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Anders Eliasson -> Questions about guitarbuilding (long) (Jun. 13 2007 9:45:39)

Hi Guys.
I get a lot of mails with questions about guitarbuilding. I try to answer all, but its time consuming and sometimes I get mails which should have been send to someone else.
Today I got one of these and I decided to post it here, without mentioning the name of the guy who send me the mail.

Here you have it:

I've got a question to you regarding the thicknessing or tuning of the soundboard.

I'm currently in the thicknessing process of the soundboard for my next flamenco guitar.
The plan indicates that the soundboard is tuned to F# G. This means that the main top resonance of the soundboard would be equal to the
helmholtz resonance of the soundbox just an octave higher.

Now the question. Is that a good idea to tune the soundboard to the same frequency?

I have my doubts as i'm affraid the guitar could sound boomy around this frequency, but lack response elsewhere on the scale.

My soundboard material is rather stiff. It has now a thickness of 2.3mm thinned to 2.1 at the periphery. I don't yet have a signal generator to measure the top resonance accurately but by humming the soundboard it seems it responses now on a bflat.

I would be glad to hear your opinion.



Anders Eliasson -> RE: Questions about guitarbuilding (long) (Jun. 13 2007 9:47:53)

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.



Per Hallgren -> RE: Questions about guitarbuilding (long) (Jun. 13 2007 11:24:30)

This is an interesting question and extremely difficult to say something useful in just a few words. I agree in most of what you say Anders and I also get those mails. I believe that the best advice to a person who hasn't build enough guitars to "know" what he's doing is to focus on other details than tuning of the plates and box. The tuning is important but not in the way most people seem to believe. What to concentrate on is to build a guitar with all the "big details" correctly done. In time one learn to look deeper into it finding more and more details to focus at and their relative importance to sound. It is like music. You cannot learn music by only analyzing it, you have to play, over and over and in time you will hopefully get it. I have come to my intuitive way of building through all this with tuning, sine wave generators, frequenzy analyzing, left brain thing. For years I thought that I had correct theories about how an instrument "should" be built, but too often the instrument showed that I had not the whole picture. This led me into a more and more holistic approach and since I am working alone and am too lazy to try to express what it all is about I have never theoreticed about what I am doing. I am making progress, and that is enough to me.

I understand that the question is not about if the guy shall tune his top to this or that note but how he shall know when it is right. So my advice is to leave the tuning totally. The guitar will be tuned anyway...[:D] What he need is a map of the important details expressed in statistically average measures, shapes, angles etc. and build according to these details making intuitive adjustments from what his own material need. Is there another way?



Anders Eliasson -> RE: Questions about guitarbuilding (long) (Jun. 13 2007 16:37:50)

Hi Per

Thanks for joining in. I follow all what you say and I agree.[;)]



Armando -> RE: Questions about guitarbuilding (long) (Jun. 13 2007 21:25:29)

Hello Anders

First of all thanks for your answer.

The guy who send that question to Anders was me.

Anders, i appreciate your answer. Nevertheless the way you write makes me understand that i have no idea about guitarmaking.

In a certain way you might be right because otherwise i wouldn't have to ask that question. However i would like to point out here that this is not really the case. Eventhough i'm an amateur builder i have built already a couple of guitars including one built at the guitarmaking course with José Romanillos.

Concerning your comments about the left brain luthery approach..
I'm aware too that there are the intuitive and the left brain approach. Basically i share your opinion about the left brain approach, but what can i do if i simply don't have the time to build enough guitars to get everything done right just be intuition and feeling. This is not so easy if you have to earn the bucks to maintain a family with three kids?

So now i'm just trying to avoid an error and i have some uncertainties about whether to thin my soundboard more or to leave it how it is. I know that this is difficult to say without holding the soundboard in your hands. Nevertheless i jus't asked because i thought you might have some experience with soundboard tuning.

If you say that you don't work with the left brain approach i understand that and i respect it. It indicated that you have reached a level where you can leave that approach out.

From Per Halgren i know that he works also with the left brain luthery approach. At least i think so because i have read an internet article about tap tuning written by him.

best regards

Armando



Per Hallgren -> RE: Questions about guitarbuilding (long) (Jun. 14 2007 7:58:18)

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...[:D]). 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...[8D]). 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.



Anders Eliasson -> RE: Questions about guitarbuilding (long) (Jun. 14 2007 8:35:13)

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.[8D] 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[:D])



Anders Eliasson -> RE: Questions about guitarbuilding (long) (Jun. 14 2007 8:41:02)

quote:

If you say that you don't work with the left brain approach i understand that and i respect it. It indicated that you have reached a level where you can leave that approach out.


Armando... Of course I use left brain as well. To meassure, to tap and to write observations down is all left brain. (I have a university degree, so my left brain is very trained) I basically just find that the human machine is still far superior to the human made machine when it comes to working with natural materials such as wood.



