
 

RE: vertical string pull on the soun... (in reply to TonyGonzales84

quote:

esting with "Spectrum Analyzer and a mic." Your description tells me that you do get it, just that the analyses, upthread, are at such a basic, fundamental level, that, maybe you're not seeing the forest for the trees? -- these analyses would result only in the static loads to, at the next stage of analyses, apply to the guitar structure, to ensure it does not "break" when it's just sitting there. The guitar-strings-air system is so complicated that, I would be absolutely surprised to see anyone claim to be able to perform any level of hand analyses predicting any level of testable frequenc


I cut passed the original question, because it’s the wrong question. People have been making successful guitars long enough to have an oral tradition and rote learning base of knowledge to get the structure of the top right to not collapse. The several generations that came before is settled much of this by watching and passing on information. It’s not an important question unless you’re an engineer with a curious mind for arcane info. Which is cool.

The guitar world ‘literature’ on main air resonance and the main top modes, the long mono pole, the cross di pole and the other modes and their relationships to the frequencies of stopped notes has been discussed by enough observers to come to a consensus about how they work. Alan Carruth and Trevor Gore are two main investigators who’s work mostly concurs, and along with them dozens of other significant folks have repeated the investigations and come up with compatible results.

You might say within the guitar maker community the folks that are invested in that kind of analysis have pretty much reached peer review agreement on the fundamental truths of looking at main air mode and main air resonance

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 30 2020 3:23:37
 
TonyGonzales84

 

Posts: 78
Joined: Apr. 23 2020
From: San Diego, CA

RE: vertical string pull on the soun... (in reply to TonyGonzales84

quote:


RE: vertical string pull on the soun... (in reply to TonyGonzales84) 

quote:

esting with "Spectrum Analyzer and a mic." Your description tells me that you do get it, just that the analyses, upthread, are at such a basic, fundamental level, that, maybe you're not seeing the forest for the trees? -- these analyses would result only in the static loads to, at the next stage of analyses, apply to the guitar structure, to ensure it does not "break" when it's just sitting there. The guitar-strings-air system is so complicated that, I would be absolutely surprised to see anyone claim to be able to perform any level of hand analyses predicting any level of testable frequenc


I cut passed the original question, because it’s the wrong question. People have been making successful guitars long enough to have an oral tradition and rote learning base of knowledge to get the structure of the top right to not collapse. The several generations that came before is settled much of this by watching and passing on information. It’s not an important question unless you’re an engineer with a curious mind for arcane info. Which is cool.

The guitar world ‘literature’ on main air resonance and the main top modes, the long mono pole, the cross di pole and the other modes and their relationships to the frequencies of stopped notes has been discussed by enough observers to come to a consensus about how they work. Alan Carruth and Trevor Gore are two main investigators who’s work mostly concurs, and along with them dozens of other significant folks have repeated the investigations and come up with compatible results.

You might say within the guitar maker community the folks that are invested in that kind of analysis have pretty much reached peer review agreement on the fundamental truths of looking at main air mode and main air resonance


Thanks for pointing out that the OP's question is the wrong one and that, it's cool if one is an engineer interested in arcane info...such as what we're discussing.

Evidently your literature "list" is a fallback to two highly scientific, highly respected and experienced practitioners/investigators (one might be so bold as to say they have "curious mind(s) for arcane info" -- ha ha ha). Very early in this thread I mentioned being impressed by Alan Caruth's work, and it's nice to see your holding him in high regard.

Is there anything, at a more elementary level, that you can offer the OP, that may help him? Your ready and detailed discussion of the vibration modes and their couplings, and possible ways of decoupling them, does show a commendably advanced empirical understanding of how a guitar works, but can you succinctly explain, Do 1, 2, and 3, then do A, B, and C; if xyz happens, then stop and correct it by jkl. That may be helpful to Armando.

Keep smiling...

