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I'm trying to glean some information that I thought would be more readily available: How to shave braces to adjust for tone. I'm working my way up to building my first guitar but before I start, I'd like to learn as much as possible about the structure of the instrument. To better get there, I've bought two guitars that I'm treating as 'patients'. The first is a very lightly built Recording King Indian/sitka 000 that has a wolf tone. I've reshaped the neck of this one, along with finish sanding the underside of the top. The Second is an Epiphone AJ shaped Indian/Sitka that I've been sanding the finish away from slowly as well as finish sanding the interior, and I re-attached the lifting bridge with HHG (after shaving and reshaping it. This was much fun!).

I've learned a ton so far but I'd like to adjust the tone of these guitars by selectively shaving the braces and sanding areas of the top and back. I haven't been able to find direct ideas that I can use as loose instructions as of yet and I'd love it if those of you more versed in this might help?

I've read that sanding all around the edges of the top emphasizes the bass and that shaving the bottomost two back braces does the same. That's all I can find. Is the treble end of the spectrum a function of the stiffness of the top?

Thanks to any and all anwerer's!

I personally don't like to shave anything much between the bridge saddle and the upper transversal.... Too much important structure that lives in that area....

I find that if your top bracing is more or less within the right range.. but you still need to "Fine tune" the balance a bit -- bridge and back brace shaving are where to go for the bang for the buck.. Al Carruth has written up the best info I have seen so far, and has said it much better than I can....

One thing that I found is that initially -- if you are way too stiff... nothing much happens when you shave.... Then, as you get closer and closer.... less and less material makes bigger and bigger changes...

A strange thing I have noticed is that it seems like an instrument takes a while to adjust to bracing modification.... Shave it and it may sound a bit odd for a few minutes, then it seems to settle in again after a while and sounds pretty good....

Translation -- go really slow.

Thanks

John

This is something that you should not do at this point. Study a few books on voicing a top. You can go from great to dead in a millisecond. Also , don't believe all that you read . having been doing this for over 10 years , I built over 100 guitars and early in my day I was like a trout after a new hatch mayfly , most of the information I found on the internet was bogus.
Beware of your sources. Ask them how many guitars they had built. You may be surprised at how many posters want to he helpful but or often not educated . A few pointers I will give you . 1st. You can safely sand on the edges of the braces and break the sharp edges. These become focal points of force . A top needs to have all the energy dispersed . Sharp corners seem to divert energy . Look at the ends of braces that do not get inlayed into the kerfing and make sure the edges are faded onto the top without a thick end.
See that you have a sound bridge plate and that any brace that is butted against another is tight . Be sure you have a proper mate with the saddle to the bottom of the bridge. Another point is the nut slot. A steel string will not bend at 1 given point. Be sure the nut slot has a slight radius to it so the apex is on the front of the nut.
This is enough to get you started and be safe

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I want to be helpful...I am not formally educated in guitar building but I have managed to successfully build 20 something acoustics and 5 electrics over the past 10 years. Those guitars have been in the capable hands of real good players and it's been difficult for me to retrieve them. John...please consider your cajones busted!

So that's my resume and you can take my advice in light of that experience. Here's the secret...copy the bracing pattern of your favorite model that you are building. Do everything you can to measure and determine the profiles, angles, thicknesses of those braces. Tap along the way during your brace profiling and try to hear the differences as more material is removed. Assemble this 1st guitar with the objective being that you will make every joint as tight and secure as possible. Concentrate on construction, fit and finish and playability and let the sound fall where it may. Use this first guitar as a mule to which you will compare others. In the process, you will have a first guitar that will sound better than you expected and you will amaze others and attract more women!

My first realization of what the voicing process was all about was when I studied John Mayes' DVDs...I believe he has 2 on voicing alone which were the most helpful of the whole series.

Good luck and keep us posted as you progress.

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JJ
Napa, CA
http://www.DonohueGuitars.com

I think a bio page should be available with this type of detail. It really would help to have an idea of who is telling you what, both in quantities and models and build philosophy.

About the voicing, after building 1 guitar, 2nd ready to string, I agree with John and Todd, do everything you can to get your mind of voicing and bracing, it can drive you nuts. Instead of voicing your junkers, work on the set up. Perhaps refret them. There is so much work, skill and learning to make a good neck, and to bend the sides, that really the top and back voicing are a blink of time in the build.

