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Here's something that occurred to me while I was noodling around on some guitars at a store today. Bear in mind I may be way off base here.

If one particular model/size of a factory's guitars are all made the same with regard to plate and bracing dimensions, then perhaps the best sounding guitars of that model would be those with the least stiff wood.

Here's my reasoning, FWIW: A factory might be likely to specify top thickness and brace dimensions so that its least stiff materials would still be just adequately suppported against the force of the strings. This way, the least stiff materials they use would still provide an adequate structure to resist the pull of the strings.

However, any wood used in that factory's guitars which is stiffer than the least stiff materials they allow will make the top stiffer than what is needed for the top and bracing dimensions they use. We now have something more than a minimum adequate structure (to paraphrase Cumpiano). The "extra" stiffness makes the structure stiffer than the minimum required, probably with more mass than is needed.

So, the best sounding instruments from a maker or factory that uses consistent bracing and top dimensions but doesn't do individual voicing could well be those with the least stiff wood.

Does this make any sense? Sound plausible? Obvious? Nuts? Whadda ya think?

P. S. I have been known to beat to death the blatantly obvious.

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now known around here as Pat Foster
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That sounds about right to me Pat.

That may be why you hear so many times that the majority of factory instruments are average or good, and only a small number of them are execelent or very good.

Sound is a very relative thing though isn't it. I'm sure there would be some who think the average is excelent and the excelent is just good etc...

I bet you though that when a "big name" artist is having an instrument built, take Leo Kottke for example, he has a 6 and 12 string signature series with Taylor. I bet you that these signature guitars don't get the "typical" brace treatment. I bet you Bob or one of the other senior guys at Taylor tune the tops on those instruments.Rod True38916.0148958333

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Yep. In the manufacturing world we call this acceptable manufacturing tolerancing. It is a necessary evil of mass production to assure that this component fits or works with the next component without intensive labor required. Truth be know even custom builders use it but to tighter tolerance ranges depending on the process. In a factory there are tolerances on each top, brace and every other component. The better factories control the stacking of these tolerances and produce good production instruments, and hand build great custom versions for top artists as a promotional and advertising tool. This ploy gets the average Joe to walk in to music stores and buy a copy of the guitar they just saw their favorite performing artist play on stage last Friday night.

I don't knock them for these practices because if they took the time to build as we do, a $1500 Taylor would be a $3000 Taylor. MichaelP38916.4271875

Good thinking there Pat.

I too was noodling around recently at a guitar store. We played everything in the room. We kept coming back to a Sitka topped 414 CE Taylor with Ovangkol back and sides. Ohhlala! 1800 but worth every penny.

Can't wait to try some of the new Taylor Grand Symphony models. You just may be onto something Pat.

Now wait a minute there.... always being the skeptic..... Are you saying a floppy top braced well enough to hold strings will sound better that a stiff top with the same weight, design and mass of bracing?

If you are saying that you could be right, but I have a feeling it is would require a leap of faith to get there.

Please feel free to scold or otherwise correct me. From time to time I deserve it. Joe Beaver38917.8459722222

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Joe Beaver
Maker of Sawdust

[QUOTE=Joe Beaver] Now wait a minute there.... always being the skeptic..... Are you saying a floppy top braced well enough to hold strings will sound better that a stiff top with the same weight, design and mass of bracing?

If you are saying that you could be right, but I have a feeling it is would require a leap of faith to get there.

Please feel free to scold or otherwise correct me. From time to time I deserve it. [/QUOTE]

"Floppy" is kind of a loaded word.

I think what Pat is saying (and it makes sense to me) is that a too-stiff top won't sound as good as an optimally stiff top.

Phil

Right, if you over-brace a top, you can choke off the sound. Lighten the braces, and the sound opens up. Remember, the goal is to build the guitar so that it is on the edge of folding up.

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Joe Breault
Merrimack, NH
Perpetual novice

[QUOTE=Joe Beaver] Are you saying a floppy top braced well enough to hold strings will sound better that a stiff top with the same weight, design and mass of bracing?   [/QUOTE]

Joe, yes that's exactly what I'm saying, if the bracing is made so that there is minimal risk of the top bellying. Phil, you made it a bit clearer and leads me to think of the issue in a new light:

Let's think of a factory setting where all the braces and tops are made to the same dimensions for a particular model. In this instance, we'll exclude those settings where the tops are voiced before the box is closed.

If we think of arriving at optimum stiffness – building it so that it's on the verge of folding up as Joe B says – as a combination of optimum dimensions and stiffness inherent in the specific materials being used, then we could say that we get to that optimum place by balancing material stiffness with the dimensions of that material. To get to that optimum place, we increase one, let's say by choosing very stiff wood for the bracing, and decrease the other by removing more wood while shaving the braces. With this approach, we've balanced one variable with the other, and hope to have built an optimally stiff top. This is a sort of luxury that hand building provides.

But in a factory setting, the dimensions from one guitar to the next remain the same for a particular model, once the designers determine those dimensions. Now, one variable is lost: the dimensions have become a constant, since they won't change in our factory setting as tops and braces move through the assembly process. That leaves material stiffness as the remaining variable. BUT, in the factory setting, material stiffness varies enough to have a significant effect upon the completed top (as Hesh's example illustrates), even though we can expect that wood selection would keep this range of material stiffness within some sort of tolerance. So now, of the two most significant variables affecting sound, the factory has control of one, that being dimensions. The other, material stiffness, is not controlled, at least not once the wood gets to the factory floor.

