Please explain Martin's bracing

lgehrig4

Member
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6,174
This question probably applies to all acoustics, but I was looking at some Martins today and I noticed this.

The lesser priced models lack the vertical (as viewed when the guitar is hanging upright) brace that the more expensive models have.

Why?

Does it really cost much more or is it that much more difficult to glue a small piece of wood in that direction? It's seems there is good reason to have it and no good reason not to have it on less expensive guitar. I can see the more expensive models using more expensive woods, hardware, etc, but that brace does not make sense to me.
 

RichSZ

Gold Supporting Member
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1,966
I just went through this whole thing as I was heavily shoppong acoustics. A good place to start would be to study the different styles of a particular model such as the D-28. There is the D-28, the HD-28, the HD-28V which all have different bracing.

D-28: non scalloped
HD-28: scalloped
HD-28V: scalloped and forward shifted

I'm sure there's more but the V is more like the pre WWII Martins (I think).

Gibson's have their own bracing style and others seem to be some variation of either Martin or Gibson bracing. Careful...this topic can get as heated in the Acoustic forums as a "John Mayer's Dumble" thread over here.

-Rich
 

lgehrig4

Member
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6,174
Didn't realize it was such a heated topic. I realize there may be different bracings, but almost all the of high end acoustics I've seen have that one brace down the middle, except the lower end Martins. I'm just trying to understand why.

P.S. I'm only referring to the bracing on the back
 

zombywoof

Member
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4,647
I would assume that the presence or absence of a long brace running the length of the back would have to do with whether the back is one or two pieces as the brace would be used to strengthen the joint.
 

Rob Sharer

Muso-Luthier
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2,822
I would assume that the presence or absence of a long brace running the length of the back would have to do with whether the back is one or two pieces as the brace would be used to strengthen the joint.
"Brace" would be a strong word for that thing. It's a cross-grained reinforcement strip, unnecessary on guitars with plywood backs which explains its absence in the cheaper Martins.

Meanwhile, look at an HD-35 - they've got two!

 

lgehrig4

Member
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6,174
Not sure I understand. Wouldn't plywood backs be on cheaper guitars and solid wood on the more expensive guitars? It's the more expensive guitars that have it.

BTW, I ended up purchasing a Martin GC-MMV. The back is solid like the more expensive models, but it does not have the long strip of wood running form the neck to the end pin.
 

jackaroo

Member
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5,142
Yes...plywood is stronger than solid wood piece glued together. So the solid wood guitars need the extra piece of wood to add strength.
 

lgehrig4

Member
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6,174
So the question is, why doesn't mine have one when it is advertized as having a solid back? Guess I will have to contact Martin. Guitar sounds great btw. I was A/Bing it with a D28 and I actually liked this one (tone wise) slightly better. Difference could have been strings, setup, etc though.
 

zombywoof

Member
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4,647
I am a bit confused still as to what the issue is.

At one time the center strip was probably necessary to stablize the two piece backs. But with today's modern adhesives the center strip is simply no longer necessary.

Since the strips no longer serve a purpose Martin can eliminate them if they want which helps streamline the build process and cut the costs a bit - I believe the D-16 does not have the center strip. That those strips still exist in many Martins is probably more an issue of tradition than anything else.
 

PeakeGuitars

Member
Messages
32
The back reinforcement strip is there to reinforce the glue joint that joins the two halves of the back (or 3, in the case of a 3 piece back). All traditionally braced, solid wood acoustics have this. If they do not - it means that they either have a 1 piece back (this is very rare) or that the back is plywood of one type or another.

Back thickness on a standard acoustic guitar is usually about .125" (1/8"). No glue is strong enough to be able to safely get away with disregarding this brace - there just is not enough surface area. If you look closely at this brace you'll see that the grain runs with the width of the guitar, whereas the grain of the back will run along the length of the guitar. Laminating this thin piece of wood in there along the back joint does a lot to make this a much stronger joint (as you know, wood is much harder to break when you bend with the grain rather than across the grain).

Those "1 piece" Martin backs are either "plywood" or their HPL (high pressure laminate) material. HPL is fake wood - kind of like the fake wood you might see on some non-solid wood furniture.

I hope this helps clear it up a bit!

Best,
Trev
 

lgehrig4

Member
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6,174
I would hope then that my guitar has a one piece back since it's advertised as having solid East Indian Rosewood back and sides.

Makes sense now because the more expensive models do have that design going down the middle.
 

David Collins

Member
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2,246
The center graft was there to reinforce two piece backs which were joined with a purfling strip in between them. If there is no purfling strip down the center, then there is no need for the center graft on the inside. Many makers today will join the back halves directly, and inlay a shallow depth center purfling from the outside rather than joining back with a full strip in the center, which likewise eliminates the need for the back graft (though some may still use it out of tradition).

The lower line Martins do not have any decorative purfling strip down the center joint of the back, therefore no need for the center graft on the inside. Just a simple, joined, bookmatched two piece back. It's one teeny-tiny factor that contributes to the differences between lower and upper models, and certainly one of the least significant among many.
 

zombywoof

Member
Messages
4,647
The back reinforcement strip is there to reinforce the glue joint that joins the two halves of the back (or 3, in the case of a 3 piece back). All traditionally braced, solid wood acoustics have this. If they do not - it means that they either have a 1 piece back (this is very rare) or that the back is plywood of one type or another.

Not all - Larrivee, for one, does not use the internal brace to support the back center glue seam. I have been told, as the above poster noted, that the reinforcement is only necessary when there is a decorative seam in the back.
 

zombywoof

Member
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4,647
I would hope then that my guitar has a one piece back since it's advertised as having solid East Indian Rosewood back and sides.

Makes sense now because the more expensive models do have that design going down the middle.

Except that Martin does not make a one piece back guitar.
 

PeakeGuitars

Member
Messages
32
It is certainly up to the builder whether to use that reinforcement strip or not. The only guitars I have built that did not use it had an "arched back", i.e. the back was carved like an archtop guitar's back. These did not use any back braces at all, but the back was about 3/16" thick in the center. I would guess that Larrivee uses thicker back material than most of us. They certainly build nice guitars...I'm sure that whatever they are doing has been well thought out.

Trev
 






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