Gore method/Tap tune/Siminoff...help!

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davidafterwork
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Gore method/Tap tune/Siminoff...help!

Post by davidafterwork » Sun Jun 09, 2019 3:21 pm

Hello all
I am new here so a quick hello and intro to give you some idea of where I am at re Guitar building.
I started to build as a hobby in 2015 and so far I have built around 12 guitars
All have been donated to various charities so I have no commercial interest in luthiery but it has become a bit of an obsession...in a good way I hope and the people I give the guitars to are happy about that!
My problem is that I want to take my guitars up a few notches and the main area that bothers me and tells on my guitars is the finished sound so I need to do something re tuning the tops/backs etc so that I can get some consistency going. I would love to arrive at that big Lowden type sound or my own Santa Cruz 00 which also sounds fantastic.
So here's the problem....
I bought the Gore/Gilet books and first of let me say that the 2nd one is excellent and better by far than anything else I have seen out there.
However I did not realise when buying it that it was based around the use of computer software for tuning the tops etc ( I know now of course but foolishly didn't realise it at the time )
I thought that I would be a traditionalist and tune my guitar tops by ear but I am realising now that I do not really have the time needed to develop that intuitive skill ( it seems to me that you would need to build at least 25 guitars and note down all that you done to each time to have any chance of arriving at the required sound and I just do not have that time available)
I have bought books and even a DVD on tap tuning but found it all so vague and imprecise that I have given up on it.
I now want to return to the Gore/GIlet method but fear I will never get the hang of it as I am not really a techie type person re software etc.
Here are my questions if anyone has the time to help out it would be great and thanks in advance
1 Has anyone tried the Gore method and found it too technical and returned to tap tuning?
2 Is there a simple version of the process available anywhere for technical dummies like me? Or videos??
3 I was going to get the Peterson Strobe de luxe program as it looks the most user friendly and also has a facility for intonation which I also need. Has anyone anything to say on the Peterson program good or bad??
4 I have the Siminoff book and it seems to be a simplified version of the Gore method at a quick glance..is that true or is it based on different principles altogether??
5 I have a top braced and carved and ready to go but the back is already on the sides so is it too late to use the Gore method on this guitar?

Thanks for taking time to read this and please feel free to make any suggestions at all on this subject and if you have found simple summaries of the method please let me know!
Cheers
Davidafterwork

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kiwigeo
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Re: Gore method/Tap tune/Siminoff...help!

Post by kiwigeo » Sun Jun 09, 2019 7:35 pm

davidafterwork wrote:
Sun Jun 09, 2019 3:21 pm
Here are my questions if anyone has the time to help out it would be great and thanks in advance
1 Has anyone tried the Gore method and found it too technical and returned to tap tuning?
2 Is there a simple version of the process available anywhere for technical dummies like me? Or videos??
3 I was going to get the Peterson Strobe de luxe program as it looks the most user friendly and also has a facility for intonation which I also need. Has anyone anything to say on the Peterson program good or bad??
4 I have the Siminoff book and it seems to be a simplified version of the Gore method at a quick glance..is that true or is it based on different principles altogether??
5 I have a top braced and carved and ready to go but the back is already on the sides so is it too late to use the Gore method on this guitar?
My thoughts/comments:

1) No...I haven't found a reason to abandon Gore's computer assisted tap tuning method. Some people have the skills and usually experience to judge how a good top should sound in its raw form relying purely on their ears...but I find approaching the process using modern tools such as FFT software a lot easier and the resultant data is quantitative.
2) Trevor's method isn't that complicated....some of the maths looks a bit scary at first but Trevor provides options with less maths.
3) Ive got the Peterson software on computer and iphone. It's easier to drive than VA but I find VA more versatile. It's a bit like comparing Unix and Windows...Unix a bit harder to drive if you don't know it's ins and outs but it's far more powerful than Windows. VA also allows for saving of data as text files and uploading to a spreadsheet from which you can create useful charts.
4) I've got Siminoff's books but I haven't opened them since getting Trevor and Gerard's books. Siminoff's approach is a bit more qualitative then Trevors quantitative approach to guitar acoustics.
5) You may be able to but it depends on current tap test results of the braced top. If your main air and top frequencies are such that they can be trimmed once the top is on then it may work. Ditto for the back. I'd start by doing some accurate tap testing on the back and top and decide where you go from there.
Martin

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Re: Gore method/Tap tune/Siminoff...help!