Since there is this variable running wild, so to speak, the design must compensate by calling for larger dimensions to ensure that a less stiff top or set of braces won't result in a "tubby" sound or bellied top with potential for a neck reset under warranty.

So the factory is stuck with this problem of deciding how close to the "edge" they want to spec their dimensions. The closer they are to having no bellied tops, the further they shift all of their top/brace assemblies away from optimum stiffness. If they set the spec closer to optimum stiffness, they risk more neck resets and some tubby sounding guitars. All of this because one of the big variables, material stiffness, is a moving target, which makes the stiffness of the top assembly a variable in itself, while what we want is for that stiffness to be a constant. So they need to place the "range of resulting top/bracing assembly stiffness" somewhere along a scale that has tubby sound and/or big-bellied tops at one end, optimum next to that, and poor sound/no neck resets at the other end. We could of course anticipate that the two undesirable extremes on this scale, the tubby/bellied-neck-reset-risk end and the poor-sound/safe-from-resets end, are broad and open-ended, while the desirable range is tight and closed, making it a small target. Thus we have a whole lot of factory guitars that sound just OK or worse, with a small percentage that sound great.

Seems like a factory could actually test their tops and braces individually for stiffness and size them accordingly. Could even be done somewhat automatically, where an operator would load braces into a device to test deflection with an attached CNC to trim or thickness.

Building by hand provides the opportunity to voice the top, whereby using a wide variety of methods, we "dial in" both variables, material stiffness and dimensions and arrive at a constant, which is optimum stiffness. This sounds to me like a path to a higher percentage of successes.
Factories are instead bound to making a variable (dimensions) into a constant, trying to keep another variable (material stiffness) in some reasonable range (constant) and arriving at a another variable (which should be a constant), that being a range of sound quality. I think this is the lot that manufacturing in general finds itself in, especially one that uses such irregular materials as wood and seeks to arrive at such a variable, subjectively evaluated end product as a guitar.

But back to the gist, which is that the factory, if it's interested in minimizing the risk of neck resets or worse, new tops, under warranty, then it's going to make its tops and braces somewhat overbuilt. The least stiff tops and braces will still produce a structurally sound guitar. If that combination produces a top that's at or near the optimum, it might sound good, but probably not great owing to extra mass. Wood that would be considered superior by virtue of stiffness would produce overly stiff tops with possibly tight sound, weak bass, or poor volume owing to their excess stiffness and excess mass.

I'd really like to hear more on this.

woa. I'm going to be late for work.

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now known around here as Pat Foster
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http://www.patfosterguitars.com

Pat, you're late for work! Great thread BTW! Thanks!

Interesting thread!

I think I remember from Frank Ford's page, a tour of the Collings factory. The production process relies heavily on the use of CNC. For a given model, all the braces, dimensions, etc., are identical. Except for the tops. The tops are tapped, and based upon the experience of the "guru top-tapper", are sanded to a particular thickness, to give whatever quality said top-tapper desires for a given model. Then these tops all get the same bracing pattern, located in the same place. Now I don't know if they test the braces for stiffness or not, but I do know Collings are some of the most consistent sounding production guitars out there. I've played a lot of newer Martin D-28s (Whenever the local music store gets one, well I just have to check it out) - some are good, some are OK, and some just don't sound right. I played three Collings of the same model when I bought mine, and I could not tell the difference at all. When I went to a guitar camp a while later, another guy was there with the same model, purchased about the same time, and they sounded virtually identical. So it seems that it is possible to get consistently good results in a production environment. Is Collings getting the absolute best sound from every piece of wood? Probably not. But they do get consistently GOOD sound.

Where individual luthiers like ourselves have a leg up on even small production environments, is we can tweak those braces to match them to that top, and bring the best out of every piece of wood.

-Mark

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Ok, maybe so but.....

I agree that there is a need for a factory guitar to be build so that the more flexible components in a production run still make an ok guitar. There is also a need for the stiffer components to make an ok guitar.

What is giving me trouble is when you say that when all other factors are the same, the more flexible top will sound better.

To my thinking, all other things being equal, the more flexible top will sound less crisp in the highs with less overtones and perhaps a little more boomy (is that a word?) in the bass. I'm not sure that makes it better. I'm not sure the stiffest top in the run is any good either. That would lead to lower sound production and less bass. I suspect the best sounding production guitar is the one with average top stiffness.

I could be wrong, it has happened before......Joe Beaver38919.9297569444

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Joe Beaver
Maker of Sawdust

Michael, in reading your post I see what you're getting at with tolerance stackup. I believe you're talking about tolerances in dimensions, if I understand you correctly. I'm thinking more about the range of stiffness being something there's not so much control over, within the range of the selected wood.

I didn't know Collings did that in their production process, as Mark said, thinning tops to different thicknesses according to stiffness. If Collings can do it, why not the others?

Well, Joe B, I could certainly be wrong. Wouldn't be the first time for me either!
burbank38920.0261458333

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now known around here as Pat Foster
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http://www.patfosterguitars.com