At this point, the magic of the build is not in the voicing, it is in the attitude of the time spent in the shop, have fun building with the shop time, and you will want to build another, let your attitude create the voice on the first few.
Rob

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There have been a lot of attempts to correlate various factors with outcomes in medicine. In the area with which I am familiar, total joint replacement, only one factor has been statistically significant. Volume. Below a certain critical surgeon/hospital volume complications are higher, above a certain number volume no longer correlates with better outcomes. There appears to be a “sweet spot”.
I would submit the same holds true for lutherie. I don’t know what that number is but I’m at 40 and I don’t feel like I’m there yet. I would guess at around 100 you would have enough “out there” for a long enough time to allow flaws in construction to show up and would have built for a large enough variety of players to have a good handle on getting the tone folks want.
Bracing/voicing? I agree with the previous posters. Stick to established specs, build a few, get some feel, and then start delving into the popular DVDs or spend some time with an established teacher.
I’d actually like to see the numbers of years building and volume as part of a builder’s profile on this forum.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

We seem to be straying off topic, but....

The problem I see with build counts and other such info is that it may not be an accurate indicator of how good the instruments are or how valid the builder's knowledge might be. I know a builder who gained great popularity early on, but had to farm out returned instruments for repairs. He was so backlogged that he didn't take the time to learn about voicing, fretwork, structural integrity etc. I fear that some of his instruments will not stand the test of time. They sound pretty good right off the bench, though.

There's also the issue of a builder's past experience with working wood. I would put more faith in the workmanship, tone and durability of Todd Stock's first guitar than the 20th of some, though chances are if a builder makes it to 50 or 100, they must be doing something right.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

Number of guitars and years are maybe more relevant than a mere post count, but are far from being a real quality mark. The famous Romanillos played by Bream was a very low number (under 20), Bouchet barely made it to 100 in his entire life, and we all seen firsts or seconds with excellent workmanship, better than what others achieve after 20 years of trying. We are not equal....

(( only made 8 so far so take my post with lots of salt Btw my post is not driven because I think too highly about my work, but I do improve at a good rate. ))

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Build log

As a learning exercise, I did a similar experiment on a heavily-built import 000. I did find it valuable, and wrote it up in post #50 here--
http://www.acousticguitarforum.com/foru ... 598&page=4
(I wouldn't take my findings as generalizations, though. And I'd suggest Audacity for the frequency measurements.)

That said, if your RK 000 is indeed lightly built, I wouldn't suggest shaving it. The wolf tone can be changed by adding a small mass to the top -- search the archives for Alan Carruth's posts on this.

Is the Epiphone an AJ500? If so and similar to mine, those are definitely lightly built and I'd not suggest shaving it either. My AJ500 has a 0.105" top and deep scallops in the Xs (1/4" tall) -- that combo is pretty unusual for a 16" factory guitar.

As for direct ideas/instructions, there just isn't much out there in the sense of "shave ___ and you'll get ___", because there are so many variables in each guitar/design. Yes, the stiffer the top+bracing, the more treble and less bass. The archives have some great info from Alan C on selective thinning of the perimeter, the effect of X-scallops, and main air and body resonances (which affect tone and are affected by the braces). There do appear to be "sweet spots" in these resonances -- I can send more info if you want.

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David Malicky

Danny : Read Todd Stock's post 5 times and then build your first guitar...!
Tom

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A person who has never made a mistake has never made anything!!!

I'd recommend Al Carruth's method. Because it's visual you can actually check your results. And no metaphors are involved! Even if you don't get the exact shape that Al goes for, you're not likely to over build. You're also not likey to underbuild.

John

Thanks to you all for your advice and the caveats. My guitar #2 is indeed an Epiphone AJ500RE (Guitar #1 is a RK ROS-647) but, if overall weight is any indication, this is not a lightly built guitar. I have succeeded in changing the resonant frequency of this guitar dramatically, mostly by carving the bridge and the sanding done mating the top to the bridge on the remount. Taking finish away from the back seems to have made the guitars sound more ringing and lively, though I keep getting fooled on this particular point by varying ambient noise levels, temperature and humidity changes.

More than one person has brought up Al Carruth and I found some interesting papers on his website (Thanks for the lead!). Would someone please tell me what his screename on this forum? My search didn't turn him up.

On the issue of how many people have built: I understand that credibility is a precious battle but I've found that conceptual ideas are often best discussed by a mix of the 'certified' professional's and the rest of us. This thing I'm asking after is alchemy after all. 'Out of the mouth's of babe's' and all that.

I'd like to hear ideas from every level and direction and good debate that can become the basis for what I need to know. I've been studying intently for the last two months and I'm a rank neophyte, yet I've learned plenty from actively doing and I'm not afraid to spell out what I think the results are. I'd like others to have no fear of doing the same.

