My Guild's top is bulging? why, and what can I do.

[ESP3500]

I recently bought a Guild F512 12 string guitar. I love this guitar

I got it 50% off retail but it was not until I got it home and looked at it in a different light I understood why.

the top ( behind the bridge, about where your arm comes across)

Is bulging, or swelling up. the bridge looks like it is still in the correct place but I can see the spruce swelling up around it. now that I see it, it looks like it has lifted pretty high ( over 116 In.)

What would cause this. the finish looks fine, no cracks or anything, and it still seems to play wonderfully, but I don't want it to get worse ,but I don't know what is wrong.

They said it was too dry? I thought that would shrink it, not make it bulge up?

any ideas, and what can I do?

Thanks

Eric

[bigmo66]

A swollen top would (usually) indicate over-humidified, but I guess strange things can happen. I have seen under-humidified tops and they have all been sunken in.

 

How are you storing the guitar? If you have the opportunity to leave it out in a controlled environment, you can keep on eye on it and see if the swelling goes down.

 

Good luck

[ESP3500]

I have been watching it for the past few weeks and it seems unchanged. I keep my house 70 - 75 deg f and between 45-55% humidity.

[bjorn-fjord]

I apologize if I'm telling you something you already know but a guitar top should not be dead flat. All guitars should have a slight dome to the top. In my opinion, an ideal top shape should be domed about 1/16 with the apex of the dome located just in front of the bridge. The puts the bridge at a very slight back-set and places the strongest part of the soundboard (from an engineering POV) between the bridge and the soundhole. This counters the potentially top destroying force of the pull of the strings and will result in a longer lasting instrument.

 

Is it possible that this is what you are seeing? Because with this type of soundboard design, it will appear as though there is a bulge behind the bridge (and in front of it).

 

Now here's the test: Has the soundboard sunken between the bridge and the soundhole? If so, this could be an indicator of problems (although Gibson guitars come out of the factory looking like this).

 

It would be very unusual for a quality guitar like a Guild to suffer premature stress failure. Most factory instruments are built quite heavily. Especially 12 strings.

 

Have you noticed a change in shape since you bought it? Comparing the shape of the soundboard of this guitar to another might lead you astray. Every manufacturer builds their tops a little different. Could it be that what you are seeing is simply the "Guild shape"? The fact that it still plays well suggests that nothing very dramatic has happened to the guitar. If the soundboard had deformed 1/16th of inch since it was built the action would be affected.

 

OK, I'll stop bothering you now.

[slider]

a slight bowing behind the bridge is normal. those strings have alot of pounds of tension on them. acoustics are built for the stress.

dont worry.

[ESP3500]

The hump mine has is off to the side, at about the place and angle that your arm would rest, and you can follow the bulge to the very back ( or bottom ) of the guitar were it comes to a dull point. I can't tell if it is following the line were the brace is or not.

 

So although it does start at the bridge it doen't go straight back instead it goes back and up. and it is hard to tell if it is getting worse or if I am just seeing it better.

[slider]

Guilds are really well made. you shouldnt worry.

oh, I assume your tuning is standard. some high tunings can cause a hump problem. if you tune to C or C6 definately get lighter gauge strings.

a tweleve string is built like a tank. I have heard that over 180lbs of tension is required for standard tuning. sounds awful, but not to worry.

 

go play your guitar and have fun.

[valleyguy]

I have a Takamine 12 string from the 70's, and it has a bulge below the bridge. Been there for the 2 years I've owned it.

 

I ignore it.

 

I keep it tuned to normal tuning, no case, no humidity control, and I live in Southern California's 10% humidity.

 

Enjoy your Guild.