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Jumbo 12'ers

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(@brian-f)
Estimable Member
Joined: 19 years ago
Posts: 122
Topic starter  

This is really two questions (OK, its three):

First, acoustically speaking, why does maple seem to have such an affinity for the jumbos of the world? What are the dreadnaughts doing wrong?

Secondly, I'm seriously considering buying a twelve string acoustic, probably used. Now it seems that my first concern should be the neck, since many necks I have talked to say that the tension of all twelve of those strings is a force to be reckoned with. I've been led to believe that a 12'er less than 10 years old is a good choice due to this relationship. Would it make sense, and ultimately extend the life of the neck, if one were to keep the guitar tuned down one-half step and capo the first fret? (I do this now with my 6-string because I've been working on GNR's "Patience", and I don't want to continuously re-tune.)

Thirdly, does anyone have a good acoustic arrangement of Petty's "American Girl" for one guitar? (I've got a bass player). A simple strum pattern maybe?

Thanks!


   
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(@gnease)
Illustrious Member
Joined: 20 years ago
Posts: 5038
 

I'll answer the second question: The neck is not usually the weak point for a modern 12 string flattop -- it's the top. All that tension tends to belly the top, raising the action and sometimes even lifting the bridge. The are plenty of well-made 12s these days with great action and strong necks, but the tops are always vulnerable. There are several solutions.

1. Lower the tuning (tension) and capo back up.
2. Use extra light strings
3. Buy a 12er with a JLD Bridge Doctor (e.g., a Breedlove) or install one. Did this on my older Guild 12 after repairing the bridge. It works well to keep the top from bellying and bridge from lifting.

-=tension & release=-


   
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(@jminor)
Estimable Member
Joined: 18 years ago
Posts: 168
 

Buy a 12er with a JLD Bridge Doctor (e.g., a Breedlove) or install one. Did this on my older Guild 12 after repairing the bridge. It works well to keep the top from bellying and bridge from lifting.

How did this affect the tone on yours ? Did your axe sound "richer" and "louder" like they say on their site ?

..Seems hard to believe, but i'm pretty skeptical when it comes to these things.

It would be a great solution for my old 12... if it works :?

Insert random quote here


   
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(@u2bono269)
Noble Member
Joined: 21 years ago
Posts: 1167
 

i'm also interested in the JLD thing. I'm thinking of using one on my old Ensenada acoustic. It needs a new bridge, and it has a belly in it already so I was thinking of putting a new bridge on and using the bridge doctor to help bring the belly down and keep it down.

personally, i think the maple helps balance out the boominess of the jumbo. maple is a bright sounding tonewood, and it seems that the huge dimensions of a jumbo create a lot of bass and projection, so the maple's brightness balances it out. this is me thinking logically of course and i could be 1000000% wrong.

http://www.brianbetteridge.com


   
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(@gnease)
Illustrious Member
Joined: 20 years ago
Posts: 5038
 

Buy a 12er with a JLD Bridge Doctor (e.g., a Breedlove) or install one. Did this on my older Guild 12 after repairing the bridge. It works well to keep the top from bellying and bridge from lifting.

How did this affect the tone on yours ? Did your axe sound "richer" and "louder" like they say on their site ?

..Seems hard to believe, but i'm pretty skeptical when it comes to these things.

It would be a great solution for my old 12... if it works :?

I don't think it really improved the tone. But it was difficult to tell, as the guitar had been out of service for several years before I repaired it. I'm not really sure why it would improve the tone, either. Unless the ability to tune to normal tension (tune to E) helps. As the Bridge Doctor adds only a little mass to the bridge, I wouldn't think it should change things too much. Anyway, it did the job.

-=tension & release=-


   
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(@gnease)
Illustrious Member
Joined: 20 years ago
Posts: 5038
 

i'm also interested in the JLD thing. I'm thinking of using one on my old Ensenada acoustic. It needs a new bridge, and it has a belly in it already so I was thinking of putting a new bridge on and using the bridge doctor to help bring the belly down and keep it down.

It won't really bring down a belly that much, but will prevent it from worsening. You should re-flatten the top by other means. When I repaired my Guild, I removed the bridge, checked the bracing integrity, did a preliminary flattening of the top, before regluing the bridge and installing the JLD. The preliminary flattening was done by placing increasing weight (stacking books) on the top of the guitar over a period of a couple weeks. I did this to make the original bridge fit nearly flush/flat on the top before regluing, as bellying tend to screw this up. After re-gluing the bridge -- which also helps flatten the top a bit further, and installing the JLD, I once again weighted the top with books and over a period of time tightened the JLD to maintain the flatness the weighting slowly achieved. This was a week or two process. So the Bridge Doctor didn't really do the flattening, but now maintains the flattening I did by other means.

-=tension & release=-


   
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(@u2bono269)
Noble Member
Joined: 21 years ago
Posts: 1167
 

ah ha! that sounds like a wonderful technique

btw, how'd you remove the old bridge?

http://www.brianbetteridge.com


   
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(@gnease)
Illustrious Member
Joined: 20 years ago
Posts: 5038
 

Hot, slightly moist palate knife and patience. It is pretty easy to ruin the tpp as the you will need to slide in from different directions (neck verus tail) on the top half and bottom half of the bridge -- the bookmatched top will have grain runout in opposite directions. Recommend picking up a Dan Erlewine book on the topic.

-=tension & release=-


   
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(@slejhamer)
Famed Member
Joined: 20 years ago
Posts: 3221
 

personally, i think the maple helps balance out the boominess of the jumbo. maple is a bright sounding tonewood, and it seems that the huge dimensions of a jumbo create a lot of bass and projection, so the maple's brightness balances it out. this is me thinking logically of course and i could be 1000000% wrong.
I think that's probably about right. My maple-backed Alvarez jumbo 12er has almost a scooped tone to it - good bottom end and very bright at the top.

And I found this at Luthier's Mercantile, which adds to what U2Bono269 said:
Maple is well known for imparting bright tone to an instrument, with excellent separation (a guitar with good separation allows each note of a chord to ring independently as opposed to sounding thick or clustered). It has long been a popular choice on the Gibson Jumbo series because the bright tone helps balance out the boomyness of guitars that have a large body.

"Everybody got to elevate from the norm."


   
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(@u2bono269)
Noble Member
Joined: 21 years ago
Posts: 1167
 

wow, it seems like hours of reading on the internet about guitar construction and tone finally paid off

im actually kinda impressed with myself

http://www.brianbetteridge.com


   
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