Post by jeffhigh » Mon Jun 10, 2019 8:08 am

IMHO forget Siminoff He is worse than useless because his principles and methods will lead you astray

The Main aspects of the "Gore Method" are

-materials testing by tap and then plate thickness calculation
-Modal tuning where the finished guitar is tested and adjusted

It does NOT tell you how to trim or test free plates (top or back) before they are assembled to the rim.

Even if the materials testing is too much for you, it is worth doing the Modal tuning and you really need to use the spectum analysis software rather than any form of tuner because you need to identify at least the 3 lowest mode frequencies not just the dominant air mode which is what a tuner will identify.

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Re: Gore method/Tap tune/Siminoff...help!

Post by Dave M » Tue Jun 11, 2019 2:03 am

For checking after the build is complete you need to be able to examine the spectrum so as to identify the first three resomances as Jeff says. Trevor describes how in detail. Many of us here use VA software for this. It is free and runs on Windows. It is not trivial to learn how to drive but there is at least one thread on this forum covering it's use. And any questions concerning it will be quickly answered. (no thirteen year olds available?!)

If these frequencies are badly in the wrong places then Trevor describes in the books how to change them - adding weight, trimming braces etc.

You will need a microphone for this testing which means that you could use a software tuner. I particularly like AP Tuner for it's large display and other features.

For future builds you could then try Trevors methodology for measuring the properties, specifically the Youngs Modulus, of your timber. Then using the calculations to establish the right thickness of the top plate. I have to say this is not trivial!. I am still not using the method fully. However you will find somewhere in the book a range of typical thicknesses used which can help in making an estimate depending on how stiff you fell your top is. ( I will be taken out at dawn for this suggestion!)

So I think getting into this type of tap testing is worthwhile. It is based on some science unlike so much that is said. And it is also good fun. There is nothing liks seeing the look on you partner's face when they find you hitting your guitar with a little rubber hammer and recording the output!

Good luck
------------------
Dave

davidafterwork
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Re: Gore method/Tap tune/Siminoff...help!

Post by davidafterwork » Tue Jun 11, 2019 2:37 am

Thanks for the reply
Some clarification if you have the time ( i just spent 25 mins replying in detail and then somehow lost the draft!!..shows how technical I am...)
You say that Trevor provides a simplified summary of the method?? Where can I get this as it really appears quite detailed/technical...

I am about to order the Peterson tuner as I was going to get one anyway for intonation so will it do the job for the Gore method??
In the method it seems the top is fitted before the back, is that the case ( I do the opposite so I can clean out any glue if necessary from the back joining the sides)

A microphone seems to be needed either way or will the Peterson pick up sound when on my Mac??

Has anyone using the Gore method now switched from previously tap tuning by ear etc and if so was there a significant improvement in the sound of the finished guitar??? At the moment I do the "sheet metal " test on the sound board before bracing and then tap for resonance etc when carving the braces but with very widely different results so consistency is what I am chasing..and the big clear sound!

Thanks again lads
Dave

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Re: Gore method/Tap tune/Siminoff...help!

Post by Dave M » Tue Jun 11, 2019 7:39 pm

There are much better qualified people who could answer - but here goes.

I have no experience with that tuner so don't know, but see Martin's comment above.

I was talking about testing the finished, strung up guitar so how you put it together doesn't matter. (Trevor does justify his method in the relevant build section.)

So having looked at the spectrum for the finished guitar the first three significant peaks will be the main air resonance, the top monopole and possibly the back, possibly the cross dipole. Section 1.7.1 in design book 1st edition. Now one of the main reasons you might want to move the frequency of one of these peaks is that they fall on a scale note. For instance the main air is often around 100 hz but may end up at 98 hz which is the G on the bottom string thus giving a wolf note. You can identify others.

The means for changing these frequencies (Modal Tuning in Trevor's terminology) is detailed in the build book section 22.3 Trimming Body Resonances.

Trevor has repeatedly said that testing the free plates has not helped him as the change from free plate to completed guitar is too unpredictable.

It is worth saying that there is a huge amount of information in the two volumes and it takes a long time to get a grip on it.

Finally just for interest some people on the forum have run Visual Analyser on Windows simulator on Macs.
------------------
Dave

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Re: Gore method/Tap tune/Siminoff...help!

