Brace tuning

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Brace tuning

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theodoropoulos

Posts: 10
Joined: Mar. 23 2014

Brace tuning

i am confused by the bass bars in violins..and what i mean??i see that we add mass in a tone bar to get bass in sound....
So when i have a tone bar and want to add bass in sound should i make it tall in the middle and add more mass this way,or am i saying nonsense??
I feel that less mass=bass in sound....
but i have stucked with violin bass bars....
any lights????

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 26 2014 11:54:22

bernd

Posts: 680
Joined: Feb. 15 2004

RE: Brace tuning (in reply to theodoropoulos)

As not being a violonist, I assume that bracing bars´ excercise is at first bringing stability to the top. That´s my statement as a guitarist. I´m sure the luthiers on this forum can give a much more qualified statement.

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REPORT THIS POST AS INAPPROPRIATE | Date Sep. 26 2014 13:04:21

Joan Maher

Posts: 213
Joined: Dec. 3 2013

RE: Brace tuning (in reply to theodoropoulos)

Wrong Foro.. it's for Flamenco guitars try here https://www.violins.ca/forums/

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Joan Josep Maher

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 26 2014 14:28:21

theodoropoulos

Posts: 10
Joined: Mar. 23 2014

RE: Brace tuning (in reply to Joan Maher)

wrong answer Joan!
i know what i am writing and saying....I build guitars and made a parallesm with violins...
and to be more clear:
if i add mass to a brace does the pitch lowers or gets higher?

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 26 2014 16:24:51

estebanana

Posts: 9370
Joined: Oct. 16 2009

RE: Brace tuning (in reply to theodoropoulos)

Tall thin braces = higher
Low wide braces - lower

Is it fun to troll? I mean in fishing, trolling means to let out a lot of line with bait and pull it until you catch fish? You line fishing by trolling or with bobber and worm?

I guess it depend if you want catch the trouts, those eels or the flounders.

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REPORT THIS POST AS INAPPROPRIATE | Date Sep. 26 2014 21:04:15

Jeff Highland

Posts: 401
Joined: Mar. 5 2010
From: Caves Beach Australia

RE: Brace tuning (in reply to theodoropoulos)

It's a simple question for which there is not a simple answer.
You need to take account of both the mass AND the stiffness at the same time.
Looking at a brace or tone bar in isolation, not glued to a soundboard.
Basic marimba bar tuning
-remove material from the middle you lower the stiffness in the centre and lower the pitch
-remove material from the ends you lower the mass at the ends and raise the pitch
-add mass to the centre, lower the pitch

Try it yourself with a bar of wood, hold it in your fingers at about 25% from the ends, adjust position till you get a clear note tapping it in the centre. record the pitch.
Now add some mass to the centre, by taping on a coin, record pitch
Now take off the mass and scallop the centre etc

But none of this is a simple predictor of how you will affect the voicing of a guitar

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 26 2014 21:08:49

estebanana

Posts: 9370
Joined: Oct. 16 2009

RE: Brace tuning (in reply to theodoropoulos)

I still don't understand the first question. It's not clear what he's asking about. One reason is that there is no context relating the question to a specific part of the guitar. The violin bass bar is a different kind of brace than the transverse braces in guitars. One main reason is that it is not coupled to the sides.

Tuning braces> It's not as simple as just removing material from middle or ends to raise of lower the pitch of the bar stopped at a node. The weight and stiffness of the braces relative to the thickness of and flexibility of the back or top plate is more important.

Issue is not tuning the braces, that is a illusion. What is really happening is that when braces are cut down after being glued to a top of back weight and stiffness are being redistributed and it effects flexibility and mass of the completed structure.

I think tuning braces is a dead end, weight and stiffness is key. There are four main sub assemblies, Top, Back, Ribs, Neck...each needs to be in target stiffnesses and weights, like why stop to tune braces? There's already too much work to do.

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REPORT THIS POST AS INAPPROPRIATE | Date Sep. 26 2014 22:42:57

Jeff Highland

Posts: 401
Joined: Mar. 5 2010
From: Caves Beach Australia

RE: Brace tuning (in reply to theodoropoulos)

Agreed 100% Estebanana ,Tuning of individual braces was advocated by Siminoff and adopted by Bogdanovich, but I consider it BS.

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 1:17:01

theodoropoulos

Posts: 10
Joined: Mar. 23 2014

RE: Brace tuning (in reply to Jeff Highland)

ι have the ART OF TAP TUNING of Siminoff and when he removes wood from the end of the braces the pitch lowers and that is the opossite of what you suggest(if i understand correct in isolated brace)
thats the tricky part when you glue to tje soundboard.The brace's stifness alters and i think you cannot predect..to be honest i have never seen removing wood and raise the pitch.....
the connection between mass and stifness is very correct in my opinion as you said...
Forgive me if i confused you with violins..just forget it....

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 2:26:34

Jeff Highland

Posts: 401
Joined: Mar. 5 2010
From: Caves Beach Australia

RE: Brace tuning (in reply to theodoropoulos)

The biggest improvement you will get is to remove the mass of any of Simminof's books from your bookshelf.

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 3:18:19

theodoropoulos

Posts: 10
Joined: Mar. 23 2014

RE: Brace tuning (in reply to Jeff Highland)

why you say that???

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 3:25:31

Jeff Highland

Posts: 401
Joined: Mar. 5 2010
From: Caves Beach Australia

RE: Brace tuning (in reply to theodoropoulos)

Because they are full of misinformation
Siminoff has been great at self promotion but not at accuracy

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 3:27:50

Jeff Highland

Posts: 401
Joined: Mar. 5 2010
From: Caves Beach Australia

RE: Brace tuning (in reply to theodoropoulos)

Removing wood from either the centre or to a lesser extent the ends of a brace glued in place to a soundboard attached to the rims will lower the pitch Not because you have reduced the mass, but because you have reduced the stiffness.

