Reducing belly bulge

cameronl · #1 01-06-2009, 09:01 PM

Hey everybody, I have a question about belly bulge on acoustic guitars. I have a Johnson Carolina Series JD-27 dreadnought guitar which isn't too many years old. It has a solid Englemann Spruce top. Anyways, back to my question, Is there any way I can reduce slight belly bulge behind the bridge. The bridge is fine and not lifting whatsoever, so I don't want to mess with that. I understand acoustic guitars, maybe dreadnoughts in particular, experience this over time from the constant pull of medium gauge strings, but how much belly bulge is normal. I understand that you can't expect to get a completely flat top on an acoustic guitar while using medium gauge strings on it over the years. But how much belly bulge is normal and is there a way to reduce it without installing a JLD Bridge System. I don't really want to go that route. Does belly bulge have anything to do with humidity? Is there any way I could add or take out humidity to correct this problem? Or is that not an option? Could someone please shed some light on this for me?

ayavner · #2 01-06-2009, 09:06 PM

i think a pic would be useful. certainly an arch is normal, though barely visible...

cameronl · #3 01-06-2009, 09:22 PM

I would put a pic up, but my camera isn't working right now, sorry.

Sugar Bear · #4 01-06-2009, 10:59 PM

Take a good look at it, and if the highest point of the top is not more than 3/16 inch above the top edge of the sides, don't worry about it.

If it bothers you too much, you could go to a lighter gauge of strings.

If it's more than 3/16 inch, it needs help. Without teaching a class, you could clamp the top to flatten it and install a bigger bridge plate.

But the whole thing is pretty complex, there are a number of considerations to deciding exactly how to proceed in a given case, so if you're a beginner at this sort of thing, you should probably have a luthier do it.

It's tough working through the sound hole, and the alternative is removing the back. And of course, the bridge will have to come off. And so on...

Sugar Bear

BBWW · #5 01-06-2009, 11:34 PM

Buy an original design Breedlove?

Or a bridge doctor....sorry....but they work.

ljguitar · #6 01-07-2009, 12:13 AM

Hi cameronl...
Slight bulges on solid tops are to be expected. In addition, if the top is radiused, then the top has a curvature.

Take a straight edge and lay it across the lower bout near the bridge and see how high the edges are from the bottom of the straight edge on each side - when the gaps are equal you can tell how much radius combined with bulge there is.

All four of my guitars have a radiused top, so even if the tops look perfectly flat, there is still a gap at the edges between the guitar top and the straight edge.

rcemech · #7 01-07-2009, 12:24 AM

Could be that mediums are too much for that guitar. Take a ruler and lay it perpendicular to the fret board so that it passes the sound hole and the end sticks past the bridge. If there is a depression or trough under the ruler and a bulge behind the bridge then you have a problem with the bracing or bridge plate and the medium strings are too much for the guitar. If this is the case then it will look like the bridge is tilted forward towards the soundhole. Also I would get a dentists mirror and check and make sure that the braces are not loose or coming unglued. The bulging can affect the intonation and action on the guitar and if a brace is loose then it could ultimately be a warning sign of impending implosion, but I have seen a bunch of older guitars that have lived with bulges (older guitarists too

). It ultimately is something you should get fixed by a luthier unless you are supremely confident in your woodworking abilities.

Also, over humidity can cause bulging. Silica packs and some other products can remove the humidity over time if you keep the guitar in the case with them, but be warned you can go too far the other way too.

The bridge doctor can correct the bulge, but who knows what will happen to the tone of the guitar. My brother used one on his guitar and it worked. I cant speak for the tone because he plays so softly that its hard to tell if it is affected.

Goodluck!
Rich

birkenweg42 · #8 01-07-2009, 01:22 AM

Let me know if you want to go the Bridge Doctor route. I bought one two month ago but then decided I have the guitar fixed professionally. I'm glad I did. If you wnt it you can have it cheap.

