Help with Shaving Braces

[t_rockford]

I see people talk about shaving braces to improve the overall guitar tone. Does anyone know where there is detailed instructions on how to approach such a task? I have a "beater" which is not worth much, and would like to try to improve the sound.

I know that trying to do this with an assembled guitar is like building a ship in a bottle, but I can't seem to keep myself from tinkering.

Any help would be greatly appreciated, even if it's to tell me STOP don't do it

[wildbill1962]

I cant wait to see the replies, I have been thinking about trying the same thing on one of mine.

[gitnoob]

This should give you a good start:
http://www.acousticguitarforum.com/f...4&postcount=50

[t_rockford]

Is this what you did on your T170? Did you shave the lower front brace?

Did you use the tuner or the o-scope approach?

Thanks for your help.

[gitnoob]

I took tap tones of a few guitars by recording in Audacity and using the spectral analysis feature to determine the dominant frequency.

When shaving, I concentrated on the lower legs of the X, since that seems to be a fairly active area of the top.

I figured the bridge plate, bridge, and finger braces added a lot of stiffness, so I primarily concentrated on lowering the legs of the X near those braces.

A few additional guiding principals:

• Stiffness increases with the cube of the height of brace.
• Stiffness increases linearly with the width of a brace.
• Shaving near the center of a brace will have a greater effect than shaving near the ends.

These guidelines can be used to help determine what sort of shaving might have large effects vs "fine tuning" effects.

[t_rockford]

Thanks for your input, if I decide to tackle the task, I will try to document my steps. I have a small set of planes, but they are all flat, so I may have to modify one for the correct radius.

Thanks again,

t_rockford

[mderek]

Check out Roger Siminoff's book "The Art of Tap Tuning" I re-read that book regulary and the latest edition has a DVD included with it. His site www.siminoff.net has some cool downloads on Lloyd Loar who was a visionary in the field of acoustics and "tuning" braces and tops for Gibson in the early 20's.

[martinedwards]

IMHO the science behind a first reading of Mr Siminoff's book is fundamentally flawed.

shaving the braces to get the top to a resonant frequency AFTER THE TOP IS FITTED, BOUND & FINISHED is the only way to have any chance to get a top resonating at a chosen frequency.

during construction, when the top is unattached, it is bigger than the rim, hasn't been finish sanded, hasn't been varnished or had a bridge attached.

if you get a free hanging braced top to tap at a specific frequency, will it still resonate at that same frequency once the top is held all round the edge by a rim (which obviously is smaller than the top), then been sanded, had varnish and maybe a scratchplate added, a bridge added, holes drilled for bridge pins, then the pins and strings added.........?

not

a

chance.

pre tuning a top will get it in the ballpark, but every piece of wood is different, as is every bone pin and saddle.

If you want a top to resonate at a specific frequency then after the fact is the ONLY way you are going to do this.

but why do you want the top tuned to a specific frequency ? isn't it the range of overtones that makes a guitar sound good? I don't WANT an instrument that is loud and resonant when I play a C but less so playing any other note.

so, will carving braces "improve" the tone?

maybe, up to a point.

factory made guitars will most likely be built slightly heavy. so shaving things inside will help by lightening the top. you'll get more volume and bass.

until you take too much off and the top collapses

do it on a beater that you don't mind killing, but PLEASE don't try it on anything you'll miss!!

[gitnoob]

Originally Posted by martinedwards

why do you want the top tuned to a specific frequency ? isn't it the range of overtones that makes a guitar sound good? I don't WANT an instrument that is loud and resonant when I play a C but less so playing any other note.

I think Somogyi talks about tuning the top to the back. How you do this is still a mystery to me, though. The back will always be more stiff than the top, so he's obviously not suggesting that the primary modes of the back and top be in phase....

so, will carving braces "improve" the tone?

maybe, up to a point.

factory made guitars will most likely be built slightly heavy. so shaving things inside will help by lightening the top. you'll get more volume and bass.

That's been my experience -- shaving braces is a pretty crude but effective way of increasing bass and volume.

[Tone Gopher]

Originally Posted by gitnoob

I think Somogyi talks about tuning the top to the back. How you do this is still a mystery to me, though. The back will always be more stiff than the top, so he's obviously not suggesting that the primary modes of the back and top be in phase....

That's been my experience -- shaving braces is a pretty crude but effective way of increasing bass and volume.

Shaving the braces is exactly what Somogyi did on one of my guitars 20+ years ago. In the hands of someone who knows their business, it is an effective way of optimizing a top's response. By adjusting the balance of the instrument, he made a great guitar even better.

As I understand his approach to tuning the top to the back, it is a matter of tuning the tap tone pitch interval.

Regarding stability, I still have that guitar and it has been strung with medium gauge strings for its entire life with no indication of excessive bellying or other deleterious maladies.

[martinedwards]

Originally Posted by Tone Gopher

Regarding stability, I still have that guitar and it has been strung with medium gauge strings for its entire life with no indication of excessive bellying or other deleterious maladies.

obviously it wasn't shaved too far!!

factory built guitars are built so that the can withstand all the abuse that the worst owner can throw at 'em. the reason that handmades are lighter built are that if you are going to drop handmade money on a guitar, you're going to look after it, right?