Official Luthiers Forum!

Anyone done it? Any opinions?

Thanks in advance

Steve

What I can say is the very, very small taste I got at Northwoods this year... go do it!


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You might want to talk to Sam Guidry who posts here, as I believe he's the guy that actually gives it...

Having said that, I would imagine that most of the info can be found in the Gore/Gilet books, though I bet they have lots of ideas on how to put that info to use, and I expect their overall approach is quite different from Gore.

I think part of the Galloup approach is to use the same sort of quantifiable aspects of wood testing to select wood within a very narrow window of acceptability. I think I recall reading that they will reject thousands of dollars of wood before accepting just the right top, where as with the info in the Gore/Gilet books, you can learn to use data measurements to get the most out of wood that you have. Two sides of the same coin really. But I'm speculating here, not having taken the course.

For myself, I'd love to go just find out if there was even more to know than what can be found in the G/G books, both to set my mind at ease and sort of as due diligence. I really like having a quantifiable set of specs so I can always know that I've hit the mark. But how can you know if you've hit the mark if there isn't a mark, i.e. quantifiable specs? But I have quite a different outlook on what's important and not important than a lot of folks.

However, with the course cost and travel to the US, it's around 5k$, and since I actually build for a living, coming up with 5k$ is kinda tough.

Anyway, bit of a blather there

“Blather” aside, thanks Ed. All perspectives appreciated.

Steve

I suspect very few people have done both the Gore course and the Galloup course, but Greg Maxwell, who often contributes here, has.

If Greg doesn't chime in, I'll refer you to what he said previously on this forum.

Robbie and I will be getting together again in Denver, beginning of August 2018. We all had such a good time last time around that we had to do it again!

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

...

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It will probably be alright.

I'm curious then as to how you source your wood. Do suppliers not grow weary of you returning the majority of your orders? Doesn't the return shipping eat away at your money?

Here are some of the topics that Trevor covered in his master class I hosted last year.
• How strings drive your guitar
• Visualizing and understanding modes of vibration
• Relating modes of vibration to guitar frequency response curves
• Measuring frequency response curves
• Relating frequency response curves to generic guitar types (classical, flamenco, steel string rhythm, steel string finger picking)
• Introduction to theory of modal vibrations
• Mechanical impedance and admittance
• Targeting the “right” modal frequencies and avoiding the wrong ones
• Requirements of a guitar as a static and dynamic structure
• Measuring material properties so that you can make the best of the wood you have rather than wishing for the wood you would like
• Bracing schemes for backs and tops
• Practical tuning of guitar modes: Moving from “as built” to “to design”

Students also have the opportunity to have their guitars tested and analyzed for "faults" and then a "how to fix" plan can be developed.
As Trevor said, we will be offering this class again in 2018.

One of the difficult elements involved with testing wood is how to deal with unwanted sets. Some suppliers will work with you, many won't. You can resell sets to those who aren't interested in sorting wood based on material properties. In fact, many sets with average scores look very nice and would get an "AAA" grade based on visual analysis.

I have been fortunate to acquire consistently great Sitka from Alaska Specialty woods, one of our sponsors here. For me, tonal considerations come before esthetics, so I am willing to accept tops that are wider in grains per inch than what many people would want, along with "bear flaw" which is minor grain indentation commonly referred to as bear claw figure, as long as the tops score in the range I am looking for. Of course, major defects such as knots and pitch pockets are a deal breaker.

The bottom line is, we all have goals for our instruments, and these are highly personal. The Galloup method is not the only way to make a great sounding guitar, but it has worked extremely well for me. I got into building because I wanted better sounding guitars than what I had played my entire life from factories, and I wanted to know WHY some guitars sound amazing and most sound like all the others. I'm willing to take on the time and expense of acquiring and sorting Spruce tops because doing so has produced the results I am looking for.

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It will probably be alright.

Greg,

Do you find that some characteristics in the wood tend to skew the wood towards "better" scores out of the gate? For example - do low runout or thick late wood lines make a significant difference in these wood scores?

I have gotten some pretty beautiful wood that felt like cardboard in my hands and vice versa...

If you have ever thought about buying 5 "Mastergrade" tops, buy 100 sets of "A" grade tops instead. You will probably find more that have better material properties in the "A" grade tops than you will in the "Mastergrade". Obviously you only need to find 6 out of 100 for this to be true, but then all 5 Mastergrade tops may not test that high in "material properties" (possibly none of them will). As long as cosmetics determines grade, luthiers have the opportunity to buy good tops cheap.

