X bracing versus conventional bracing F4 top

[Kennyz55]

I bought a Smith Creek F4 top to replace the broken top on my Savannah mandolin. I was thinking of using X bracing but I'm not sure how to do x bracing and wondering what the advantage would be. Thanks in advance for your help.

[Pete Jenner]

There is a good tutorial here by Peter Coombe. It's for an oval hole mandolin but the principle is the same for an F hole mandolin. Note that Peter crosses the braces further towards the neck on the F holes. It can take quite a while to get a good fit. Make sure you don't rush it. I have noticed that some violin makers glue little temporary blocks alongside the braces while chalk fitting bass bars to keep them properly aligned.

[sunburst]

I have noticed that some violin makers glue little temporary blocks alongside the braces while chalk fitting bass bars to keep them properly aligned.

Hint: some mandolin makers do that too.

[Pete Jenner]

Hint: some mandolin makers do that too.

I was hoping they might. I think I'll take that hint.

[Lefty Luthier]

X bracing will certainly work but it is very difficult to adjust tuning compared to parallel tone bars. I use x bracing on the occasional oval hole A-style but even there it takes quite a bit of careful trimming to get close to correct tuning.

[barry k]

How in the world would one use parallel tone bars on an oval hole? Is it possible? The top on an oval hole mandolin is unstable anyway, I would suspect that only X bracing would adequatly support the tension, especially a hybrid. On my flat tops, they are Braced like a guitar but with carbon fiber braces underneath where the bridge sits...

[Pete Jenner]

I'm of the opinion that top bracing is not entirely necessary on a mandolin but I'm too gutless to prove it.
I may however try out a balsa X brace although the brace probably doesn't contribute enough mass to give a significant result.

[barry k]

Pete....try it on an oval hole....You want my predictions of what would happen?....BK

[Pete Jenner]

I can guess Barry.

[Kennyz55]

Pete
I read Peter Coombe's article and the accompanying Free Plate Tuning of Mandolins. My head didn't explode but it was really close. I am a former math and computer teacher. The x bracing part was very helpful. Thanks to everyone for the help and answers to beginners questions.

[robert.najlis]

oh, when I read conventional bracing for an oval hole, I had assumed a transverse brace, like in the old Gibsons from the teens and twenties...

[Willie Poole]

About 12-13 years ago at a festival in Florida I was having a nice talk with Charlie Louvin and the subject of Ira`s F-4 came up and one of Charlies friends told me that Ira was a good luthier and that he had replaced the X bracing in his mandolin and installed tone bars like the F holed mandolins have...NOW, That is just something that I heard, no proof so don`t read a lot into it, but if tone bars were installed they probably wouldn`t make a whole lot of difference in the sound would it?

I wish I had the true answer to this myself because Ira`s F-4 had a little different sound than most F-4`s

Willie

[jim simpson]

I x-braced an oval hole project using a small washer alongside of the brace. By holding the pencil against the bottom of the washer's hole, I was able to get an accurate shape. I'm pretty sure I got that tip from here on the cafe. I'm not sure if I explained it very well, it seemed pretty simple to do.

[Bernie Daniel]

About 12-13 years ago at a festival in Florida I was having a nice talk with Charlie Louvin and the subject of Ira`s F-4 came up and one of Charlies friends told me that Ira was a good luthier and that he had replaced the X bracing in his mandolin and installed tone bars like the F holed mandolins have...NOW, That is just something that I heard, no proof so don`t read a lot into it, but if tone bars were installed they probably wouldn`t make a whole lot of difference in the sound would it?

I wish I had the true answer to this myself because Ira`s F-4 had a little different sound than most F-4`s

Willie

Maybe you meant to say that he replaced the transverse brace in his F-4 with tone bars?

If this was Ira's Gibson F-4 mandolin it should not have had X-bracing to start with -- should have come from Kalamazoo with a single transverse brace?

[barry k]

Willie when did Charlies mandolin developed that particular tone you describe, before or after the alteration of the tone bars?..if it didnt sound like a typical f4 what did it sound like ? F5?.....did he (Charlie) change out the neck also to the longer scale?......if he didn't I wonder how parallel bars would work considering the bridge placement?

[Willie Poole]

I used the term X bracing incorrectly, I heard he removed the braces that originally were installed...

Barry, I just remember the sound was sort of in between an oval hole and an FF hole mandolin, I am not sure when he changed the mandolin or even if he really did, I am just repeating what I have heard....I am not sure about the neck length, I will have to try and find some pictures of Ira`s mandolin to see if it is the long neck.....I just know that it had a nice sound and unlike all of the other oval hole mandolins that I have heard.....also Gibson made F-7`s and some F-12`s with short necks and they had parallel tone bars so bridge placement shouldn`t have changed anything

Willie

[Rob Grant]

I braced an f4 like this years ago ("mongrel/hybrid"<G>). Not bad tone and projection for an oval hole...

[StuartGold]

This is a very interesting thread for me. I'm still in the middle of building an F4/5 oval hole hybrid and have been going back and forth with my design for the bracing. I was all set to go with "X" bracing and then I stumbled across some Youtube videos (https://www.youtube.com/watch?v=agr8AuU2rRc ,https://www.youtube.com/watch?v=EQ4HQ3KBth8 , https://www.youtube.com/watch?v=JAi7CgBamlA ) of Jaroslav Prucha's work in Czechoslovakia (http://en.pruchabanjos.cz/mandolin.php?mandolin=f4)

To me these were great sounding mandolins. I wrote to him and he told me that he uses a standard F4 single transverse brace just under the soundhole and basically Loar specs for the graduations.