Post by jfmckenna » Tue Jun 18, 2019 2:03 am

If you already have a computer and a microphone then it's really not that complicated. The first book is really a text book and almost deserves an actual class taught by a professor over the course of a college semester. But you don't really need to understand it in order to use it. There are already free spreadsheets out there that you can just plug the numbers into. There is free software out there that can make the necessary recordings and have the right analytics. I use one called Audacity.

It seems really complicated (becasue it is) but in practice it's very easy to do.

So far I have only used the method to compare to my standard method which is that of deflection testing and I found that the two methods matched up almost perfectly. The goal is to find the optimal target thickness of the top plate of the guitar. That of course depends on the physical properties of the wood. Some spruce is very stiff while other pieces are very flexible. The idea behind this method is to take any given top of any given physical properties to figure out what thickness yields the optimal stiffness. There's a bunch of fancy words with a lot of math behind themt like Youngs Modulus and so on but it's really just stiffness. Tops range in stiffness along the grain. Some are flexible others incredibly stiff. None of them are bad, you just make the flexible ones thicker and the stiff ones thinner to yield the same result.

Using scientific principles yields more consistent results. tapping and listening to plates is great but sometimes you might hear what you want to hear and it's not a very reliable indication of target thickness.

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Re: Gore method/Tap tune/Siminoff...help!

Post by kiwigeo » Wed Jun 19, 2019 8:34 pm

VA will run fine on a Mac running a virtual Windows OS but I found moving the data files around a pain in the proverbial. Theres also the issues of the Mac's line input (they dont really have a mic input as such). I ended up running into the Mic via a pre-amp to boost up the signal from a Shure microphone. In the end I bought a dirt cheap HP laptop for $400 from Auspost and that machine is my dedicated tap tuning machine.
Dave M wrote:
Tue Jun 11, 2019 7:39 pm

Finally just for interest some people on the forum have run Visual Analyser on Windows simulator on Macs.
Martin

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Re: Gore method/Tap tune/Siminoff...help!

Post by davidafterwork » Thu Jun 20, 2019 3:07 am

Thanks again everyone for the help
I must say that voicing is the subject of all subjects in guitar making. Everything else is easy to learn in comparison.
There are 3 methods I see now and which one to go with is ....hard to know!!!
1 Trevor Gore , a bit too technical for me I fear
2 Siminoff, seems more doable but I still can't find what note the various parts should be tuned to from him! It seems that the back should be approx 3 semitones higher than the top but that's as much as I can tell from his book!
3 The intuitive way, that seems to be Somogyis way and although I am reading his book its difficult to learn that method by reading about it and I would need to build 50 guitars to "get a feel" for the whole thing.

Not an easy subject at all and i will carry on looking to see which method to follow before I start my next build.
Dave

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Re: Gore method/Tap tune/Siminoff...help!

Post by johnparchem » Thu Jun 20, 2019 8:57 am

When I read your three choices, from your descriptions it seems like there is only one choice. "1". I never understand when i hear that Siminoff is more doable than processes in The Book. I read 'The art of tap tuning" and watched the DVD that came with it. There is no prescriptive method and in the DVD demonstrations he invalidates most of what he says and what he wrote. The Gore\Gilet books are both prescriptive and descriptive. Trevor's methods are no more or less technical than Siminoff, just more complete and accurate.

davidafterwork
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Re: Gore method/Tap tune/Siminoff...help!

Post by davidafterwork » Fri Jun 21, 2019 4:05 am

John
thanks for the reply. I have just spent a while looking at your website and its very nice and lovely work too!
Can I ask what method you used before Trevors and if you heard a clear difference in sound from the Gore type builds than what you were doing before??
I agree about the Simonoff, its just not definite or clear enough, for me anyway and thats real pity as I bought both books!!
I would love to know what the big boys do in terms of voicing ( eg Lowden, Santa Cruz etc. I have a Santa Cruz 00 myself and would love to know how he got so much clear sound from such a small guitar!! )
I asked another Luthier (professional) and he told me that tap tuning was "all rubbish, we just thickness them to the right thickness and thats it" Not very helpful unfortunately.
I also build just as a hobby and while the software element of the Gore books is very intimidating to me I have to give him top marks for the build book, its my most used Luthier book of all I have and if I was starting again its actually the only one I would buy. Maybe I will just jump in on the next build and use his method. I have Peterson Strobe Tuner so I am hoping I don't need anything else and that the mic on the mac will do as well.
Dave

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Re: Gore method/Tap tune/Siminoff...help!