The spreadsheet used by the folks at Galloup produces a Q rating for each top tested. The higher the Q rating, the lighter and stiffer that top will be at final thickness. The spreadsheet also calculates a final thickness for each top based on a target deflection and determined by the modulus. Any factors in the top being tested that would impact the material properties being measured (such as runout) would be reflected in the Q rating and deflection prediction.

Various factors contribute to the Q rating so all the data for a potential top must be evaluated. Generally, a top with less mass will be more responsive than a heavier top even if both have the same Q.

The builder might use the Q rating along with other factors including visual appearance to assign a final number to a top set. This is based on the builder's own goals and personal preferences.



This can indeed be accurate. I have an AAAA Master grade top in my stash that scored below my threshold for use. And some of my best tops have wider grain that would be rejected by some due to the belief that high grains per inch always translates to a superior top. Bottom line, the wood needs to be measured for the important material properties in order to quantify it's potential as a top, or before it can be compared in an "apples to apples" manner with other top sets.

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It will probably be alright.

So basically, they are just looking for the highest stiffness to weight ratio?

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Pat

I think Q measure velocity of sound as well...

Yes it does.

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It will probably be alright.

Torres made some guitars with tops of multiple pieces. It would be a tough sell in today's book match market, but might be another way to get a superior soundboard from tops that have uneven quality wood.

Somogyi's classes were ALL about wood selection for the entire first day. He, like Sam feels that wood selection is absolutely key to a great sounding instrument. I never got to go, had a kidney stone hospitalize me but my friends in the class told me what the class was about.

Although this is more difficult for small builders who don't have infinite cash for the stash... it's not impossible. I've visited a number of wood suppliers who let me toss though the piles. Or, at the very least you can set expectations with who you source from as to what you want and that if it doesn't test well you are returning it for another try. If they object go somewhere else..... Business must be earned at times....

F*ctories or places on the planet with out large, local supplies of decent spruce have to be more keen to getting more out of less and I agree that this is possible. But I'm not sure that I would agree that more out of less is equivalent to an exceptional piece of tone wood that tests clearly "in the lane...."

Sam has done a LOT of work since 2011 and folks who I talk with tell me that he's taken voicing to new levels and may be one of the preeminent experts on the subject today. I also from time to time work on some of the custom instruments often for famous folks that Sam, Bryan and crew have crafted and they are some of the best that I've ever played and enjoyed their "audiophile" voices. One of Jeff Daniel's the actor in the Martian comes to mind. Great guitar that sounds like heaven!

To each their own but my personal expectation from guitar building was ALWAYS that I didn't want to be like just another f*ctory or even worse knowing how to milk an existing pile for the best properties but instead I believe that my value add was truly something exceptional in respect to tone and everything else.

As such for me the concept that really, really decent tone wood is one in a hundred tops or even less was never a surprise to me and again not something that I found impossible to get either. One sponsor here these days who did not exist in my building days seems to understand this and it's in their materials, you will just have to figure out who. I suspect that they are not alone especially if you are clear how your own sourcing search may include returns.

I'm also sure that both Trevor and Sam can add a lot of value to someone who is a blank slate with voicing and structured, quantifiable methodologies for receiving desired results.

But my money is on Sam and that's where I would go. He was also Dave Collin's first apprentice with me having been Dave's second. I know what Dave expects and I also know that it's the pinnacle of possibilities always completely backed up with accepted science, you know.... science..., physics, math, and some patience for the flaws in our human thinking about subjectivity and tone that is prevalent with all of us bags of mostly water.

With this said and based on my own observations of direct personal experience with instruments voiced in Sam's shop I would be signing up for Sam's class first and if possible take both offerings.

Lastly seeing very careful wood selection as key to what results as a negative is misplaced in my view. Would you apply the same logic to other things where we tend to be selective such as selecting a guitar to own and play or would you be selective with which guitar, car, tools, guns, homes, spouses..., friends, scotch, medical pot, tube amps, or lunch place you want to own or select? See what I mean, being selective is already a huge part of all of our lives.

It's no less important with tone wood, top wood than it is with anything. In my experience I expect that material selection criteria would be HUGE when it comes to what results. After all we are not simply saving up to be the next f*ctory.... produced instrument..... we're supposed to do far better!

Hesh, you make some good points and thank you everyone for your feedback. But the Galloup method raises some interesting questions to my mind.

Let’s assume I’ve been given the run of LMI and get to choose any tops I want.

Don’t they all have to be dimensionally consistent for any measurements to be effective?

