We have this older Gibson A4 (Appears to be from 1918-22?) in the shop and are uncertain about what it was originally like and what we've got ahead of us in a repair. Maybe some of you who specialize in mandolins have some experience with this particular model. (more below)
The owner brought it in because the back is separating from the heel/block area and the action is so high it's unplayable.
When we started looking at it, we noticed the flatter profile of the top (below) and were certain that the top was collapsing because of loose or broken braces. But we looked inside and found that to not be the case. The bridge is very tall and could certainly be lowered to get the action down. But should we be re-inforcing the top somehow first?
Then I started looking at the fretboard area of the body, particularly the way it falls toward the sound-hole (above,) and got to wondering if that lower arch wasn't a deliberate part of the original design. So that's the first question: Could an A4 of this era have been built with a flatter arch?
Next we noticed and the owner confirmed that the center seam had been repaired at some time. Could enough material have been removed from the center to make the top collapse this much? If that's the case there really isn't a way to replace that material and make the arch taller.
In good shape, an A5 could be worth over $2k and it's a family piece that the owner is interested in playing so he's prepared to put a few hundred into the repair. We figure the back will need to come off to fix the separation and that it won't fit back perfectly when it's time to reassemble.
Wondering if anyone is familiar with this model's particulars. While we work on lots of mandolins here - new and vintage - we don't build (or re-build) them and because of the top issues, this is somewhat unfamiliar territory. Any thoughts or insights would be great.
I am not an expert, but that looks more like 1910's than 1950's.
You might be right - logo is "The Gibson." I'll see if I can better identify it.
Looks like a lot of the neck angle problems are from the back being loose. Not sure about the top arch, but the bottom of the bridge seems to have about the right curve to it. I should add "maybe" to this.
It's a bit hard to do any real dating because the pictures are more for damage ID than instrument ID but IF the parts are all original, I think it may be a bit earlier than 1918 but not much. If I remember correctly, the pin on the pick guard that fits into the bridge was dropped before the solid bridge was changed and IF I remember correctly that bridge was dropped in 1920 or so. The Burst is larger than I remember the A style mandolins showing in the 20's but I think that red was only introduced in the teens. I can't tell of the tuner buttons have inlays but I don't think that made it past the mid teen on the A4s either. I think the Script is tilted which didn't change until the late 20's or early 30's. ( Again, if I remember correctly.) I think I read once that Gibson wasn't always too concerned about using whatever was at hand when they ran short of things so it's possible for one model of instrument to have hardware and fittings from a different or older model. In other words, I'm fairly sure that the pickguard pin was deleted several years before the solid bridge but that doesn't actually mean that this mandolin is older.
Without looking at the instrument first hand and considering that you have already checked to insure that the brace is OK, I would look closely at the neck block to find the problem with your neck angle. I seem to remember that we've had others mandolin questions about the top here before and that it was reveal that some of these old Gibson's did have a bit of a problem with some sinking on the top but that it's was usually not terribly pronounced. It's hard for me to see it well in the picture but it doesn't look TOO bad to me. I could be missing something.
The pictures don't show if the back and the body/heel are aligned where they are loose. Can you push the back directly into place with out pulling the neck back to align things?
I've worked on a few older Gibbies in the 1905-1910 range which I found to be built with a flatter arch, considering Orville started with a completely flat arch, some time was required to transition to the Loar arch we know today. That being said, this top has definitely compressed in the bridge area, but not more than would be expected after 100 years. I'm compressed in the bridge area a bit myself, and I'm only 55. I have to agree with Steve W that the loose headblock is at the core of the problems. Removing the back is the correct procedure, as it presents some options regarding the compression issue. Frank has documented several repairs that apply and will be helpful.
Either adding a thin bridge plate or replacing the brace would be excellent choices. I would address the center seam crack with a couple of cleats while I had the opportunity as well. A mold would be helpful in getting the back realigned correctly. I would think the back plate has some warpage at the block that will need to be coaxed flat again, and the sides will need to be eased back into form as well. I use hot water in strategic places and slowly increased pressure to bring the sides back in line. Here's an '05 A4 that's up on deck in my shop.
Oh and for dating while the back is off check this one. http://www.frets.com/FretsPages/Luthier/Technique/Mandolin/RevealNu...
Thanks guys. We'll be checking all those links out and appreciate the ideas. We're formulating a plan here and will see if we can't get this thing back up and playing again!