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 30 2020 4:01:03
 
estebanana

Posts: 7999
Joined: Oct. 16 2009
 

RE: vertical string pull on the soun... (in reply to TonyGonzales84

quote:

Thanks for pointing out that the OP's question is the wrong one and that, it's cool if one is an engineer interested in arcane info...such as what we're discussing.

Evidently your literature "list" is a fallback to two highly scientific, highly respected and experienced practitioners/investigators (one might be so bold as to say they have "curious mind(s) for arcane info" -- ha ha ha). Very early in this thread I mentioned being impressed by Alan Caruth's work, and it's nice to see your holding him in high regard.

Is there anything, at a more elementary level, that you can offer the OP, that may help him? Your ready and detailed discussion of the vibration modes and their couplings, and possible ways of decoupling them, does show a commendably advanced empirical understanding of how a guitar works, but can you succinctly explain, Do 1, 2, and 3, then do A, B, and C; if xyz happens, then stop and correct it by jkl. That may be helpful to Armando.

Keep smiling...


Rookie. If I wanted to be salty you’d have known it. I just said what anyone with common sense would say.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 30 2020 13:36:58
 
estebanana

Posts: 7999
Joined: Oct. 16 2009
 

RE: vertical string pull on the soun... (in reply to Richard Jernigan

quote:

Estebanana-

An anecdote, a question and an opinion.

While Bernabe, Sr.'s shop was still just off the Plaza Mayor on Arcos de Cuchilleros I stopped by one afternoon. I was the only one there. Paulino Jr. was behind the counter. I asked if they had any "primera clase" classicals on hand. They never did when I was there, but Paulino Jr. came out with an "experimental model" whose fit and finish corresponded to their best instruments. I played a few scales. The note "A" was louder than all the rest, no matter which string or which position. I played a couple more "A's", said nothing and handed the instrument back. Paulino apologized for not having any "primera clases" on hand, and I went on my way.

Question: I have read that some of Torres' instruments have a main air resonance down as low as E-flat. Of course standard pitch was lower--and not nessarily the same everywhere--in Torres's day. I've played one with a tornavoz, which seemed to have a low main air resonance, but I didn't measure it, and I've heard recordings that I liked. What do you think Torres was up to?

Opinion: Analyses that can be written up in a short internet post will seldom give much insight into the sound quality of a guitar. (Main air resonance may be an exception.)


I think you may have mentioned that to me before about Bernabe’s shop. You’re so lucky to have been able to have business to go to Spain in that time.

About the Torres question, I don’t know what to say, and probably no one has done enough of a survey on Torres to have a comprehensive list of which guitars have which main air modes.

Alan thinks the tournavoz has something to do with making the guitar sound like a big lute, forgot his line of thinking. But he has looked at guitars with tournavoz and says yes it drops the main air res into the Marianas trench. The one guitar I made with a tournavoz is small bodied and should probably have a main air much higher, but it’s a bit below F#.

Really that stuff makes most people crazy because there are too many variables to establish any good rules of behavior. Guitars are strange animals, they work and we don’t always know why. We kind of have a basic format we inherited ( and are fools to try to disprove or make better) so we follow it more or less.

I made a really tight classical in 2018 that had a high pitched main air res. What happens in general with those guitars is they are hyperactive in the high partial range, they can have overtone support that gets in the way of the guitar. Like that Bernabe with the hyperactive A. There is a thrill to this kind of energy, but you get listeners fatigue quickly because it focuses on too much at once. Lots of interference in the radar. So we want to dial it back.

Here’s the thing, guitar making isn’t one of those things that you get good at fast, you make a few poor ones in the beginning, then you make huge progress the next twenty or so, then you hit another wall and it becomes harder. Part of getting through that plateau and feeling confident is a few are going to fail. You take the fails with a lump of sugar and keep your chin up.

That Bernabe with the hyperactive A notes, Paulino and the kid observed that and said one lump or two? They just moved on. Lucky the one I made with the new bracing that drove up the harmonic busyness was fixable by a bit of modification to the bridge.

