Top Deflection

[Tiderider]

I have a two year old A9. The top appears to deflect down under the feet of the bridge causing the center seam to nearly touch the top of the open center of the bridge. It sounds great but is this something that should have me concerned?

Lee

[Rob Grant]

lownote, any chance of a photo of the situation?

Deflection is not uncommon with mando tops. With my own instruments I find those that show SLIGHT deflection around the feet produce the desired volume I want. I like to put my tops "under pressure."

This deflection is not desirable if your bridge feet continue to sink or the top doesn't recover when you remove the strings. Situations like this can possibly occur when one loads "heavy" strings on an older mando designed for "lights" (eg.: vintage instruments).

[troika]

I've noticed that mandolins with the bridges "dug in" just a tad tend to sound good. Every bit of that bridge is transmitting vibrations to the top. I would be concerned if the bridge was leaning toward the neck too much.

[Tiderider]

Thanks for the peace of mind. #The top returns to normal when "unloaded" and the bridge does not lean forward....it sounds great. I've used J-74's since it was new, so I suspect it's been under a fair amound of strain for a couple of years. #Rob, it's been hard to get a clear picture but I'll give a try this evening. Thanks.
Lee

[Jim Rowland]

Sometimes, on a very shiny top,a small,ie normal,deflection is exaggerated by a kind of optical illusion.
Jim

[Tiderider]

Here's some pictures, pardon the quality. This mando is a player so again pardon it's less than prestige condition.

Lee

[Tiderider]

Another

[Tiderider]

Last one. Thanks.

[Gavin Baird]

Lownote,
There is something really wrong here. That bridge/saddle arrangement is very unstable looking. If the Mando is stabalized and the top is not sinking, you could have a new bridge made to take up the extra ordinary height. The saddle as shown must be right to the top of the threaded posts...G

[Tiderider]

Gavin, it's not cranked up all the way still a little of a quarter of an inch left. It will play just fine considerably lower but I like the current height. There's about .025" between the top and the center of the bridge. But maybe a new bridge is in order. The mando has been this way since new.
Lee

[Michael Lewis]

For a situation like this I would recommend a full contact foot for your bridge. With a top that flexible you should have little or no trouble making the top conform to the new bridge foot. Often the top will start to crack at the inner edges of the cut out where the top pooches up.

[Rob Grant]

lownote,

Excellent photos, especially that second one.

Just curious, your saddle seems to be cranked pretty high. In the position you have it in the photos, what is your clearance at the twelth fret (bottom of string to top of fret)?

[Tiderider]

Thanks Michael, I can see how this could lead to cracks. Rob the measurement of the G string at 12 is .069". Any of you feel as if this is a Gibson warranty issue? Thank you.

Lee

[fatt-dad]

Ah, for the price of the UPS truck, I'm sure that the folks at Gibson could see if it's a warrantee issue, comment on the stability and (if not for warrantee) price out the fix. If you bought it new and it is not standing up to normal play wear, I would certainly consider sending it to the point of origin for their thoughts (i.e., may be better than ours).

f-d

[Tiderider]

F-D Thanks for the advice. It's been like this since new and it sounds and plays pretty good. Hopefully it's just a characteristic of this particular top.

Lee

[Charlie Derrington]

Looks strange to me.

Get with dan.mills@gibson.com and send it back. Something is definitely wrong.

Charlie

[Frank Russell]

There you go. I'm continually amazed at the quick response here on issues that would take many other companies lots of time to assess. Hats off to Charlie and staff. Makes me wish I still had a Gibson. Frank

[250sc]

Is that the original finish on the A9? It looks glossy and is a different color that the A9s that I've seen.

[Steven Stone]

Gibson makes several different height bridge top sections. You could go to a bigger one and not have to crank up the bridge screws as much. It also makes for a more stable bridge system. I had to do that with my Gibson Fern. Just contact Big Joe at Gibson.

[mandoman4807]

Gibson makes several different height bridge top sections. You could go to a bigger one and not have to crank up the bridge screws as much. It also makes for a more stable bridge system. I had to do that with my Gibson Fern. Just contact Big Joe at Gibson.

Or you can simply use the longer bridge screws, and re use the same saddle.
That is what I had to do, when quite a bit of the bridge base was sanded to fit the mandolin top.


D.S

[Philip Halcomb]

It almost looks like the base had too much material removed. But I would take Charlie's advice send it back and if they need to outfit it with anothere bridge then they will.

[labraid]

Maybe I'm nuts, but it looks like that upper bridge half is backwards.. ie, treble vs bass, the compensation looks backwards? Besides the point, I know... My vote, new bridge.

[atetone]

I'd say that if Charlie Derrington says send it back, then send it back.
I think he knows of what he speaks!
He treated me fabulously when I had a problem with my A5L even though Gibson was not liable for my particular problem.
Ship it. Then you know for sure that the problem is over for good.

[troika]

I had a master model that looked like that. I sold it.

[Tiderider]

Sorry to leave this thread hanging but here's the final solution. I decided to change the bridge before shipping it off to Gibson (thanks Charlie), so I ordered and installed a Randy Woods Loar style bridge. Now the top deflection is barely noticable and I only need to raise the bridge about a quarter as far as with the original bridge. Best of all it made a significant difference in the treble response. I'll post pics if anyone is interested. Thanks for everyones advice. I can only suspect the other bridge had been flawed from the git go.

Lee