One question that's been nagging me: What is the function of the two bottomost braces (on a x-braced steel string top) that are named 'tone bars'? They look as though they control the largest area of free spruce from uncontrolled vibrations (They don't look structural) are these the braces with which bass articulation is worked out?

Screen name for Al is "Alan Carruth"

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Yes, "lightly built" is ambiguous. I was referring to the top, back, and bracing only. Overall weight is often not correlated to those. Try measuring your top thickness at the soundhole with a micrometer or caliper to see what you're starting with. (I think) a factory 000 over 0.120" would be on the heavy side, under 0.110" on the light side. Also try measuring the 'main air', 'main top', and 'main back' frequencies.

Try "Alan Carruth" in the author field, plus words like "main air", "thinning", and "scalloped" in the keyword field.

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David Malicky

It's pretty hard to learn Al's technique from papers but they're good to read. Al has a video, which I haven't seen, but I imagine that would be a big help.

What I would really recommend, if you can swing it, is a field trip up to Al's shop when you have uncarved braced back and top ready, and maybe sides too. A bit of hands on training will go a long way. There's no reason why your fist guitar can't sound great. And you'll be learning much faster than you can on your own.

John

As you can see... There are quite a few different schools of thought... I truly believe that they are all valid -- because each one is a response to how people learn... and Different people learn different ways....

1 school is that you should just build and see how they come out... Eventually you will learn and get the hang of it...
But... What do you do with the early ones that weren't any good?

Another school of thought is that you should experiment and fiddle around -- adjusting, sanding, carving -- to see if you maybe can figure out some correlations between what you fiddle with and what happens....
But.. What do you do with the ones you wreck... which may be many or all of them? And.. How do you keep yourself from tracking off into the weeds lost?

I have to admit falling into the 2nd category.... and I will willingly admit that I am not well known for just "Leaving well enough alone"..... The way I look at it... If you go too far and wreck your "Test Mule" Guitar top... It's just an excuse to learn how to Re-top....

So.. for the record.... How many guitars have I built? 2.5 if you count a Retopped Esteban as 1/2 of a build.... I have 2 more in progress... Am I an expert.. Heck no... Do I love to fiddle around and experiment? Heck yes! Will I stop because someone smarter and more experienced than I am tells me to stop.... Nope... because that's the way I learn.... I have to learn the hard way most of the time... Do I respect those guys -- Certainly.. I have seen and played some of their instruments, and they are a testament to their exceptional skill and abilities.

I vote for try it out.... but be prepared that you could easily wreck an instrument.... I bought a junky old Fender Athena Acoustic Project that bears this out -- The previous owner scalloped the heck out of the X-brace... and the top split at the Bridge... Right across the scallop! Bet he wasn't expecting that, was he?

Thanks

John

JJ I remember how intense you were to learn every aspect of building . You even named a guitar for me and I would not call you an amature. There were 5 people that got it right from the get go. You were one . I think my point on advice , still stands. When you don't know what your doing , and this is part of any forum , advice is often given that is parroted from others and books. You can read many books and while you may learn theory , it is still experience that really teaches you . So it is hard to know what is good and what isn't till you apply it .
I do not profess to know everything and I am a voice that will admit , it is best to find a technique that will work for you , and with that being said , there are often people that spew advice without really knowing what they are talking about . So to that I will say this
" You don't know , what you don't know , till you know it ". If I ruffed a feather or two , it wasn't to upset anyone in particular but to spew a real truth , there is a lot of advice given here , and often it may not be the best advice so get a good BS detector and enjoy . I do love this forum and have supported it since the beginning. Many here started with kits and you all know I have spent many follow up hours on the phone helping . That is what we do. I will continue to do so.
I will continue to read anything Mr. Carruth will post . David LePlante is another . Rick Davis when and if he posts. I enjoy Todd and consider him a good friend.
No hard feelings on my side and I hope there are none from the other. Learn , and share info .

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

John...none of my feathers got ruffled in the slightest. Most of what I was stating was tongue-in-cheek and just being my irreverent smartass self. Thanks for the kind and unexpected words...I'm still blushing

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JJ
Napa, CA
http://www.DonohueGuitars.com

it is hard to believe that I have been doing this as long as I have. Tomorrow is an annual thing at Nazareth. Anyone that lives near here needs to visit Saturday for Martins on Main Street. They close up the town and have stages all over for jam sessions and scheduled players. It is a blast.
May you all have and keep the passion for building.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Danny,

While I still think that you'll be better served getting some sound instruction from Al Carruth. And if nothing else, reading this thread should give you some idea of how long and hard the learning curve for some of this can be if you try to figure it out for yourself.