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 3:44:37

estebanana

Posts: 9370
Joined: Oct. 16 2009

RE: Brace tuning (in reply to Jeff Highland)

quote:

The biggest improvement you will get is to remove the mass of any of Simminof's books from your bookshelf.

That was funny.

The other day you mentioned Kasha design as poor design. I have know makers who've actually made good flamencos with Kasha bracing. I think it does make a stiff middle under the bridge, but leaves the areas out side the wings of the bridge more open. The areas the Kasha design seems oy brace are not super remote from where a five fan under the bridge design would hit. I can see how you could make it work with a thin top and the right bridge.

The part of the Kasha system I don't think is good intentionally putting weights in the headstock to create whatever they called it an "intertial stop" or some off term. But mechanically if you did the Kasha bracing I cant see why it is much different than variations on lattice bracing which stiffen the center and radiate out. It's a mechanical thing not a theoretical thing. If you stiffen the top with some braces it will do something, but when Kasha tried to explain with a formula that leas with acoustics it over complicates some think that is real simple in concept.

They used terms like Bridge Impedance, meaning the bridge cancels out some string energy and tried to fix this by making a funny looking bridge. Why not look at the bridge as another kind of brace?

So I think the Kasha braces, not too big, and a thin top a Spanish bridge would make a flamenco guitar, but why bother to explain it with maths? Or why bother when fan braces work even better and you don't l have make bunch of braces that look like fish bones.

What I think is Kasha and Richard Schneider liked going fishing and they ate a big fat sea bass and looked at the bones left over as they pulled the delicious meat off the skeleton. They they said OK lets make some guitar braces that look like this fish skeleton and come up with a theory that makes it sound really super duper. And they did, and nobody plays them anymore.

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REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 4:03:20

Jeff Highland

Posts: 401
Joined: Mar. 5 2010
From: Caves Beach Australia

RE: Brace tuning (in reply to theodoropoulos)

Not so much the final implementation of what we know as Kasha Bracing but the concept that Kasha as a scientist (physical Chemist) thought he could redesign the guitar by application of scientific principles alone.
That seems pretty arrogant to me.
I don't particularly like the discontinuity of the bracing at the bridge area.
The was a similar radial bracing desigh by an Australian Luthier whose name I cant recall at around the same time

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 5:30:54

theodoropoulos

Posts: 10
Joined: Mar. 23 2014

RE: Brace tuning (in reply to Jeff Highland)

i think that Kasha tries to make a sculpture under a top rather than pay attention to distribution of resonances....

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 5:55:14

Anders Eliasson

Posts: 5780
Joined: Oct. 18 2006

RE: Brace tuning (in reply to theodoropoulos)

why do you want to learn about guitar building talking about violins?
I build both, and besides being made out of wood, having a box and a stick with strings on, IMHO, they have very little in common.

I think Siminoff designed the ovation guitar? If thats true, it explains everything.

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REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 6:53:36

theodoropoulos

Posts: 10
Joined: Mar. 23 2014

RE: Brace tuning (in reply to Anders Eliasson)

yes you are correct about violins...
hmmm but in mandolins for example???why is there a bass bar???
violin was an example my friend to show if mass=more bass...ok?
and what about ovation?what do you mean?
ovation is bad??i just ask.....i also dislike non wood back guitars...

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 9:19:37

Tom Blackshear

Posts: 2304
Joined: Apr. 15 2008

RE: Brace tuning (in reply to theodoropoulos)

The way I tune the voice in a guitar is first, I make sure everything in the building process is done and balanced as correct as it can be, and then for the final tuning, I adjust the bracing by using a slight sanding-polishing method to bring each brace into a synergistic relation with the other braces to finalize and create total harmony, as best I can.

https://www.youtube.com/channel/UCn_ftUZWUdp9OzO-aOAFRUg

This final tuning helps set the articulation and top tension, as well.

Also, the top tuning can be adjusted up or down in its key, to a certain extent, with how the braces are treated in the adjustment phase. But there will come a time when it's better to stop the tuning process, or you will lose the gain you have created.

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REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 11:36:55

Tom Blackshear

Posts: 2304
Joined: Apr. 15 2008

RE: Brace tuning (in reply to Anders Eliasson)

I think Siminoff designed the ovation guitar? If thats true, it explains everything.
[/quote]

Anders,

I think Charlie Kaman designed the Ovation guitar.

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Tom Blackshear Guitar maker

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 11:54:35

theodoropoulos

Posts: 10
Joined: Mar. 23 2014

RE: Brace tuning (in reply to Tom Blackshear)

by the way ,
my soundboard weight is 140 gr...
is that ok for a flamenco guitar?
i used cedar top and cedar of lebanon braces...

REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 13:20:26

Tom Blackshear

Posts: 2304
Joined: Apr. 15 2008

RE: Brace tuning (in reply to theodoropoulos)

The width between lines does not matter but how the top is braced. Most older masters are thin toward the center and grow wider toward the outside edge.

A good norm is about 1 MM between lines, and a little thinner toward the middle.

The weight should be determined by the bracing design.

Fewer braces; thicker the top. More bracing should have a thinner top.

The louder the sound is sometimes adjusted by using a thinner brace.

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REPORT THIS POST AS INAPPROPRIATE | Date Sep. 27 2014 13:34:05