guitar belly

[brianhejh]

Hi Guys.

I have a Gibson j50 with belly bulge.

I have read about the bridge doctor and know that there is mixed opinions about how effective they are.

I was thinking about trying this method: (1) piece of angle aluminium 1/4" that spans across to the guitars very edges crossing underneath the bridge. The ends of the aluminium resting on a small block on the outer edge of both sides of the guitar.

Attach 2 screws through the bridge and connect to the aluminium angle
beneath allowing for the adjustment to pull down the top/force against the aluminium underneath. I don't believe it needs a neck reset.

There may be some sacrifice of tone but may fix the overall problem?
Any thoughts or comments would be appreciated.

Brian

[RRuskin]

Most steel string guitars will develop a bulge at some point. How has yours effected playability and sound? If it plays ok, leave it alone. If the action is up higher than you like, lower the saddle. If there isn't enough material to lower, it's time for a neck reset.

[brianhejh]

Yes the saddle is very low however when i place a straight edge to the bridge it still measures above the bridge. If I gave it a neck reset will I not still have the belly?

Brian

[Martin_F]

Have you taken it to a luthier to have a look at the guitar? You might have an issue going on in the bracing that can be repaired without too much issue. Guitars will belly over time, but it can also be an indication of a problem.

Good luck!

Martin

[pagedr]

Yeah definitely take it to a good repair person to get an opinion. As mentioned some bellying is ok and a neck reset might fix your issue, but too much could mean damage to the bracing. If you want to measure the belly, put a straight edge flat across the guitar just below the bridge, and then measure the gap between the straight edge and top of the guitar on either side. The amount of acceptable bellying depends on the guitar but there are some people on here who can probably give you some advice as well.

[brianhejh]

Thanks for your comments.

I checked the bracing all seems good.

The measurement at both ends of the straight edge behind the bridge is:

Strings on 3.2mm
Strings off 2.2mm

Is this measurement within the problem range?

Thanks again

Brian

[Parlorman]

Screwing a piece of aluminum to the underside of the top seems like a drastic solution and would almost definitely effect the tone.

You should follow the previous advice to have a good luthier look at your guitar.

Is the bridge still solidly attached to the top? Can you slip the edge of a piece of paper under the bridge - even a little? Usually this would be most noticeable at the ends of the bridge.

[shockfinder]

Originally Posted by brianhejh

Thanks for your comments.

I checked the bracing all seems good.

The measurement at both ends of the straight edge behind the bridge is:

Strings on 3.2mm
Strings off 2.2mm

Is this measurement within the problem range?

Thanks again

Brian

From everything I’ve read that’s not a lot. I might be wrong though. One question is how well humidified is it? I got a guitar that had some belly and a bit of sinking in between the bridge and sound hole. It was really dry. After getting it properly humidified, it still has a bit of a belly but the sinking is gone. It’s also the best sounding guitar I own.

[JayBee1404]

Your guitar should have slight belly. The total of 6.4mm (3.2 x 2) is 1/4” in real money. For a Martin, a total of less than 1/2” (12.7mm) is considered ‘within range’, I can’t imagine a Gibson being very different.

‘Flat Top’ guitars don’t have a flat top - they are built with a slight radius, yours sounds fine. Stop worrying and play the guitar.

The usual disclaimers apply......IMHO, YMMV etc.

[Malcolm Kindnes]

It sounds perfectly normal to me, I have several guitars with bellies.

[JayBee1404]

I have a ‘guitar belly’ myself...

[ljguitar]

Originally Posted by brianhejh

Hi Guys.

I have a Gibson j50 with belly bulge.

I have read about the bridge doctor and know that there is mixed opinions about how effective they are.

I was thinking about trying this method: (1) piece of angle aluminium 1/4" that spans across to the guitars very edges crossing underneath the bridge. The ends of the aluminium resting on a small block on the outer edge of both sides of the guitar.

Attach 2 screws through the bridge and connect to the aluminium angle
beneath allowing for the adjustment to pull down the top/force against the aluminium underneath. I don't believe it needs a neck reset.

There may be some sacrifice of tone but may fix the overall problem?
Any thoughts or comments would be appreciated.

Brian

Hi Brian
A bulge between the bridge and tail is expected/normal for guitars.

Of concern would be a cupping or dipping between the bridge and soundhole.

This is the top of my Olson in 2013 - and it looks the same in 2020.

One of my guitars was built with a radiused top, so of course the top is lifted behind the bridge. But the Olson is a true flat-top, and the pressure of the strings causes the lift.

If you put in a bridge doctor or otherwise hamper the vibration of the top, I'm guessing it will affect performance.

And I don't see the reasoning about a neck reset having anything to do with lift behind the bridge.

String tension is string tension…and I'm guessing it's the same amount of tension no matter how high or low the action is set.

[mcduffnw]

Originally Posted by brianhejh

Thanks for your comments.

I checked the bracing all seems good.

The measurement at both ends of the straight edge behind the bridge is:

Strings on 3.2mm
Strings off 2.2mm

Is this measurement within the problem range?

Thanks again

Brian

Brian...

Your a man with a "solution" in search of a "problem" here...and it is HIGHLY likely that your guitar does NOT have a problem and is just reacting normally to string tension load.

Just take the guitar to a good luthier/repair tech and let them have a look at it.

Tell us where you live and the good folks here on the AGF can give you a list of names for really good luthier/repair tech's who are in your neck of the woods.

Don't do anything to the guitar until you've had it look at.


duff
Be A Player...Not A Polisher

[mcduffnw]

Originally Posted by Parlorman

You should follow the previous advice to have a good luthier look at your guitar.

Is the bridge still solidly attached to the top? Can you slip the edge of a piece of paper under the bridge - even a little? Usually this would be most noticeable at the ends of the bridge.

It is not uncommon for bridges to develop a wee bit of seperation at the corner edges of the ends, or "wings", in part either because the top does have a "built in" radius/arch that peaks in the bridge area, and because most guitar tops belly a little bit under load.

Also, sometimes the guitars finish manages to get applied to just a tiny bit of it is also on the guitar top at the edges of the bridge "footprint", so the glue on the bridge does not get fully down into the wood and adhere completely at the very edges of the bridge. This to is not uncommon, and not a problem.

So it can be possible to slide a little edge of a piece of paper under the bridge at the ends or the back middle, and yet the bridge is actually perfectly fine and well glued solidly down to the top.


duff
Be A Player...Not A Polisher

[Goat Mick]

Honestly it sounds like your solution of using aluminum braces is actually worse than the problem you're describing. The first thing I would do is hydrate the guitar in it's case for a couple of weeks with a soundhole humidifer (they're inexpensive) and see if that helps the situation. I had the same issue with my J-45 even though the relative humidity in my house stays 50% or above. A couple of weeks getting humidified in the case took care of the issue. Now I give it a drink in the case a couple of times a year and it stays happy.