Paper dust cap problem

[BerntR]

I have a pair of speakers with 10" basses from TC Sounds.

........ and small kids.


BTW, it's a paper cone. Very rigid.

The dustcap has been dented more than once, and the vacuum cleaner has been a handy repair tool. But now, the structural integrity of the dustcap has been damaged. There are soft spots and seams, and the woofer radiates annoying (harmonic?)distortions quite high in frequency on certain freqyenceies. It seems like parts of the dust cap is vibrating, but it could also be that the cone and the coating has separated and is vibrating against each other..

Is there any way I can repair this properly. I was thinking stiffen the spots and seams with some sort of glue, coating etc.

Thanks,

[SY]

Having lost some irreplaceable metal domes to the probing digit of my own Mini-me, I sympathize.

Anyway, if the dome is paper-based, try painting it with some white glue that has been diluted with water. Here in the US, the best one for this treatment is Elmer's Glue-All, but I don't know equivalent European brands.

[BerntR]

Thx,


I was a bit unprecise above.

The cone itself is fine.

..... it could seem like the coating and the dust cap is vibrating against each other.


Will the glue coating be stiff or does it have to soak into the cone paper to work? The reason I ask is that the outer coating seems very waterproof.

[SY]

Ah, that changes things, not for the better. You'll have to stiffen the dome up by essentially forming another dome on top of it, rather than by reinforcing it internally. Finding a coating that will do that and adhere well long-term to the coated dustcap is going to take some trial and error.

If you're ambitious, you might chase down replacement dustcaps. Most of the old one is then cut away and a replacement is glued down. It sounds scary, but if you can work with an Exacto knife in a well-lighted dust-free area, it is not terribly difficult. I've done it on my woofers, which are rather expensive paper cone drivers.

[BerntR]

Of course one option is to detach the dustcap, and do your prescribed procedure on the inside and then reinstall it.

Is that duable and if so - which glue should I use?

[poobah]

If the dust cap has internal delamination or something try the thin style "crazy glue" (cyano-acrylate)... the glue will wick into coarse papers. As much as it hurts, you may need to to poke a pin hole or two. Also, you want to do this with cone tipped well forward, if not completely upside down. It would almost impossible, but not completely so, to glue your voice coil if some freak glue mishap occured.

You can also buy new caps...

What is the fascination children have in poking dust caps... my own did it???????????????

[SY]

Bernt, I cut away the old dome as close to the former/cone junction as I safely could, being oh-so-careful not to nick anything there. I then attached a dome that had a slightly larger diameter than the original and with an outward fold at the periphery to form a broad gluing surface. My cone is heavy paper without doping, the dome a thinner, more compressed paper, so white glue was perfect. A day or two to cure, and all was well.

That disaster was feline, not filial.

[BerntR]

Originally posted by poobah
If the dust cap has internal delamination or something try the thin style "crazy glue" (cyano-acrylate)... the glue will wick into coarse papers. As much as it hurts, you may need to to poke a pin hole or two. Also, you want to do this with cone tipped well forward, if not completely upside down. It would almost impossible, but not completely so, to glue your voice coil if some freak glue mishap occured.

I dit a little trial on a news paper sheet. The result was interesting.

I have a hard time seeing myself being sucessful with distributing the glue appropriate through small holes.

How about: sanding away most of the coating - treating with super glu - coating?

Do you think this will work?

Anyone who knows which black coating is normally used?

[poobah]

Hmmmmm... does your speaker have a hole through the pole piece? You know... a hole all the way through from the rear?

I ask because I think some dust caps need to "breath" so as not to excessively dampen the cone. If your cone is "coated", maybe you have the hole?

And, if you do have center hole it would be quite simple to drop some glue right on the back side of the dustcap and then roll it around.

Otherwise I would consider removing the cap by cutting as close to the glue line as possible... or through it, if it is soft enough. Make your repairs on the back side and then glue it back in place.

I believe most speakers these days are assembled with the C-A type adhesives... LOCTITE is big into the adhesives for it.

[soongsc]

Possible solution:
Support the driver in the air facing down.
Poke a hole through the problem area.
Poke three or four holes evenly around the cap forming a circle with the problem area in it.
Use crazy glue in a syringe to inject maybe 0.25ml through each hole. Put the needle in a slanted position when doing it so that the gule will not come down along the needle. The needle should be poked in as little as possible just more than the thickness of the cap (maybe only 1mm into the cap)
Let dry.
If this doesn't solve the problem, you can still replace the cap. Just don't let the glue get to the cone if possible.