Two weeks ago at the Grass Valley Bluegrass festival I had the occasion to speak in depth with Roger Siminoff about exactly this and he told me that in his opinion and experience the top with Loar graduation specs had more than enough strength to hold up to the pressure of the strings and that the transverse brace was used primarily to keep the edges of the sound hole from cracking. In rogers opinion, he thought that the
"X" bracing for an oval was great for a guitar but the mandolin didn't really distribute vibrations and resonance like a guitar so that it did not add anything to the mix and wasn't necessary.

I am now leaning strongly toward the transverse brace for my F4/5 hybrid. time will tell.

[Pete Jenner]

I don't often agree with Roger but I think he has a point about the purpose of the Gibson transverse brace.

[barry k]

Someone needs to tell Steve Gilchrist that X bracing doesn't work for mandolins...it won't be me though...

[Bernie Daniel]

This is a very interesting thread for me. I'm still in the middle of building an F4/5 oval hole hybrid and have been going back and forth with my design for the bracing. I was all set to go with "X" bracing and then I stumbled across some Youtube videos (https://www.youtube.com/watch?v=agr8AuU2rRc ,https://www.youtube.com/watch?v=EQ4HQ3KBth8 , https://www.youtube.com/watch?v=JAi7CgBamlA ) of Jaroslav Prucha's work in Czechoslovakia (http://en.pruchabanjos.cz/mandolin.php?mandolin=f4)

To me these were great sounding mandolins. I wrote to him and he told me that he uses a standard F4 single transverse brace just under the soundhole and basically Loar specs for the graduations.

Two weeks ago at the Grass Valley Bluegrass festival I had the occasion to speak in depth with Roger Siminoff about exactly this and he told me that in his opinion and experience the top with Loar graduation specs had more than enough strength to hold up to the pressure of the strings and that the transverse brace was used primarily to keep the edges of the sound hole from cracking. In rogers opinion, he thought that the
"X" bracing for an oval was great for a guitar but the mandolin didn't really distribute vibrations and resonance like a guitar so that it did not add anything to the mix and wasn't necessary.

I am now leaning strongly toward the transverse brace for my F4/5 hybrid. time will tell.

I think Roger Siminoff has been a very positive force for mandolins in the US (especially getting Gibson started back to respectability) so if he thinks the transverse brace will do I would defer to him.

OTOH we know that hundreds of the 1900 - 1921 era Gibson oval holes (both A and F; mandolins, mandolas and mandocellos) have developed significant top sag of their lifespan. I guess Roger is implying that with the advent of the Loar influence that the oval hole mandolin top graduations were reassessed and given more top support (thicker) compared to the ones built before him?
(Maybe that is already a known thing?).

Come to think of it I don't know as I have ever seen a post 1921 Gibson oval with top sag?

[StuartGold]

I think Roger Siminoff has been a very positive force for mandolins in the US (especially getting Gibson started back to respectability) so if he thinks the transverse brace will do I would defer to him.

OTOH we know that hundreds of the 1900 - 1921 era Gibson oval holes (both A and F; mandolins, mandolas and mandocellos) have developed significant top sag of their lifespan. I guess Roger is implying that with the advent of the Loar influence that the oval hole mandolin top graduations were reassessed and given more top support (thicker) compared to the ones built before him?
(Maybe that is already a known thing?).

Come to think of it I don't know as I have ever seen a post 1921 Gibson oval with top sag?

Perhaps that is what is meant by "Loar Specs" He didn't take over and do the re-design til after 1921. How did the F4's before him compare with the ones produced in the factory when he was there?

[Bernie Daniel]

Perhaps that is what is meant by "Loar Specs" He didn't take over and do the re-design til after 1921. How did the F4's before him compare with the ones produced in the factory when he was there?

That is the question I had too. I have not had much experience with any post-1920 F-2/4's but I have often heard many on this site say they sounded different than the pre-1920 models. Of course in addition to the top plate -- which we are speculating on here -- one change that we know happened was the addition of a truss rod.

[barry k]

Not my solution to the OP's question, but it appears that the majority believe No X bracing is required and just a transverse brace is required on an oval hole? Am I reading the responses correctly? And this is all dependant on one persons opinion.?.. I build a substantial amount of oval holes and would love a definitive anwser to this question. Is parallel tone bars with a transverse brace the experts choice then for an oval hole mandolin or just the transverse brace alone?.....curious

[Bernie Daniel]

Not my solution to the OP's question, but it appears that the majority believe No X bracing is required and just a transverse brace is required on an oval hole? Am I reading the responses correctly? And this is all dependant on one persons opinion.?.. I build a substantial amount of oval holes and would love a definitive anwser to this question. Is parallel tone bars with a transverse brace the experts choice then for an oval hole mandolin or just the transverse brace alone?.....curious

Would the answer to that question be "it depends"? That is it depends on how you graduate the top?

I am not a luthier but I have heard luthiers talk "luthier talk" and I am often not on the same wavelength and don't always follow the argument but I am guessing that you could carve the necessary support into the top board so that even no bracing was required?

But I also reason to the position that perhaps there is that "sweet spot" that is just the right combination of top graduation thickness and support (transverse/tone bars/X-brace/other)?

Also perhaps there is more than one way to arrive at an oval hole mandolin with both a stable top and great tone/projection?