But you might find something helpful for the guitars you're modifying at Brian Kimsey's web site. Here's a link. (Don't forget to check out his instruments under MUSIC)

http://www.bryankimsey.com/

As far as I know, Bryan doesn't build guitars- he hot rods them. I only know him through the intenet but I have analyzed the sound some of his guitars put out after he's tweaked them, and as far as I can see, they do what he says they do.

John

Back in your original post -- you talk about "Tonal Adjustment".... and you kinda imply you think that maybe each brace does something.... The sense I get is that you want to "Change" the way an instrument sounds....

My conclusion was that fooling around with Factory Instruments wasn't really worth the time vs Building from Scratch.... Yes, it's true that you might be able to change them a bit.... but it's usually only akin to an EQ adjustment... Changing the balance a bit and maybe a slight amount louder...... Say you can get 1 unit of "Better" out of it... where a Hand Made instrument may already start out 5 units of "Better" than the cheap Factory instrument....

Unfortunately, you have NO information about how stiff the top is, how stiff the bracing is, whether the Top or Braces have defects in them, how well the braces and bridge are glued, or what other EVIL lurks beneath..... and trust me on this... Factory Guitars have PLENTY of Evil lurking beneath.... This sort of information is key to getting closer to the "Potential" ... and you are more or less flying blind.... For example -- what can you honestly do about a giant, heavy, thick bridge plate? What can you do about a Top that is made of massively heavy and dense wood or Plywood filled with voids? What can you do about a Bracing pattern that isn't what you really wanted?

By the time I was done with fiddling around in those Factory Guitars.... I decided that I would much rather take a swing at "Building" better sound in at the beginning... Then, if slight adjustments needed to be made -- I would already be closer to "Right" to begin with....

The 1st one I fooled around with was an Esteban Dread... Heavy plywood top and back, ill thought out bracing pattern, etc.... Brace shaving did a little, but not really anything much beyond an EQ adjustment -- changing the balance a bit... I eventually retopped it with a Sitka top -- which was a *GIANT* change -- About 50x the change vs just fiddling around with the bracing.... Just for reference, the Plywood top I removed weighed about 1 lb... The braced Spruce top I replaced it with weighed 7-oz....

The next one I fooled with was a Cedar topped Tak... It had a GIANT thick bridge plate and MASSIVE bracing... Eventually, I was able to get it close to the Retopped Esteban.... but it took a LOT of time and a lot of fiddling and thinking and waiting and playing.... Eventually, I gave it to a friend who was learning Guitar... He loves it and plays it quite a bit.... It is definately better than a $99 Jasmine or another $299 Cedar topped Tak, but it certainly won't hold a candle against a Factory Martin D18.......

What I am getting at is that you can only go so far before you run into the wall that is "The Way it was DESIGNED"....

Thanks

John

>>>[quote="truckjohn"]Back in your original post -- you talk about "Tonal Adjustment".... and you kinda imply you think that maybe each brace does something.... The sense I get is that you want to "Change" the way an instrument sounds....>>>

My guitars are both insulted . Neither is nearly as bad as a Takamine or an Esteban, neither is a 'cheap' guitar. I chose the guitars I did because they are supposed to be very well thought of, copies (or close to it in the Epiphone's case) of time-honored designs (Standard bracing patterns, or so I've read) and they're both pretty good instruments that only need some 'tuning' to bring them up to their better potential. The Recording King in particular, which has the wolf tone, is a very interesting sounding guitar outside of that harmonic problem (Which is fairly light anyway. It's a doubling up of the harmonics at B through E).

My interest in this is to understand the subtleties of the bracing and what kinds of changes lead to what kind of result. I've been reading through Alan Carruth's post's since yesterday and I'm sitting here taping a quarter to different parts of the bridge and top, listening to what added weight does to the sound. Interesting stuff (For me at least).

>>>My conclusion was that fooling around with Factory Instruments wasn't really worth the time vs Building from Scratch.... Yes, it's true that you might be able to change them a bit.... but it's usually only akin to an EQ adjustment... Changing the balance a bit and maybe a slight amount louder...... Say you can get 1 unit of "Better" out of it... where a Hand Made instrument may already start out 5 units of "Better" than the cheap Factory instrument....<<<<

I understand what you're trying to tell me here and appreciate that building is going to be far more instructive, I just want to have some basis to start from that satisfies my curiosity.

>>>>>Unfortunately, you have NO information about how stiff the top is, how stiff the bracing is, whether the Top or Braces have defects in them, how well the braces and bridge are glued, or what other EVIL lurks beneath..... and trust me on this... Factory Guitars have PLENTY of Evil lurking beneath.... This sort of information is key to getting closer to the "Potential" ... and you are more or less flying blind.... For example -- what can you honestly do about a giant, heavy, thick bridge plate? What can you do about a Top that is made of massively heavy and dense wood or Plywood filled with voids? What can you do about a Bracing pattern that isn't what you really wanted?<<<<

Nothing I can do about the bracing patterns but the evil beneath? That sounds interesting. Maybe I should take the back off and have a look?
I'll definitely have a feel around for the size or the bridgeplates.