Eventually sold it for very handsome money.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 30 2020 14:07:34
 
TonyGonzales84

 

Posts: 78
Joined: Apr. 23 2020
From: San Diego, CA

RE: vertical string pull on the soun... (in reply to TonyGonzales84

Stephen, I really do wish we could share a few sifters of Suntori Hibiki (or whichever adult beverage you’d pick); I’d buy the first round, and if you were good with it, we could alternate, after that. In nothing that I’ve said have I meant to impugn your abilities and experience as a luthier: clearly you are respected, and I commend you for having Jason McGuire playing one of your guitars on your website!

My question on a set of references, based on your statement of vetted literature, was sincere, in always looking for more ways of learning and being more informed. I’m used to people invoking “the existing literature” (my quotes, not yours) immediately being able to produce said references, bibliographies, review articles, etc. You contacted Trevor Gore, who is generous, and very giving and free with his hard-won knowledge, and it looks like you purchased his book (again, I commend you).

I hope you understand I mean you no harm.

Tony

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 30 2020 20:07:03
 
estebanana

Posts: 7999
Joined: Oct. 16 2009
 

RE: vertical string pull on the soun... (in reply to TonyGonzales84

I’m not worried you mean me or anyone any harm.

In reading the whole thread, all builders who’ve made a significant number of guitars and who really know how to make Spanish style instruments are all saying a variation in the same thing- math isn’t a substitute for success and failure learning. What’s more, even the masters of guitar maths say the same thing because fundamental concepts in building Spanish guitars were solved long before modern ( mostly American) makers began trying to create engineering models of this style of guitar.

It’s over thinking concepts that were figured out by trial and error and traditional rote transmission of knowledge.

That’s why we discussed break angle as an example of received wisdom that works. Then the knowledge was challenged by builders who gained anecdotal advantages from higher break angles, then this notion was challenged again, both with human testers ears and some mathy doings.

What was proved was that the old boys of yore knew that building in extreme break angle gave diminishing returns in this style of building. There’s no substitute for having the notion your top is too stiff and then making the next one less stiff, if you think that will help. If there are short cuts, and some math does work for giving you an idea of density of the spruce you use vs. its weight- helpful for keeping records.

When some cat says “l’m not building enough to remember where I left off with feeling top flex.” They have to do something like keep careful records of wood stats and deflection tests, or try to build more often.

But encouraging people to use esoteric information that probably will not move them forward is not really being honest with them.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 31 2020 10:38:21
 
Tom Blackshear

 

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Joined: Apr. 15 2008
 

RE: vertical string pull on the soun... (in reply to estebanana

quote:

A back turned quite a bit higher than the top can make a good guitar. But again flamenco sound in part comes from slightly more lower pitched backs. Not a hard rule, but in general.


Actually, the 2003 Reyes reads a B-flat back with middle frequency G to F# 3rd and 4th string on the top.

The Miguel Rodriguez guitars are quite different with a lower tuning in general although I've actually studied higher tuning in some of his work.

However there are other tunings, like you say, that work well.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 31 2020 14:21:02
 
JasonM

Posts: 1565
Joined: Dec. 8 2005
From: Baltimore

RE: vertical string pull on the soun... (in reply to Tom Blackshear

quote:

That is maybe the right way to do it but very hard in my opinion, unless you are Tom Blackshear.


Regarding sanding braces to loosen the top... I followed Toms’s instructions and the top on my guitar definitely loosened up a bit. I will say it’s responds differently though. It’s has maybe just a little more snap on the bass side than I would like. Which is weird because you can feel how the top is thicker. Especially when you golpe. Playing it A lot these past months has loosened things a little further. The bass also got darker from sanding the brace on on bass side , the trebles did not change.

I will say that I don’t think I want to touch another brace until I have Gore’s book in front of me! I don’t understand how you can “tighten” things up by removing mass. Seems counterintuitive.

