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Questions about guitarbuilding (long)
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Anders Eliasson
Posts: 5780
Joined: Oct. 18 2006
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 RE: Questions about guitarbuilding (... (in reply to Anders Eliasson)
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Well, here we have one of these almost impossible questions. Or lets say that this question is directed to the wrong builder (me). That’s why I post it here, because I´m sure someone else will have different things to say.
Words like: helmholtz resonance and signal generator are not in my vocabulary. This leads to a fundamental understanding of what guitar building is…. (getting scary hah???) 
IMHO you can roughly devide guitarbuilding into two different orientations.
1) The intuitional approach used by most or almost all Spanish builders before and nowadays. To some of them words like the above mentioned ones are nonsense and even words like taptuning is a waste of time to them. I taptune, so personally I´in this box, but on the soft side.
2) The technical approach, used by many especially american builders. In this approach you don’t trust you intuitive sensations but try to make machines (strobe tuners, computers and many other technical things) tell you what to do. These builders find that machines are more precise than human beings… For people interested in this approach I can recommend books by Siminoff.
Nowadays the last approach is getting more and more used. A big reason is that its easyer to discuss, because there´s a “thing” to discuss. A certain vibration, a machine you can use, etc. Intuitive feelings are difficult to explain and almost impossible to explain using words. You have to feel. Before I started building I had the luck of touching and feeling hundreds of soundboards (raw, in process and finished). I had them in my hands and they told me their story. It sounds super hollistic, I know, but its nothing special. Its nothing else than being there, you might call it to be concentrated, but I prefer to call it to be there. Its like fishing, being out there with your hook and you fish…. When you are there, you learn, you record, and little by little you understand. The same when you play. When you are out there in your fingertips, you understand what to do. This you record and you remember.
Back to the questions.
F# - G is great for a finished instrument, but there´s 100 or more ways of getting there and the sound and pulsation of all 100 ore more ways will be different.
I don’t tune a soundboard before assembly. Soundwise its message is not clear. BUT feeling wise, that’s when you get most information. Before you brace… The vibration and flexibility tells millions of stories before the soundboard is glued to the sides and the back. In all building, getting the soundboard balanced will be the most important thing.
The guy asking says “My soundboard material is rather stiff. It has now a thickness of 2.3mm thinned to 2.1 at the periphery.” Hmmm. Two observations: if the soundboard is a good and stiff one, 2,3mm is thick!!!! And to make a difference of 0,2mm at this point is to complicate life a bit. If you are capable of finish sanding the guitar without taking more of the periphery, it could be ok, but very few are. You have to clean of after gluing bindings and purflings and its very difficult not to take more off the periphery than of the center.
Advice. Instead of buying a machine. Buy a Hacklinger Caliper, an instrument capable of meassuring thickness of plates on an assembled instrument. This will tell you a lot..
I said that I taptune. And I do, but I tap after assembling the box. This I do mostly to even out frequencys and not so much in order to get a certain note, but at this point you get a quite good feeling of the final voice of the instrument.
Another thing. He writes: The plan indicates that the soundboard is tuned to F# G.
Hmmm typical. The plan says something, but it doesn’t say anything because it doesn’t talk about all the ways you can use to get to F# - G. All the plans I´ve seen are full of info that doesn’t help you. Quite the contrary. They confuse you. A lot of the important info is not there. Basically because its impossible to describe, So use plans with a lot of filosofy……
I will end this with repeating myself. In my experience, the final note of the instrument will be helpful, but you can reach that note in many different ways, so don’t get to fixed on what you hear.
So, now its up to you guys to do a follow up. We need to help this guy, because as I´m not really the one to ask.
_____________________________
Blog: http://news-from-the-workshop.blogspot.com/
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Date Jun. 13 2007 9:47:53
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Per Hallgren
Posts: 241
Joined: Jul. 1 2006
From: Sweden
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RE: Questions about guitarbuilding (... (in reply to Armando)
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Armando,
I understand your situation, and whether or not you believe it we never really come to a level in our craft where we reach totally security of what we do. We can never know that what we created in a guitar was the very best way to do it since the very best guitar doesn't exist. I am sure that Romanillos has given you much about this since he seem to be a very philosophical man. Anyway, we have to confront this insecurity in every new instrument. With more experience I have learned to live with that and to trust that what I do will produce a guitar in the end, no matter what approach I have, left or right brain attitude or what ever. Some guitars I like more than others, and some guitars that I don't like very much are much appreciated by others. That is the way it is for all of us, even the legendary makers.
Yes, I wrote an internet published article about fine-tuning a guitar. It was a part of a project that Tom Blackshear started in 2001. Since then I have dropped some of the procedures I write about in this article, such as measuring the Young's modulus for example. I really never got it to speak to me and it was very time consuming. What I still do is very basic techniques of keeping track of density and weight in the material I use, measuring static stiffness at different points of construction (I guess all the techicians on this Foro will nail me for using the wrong vocabulary now...  ). I also still use a computer to frequency analyze the box during the last stages of the process. The rest has come to be very intuitive, i.e. something I just do without a leftbrain explanation of it.
