MM Blues - Rattles from the guitar top

[slidincharlie]

I am starting using more intensely my 12-fret MM Blues that I bought quite a few months ago. This guitar has tons of volume, and has been set up perfectly by Robin with a .016 string set according to my specifications.
Now this guitar has got only one problem: there are some rattles developing from the guitar top in both f-hole areas when I pick the guitar and start playing. I am pretty sure that the rattle comes from the top and not from the cone (luckily!) because if I press on either f-hole the rattle stops and it does not come back... until the next time I pick the guitar and play.
IIRC I've read somewhere that MM guitars have a thinner top if compared to vintage Duolians, so top thickness could be an issue.
Has any MM Blues owner ever noticed this kind of issue?
Would a wooden post, maybe a cylinder inserted between the top and the bottom in the f-hole areas help stopping rattles definitively?

[Deleted]

Im sure you know this, but under the top between the tops of the f-holes is a 1cm thick slab of ply that the fretboard screws on to. Maybe this is loose?
You could prise the dots out and screw it on better, but maybe applying a bit of glue in any gap (use a dentist mirror and syringe?) would be less invasive.
Also, sticking in a cylindrical prop there would be difficult 'cos the neckstick is in the way. Between the neckstick and 'slab' is a gap (can't remember how wide - 1cm?), so a wedge might be a better option.
TT

[Michael Messer]

Hi Slidincharlie,

I am sorry to hear that you have a problem with a rattle. As far as I know, we have not come across this problem before.

It is always so difficult trying to help with a fault on a guitar when I am talking on the Internet, rather than being in the same room as the guitar.

Here are some thoughts on what might be causing your rattle;

Top thickness is not an issue. There is nothing in the design of MM instruments that makes them less durable than a real National guitar. They are properly built with the correct components.

Buzzes and rattles are an inherent problem in all resonator guitars. Over the years one learns how to avoid making them rattle when we play them, and how to fix the rattle when it starts.

Although you think it is not the cone, it is possible that pushing down on the F hole area of the top could affect a cone rattle, so I would not rule that possibility out.

Also, pushing down on the top will put pressure on the mushroom posts (pit props), that you call cylinders. It is possible that one of the mushrooms has come loose. It is possible that the flat piece of wood under the fretboard is loose, but I don't think it is.

Another possibility is the tailpiece and the ball ends of the strings. Sometimes a ball end can be in a position that makes it buzz/rattle against the body and putting pressure on the top can temporarily stop it buzzing. The tailpiece itself can also settle in a position that makes it buzz, so check that too.

You should also check that all coverplate screws are tight.

I would do all the outside checks before opening the guitar.

If you are unable to cure the problem, give Robin a call and ask him. He has set up hundreds of MM guitars and knows everything there is to know about their construction and how to work on them.

I hope this is helpful.

Shine On
Michael.

[slidincharlie]

Thank you guys. Sure I will check the outside before opening the guitar. I have opened my Nationals several times in the past, and I know that when you close one it is very easy to find some buzz or rattle that wasn't there before opening...
I'll post the results.

[robn]

Hi Carlo,

I've dropped you an email with my Skype address. As Michael says it could be that a wedge or mushroom post is loose. It may be quickest if I can see your guitar via Skype and show you the solutions using a guitar I have here as a model.

Robin

[slidincharlie]

Thanks Robin.
You have a new email.
--Carlo

[slidincharlie]

I talked with Robin via skype. Excellent support as always, and skype has proven particularly useful.
Robin told me that either the wedge located beneath the fretboard bottom or the mushroom might be a little loose (not easy to explain or to understand without a schematic drawing, but locating either spot will be pretty straightforward with the cover plate off). So pushing or glueing either piece firmly in place should fix the rattle. Otherwise, more rudely but also more easily done, a slight bend of trhe metal in the f-hole area might be the cure.
Anyway the rattle is not a big issue now, since it is not always there and it goes away just pressing the f-hole area with my hand. If it is still there at the next string change I might decide to open the guitar apart.
--Carlo