Official Luthiers Forum!
http://w-ww.luthiersforum.com/forum/

Underbraced Guitar and its tap tone signs, etc
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=16636		 Page 1 of 2
Author:  Frei [ Fri Mar 28, 2008 10:29 pm ]
Post subject:  Underbraced Guitar and its tap tone signs, etc
Ok, reading about a guitar that doesnt sound good (right now) got me thinking,- What will an underbraced guitar sound like right off the bat, and just the top tap tones? I think I may have underbraced, as I was watching the Mayes tape when I was tap-tuning, and I was not shy about taking wood off. My first top really has a bassey feel to it (unusable anyway). Capathian top and Engleman braces.

Has anyone ever got too chisel happy with the braces and took too much off? beehive What are the sound signs?
Author:  grumpy [ Fri Mar 28, 2008 10:55 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
What are the sound signs?

Mud.

Lack of focus.

Lack of note separation.
Author:  Frei [ Fri Mar 28, 2008 11:28 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
Ok, and how about just the top plate with braces? What are the signs so they can be taken off and redone? Thanks
Author:  grumpy [ Sat Mar 29, 2008 10:31 am ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
??
Author:  Rick Turner [ Sat Mar 29, 2008 10:51 am ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
Engelmann would not be my choice for brace stock...
Author:  grumpy [ Sat Mar 29, 2008 10:53 am ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
I've built with lots of Engelmann braces. It varies a lot, but the good stuff is very good.
Author:  ClintB [ Sat Mar 29, 2008 12:27 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
grumpy wrote:
??



I think he's asking if there's anyway he can tell if it's too thin/light before assembling a muddy, unfocused instrument.
Author:  grumpy [ Sat Mar 29, 2008 1:03 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
'sperience is all it takes. It's a fine line once you reach it, and the only way to find it is to walk up to it, then cross it to see what's over the other side.
Author:  Frei [ Sat Mar 29, 2008 1:16 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
Rgr that, thanks

I used some engleman brace stock I had on the bad top I did. I got some cheap carpathian tops, and blew the first rossette. I braced it up for practice on the Mayes video. It really helped, but either I did really really good, or it may be a bit unerbraced. I still really like the tap-tone. Its wall art now. Eat Drink
Author:  grumpy [ Sat Mar 29, 2008 1:30 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
Having never seen the videos, nor played or heard a Mayes guitar, I have no idea what you're speaking of in terms on where you are.

Photos?
Author:  John Mayes [ Sat Mar 29, 2008 4:26 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
Yeah if you can post a picture. While that will only give us a small clue as to what is going on with the top it will help. We still won't know the stiffness, ect of the parts/top you used it will, however, give some ideas.

Really the only way to tell for certain is as Mario says...experience. Even if the first end result is "failure" you'll learn a great deal. I'd say any luthier who has built a considerable amount has had his/her fair share of failures in one way or another.... I certainly have.
Author:  Christ Kacoyannakis [ Sat Mar 29, 2008 4:38 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
Lacking years of experience or the making of hundreds of guitars, is there some way to measure the relative stiffness of a given top? I thought of sanding every top down to a predetermined thickness, and then making some sort of jig to hold the top and putting on a specific weight to see how much the top flexed under that load with a dial caliper.
Author:  KenH [ Sat Mar 29, 2008 4:56 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
there wasw a long and heated discussion on here a while back about deflection testing, which is what you are talking about. If you do a search for "deflection testing" you should be able to find it.

I met with another noobie in my shop the other day and he brought over one of his tops that he was ready to put the braces on. It just so happened that I had a top in the same condition and I let him test bend mine Vs test bending his. His eyes were opened and he now knows what he is looking for. Until someone actually lets you hold one in your hands and shows you what it shoudl feel like, I dont think any amount of book learning can help. Once you know the feel, you will knoe it forever.

If you think the top is too floppy and it is between .100 and .120, then add a little height to your braces to make up for it.

If this top is already attached to the guitar, you can always go in and add a "mario's magic tone bar" to stiffen up the top. You can find that information on his web site or maybe he will be kind enough to post the link here.

This tone bar will help give volume and balance out the tone some.. experimentation is the key to making it work.
Author:  Frei [ Sat Mar 29, 2008 5:16 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
Yes I suppose you could add splices of spruce if its really a dog, pics coming tomorrow/ 8-)
Author:  Frei [ Sat Mar 29, 2008 7:16 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
Ok here was my first attempt, its close to my second. The finger braces seem small. Its about 1.08 thick, Carpathian top. Nice tap tone to it. nice little ring.
Yes, a bit sloppy, but other than that? (I can get a dread size just barely on it, its about 1" longer than dred size.)

Image

Image
Author:  Alexandru Marian [ Sat Mar 29, 2008 7:34 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
First, you need to avoid abrupt changes in height. There is too much a difference between the peaks and the valleys. The shift has to be much smoother.
Since you can't add the wood back, you can shave a bit off those peaks, make them less sharp. Considering the wood removed after you will sand them to a smoother profile, you'll probably need to use very light strings on this guitar.