Per Hallgren -> RE: Questions about guitarbuilding (long) (Jun. 14 2007 8:44:07)

quote:

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.


Thanks Anders, my example had this thought inexplicit. Maybe I should have been clearer with what I really meant. Anyway, it really shows the inexactness in the tuning concept. A too stiff top together with a too heavy bridge tune out at the same frequency as a less stiff top and a lighter bridge!



Armando -> RE: Questions about guitarbuilding (long) (Jun. 14 2007 11:06:54)

Thanks Per and Anders for the explanation.

Some of your explantions are interesting and could be helpful to me.

Just to make things clear. I'm not a left brain luthery fanatic or disciple at all. I actually don't like all that math and physics stuff for guitarmaking. However i think that some of the things they do could help to get more consistent results and to enlighten some parts of the "great unknown".
Romanillos in fact does not believe in the left brain luthery approach at all. He rather goes for best quality materials and a good construction.
We were building the Bream model at the course but most of the soundboards were worked to a thickness of about 2.4 - 2.6mm.
But what to talk about soundboard thicknesses. My question was not to ask which thickness is best, because i know that this depends on the stiffness of the material and many other things as well. I just wonder if it is wise to tune a top to the same frequency as the helmholtz. According to Tom Blackshear, Reyes does it. At least it was the case on that particular guitar which he took measures from for his plan. Reyes guitars however are known to have nice trebles.
Of course i try to also develop my intuitive skills as i agree that they are very important. On the other hand i try to find some rules to follow because the whole thing with luthery is very relative. Everything you do might be good or bad depending on ........thousands of different parameters. Because its almost impossible to know which way to go i try to find out which way not to go. This is probably easier. I hope so..

Armando



Per Hallgren -> RE: Questions about guitarbuilding (long) (Jun. 14 2007 11:32:31)

quote:

I just wonder if it is wise to tune a top to the same frequency as the helmholtz. According to Tom Blackshear, Reyes does it.


Honestly, I don't know. I can not see that relation on my best classical guitars And I am still too young in flamenco building. But this answer also is depending on how close those the two resonances should be a true octave (because that is what I believe you mean, not the same frecuency) to fit into Blackshear's statement. Should it be an octave +/- 0 cent, +/-10 cents +/-20 cent or what? Has Blackshear used a computer to analyze the Reyes guitar or has he used the traditional approach (which is blowing/humming into the soundhole and tapping the top at the center)?



Armando -> RE: Questions about guitarbuilding (long) (Jun. 14 2007 14:10:41)

quote:


Has Blackshear used a computer to analyze the Reyes guitar or has he used the traditional approach (which is blowing/humming into the soundhole and tapping the top at the center)?


Hi Per

To be honest as well, i don't know what methods Tom uses to determine this things.

Yes, the frequency of the soundboard would be a full octave above the helmholtz. I don't know though if his statements were accurate or just approximations. If you want to have it exact you need the numbers in hertz anyways. To determine the frequency to be around F# and G is not very accurate.

regards

Armando



Per Hallgren -> RE: Questions about guitarbuilding (long) (Jun. 14 2007 16:48:52)

quote:

To be honest as well, i don't know what methods Tom uses to determine this things.

Yes, the frequency of the soundboard would be a full octave above the helmholtz. I don't know though if his statements were accurate or just approximations. If you want to have it exact you need the numbers in hertz anyways. To determine the frequency to be around F# and G is not very accurate.


Well, that leave us in the dark then. Even if we knew that tuning is the only answer it would be impossible to give an exact advice when the premisses are that unsecure.



stephen hill -> RE: Questions about guitarbuilding (long) (Jun. 14 2007 19:01:57)

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!



Anders Eliasson -> RE: Questions about guitarbuilding (long) (Jun. 15 2007 8:53:42)

Armando

Lets do some conclusions.

1) It seems like left brain approach is not fashion on this foro, so your questions should be asked somewhere else. I chosed to put your mail on the forum in order to have a discussion, which could be interesting to all. Maybe some others will join and say something else.

2) Take it easy. You have builded enough to have an idea of what you do. You have participated on this forum for a long time and your posts, your guitars and your sound examples show me that you know what to do. That you´ve gone a long way already[:)].

3) build that guitar. So far I´ve been the only one saying that you should change something. I found that your soundboard was thick. But build the guitar the way you feel it, take notes, listen, tap, humm, test flexibility. Remember to put you whole hand on the top when the box is assemble and test its stiffnes pressing down on the soundboard (carefully heh[;)])

Good luck.



Armando -> RE: Questions about guitarbuilding (long) (Jun. 15 2007 19:42:58)

Hello

Thanks Anders, Per and Stephen for your replies. I appreciate all of your feedbacks and comments. I think it's time to close the thread.

best regards

Armando



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