Questions on sequence

[Dave Bagwill]

his may belong in another part of the Forum, if so please feel free to move it.

Beyond the 'carpentry' is where, all things being equal, the experience and craft comes in. If you have a good kit, say from Ken Cierp, you will have all the quality woods and the quality instructions to build a good guitar. Then as you progress, your actual construction improves to a point where it does not have to be refined much further. I call that the 'carpentry.'

Now the goal is to, theoretically, take the same materials, do the same carpentry, and add factor X to come up with a better sounding instrument.

The 'X' factor is what I am now concentrating on. For the meantime I am bracketing the question of materials and glues and all that, taking as given that we know how to construct the instrument. Beyond that there's an entire spectrum of thought from technical aids to voodoo, but for my questions I just posit the following and ask for your critique:

1. Top - we know the theoretical thicknesses for tops. I don't think that tapping the unbraced top accomplishes too much - everything will change as it is braced and further construction goes on. BUT - we can measure the stiffness-weight ratio to determine and change the responsiveness of the top. A scale and a deflection tester does the trick. I have neither yet and need to fabricate something. Bracing will not change the FACT that we have started with a top of a certain ratio to begin with.

2. So we brace and tap and shave and scallop, knowing in general what has worked for a long time and aiming for that . Once we've done those things we could do a Chladni test or something but still, it is all going to change when the top is glued to the sides.

3. I can cut this essay short by saying: the best time to do the alterations we need is after the instrument is strung up. Then all the forces are in play, there are no factors to be added in, we have everything we need. Except a way to know if we can improve it, and a way to access the interior to make changes. We know that on the outside we can sand around the rim, and if you follow Somogyi at all you know that we can sand behind the bridge a bit and that gives a good result.

4. The access to the interior problem is solved via a method from Brian Burns - and that is to TAPE the back on and do whatever tests you need to do. Then if you want to make alterations, take off the back and do them, and try your tests again with the back taped on. If you have a very good fit of the back to the ribs, this works.

5. But what tests, what parameters are good/better/best - that's a problem for me. If I'm not satisfied with the strung-up, back-taped-on sound, what can I do? Shave the braces, and look for a change in sound, either by ear or by technical means. Brian - who builds classical guitars, uses a fairly simple system of aiming for a certain body resonance. He does this without any tension on the body, which seems a bit of a weakness to his method but I'll have to talk to him about that. In any case his method yields certain results at the various monopole/dipole/tripole modes. He has targets for those modes that OVER TIME has worked for him, and he removes the back and adjusts the braces most responsible for that mode. It works well for him; his guitars are world-class.

I'm not defending Brian's method; many would disagree with him. The question is: Is any of this worthwhile? We don't have access to the woods of the 1920's and 30's, most of us will never use BRW or top quality Adirondack, yet great guitars are still made. I want to really upgrade my game, and want advice on whether to make investments in equipment, or if it is all in the ear. A question that thousands of luthiers have already asked, but it's perennial and worth asking again.

[ken cierp]

Tom Rebekkie and Charles Fox have constructed and offer guitars that have an access cover instead of a tail block so they can get inside and shave the braces etc.-- seems like they are thinking the instrument has to be strung up and set-up before and while one is tweaking the construction and structure.

[Dave Bagwill]

In the 'best of all worlds' would not the post stringing-and-set-up period be the best time to make the changes one desires? I mean, if it is necessary at all; the benchmark guitars we have all heard of were made without much sophistication in technology and none had a rear panel access that I know of. :-)

[Tim Benware]

And there is the question of - Will all the changes you make to a "young" guitar to make it sound good translate to better sound or worse sound as the guitar gets "older." Conventional wisdom is that as a guitar gets older it sounds better but is that necessarily true if certain changes are made when it's younger?

[Ken Hundley]

I was going to say something along the same lines, Ben. What is that guitar, modified for that oh so perfect sound, going to be like 3 years later? 10 years later? Not the same, I am sure, but will it still be good enough? What then? Keep shaving? Part of me says to develop a system and stick with it. I think we are all building guitars that sound really good. If you want better sound initially, try reducing the mass of your braces, either by shaving them, which could be dangerous. Maybe keep them taller, but make them a little thinner.....try experimenting with the finger braces and tone bars.....less critical, but potentially sound-changing anyway. I don't know, if I found a guitar with a huge port in the back designed to shave the braces, I would ask the builder why they didn't get it right the first time (assuming you are shelling out a few $k for one). Just my personal opinion, and most certainly not intended to ruffle any feathers here.

[Dave Bagwill]

I think I've read or heard all the sides of this thing, as most of us have.

I have decided to test my tops for stiffness/weight ratio and deflection and base my thicknessing decisions around that ratio.

I have also decided to build and use a resonance tester for the final taped-on back testing and will do further changes if needed at that time. It could be that a strung-up test would be better, but I think only marginally.

These steps will give me a good handle on the data - for what it is worth - at beginning of the process and the end of the process.

The chladni testing does not appeal to me; I'm sure its fun though.

[ken cierp]

Holy Moly!!

Charles Fox removable access panel $1200 !!!!!!

http://www.charlesfoxguitars.com/ergo_opening.htm go to options

Who care if you can make it sound better if you can command that kind of money for the ptotential?