I did read through the thread Ricardo linked to where Rui had good results sanding braces for tone. But he had to destroy a top to learn what would happen in the process!
  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 31 2020 18:21:30
 
RobF

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Joined: Aug. 24 2017
 

RE: vertical string pull on the soun... (in reply to JasonM

quote:

I don’t understand how you can “tighten” things up by removing mass. Seems counterintuitive.

I think it’s because what we hear influences what we feel and what we feel influences what we hear.* And what we see influences both, even more.

Then, of course, there’s what we read on the label which, for some, takes precedence over all.

*For example, if removing mass resulted in a faster attack with less sustain, would the guitar ‘feel’ stiffer?
  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 31 2020 19:10:09
 
TonyGonzales84

 

Posts: 78
Joined: Apr. 23 2020
From: San Diego, CA

RE: vertical string pull on the soun... (in reply to TonyGonzales84

Jason, while removing mass, you are also lowering the stiffness; this can get to be a game of, which drops faster, mass or stiffness?

Now, on braces, their stiffening influence is very powerful, because they "are so far away from the un-stiffened top" (It's not super complicated, but I won't show that relationship, although it's the very thing that, when you brace the bottom of a shelf, makes it so you orient those 2 X 4s so that the 4 dimension is furthest from the shelf -- you can easily bend a long ruler, against the wide, marked face, but try it against the skinny edge!). It's possible to lower either, more quickly, depending on how you do it.

The reason for playing the mass and stiffness against each other is that, fundamental frequencies of structural and mechanical vibrations (such as a guitar) ALWAYS look like the square root of the stiffness divided by the mass (the k, in the picture, represents the stiffness, the m, the mass; the omega is the frequency). This is true for all the various modes of vibration that a guitar undergoes (each and every one!). In fine-tuning the braces (by removing material), you may be lowering a vibrating mode's mass more quickly than its stiffness, so the the quotient becomes larger, meaning its vibrating frequency gets higher. The opposite happens when you drop the stiffness faster than the mass comes down -- the vibrating frequency is now lower than it was. If you can think of, and internalize, one relationship/equation, let it be this "root k/m": it works for ALL structural vibrations, everywhere, on everything.



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  REPORT THIS POST AS INAPPROPRIATE |  Date Aug. 31 2020 22:54:31
 
estebanana

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RE: vertical string pull on the soun... (in reply to TonyGonzales84

There you go again. The mathy mathbobs of mathitivity-

Rob F said it correctly- it's about anecdotal perception and language.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Sep. 1 2020 1:44:32
 
TonyGonzales84

 

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Joined: Apr. 23 2020
From: San Diego, CA

RE: vertical string pull on the soun... (in reply to TonyGonzales84

You could just look away...

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  REPORT THIS POST AS INAPPROPRIATE |  Date Sep. 1 2020 3:04:06
 
estebanana

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RE: vertical string pull on the soun... (in reply to TonyGonzales84

Ah, but airplane crashes are too interesting if they are happening in front of you

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  REPORT THIS POST AS INAPPROPRIATE |  Date Sep. 1 2020 4:45:09
 
TonyGonzales84

 

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Joined: Apr. 23 2020
From: San Diego, CA

RE: vertical string pull on the soun... (in reply to TonyGonzales84

Well, I’ve gotta hand it to you, you delicate little flower, you sure can talk-the-talk. Upthread, you did a verrrry impressive job of sounding like you were quoting chapter and verse from Gore, but everything I’ve seen about his book (Volume 1 of 2) includes lots of that spooky, scary, out-of-place engineering-physics-math stuff (sorry about having to use those awful trigger terms…you’ll get over it, big guy!). Here is a direct quote describing Gore’s book, from Gore’s own website:

https://goreguitars.com.au/main/page_the_book_background.html
Yes, there’s a lot of physics, engineering and mathematics in there, because I felt that was required to prove my points. Otherwise this would have been yet another book full of unscientific, unsubstantiated opinion about how guitars work and, frankly, I’ve seen too many of those. If physics, engineering and mathematics aren’t your strong suits, don’t worry! The points I make are still there, are explained qualitatively, and the concepts are still usable. However, there’s no avoiding the mathematics if you want to get quantitative. As one of my old friends in academia said, “if it was easy, someone would have written your book years ago”.