That's great! Adding weight is a perfect way to get started learning about why a guitar sounds the way it does. One of Alan's techniques is to use "poster putty" for the weight.

Adding mass lowers the frequency of modes that are moving where the added weight is. Shaving the braces basically does the same thing but it's hard to put the shavings back.

Listening to the effect is the place to start. If you want to get more technical you can slacken the strings, tap the guitar at the bridge, record, the sound, and then use a simple free recording program like audacity to show you the frequency response. This is especially useful when looking at the low end. Try with and without the mass and see if you can see anything change. It's a good way to tame the wolf note that you mentioned.


There are also ways of looking at the actual sound of the guitar and how the mass effects it but it's much harder to do that well.

It's sounds like your off to a great start.

John

The thing you have to realize about the guitar is that the designs we have are very highly evolved. This means, essentially, that if you do a reasonably good job of building and use decent materials, you'll end up with something that's objectively very nearly as good as the best. The trick is that, when you're dealing with such good designs, small differences become very important. The differences beween a WalMart box and the best guitar you ever heard may be 'small' in terms of measurements, but they certainly matter.

Another thing you need to understand is that the guitar is a whole thing, not just an assembly of parts. We often talk about how thinning a certain are of the top might bring up the bass, or whatever, but it's more complicated than that. For instance, if you wanted to get more treble you could:
1) enlarge the soundhole,
2) add a port,
3) make the top thicker,
4) make the bracing heavier and the top thinner,
5) make the body shallower,
6) use a smaller pattern,
7) use a different wood on the B&S,
8) use a smaller or lighter bridge,
9) use a longer bridge,
10) use scalloped bracing (see Proulx),
11) use tapered bracing (see Carruth),
12) thin the 'wings' of the top outward from the bridge ends,
13) etc.
Each of these things will get you more treble in some sense, but each one will effect other aspects of the sound as well. What do you mean when you say 'more treble', and how much do you want?

My opinion, FWIW, is that the 'best' results are gotten from achieving a sort of balance, so that everything works together. Again, the best designs have been arrived at through a lot of trial and error so that they get you pretty close to that more or less automatically. From there it's all fine tuning, and most of the time 'fine tuning' is _all_ you can do once the thing is together. Again, that's not to minimize fine tuning: it's often the difference between 'adequate' and 'great'. But, given 'the evils that lurk beneath', as has been said, ther'es only so much you can do most of the time. If the guitar is not at least 'pretty good' to begin with, you aren't likely to get it to 'great'.

You also have to remember what Dante said: "The closer a thing is to perfection, the more it feels of pleasure or of pain". Great guitars are often balanced on the head of a pin, so to speak, and even very good ones are more likely to be harmed by small interventions than helped. Adjustments that barely change lower-grade instruments would as likely as not be ham-handed on 'better' ones. For all these reasons, then, it's hard to learn much by modifying a less expensive instrument.

David Malicky wrote earlier in this thread:
>>>As a learning exercise, I did a similar experiment on a heavily-built import 000. I did find it valuable, and wrote it up in post #50 here--
http://www.acousticguitarforum.com/foru ... 598&page=4
(I wouldn't take my findings as generalizations, though. And I'd suggest Audacity for the frequency measurements.)

That said, if your RK 000 is indeed lightly built, I wouldn't suggest shaving it. The wolf tone can be changed by adding a small mass to the top -- search the archives for Alan Carruth's posts on this.

Is the Epiphone an AJ500? If so and similar to mine, those are definitely lightly built and I'd not suggest shaving it either. My AJ500 has a 0.105" top and deep scallops in the Xs (1/4" tall) -- that combo is pretty unusual for a 16" factory guitar.

As for direct ideas/instructions, there just isn't much out there in the sense of "shave ___ and you'll get ___", because there are so many variables in each guitar/design. Yes, the stiffer the top+bracing, the more treble and less bass. The archives have some great info from Alan C on selective thinning of the perimeter, the effect of X-scallops, and main air and body resonances (which affect tone and are affected by the braces). There do appear to be "sweet spots" in these resonances -- I can send more info if you want.[/quote]

I saw that thread and it was the genesis of my getting my hands inside the guitars, so thanks for the inspiration (I think ). Good stuff.

How did you get the camera in there with the strings on?