Sunken tops on (vintage) GJ guitars

PJD

I wonder what your experience is with sunken tops on (vintage) GJ guitars, is this a common thing in your experience, and if and how this should best be repaired.

I see a lot of sunken tops on vintage GJ guitars. They sink or can or will sink at two places. At the bridge and at the upper part of the top near the sound-hole. My local luthier (he has previously worked at Dupont) says a lot of vintage GJ guitars have been build quite lousy, the lower brace is often not placed in the right spot, so that the top at the bridge sinks in time. Often there is not must support around the sound-hole. Often the braces that are placed under the top have not been sanded correctly (to give them a (slight) arch), they are too flat which will make the soundboard sink in time. Another thing is that a lot of the vintage GJ guitars have had wrong heavy gauge strings on them in the past, these guitars are not build for that and that makes the top sink too. I think you should think of GJ guitars as something in between a classical nylon string guitar and a steel stringed folk guitar when you think about the pressure a GJ guitar top can handle. Which brings me to the question how you should best treat them when you repair a GJ guitar. For exemple if you want to do a neck-reset. I see more often problems with the top than with the neck, when action is too high, most people would say neck reset, but in my opinion the problem is not the neck which causes the high action, but the top.

The ones that have not sunken have bigger braces and the lower brace is placed nearly exactly under the bridge. So that makes me think of a probable cause of the sunken tops: the braces. So is this where the root of this problem lies?

Changing the braces would affect the sound of the guitar from what i understand, so this is not something to consider lightly and comes with a certain cost and if you like the sound of your guitar you might not want this to change.

Another option could be taking off the braces and resand them so that they become a bit arched. Does anyone has any experience with this?

I know about the classical neck reset, but I am not sure this really fixes the top.

scot

I once got a very valuable guitar at a very low price, a mid 30s Gibson Roy Smeck Radio Grande. Converted for regular playing, it had the exact sound I wanted, but the top was caving in at the soundhole and I felt like it had to be repaired. My repair guy David S examined it, determined that the top braces had come loose and had been reglued without the top being properly placed. It was repairable - not cheap, and no guarantees about what it would sound like after the repairs. He also felt like it was stable and repair wasn't necessary at the time. But dumbass me, I had the money and had him fix it. Sure enough, after a long wait I got it back and it looked perfect but the sound I liked was gone and it now had the kind of flat boom that those guitars often have. David felt like the guitar would come back but who knew how long that would take. So I traded it for a Gibson j-185 that I kept for 30 years. A happy ending - but I probably should have taken the early advice and left it alone...

PJD

Hi Scot, thanks for sharing your experience with this issue! Did your repair guy change the braces?

Gouch

First thing I would do is change or shim the bridge. Way simpler than a neck reset or brace work. Cheap and totally reversible.

PJD

Thanks Gouch, yes I understand that would be ok if it's just 1 mm or maybe 2. If you need to lower the bridge of few mm then you start losing volume.. .

Buco

The story goes that on the Busato named "the Beast" because it was the loudest guitar anyone has ever played, the top had completely caved in. When Michael (Bauer) bought it, it needed work to be playable again but afaik nobody touched the top.

Gouch

How high is the action at the octave currently? (from the bottom of the E strings to the top of that fret. You can measure it pretty accurately with picks or coins if you don’t have a fine ruler)

MichaelHorowitz

@Buco The “beast” got its name due its unusual appearance (it was also nicknamed the “Ugly Duckling.”

https://www.djangobooks.com/Item/busato-d-hole-2

and yes, the sound of this one is off the hook! However, the top is completely normal with a healthy bombe.

I think you're talking about a Favino Michael had that had a very sunken top but sounded amazing.

billyshakes

https://djangobooks.com/forum/discussion/comment/116877#Comment_116877

That's a nice instrument, Michael! On either side of the bridge, it looks like there are parallel lines. Is that wear perhaps from the bridge and moustache pieces being placed on either side there? Or is is something else? Never seen that Venetian cutaway on one of these guitars before.

Buco

@MichaelHorowitz ah, all these years I remembered it as the story of the beast. Thanks for getting me straight. But I guess the point was that a guitar can still sound great like that and doesn't necessarily need to be rescued.

Jangle_Jamie

https://www.djangobooks.com/forum/discussion/comment/116879#Comment_116879

Those are the braces underneath the top, though I'm not entirely sure why the spruce there hasn't darkened quite as much as the surrounding wood - less air to circulate? Perhaps the glue soaked into the timber a little and prevented darkening/ageing? The patterns remind me of old building foundations seen under grass in dry weather!