I don’t know if you post on the Australian/New Zealand Luthiers Forum, but if you don’t, maybe you’d better head over there, pronto pronto!, and straighten out those poor mathy-math-mathenstein folks (the horror – they’re actually discussing things with Trevor Gore, trying to implement and understand his work…getting quantitative!):

http://www.anzlf.com/viewtopic.php?f=33&t=4636&hilit=gore+book

Did you reeeeally purchase Gore’s books, and if so, how’re they doing, filling up that space in your closet? Your being so scared of it actually has me considering joining Stewmac for getting their half-price offer on the two volumes…maybe you’re an advertising ringer? Hmmmmmm…

_____________________________

Tony
  REPORT THIS POST AS INAPPROPRIATE |  Date Sep. 1 2020 5:00:08
 
estebanana

Posts: 7999
Joined: Oct. 16 2009
 

RE: vertical string pull on the soun... (in reply to TonyGonzales84

There are more solutions to the notion that you think your tops are too stiff. One obvious thing is to look at your fan brace pattern. Stiffness get's moderated in the final braced top by a few factors, but one is how the fans cross the grain at oblique angles. Theoretically, and it's pretty east to feel, the higher the angle of the fan, the more it's going to stiffen the top.

More in keeping with the way the guitar was developed is to try to learn to moderate stiffness through structure. If your tops feel too stiff either before or after they are braced, but you don't want to risk them developing the 'S' curve, ( that thing I mentioned Jim Redgate was building into his tops') the way the top pulls up behind the bridge and flattens out between the soundhole and the bridge- Work with the braces more parallell or absolutely parallel. And as long as you make them parallel and you fee you top is too stiff, use five braces and put them all more of less under the bridge, and use fairly light cross off diagonal braces where they end. Or use no diagonals at all.

Parallel braces are not adding the stiffness across the grain, but concentrating added stiffness along the grain where it's important for both structural stiffness and the higher treble notes to be clear. Parallel braces also emphasize the cross di pole mode which on flamenco guitars is so much in the mix of timbre and flavor.

The range of frequencies the cross di pole mode activates are sort of the guts of the timbre of the flamenco guitar. And to temper those sounds its also import to make sure your sides are thin enough, the heavy stiff sides reactivate vibration better and thin sides tend to absorb. One thing about flamenco guitars that's important to get is that Classical guitars ( or guitars not as well suited to rasgueado that way it's played for flamenco) is that the clarity of the tone is maintained or made more efficient with most components being stiffer, stiffer ribs beget more bell like tone ( in general) and thinner ribs eat some high frequency by being dampers, less stiff. That dampening filters out the strident parts of high partials that stiff ribs can emphasize, softer thinner more damping ribs remove that, at least to our ears, and help model a more growly tone that we like.

So you can get your worries about top collapse off the table by going with a more parallel brace pattern as seen in so many good Conde's , and as a part of the package automatically feature the cross di pole mode by omitting braces between the edge of the lower bout and the wings of the bridge. That free play space can be left open and perhaps the top will not respond in a way that feels 'stiff'.

And having the back and sides thin makes a guitars top feel more lively, but can also help mask higher partials that get over active.

And if you feel your tops are too stiff, make light bridges with slightly more flexible wood. Because the bridge is a brace and a place where the strings transmit information to the top. If the bridge is few grams too heavy for that to it can make a difference.

So if you have a the notion your tops are too stiff, you can thin the top. But if that scares you, then build to the idea that are going to give the top the least amount of added stiffness.

See, because you have to think in two or three directions at once. And you learn more by approaching the problem from more than one direction, when keeping in mind that most Spanish makers figured this out together before electricity was in common use. the 1920's 30's - The added information that math or attempts at engineering have brought precious little to flamenco guitar making and has mainly served to prove out things our esteemed predecessors already figured out.