Coffeecup · #9 01-07-2009, 03:22 AM

When reading the title of this thread I thought it was going to solve a problem that has been troubling me for some time. Unfortunately it doesn't - it relates to guitars.

dmcowles@comcas · #10 01-07-2009, 05:30 AM

The first couple runs of the Carolina series guitars had some problems with tops bellying. The people at The Music Link subsequently added a lifetime warranty to that line, now reworked and expanded, and called it Recording King. If you are the original owner, there is a good chance the dealer where you bought it has some latitude to make it right. Otherwise, if you really like your Carolina, get a Bridge Doctor. They really work, and my experience with them has been that they do nothing to diminish, or otherwise modify tone. If you go that route, you'll prolly want to have a luthier or guitar tech install the BD.

Dave

Ken C · #11 01-07-2009, 06:17 AM

Quote:

Originally Posted by BBWW

Buy an original design Breedlove?

Or a bridge doctor....sorry....but they work.

I have tried the Bridge Doctor with zip success. Everyone was telling me they were a good idea and there are some guitars that come with them. Having them, or something similar, in a new guitar, I think is a good idea, but it didn't work for my application.

The consensus was that I had let the bridge "come up" too much before I installed one. This could be.

My guitar condition was that the area in front of the bridge was settling and the area behind raising. The bridge was secure to the top. (I would rather had the bridge separating from the top.)

I was told I was using it correctly.

Oh...yeah...the guitar had ladder bracing (unfortunately) and a big 17" lower bout.

Also, it was one of the bridges where the strings enter a hole in front of the bridge, exit at the back and then is pulled over the saddle. Looking at the physics of the thing, it looked like what one would do to rotate the bridge to push the front down and pull up the back.

(What are those sorts of bridges called? Other than "bad idea.")

Ken C.

missouri.picker · #12 01-07-2009, 06:26 AM

too much humidity.........the top is getting water logged and bulging from the excess water content. play the git if it sounds dead or deader than usual then dry it out and it will flatten back to normal. Now off course too much drying can cause it to over-flatten and buzz and possibly crack. Oh the science of relative humidity and wood.

Mandarb · #13 01-07-2009, 07:41 AM

Saw the thread title and my first thought was - eat less. As to the real question - see other responses. Good luck.

bosrocker51 · #14 09-19-2011, 03:03 PM

I know this is an older thread, but I have to comment. A well made flat top guitar should never have the top deform, bridge tilt forward or any such thing if it is well made, properly braced and it is not abused with strings that greatly exceed it's capability to retain.

With that said, if it bulges, fixing it would not be worth it if it's a cheap guitar, IMO. If it's a fancy or valuable guitar, I'd be tempted to take it to a luthier. I have no idea what they do, but I assume it involves steaming and using long jaw wood clamps on top of shaped flats, enlarged, new bridge plate, or god knows what all to fix it...

Ken C · #15 09-19-2011, 03:37 PM

Quote:

Originally Posted by bosrocker51

I know this is an older thread, but I have to comment. A well made flat top guitar should never have the top deform,

We can stop right there. <g> This implies that if the top deforms, it was not a well-made guitar. But is it not possible to become attached to a poorly-made guitar? We become attached to poorly-made people.
At one time, ladder-braced guitars were common, and "X"-braced, which helps prevent the belly condition was not that often used...if at all. This is all an evolutionary process.

Quote:

bridge tilt forward or any such thing if it is well made, properly braced and it is not abused with strings that greatly exceed it's capability to retain.

With that said, if it bulges, fixing it would not be worth it if it's a cheap guitar, IMO. If it's a fancy or valuable guitar, I'd be tempted to take it to a luthier. I have no idea what they do, but I assume it involves steaming and using long jaw wood clamps on top of shaped flats, enlarged, new bridge plate, or god knows what all to fix it...

Some of these "poorly-made" guitars are so valuable to their owners that they pay to have the backs removed, the ladder bracing removed and "X" bracing put in. This is a LOT of work.
Why?
Couldn't they just put that money into a properly constructed guitar?
Sure!
But as much as we would like to pretend that these are but wooden boxes with wires attached, they become much more over time.
For just another guitar, I agree with you...but for an old friend, well, he deserved a little more consideration.