And maybe redo the bridge plate.
Author:  grumpy [ Sat Mar 29, 2008 8:35 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
I don';t so much mind the abruptness of the peaks, but wow, it's rough in there. You must try to make the scallops smooth, the transitions sooth, etc... You're creating lumps and bumps all along the braces, creating nodes and semi nodes and just plain creating trouble all over the place. So, if you can, reach in there and smooth those puppies. Or not. But the next one, please.....

Now, about that bridge plate! What's that all about?!? we have issues.... <g>

Here's what i think is your biggest issue with how it sounds. You've missed refining the details. it's the details that count. The quality of the joinery, the quality of the fit, the little things. Seeing the above, I ca only imagine the saddle's fit, the nut's fit, the tuners, bridge pins, the top and back to the ribs, etc... All of those add up to make the whole of the guitar work as a unit.

Keep this one as a test mule to try things on as you gain experience, and start a new one. They'll get better, and quickly.
Author:  Alan Carruth [ Sat Mar 29, 2008 8:39 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
In theory those of us with a lot of experience could publish some data on things like deflection tests and tap tones that could be a big help to the newbies. In practice there are a couple of problems with that. One of the big ones is many of us haven'e got that sort of data, at least, not in any form that can be written down. A lot of us work by 'feel'.

Back in the old days, when you learned to cook, you used measurements like 'butter the size of a small egg' and 'two hands full of flour'. and 'enough water to get the right consistency'. The only way you could learn to cook well was to get together with a good cook who could show you. Then Fanny Farmer published a book that gave recipies in terms of 'cups' of flour and 'tablespoons' of baking powder, and she told you how many tablespoons were in a cup, so you could make up your own set of standard measures in the right proportions. Then, of course, they fixed all that stuff in terms of cubic inches and what not, and started selling the things in stores. Now we all think of cooking on those terms, and look up written recipies with standard measures on the 'web or trade them with folks we know. Eventually something like this is going to come along in guitar making. It already has, to some extent, in the videos and books you can get, and there are more coming.

Will that take all the 'art' out of it? No; good cooking is still an art; what Fanny gave us was less bad cooking. Will it remove the 'mystery'? Well, probably some of it. Personally, I can do without the mystery of wondering whether the guitar I'm putting so much time and money into is going to be a dud.
Author:  Frei [ Sat Mar 29, 2008 9:08 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
Ok, thanks, this was just a test top. My second was a bit better, and yes, I need a plane for the braces. This top was just a wild hair: Ive got an unusable top and engleman brace wood, the DVD is coming, so why not make the best of it?

The bridge plate (and upper bout brace) is paint stir sticks, just for refrence. Again, this was the test top, so I didnt go into smothing things out, but I guess thats still good practice.... [xx(]

I was carving these for the initial sound I was getting. I just think I took it too far.

But all in all it does confirm that Im a bit too chisel happy, which is good to know. I may just go for the next box with that in mind. :geek:

As far as fit and finish, my braces get the feeler gauge blade treatment, I slide a very thin blades between the brace and top until I get rediculusly low blade. (.0032 I think) I dont glue braces off of the 100 grit dish paper :ugeek: Backsplice and bridge plate are sanded to the top/back respectively, so tis a tight joint indeed.
Author:  Frei [ Sat Mar 29, 2008 9:18 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
One think I am doing is making my brace wood less than 5/16. In between 5/16 and 1/4. Should I stick with 5/16 for a newbie? I hear so many guitars are overbraced.
Author:  Jody [ Sun Mar 30, 2008 5:38 am ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
I would stick with the 5/16 and control stiffness by adjusting the height of the brace. if the braces are too narrow they can show through the top later ... Jody
Author:  Jody [ Sun Mar 30, 2008 6:12 am ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
Thanks ... Jody
Author:  Frei [ Sun Mar 30, 2008 10:31 am ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
Well, at least now I have an idea of what the tap tone is on an underbraced guitar. Im also glad I signed up for Kent Everett top voicing class. The thing is, the sitka top I have for the class seems very floppy compared to the carpathian.[:Y:]
Author:  Laurent Brondel [ Sun Mar 30, 2008 12:19 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
ToddStock wrote:
1/4" bracing is very, very common - gets used all the time on dreadnoughts and SJs. I don't believe the issue of brace width has as much to do with 'telegraphing' as with getting adequate glue area to keep the loads on the glue joint at a reasonable level.


I agree. Telegraphing would seem to be a function of the top being too thin under the braces.
As an aside I use 1/4" braces for all guitars, except bigger than OM/000 type models where the x-braces are around .310" (5/16"). Tone bars are still 1/4", and finger braces around .200". I feel the 5/16" x-braces give me more control when tuning the top (it is tempting to over-carve thinner stock), and more confidence in the glue joint as well.

Frei wrote:
The thing is, the sitka top I have for the class seems very floppy compared to the carpathian.

Are they the same exact thickness?
Author:  Frei [ Sun Mar 30, 2008 12:25 pm ]
Post subject:  Re: Underbraced Guitar and its tap tone signs, etc
No, the sitka is thicker. It was a grade B $15.00 LMI deal for a class.
Page 1 of 2 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/