Ibanez M522 top collapsing

[neilca]

My Ibanez M522 top has started to collapse (bow) at the upper part (towards the fret board)of the F hole. I have borescoped the body and do not see any reason for this. The sound bars are still attached no cracks in the top can be seen. The top does feel springy as in I can feel it give when I press on it.

I was looking at the interface between the fret board and the body and thought it had a strange gap.



I looked at a Loar mandolin and this gap is filled.

Am I missing something? Can this be the lack of support on the top?

[neilca]

I cut the back off of this mandolin and didn't see any cracks/breaks/failures. What I did see was the top was not fully shaped. The area around the neck is pretty flat. I would have expected more "dome". I am taking it to my luthier buddy tomorrow to smoke over some options.

[neilca]

We looked it over and decided the top was misshaped and needed a stiffener. See picture.



The brace has yet to be shaped and fitted but you can see the location.

[DaveGinNJ]

We looked it over and decided the top was misshaped and needed a stiffener. See picture.



The brace has yet to be shaped and fitted but you can see the location.

I would imagine this repair cost more than a new M522??

[neilca]

I would imagine this repair cost more than a new M522??

Yes it would be. That is why I am doing it myself. I figure it is an excellent time for me to learn how to do this stuff. If I blow it, I am not out much.

[multidon]

The gap you reference is normal. This is called an elevated fret board. A mandolin with this feature allows more of the top to vibrate. In the case of your Ibanez the elevation seems crudely fashioned and a bit skimpy for fretboard support. It has nothing at all to do with the support of the top.

[Greg Mirken]

Can we see some photos that show what indicates the top sinking?

[neilca]

Can we see some photos that show what indicates the top sinking?

I did try to get some pictures but it was difficult to photograph. What got my attention was one side of the "F" hole was lower than the other side of the same hole, by about the thickness of the top.

BTW we measured the thickness of the top. It was varied randomly from about 0.130-0.145 inches.

Thanks Don for that info, I thought that looked weird.

[neilca]

I have been side tracked on another project but now I have started the tap tuning. My luthier buddy lent me his jig for the mandolin and the sound equipment for tap tuning. And books to read on the subject. Here is the mandolin in the holding fixture.



Here is the other side and sound setup.



I started with the tenor bar and was happy it was G#, but it was in the 4th octave 400 hz. This thing is really stiff. I reduced the tone bars both in length and height with little change. I believe the sound board is just too stiff to get to the second octave 200hz. I am going to try thinning the outer band of the sound board but I only have about 0.020" left to remove for a final thickness of 0.110".

Anyone have any other ideas?

[neilca]

The tuning is not going well. I have removed the bass tone bar and whittled the tenor down to a nub yet the pitch can only come down to D4 at 295 hz. So the sound board is just tooo stiff to get to the 200 hz range. My plan from here is to replace the tone bars and tune in the fourth octave to a sharp note to reduce wolf tones.

[HoGo]

Sorry to be harsh but doing all that tuning nonsense is not going to save your mandolin. First, if you ever want to use any tap tuning technique your build specs MUST be consistent and any tuning frequencies derived from many instruments and tests on the same style of build as many times as possible to even start thinking about their reliability. Just taking someones numbers and blindly adhere to them on (poorly and strangely made) import is not going to work at all even if the numbers were the holy sacred frequencies of LL himself. I'm sorry, but IMHO you are wasting time there.
What you have there is mandolin with huge top block (that you cannot simply remove) and poorly thin graduated top - or more likely pressed - assuming from the thicknesses. These tops tend to sink and that's why they used such giant bars. If you want to make the mandolin playable and strengthen the arch I would go for simple x bracing (something like 1/4" wide and 3/8" tall, tapered towards rim) with braces going under feet of bridge and crossing 1-1/2" in front of bridge and perhaps thin popsicle cross brace in the area where the top sinks. That would support the center of top and also the sinking upper part. And likely it will sound better than before. and hopefully it will survive few more years of service.

[stevojack665]

I'm not sure they're is much to gain by attempting this type of work on a $300 pressed top mandolin. If you want some practice, try building a carved top for it instead.

[neilca]

Thank you for your input, I suspect you are correct. But I am learning so much messing around with this thing. The mandolin was firewood prior to all this and if it ends up firewood that's OK, I will have experienced/learned a lot about how these things work. I am a retired engineer and naturally curious about how things work.

I like the idea of cross bracing the top. I have never done anything like that before. ; )

[Jeff Mando]

Neilca, it sounds like you are having fun and trying to apply some principles........but, I would have to agree with HoGo in that it is overkill when applied to that particular mandolin. Something like consulting NASA when a pitchpipe will do, IMHO. Or, maybe a pitchfork!

Actually, I doubt if I would have gone to the trouble of removing the back. I probably would have tried to jam something under the bridge through an f-hole to jack it up and keep it from getting worse....and call it a day. Again, sorry to be blunt.

These conversations happen on an almost daily basis in the repair world. I often have to tell a customer that his vintage $800 guitar is going to require $2400 worth of repair and that I can't, in good faith recommend him spending the money -- unless there is a sentimental reason to do so.

Again, if you're just having fun, no problem -- certainly better than watching reruns of Matlock.

[Br1ck]

I too am retired and have spent a lot of effort fixing instruments. I do try to work on instruments that would have value if fixed. Solid wood is at the top of my list.But I did buy a cheapo arch top to slip the neck block, refret, and add real binding in preparation for my mandolin build. put pickups in the thing too. it was successful and fun. I'd get a CNC top, graduate and brace it, and put it back together. If it sounded any good, refinish the thing. I think that is a better approach and worth spending time on.

[neilca]

I have finished messing with this mandolin. It is not firewood so that is good. It is louder than I expected but does have a boxy sound. I glued a JJB passive pickup system to the top before the back was glued back on in case the loss of resonance made this thing too quite. Well it does sound good plugged in, no boxiness and of course it can be changed via the knobs on the amp or preamp.



The mandolin shows scars from the operation, I call it character. It sits next to my chair in the family room for when I just want to pick. Project complete!