There are no short cuts to having guts to learn by failure. We are building guitars, not tracking the Mars Rover.

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https://www.stephenfaulkguitars.com
  REPORT THIS POST AS INAPPROPRIATE |  Date Sep. 1 2020 5:42:51
 
estebanana

Posts: 7999
Joined: Oct. 16 2009
 

RE: vertical string pull on the soun... (in reply to TonyGonzales84

quote:

Well, I’ve gotta hand it to you, you delicate little flower, you sure can talk-the-talk. Upthread, you did a verrrry impressive job of sounding like you were quoting chapter and verse from Gore, but everything I’ve seen about his book (Volume 1 of 2) includes lots of that spooky, scary, out-of-place engineering-physics-math stuff (sorry about having to use those awful trigger terms…you’ll get over it, big guy!). Here is a direct quote describing Gore’s book, from Gore’s own website:

https://goreguitars.com.au/main/page_the_book_background.html
Yes, there’s a lot of physics, engineering and mathematics in there, because I felt that was required to prove my points. Otherwise this would have been yet another book full of unscientific, unsubstantiated opinion about how guitars work and, frankly, I’ve seen too many of those. If physics, engineering and mathematics aren’t your strong suits, don’t worry! The points I make are still there, are explained qualitatively, and the concepts are still usable. However, there’s no avoiding the mathematics if you want to get quantitative. As one of my old friends in academia said, “if it was easy, someone would have written your book years ago”.

I don’t know if you post on the Australian/New Zealand Luthiers Forum, but if you don’t, maybe you’d better head over there, pronto pronto!, and straighten out those poor mathy-math-mathenstein folks (the horror – they’re actually discussing things with Trevor Gore, trying to implement and understand his work…getting quantitative!):

http://www.anzlf.com/viewtopic.php?f=33&t=4636&hilit=gore+book

Did you reeeeally purchase Gore’s books, and if so, how’re they doing, filling up that space in your closet? Your being so scared of it actually has me considering joining Stewmac for getting their half-price offer on the two volumes…maybe you’re an advertising ringer? Hmmmmmm…



You haven't been around here for long and I took a really long break from posting here, but you'll see if you stick around there are a lot of really knowledge people who get flamenco guitar making inside out. This stuff can't all be transmitted by a cerebral understanding of math or engineering. Even Trevor know's that. His books are predicated on the idea that you can reproduce a quality of sound by studying the physics, but it's not how flamenco guitars were created or how they matured and arrived at a apogee of development.

The whole city of Granada created a guitar making tradition and industry without electric gadgets to test guitars, for example, the arte was already mastered and transmitted, some books about physics helps us to understand the why, but not the soul.

If I wanted to talk to Trevor I'd just email him. And his work is important, but he's got respect for people who don't use it if they are good.

Here's the thing, if one s struggling with basics like worrying about top stiffness, you have to take a chance and plane the top at some point, what Trevor is saying is that 'the book' can be used to understand how to reproduce results once you get an idea of what you want. And the other main function is to give some information so you can teach yourself to diagnose glitches and fine tune the way the modes work together by using a tone generator. Other than that Part 2 if his books deals with Classical and Steel string construction, but conceptualized to take advantage of the physics ideas he lays out.

But we're making flamenco guitars here and that was figured out by the time Barbero died. Gores books are good to explain some physics behind the traditional designs, but too many legendary guitars have been made with these designs by making small changes and building them over and over. I sense a fragility in that some people are not willing to risk.

You're going to fail while you learn this stuff just like Bernabe made guitar that Richard said emphasized too much A. But when Bernabe followed his own recipe he made some of the best flamencos ever. And carved the most beautiful heels.