Do I do an FFT analysis of the tops right there?

Let’s say I take 100 tops home, where I test them, choose the ones I want, and then return the others. Presumable, I’ve sanded these to the appropriate thickness for testing. Is anyone going to want to take them back?

I appreciate the theory of what the Galloup folks are doing. I guess I’m just questioning the practicality.

Steve

Steve, once the modulus of different plates is known, they can be compared with each other on the basis of actual (not perceived) strength. They do not have to have identical dimensions. Strength is a constant material property, it doesn't change based on dimensions.

Two methods can be used to measure for Modulus: Static (deflection) testing and dynamic (tap) testing. In order to test wood at a supplier's location, one or both would need to be used.

When measuring thickness as part of the data for testing plates, 15 measurements are taken and then averaged. To be accurate the plate needs to be sanded to a uniform thickness. Usually this means just cleaning up any bandsaw marks, and most of the time the plate still has plenty of thickness left for gluing and thinning to the target final thickness. For this reason I won't buy top sets from suppliers who take them down to near final thickness before shipping. This is not usually a problem.

You are correct that this method is not the most practical. But the results in my instruments (and Galloups, and Sam's, as Hesh noted) has been worth the effort.

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It will probably be alright.

A small shop luthier with a descent amount of experience given any stash of wood is going to make a better guitar then a factory guitar. If you have a weak top then make it thicker or brace it appropriately , for example. Factories don't do that. It might not be perfectly ideal to base tops solely on deflection since you might get a top that deflects to what you want but in the end is heavy, but still. If there is one thing I've found out myself by experimenting with cheap materials that otherwise would never be used by any serious luthiers is that, you can make a pretty dang good guitar with cheap materials.

So if I am understanding this thread correctly there are two camps here? One is seeking out only the very best materials on all the planet earth and use those and you will build a great guitar VS just get some reasonable descent stuff and make it work. I don't really have any choice but to fall into the ladder and so far so good.

Sounds like a great class though I'd love to attend something like that some day, always trying to improve, but admiringly stuck in my ways too

I always bought ten tops when I needed 2 and then thicknessesed them to my standard, it doesn't matter what it is just be consistent, I used .140". Then I did deflection testing and again how you do it can vary a lot just always be consistent, I had a jig that I used to religiously use.

Once you see what you have, I used an excel spread sheet to compare results you can decide who the keepers are.

As for who is not a keeper, that's what the classifieds are for......................... Now to be clear this does not make rejected tops bad tops but it does and did eliminate them from my use based on testing and a desired criteria.

Lastly back in the day if you handled enough wood you gained a feel and could tell that something was pretty stiff, light, etc. I could not quantify this by feel but I could tell often that something likely would test very well.... or not. It was this experience and the learning process with testing that helped me learn what I wanted and what I didn't want.

I also made a mule that had ten different tops on it at one time or another for testing. Highly recommended! This guitar is my personal favorite these days and weighs 2.9lbs.

Just a word on nomenclature, it seems that modulus and strength are being used interchangeably. They are not the same thing and should not be confused.
Modulus of elasticity measures how stiff something is regardless of it's strength.
Strength is the rating on how much force it takes to break something.

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Jim Watts
http://jameswattsguitars.com

Ok I think I understand. So you stuck to a thickness for ALL tops (even regardless of species?) and then looked for a certain number in deflection based on what ever weight it was that you religiously stuck to over the years?

This is kind of a chicken and egg thing but how did you know what to look for? What weight to use? What deflection to get, and what thickness to use as a base? Or is this all just an accumulation of personal data over time?

I started doing deflection testing a few years ago so I'm really just still collecting data but it would sure be nice to have a base line. My idea was if I build a fantastic sounding guitar, IOW get lucky, then I should be able to at least get close to that by thinning a top out to the specified deflection. I understand that for any two tops in comparison one could be less dense then the other with the same deflection, which would probably be desirable, but given that the cube rule shows that only a little bit more or less thickness (more or less mass) to get to the desired deflection makes a very big difference in stiffness I'd think it would be close enough. If for anything to at least get close to the style of guitar you are after. But IDK

You more or less have to figure out how to make a good one and then try to repeat the recipe. As far as tops not being as stiff as needed the less stiff ones may be good for smaller guitars or ukuleles.

Right, that's kind of what I am getting at. But the less stiff tops can be made just as stiff by making them just a bit thicker without sacrificing too much mass. At least that's my understanding of it or perhaps my misunderstanding of it.