Post by johnparchem » Fri Jun 21, 2019 7:30 am

Thanks for your comments on the website. As you see I photo document all of my projects. I think that a lot of the big (factory) boys, have a bunch of parts made to pretty exact dimensions and assembles guitars from those parts in a constant way. The parts are probably sized to hit the center of the bell curve in terms of stiffness and mass, so the guitars that come out range from OK to really good. The smaller, one or a few at a time builders, can take the time to tune each guitars.

The biggest value that I am getting using Trevor's modal tuning methods is consistency in my build process. With that consistency I can decide to build at a specified set of resonances. For example I made three classical guitar one after another one with a 180 Hz top, one with a 190 Hz top and one with a 200 Hz top. I got all of the backs to pretty close to 4 semitones higher than the tops. This allowed me to compare and decide what I like but also have the flexibility to target other players preferences.

For me the biggest bang for the buck in his processes is to derive the target thicknesses for the top and back plates. Especially the top. Without some way to figure out how thick the top or back should be the guitars that are built will be hit or miss.

Before starting to use Trevor's tap and or deflection test method to predetermine plate thickness, I had and have use two different methods for steel string guitars. The first was taught to me by Rick Davis of Running Dog Guitars. He taps while thicknessing the top in a drum sander. He taught me to listen to the taps and that one will hear a point where the top sounds really good. He had me continue sanding the top until that good sound started to go away and there was a more chaotic sound. His reasoning was if the top sounds great without braces it will be too stiff with the braces. This method worked well but it is hard for some to follow without be taught in person. He also taught me how to voice an X braced guitar while carving the braces. It too relied on listening skills and a process in deciding where to take off wood from a starting point with the braces.

The second way was from Kent Everett. (He has a voicing DVD that is really good for Xbraced guitars. ) He is a great builder and a good teacher. He taught the sheet board method for determining the target thickness. While thicknessing the plate, when he is close to the range of thicknesses one might have, he holds the joined plates on the side and shakes\wobbles them. They are at the correct thickness when they sound like sheet metal. It is a very noticable change when it happens. I end up with .1-.2 mm of Trevor's method when using his suggested steel string parameters. My guess there is a point where the stiffness and the mass are just right to create this effect. He also teaches a way to hand voice an x braced guitar top.

For me the biggest problem with the above methods is they do not work for a classical guitar. When classical guitar tops are thicknessed they are floppier than a SS top so neither of the above methods work. There are builders who just feel for stiffness but that takes some skill to achieve consistency.

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Re: Gore method/Tap tune/Siminoff...help!

Post by davidafterwork » Sat Jun 22, 2019 3:21 pm

John
Thanks again for the details.
To push the question a little further...
You say you get consistency of build using the Gore method and I can see how that would be the case BUT is it of a standard that is noticeably higher/better than when you were using say the Everett or Siminoff type methods? I ask this because the logic would seem to be that if that is the case then it is a superior method for producing high quality sounding guitars consistently and yet... I don't think that say Lowden or Santa Cruz (just to pick examples from 2 ones I am familiar with myself) use that method. If I thought that the Gore method would produce those results I would definitely try it next time but I have never actually heard a Gore type guitar.
Also, do you use Peterson Strobe tuner or will I need VA as well????

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Re: Gore method/Tap tune/Siminoff...help!

Post by johnparchem » Sat Jun 22, 2019 11:27 pm

I have a bit of trouble answering a question about "the Gore method" as I think it mischaracterizes the Design volume as it is not a method book. Also the Design volume is not about "Gore type guitars". What is taught in that volume has a lot more inclusive has more depth and is more applicable than Siminoff. Everett is really teaching what he does for his sound on a steel string. The Gore\Gilet Design volume teaches about how guitars work, how the properties of the wood used contributes to the sound and structure, it provides tools to take into account the attributes of the tonewood being used and it has a great description of modal tuning including how the different resonances in a guitar affect the voice of the instrument. a great section on intonation and on top of all of that there is an in depth study on nearly all attributes on a guitars playability. The information in the volume is directly applicable to all styles of guitars and very helpful with related instruments like ukuleles. I use VA, a true Peterson strobe tuner and a Peterson strobe tuner application on a PC at various stages of building and setting up a guitar.

If you want a quick applicable example of how one luthier voices his instruments Kent Everetts DVD or Robbie O'brien's on line steel string voicing class https://obrienguitars.com/courses/steel-voicing. They are good examples of what some call "The intuitive way".

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