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If you haven't seen Ken Parker "Arch Toppery", give it a watch. I've been watching him carve braces for archtops and the care and time spent fitting and shaping them is a lot. I'm about to brace my dreadnought and was thinking about how little time I spent on my first guitar shaping braces. I know there's a big difference between archtops and dreads but it got me thinking. I saw the guy at Martin just whip through this process, experience, I know but, I wonder if he was to slow down, and give more thought to flexing and tapping, would that create a better off the shelf guitar.

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Hutch

Get the heck off the couch and go build a guitar!!!!

Really, time and care are the only advantages the individual builder has over the large factory operations. In most other areas the manufacturers hold most of the cards - they’ve got the massive tonewood stash, the team of skilled spray finishers and expensive finishing infrastructure, industrial-grade tooling, jigs and in most cases CNC, and big marketing budgets.

All the little guy has is the ability to take a little more care and time with certain steps, like bracing design and carving things a little differently depending on the materials at hand, hitting the perfect thickness for a particular spruce soundboard, and so on - the last 0.5% that the big manufacturers don’t chase, because it doesn’t impact their bottom line so much. Individual luthiers are all about that 0.5% and also about finding the customer who cares about it too.

I have developed a style of building, which is not unique really, where I focus 90% of my time and energy in getting the top thickness right and then for any given model guitar I more or less brace to specifications. Then I use intuition to take a little here or there off the bracing if I have a gut feeling. I do deflection testing after bracing but since the deflection values are so small I'm not sure they are really meaningful. But I do it anyway.

I've tried the tapping thing before and I just don't get it. To me it's like tuning a 12-string, you just start to go tone deaf and lose your mind.

Kent Everett said something about carving braces that stuck with me. I’m paraphrasing but you start with a hunk of wood then, as you carve, it becomes musical; if you continue carving it just goes back to a chunk of wood. Most of us know that and the big thing we try to do is to determine when to stop carving. For me that is tapping the top and feeling/listening to the vibrations.


Steve

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Steve Smith
"Music is what feelings sound like"

Nice observation.
Read what other people are thinking about brace carving: viewtopic.php?f=10101&t=55747

Guitar Top Voicing Demonstration by Dana Bourgeois:
https://youtu.be/Ei5-DkVTrEE?feature=shared

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Measure Twice,

Karl Borum

Good video, I like his explanation and the way he simplifies his approach.


Steve

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Steve Smith
"Music is what feelings sound like"

Yeah, Dana's video is worth watching just before starting to tune a top. I'm not far away.

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Hutch

Get the heck off the couch and go build a guitar!!!!

Yeah, Dana's video is worth watching just before starting to tune a top. I'm not far away.

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Hutch

Get the heck off the couch and go build a guitar!!!!

I've seen the Parker videos, and the tuning video before. I think they are good starting points, but I still think that we should do SOMETHING when the plates are no longer free plates. When they are attached to the ribs/sides; they need to be tuned more. I do area tuning on violins, and some on the 2 guitars I made. It is a way of evening out stiffness by sound. Now on guitars you will have tiny areas of much stronger stiffness, over/under the braces. How do you even them out?

If you could pull the back or top off easy (violin makers NEVER want to take off a back, guitar makers maybe the opposite?) and trim braces that seem stiff after it is together, it might accomplish more than just taking .005" off the edges in spots.

Tuning while playing the strings and finding weak notes would be cool. I've thought about it, but get in a hurry. I even know one maker who lets everything set, strung up, varnished and everything, and THEN go in to fine tune.

But I guess that guy really knows exactly what he is looking for.

Do you find places to cut BACK the notes that are REALLY good, and see if that opens up some of the weak notes, and then go in and try to reinforce them?

A factory has a set sound that they go for. We can go for something like that; or reach further. Either way you have to really think about it. Guitars, except for the bling go together really fast.

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Why be normal?

Maybe Michael Colbert or Greg Maxwell (if he's still lurking ) can post a pic of their setup. It's sort of like a mold but lets you trap the top plate and the mold provides the mass and so it's no longer a free plate. The braces can be carved as if the box is closed. I'm not sure who first came up with this, but I think they teach this method at Galloup.

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It may be Somogyi that first came up with that setup.

I don't think Somogyi was the first to use a dummy side set to clamp a top onto, but I can't say for sure. That's still not the same a having the top on a guitar, since the back also affects things. Also, in my experience, temporary mountings are never quite a stiff as permanent ones.

I've been using Chladni patterns, the 'tech' version of tap tuning, for decades. It gives the maker a lot more information to work with than tap tones, although it takes longer. It's easy to record what you've done, and easy to communicate to others. The equipment needed has become far easier and cheaper to get than it was forty years ago: now you can use a free app on a tablet or 'phone to generate the tones, and amplifiers and speakers are easy to come by. I've tracked Dana through a workshop that the local luthiers set up, and we end up looking at the same things, although, as I say, the patterns show you more.

The problem with relating 'free' (off the guitar) plate information to the sound of the final instrument is a difficult one. Basically, it's possible to make two guitars using the same wood and get them to sound 'arbitrarily close' using Chladni patterns, but they'll probably never be exactly the same. If you change anything, no matter how minor, they will probably diverge more. The guitar is extremely complex in the way it works, and there are lots of variables. By the time you get to about 700 Hz or so you're in a 'resonance continuum', where there are so many interacting resonances, and they overlap in pitch so much, that there is, apparently even in theory, no way to predict exactly what the guitar will do above that pitch. Fortunately, the low range, up to the 'continuum' seems to establish the 'character' of the sound: you match that by getting the lowest resonances of the top, back, and air to match the desired pitches and strengths, and there can be several ways to achieve similar ends. Sound 'quality' seems to depend more on the high end resonances, and what seems to matter most there is how many of them there are to an octave, and how low the loss factors are: you don't necessarily need to have them at the same pitches to get similar quality. People seem to pick out 'different' guitars on the basis of those high end pitches. That's where post assembly fine tuning comes in.

I really try to avoid that, for two reasons. First, I find I can usually get 'close enough' to the desired sound (the right 'character' and good 'quality') without it, and, second, it reduces the ability to use the 'free' plate data to tune the sound. In the 'pair' experiments I've done I have not been able to make two that sound 'alike', but they're always very similar, and the differences are not such that players or listeners have had a preference for either one: they're just 'different'. I find it so much easier to trim braces before the box is closed that I'd rather develop that approach to get the sound I want. It does seem to be working.

I'll note that the factories are not trying to match any particular sound, and, IMO, probably would not want to if they could. So long as the instruments bear a 'family resemblance' (Martins don't sound like Taylors) and the quality of sound is reasonably good they'd rather offer some variety. They can do that by sticking with proven designs and reasonable quality control, and rely on the natural variation in wood properties to provide a range of sounds. Carving all the braces for a particular model so that they look about the same works to that extent. Everything they make will be somebody's 'Holy Grail', and they only have to find that person. A custom maker has to know how to home in on a particular character of sound, which is roughly like nailing jelly to the wall...

Once I read the Cumpiano book, I came up with a method that seems to work pretty well for me. I start with a top that has a good ring to it. Plane it down to around .100 (or the wobble) and then glue on the braces. I shave the braces until I get a decent ring again. Just something that works for me