To frequency analyze is to check tuning, and that get me on the track to what your initial question was. My view of this is that the tuning only say very rudimentary things about the quality of the guitar. For example, a guitar with a top tuned in F will most certain be more bassy than a guitar with the top tuned in G, but it say very little about the relative quality. I have for the moment five guitars that I play regularly. Jose Ramirez II, Francisco Barba, José Rodriguez, Valeriano Bernal 1a and one of my own. (Yes, I am spoiled...  ). Those guitars show a span in tuning of the box (the main air resonance) from a low E to G, and they are all good in different ways and I like to play all of them. But to really understand the difference of those five, on a deep level usable for a guitarmaker, we need to have more information. And it is still not enough to have the tuning of the top fundamental or any other resonance. Why?
As I see it the concept of tuning is valuable only together with a lot of other ways of experience the guitar and the process of building. Take a guitar where you can measure the top fundamental to a G for example. You can lower the tuning to F# by putting on a heavier bridge. Will the guitar be better? There's only one way to know. Put on that bridge!
All parts in a guitar are coupled to eachother, one way or another, and the frequencies of the different resonances are products of all those parts. I an earlier thread I was arguing for some cautiousness with changing a peghead to machine heads because it can affect the bass response. I can measure this change on a guitar and I believe it could actually be heard in some sensitive cases where good or bad things line up. It can be a change for good or bad, we don't know until we have made the conversion and then it is too late to regret it if the change was for the worse. The interaction of all the resonances in a guitar is very complicated and in my opinion more complicated than we ever can understand. We need other major tools to create the sound we are looking for.
One of those tools is to measure the stiffness of the top and back. Together with the information of weight it will much faster give you a real sense of being in command than if you try to tune the guitar to a good result. Actually, by controlling stiffness and weight you are tuning of course. Build a simple jig where the top can be loaded with a weight (always use the same weight) and measure the deflection. I am sure you have heard about it. In only a few instruments you are starting to see a picture of how stiff the top and back should be for your taste of sound and feel in the instrument. Until you have created this list of data from different instruments all you can do is to work from drawings with known numbers telling you how thick this or that should be and assuming your material is in one way or another compared to the material the guitar on the drawing was made from. That is the best and fastest working advice I can give you except that working in company with someone who is very experienced will always be the fastest road to success. With that type of guidance you are more sure to have all the basic relations correct (which was what I talked about in my last post). I envy you your time together with Romanillos!
This is a long post and so much more could still be said. Hopefully I have given something to answer your question.
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Date Jun. 14 2007 7:58:18
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Anders Eliasson
Posts: 5780
Joined: Oct. 18 2006
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RE: Questions about guitarbuilding (... (in reply to Anders Eliasson)
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First of all. Armando, dont let my writing make you think you know nothing about guitarbuilding. It would be a wrong conclusion and its not my intention to make you think so. ok
I just think you are on the wrong way. You have to learn to trust you own judgement. No machine will ever take that very important part away from your building. I dont say that machines are useless, but in the end you´ll have to take some right brain descissions, so a good idea would be to train that part as well.
Dont worry to much about that thickness. Yes its important, but so are a lot of other things, so you can screw it even though you make the perfect soundboard thickness. You say the piece of wood is stiff. Then I can say that 2,3 is thick.... Romanillos classical guitar (Julian Bream) was 2 - 2,1mm....
In the end its all about balance. Guitars with a great balance tuned at F will end up having great trebles. It might take their time, but they will have it. Guitars in poor balance tuned at G, will have poor trebles (and poor basses) But in general working with the same bracing system tuning lower will give you more bass and less upper harmonics.
The different bracing systems tune different, but they dont have to sound that much different.(and thats the interesting point!!!!) When I build parrallel harmonic bars, I generally reach around F# - G in final tuning. When I build with slanted lower harmonic bar, I get around f - f#.
What do I like the most....... I cant say. I like both. I think the parrallel system gives my guitarm output a better consistency. They are more alike. So thats what I build the most now.
Take care with tuning down a guitar putting a heavyer bridge on it.. Its one of the most important parts of a flamenco guitar. The light bridge.
Its a lot better to thin the soundboard after having assembled the box. Use a Hacklinger gauge to check that you are working evenly!!!!!!!!!!!! You might goof it. I once did so and the almost finished guitar ended up in my woodburner. (burns fast )
_____________________________
Blog: http://news-from-the-workshop.blogspot.com/
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Date Jun. 14 2007 8:35:13
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stephen hill
Posts: 300
Joined: Feb. 16 2004
From: La Herradura, Granada, Spain
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RE: Questions about guitarbuilding (... (in reply to Armando)
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Hi Armando
I got your mail and would agree with Per and Anders. I work my guitars to an Fsharp box. This I obtain through long practise and knowing the measurements of how I build. Today I worked out that the top I am making, all strutted is pitched at A before assembly. This changes when I put on the bridge, slowing the pulsation down , and also when I put the bindings on. My experience tells me to work from one guitar to the next, not making radical changes and upsetting the long chain of building up of knowledge.
When I teach I work with students to my established pattern and have good results. The lower backbar pitch is usually a minor 3rd above the pitch of the top, heard by dampening the front. I am experimenting with a 2nd now.
So, keep making, keep fluid, take notes and be consistant. and come and do a course!
_____________________________
stephen hill - granada spain
http://www.spanishguitars.co.uk
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Date Jun. 14 2007 19:01:57
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