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https://www.stephenfaulkguitars.com
  REPORT THIS POST AS INAPPROPRIATE |  Date Sep. 1 2020 5:52:10
 
Ricardo

Posts: 12668
Joined: Dec. 14 2004
From: Washington DC

RE: vertical string pull on the soun... (in reply to TonyGonzales84

quote:

Yes, there’s a lot of physics, engineering and mathematics in there, because I felt that was required to prove my points.


Another way would be to send ME the guitar you built for comparison. Here is estebanana’s guitar:

Smokey bar Juerga :


Nerdy trio breakdown over webcam (jump to 40 min for a run through):



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CD's and transcriptions available here:
www.ricardomarlow.com
  REPORT THIS POST AS INAPPROPRIATE |  Date Sep. 1 2020 6:22:43
 
TonyGonzales84

 

Posts: 78
Joined: Apr. 23 2020
From: San Diego, CA

RE: vertical string pull on the soun... (in reply to TonyGonzales84

Sorry, Ricardo, I appreciate your point, but that quote is from Gore's website. I am not a Luthier, so I don't have a guitar to send you. The quote was solely in the context of Gore pointing out (maybe cautioning?) that his Volume 1 is very technical. The Australian/New Zealand Luthiers in the link are all in, with many pages of detailed Excel spreadsheet discussion on getting the calculations right; Trevor Gore is definitely showing he's The Dude.

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Tony
  REPORT THIS POST AS INAPPROPRIATE |  Date Sep. 1 2020 6:47:52
 
estebanana

Posts: 7999
Joined: Oct. 16 2009
 

RE: vertical string pull on the soun... (in reply to Ricardo

Now I feel like kind of a dick that I didn't give you that guitar when your car broke down. You could have sold to fix your car.

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https://www.stephenfaulkguitars.com
  REPORT THIS POST AS INAPPROPRIATE |  Date Sep. 1 2020 6:49:02
 
TonyGonzales84

 

Posts: 78
Joined: Apr. 23 2020
From: San Diego, CA

RE: vertical string pull on the soun... (in reply to TonyGonzales84

Because of my concern as to how quickly my post mislead Ricardo, I will say that, contrary to Gore's quote about his book, the force and moment posts, upthread, contain, at most, a modicum of engineering-math-physics, and only what's required for the purpose of understanding the static vertical load on the top.

Looking at the table of contents for Gore's book, I expect it to be much more extensive, with probably advanced mathematical concepts.

_____________________________

Tony
  REPORT THIS POST AS INAPPROPRIATE |  Date Sep. 1 2020 6:57:53
 
estebanana

Posts: 7999
Joined: Oct. 16 2009
 

RE: vertical string pull on the soun... (in reply to TonyGonzales84

quote:

Sorry, Ricardo, I appreciate your point, but that quote is from Gore's website. I am not a Luthier, so I don't have a guitar to send you. The quote was solely in the context of Gore pointing out (maybe cautioning?) that his Volume 1 is very technical. The Australian/New Zealand Luthiers in the link are all in, with many pages of detailed Excel spreadsheet discussion on getting the calculations right; Trevor Gore is definitely showing he's The Dude.


Are you Fk'ing kidding me!!
You are trying to teach guitar making with math and you're not even a FKing guitar maker?

The thing about Trevor is that he prioritized the information so it makes sense, and he backed it with three decades of building experience. That's how he knew how to prioritize what he teaches!

If you have the choice between random physics information and a prioritized traditional set of strategies for building a flamenco guitar, ya might want to go with the traditional info and prioritization.

I don't have issue with Trevor's book, he's done a great service of intellectual work. I don't understand all the math, because he written it with his equations, but after he shows the equation he gives the prioritized meaning of the information. Building via his physics observations of how modes work and his method of teaching people to interpret the information is his thing. A traditional avenue into making flamenco guitars is needed before what he is teaching can be applied to making flamenco guitars.

Case closed.

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https://www.stephenfaulkguitars.com
  REPORT THIS POST AS INAPPROPRIATE |  Date Sep. 1 2020 6:59:00
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