repairing a dustcap

[nyazzip]

i have an early '60s 15" jensen speaker i'm using for guitars, low power amps, nothing too loud. the speaker is probably only rated for 25 watts max i think. anyway, it sounds fine. when i got it, there were some small holes on the "dust cap"(see pics http://s265.photobucket.com/albums/ii229/nyazzip/), which look like they may be spreading in a radial pattern around the edge of the entire dust cap(note that this dust cap is flat rather than the dome type you normally see- i don't know if maybe there was an outer dome that fell off or what). the material is a very light felty gauzy stuff, almost like the stuff you scrape off the dryer exhaust screen when ya do laundry.
anyway, does anyone have any repair recommendations that wont affect sound too much? or should i just let it deteriorate and not worry about it? i guess my fear is that dust is going to get into the voicecoil housing and eventually, some decade, cause some problems
i'm thinking maybe i can cut it out and slap something else on it, but i don't know what type of fabric or adhesive to use, or if doing so might ruin the speaker.

[EWBrown]

Parts Express has a variety of replacement cardboard or paper dust caps, not the same as this felt or fabric one, but should do the job.

If you use one of these it may be a good idea to remove the deteriorating fabric cover so it doesn't get pieces of it inside the voice coil.

I'd get one large enough to cover not only the voice coil but perhaps the point where the wires are attached to the cone.

This should have little or no effect on the sound.

HTH

/ed B in NH

[nyazzip]

i don't really like the idea of slathering on a thick paper dome over top my antique speaker dustcap, with very little chance of centering it accurately, but i guess i might have to. i was hoping to approximate the period engineering, for what it is/was worth......

[EWBrown]

You could probably just cut a round patch from an old wool blanket, or something made of felt (which is basically compressed wool) and "make do "with that. It should work fine, just stick it on with a small amount of "Elmer's" (or similar) white glue around the edge of the patch. It doesn't have to be mechanicaaly strong, it just has to just keep the dust, bugs and other stuff out of the voice coil. Just leave the old dust cover in place, if it isn't too raggedy looking.... Yellow_Light_Colorz_PDT_07

Just make sure any glue does NOT run into the voice coil... :o


/ed B in NH

[nyazzip]

one of my main concerns is indeed the glue. seems to me the dustcap would be moving constantly and vigorously, maybe more than any other region of the speaker, and i could easily imagine a brittle glue like elmers failing
but the "flexible" type glues have alot of mass, stuff like silicone.....and mass can't be good either. what glues are good for speakers...? maybe i'll just cut a circle out of an old flannel shirt, and name the cabinet the "Neil Young Special"....but what to glue with...
i guess the bottom line of this is that its not rocket science...i guess i would just feel bad about compromising a 40+ year old speaker, even if it didn't cost me a whole lot
heres a pic, i worked hard on the box, stained barn red, "distressing" it then waxing it and stuff. solid pine, with a dense ply baffle, open back. i cold-chiseled the Forney logo off an old arc welder i found in an abandoned barn here in northern illinois

http://s265.photobucket.com/albums/ii229/nyazzip/?action=tageditmany

[wiredbecker]

I've heard of people using a used dryer sheet to approximate a patch for a dust cap. You could even hit it with a matte black spraycan to try to get it to blend in.

Edit: You could easily apply the patch with PVA (Poly Vinyl Acetate--archival, doesn't crack) or Acrylic matte medium varnish. You could also use Acrylic Gloss medium varnish but that will dry glossy of course!

Good luck.

[nyazzip]

the dryer sheet idea actually sounds about perfect...though any i've touched seem to feel slippery/soapy, which makes me wonder about adhesion. at least my speaker will smell nice.
maybe i'll give that a try soon...i have about 12 simultaneous projects going on right now
on a side note, i just tried a vintage jensen 12" this morning i got from eBay cheap, one with a tiny little magnet, that i noticed has been badmouthed in some internet guitar circles...anyway, the thing seems to put out more bass than my 15"!! and, its just on a baffleboard, not even in a box yet! wow. i'm sure it wouldn't be hard to blow it up, but i don't intend to abuse it
its a '61 (or '51, not sure)jensen P12T 8 ohm for those who are interested...

[EWBrown]

I've used a tiny dab of elmer's and a small patch of writing paper, to repair small punctures, tears or holes in paper cones, with good results.
I usually "paint" the white paper patch with black "magic marker" after it dries, and it doesn't even show, ewxcept upon close-up inspection. ... The tiny amount of elmer's is insignificant to the overal moving mass of the cone. Mostly this was for small (cheap) speakers in radios, etc, and not high-end ones...

The dust cap repair kits from parts express use sone quick druing form of glue, probably related to rubber cement, with it's volatile compounds.

If there is a grille cloth in front of the speaker, then the "felt" dust cap probably isn't even really necessary, in a normally "clean" environment (as opposed to a workshop or garage).

The flannel patch will weigh more than the glue used to hold it in place, any way.

[nyazzip]

i don't have a grill cloth, so thats a big concern. if i did have a grill cloth, then i would never have been constantly reminded of having a holy dustcap; indeed it would have been a case of "ignorance is bliss".
i finally ended up tearing out the compromised dust cap(it was surprisingly tenacious); so now i have none. stupid me- it was much better to have %95 of a dustcap than none at all. guess i'll try to glue something in myslef now

[K-MAN]

did you find the the terminals mounted on the drivers in bad shape like mine? It seems the insulation corroded them so the two on my woofer snapped off when I took it out. I looked and there is repair kits of the dust caps and coils but not this.

[nyazzip]

k-man: no, my a25s are pretty clean, aside from cabinet abuse. i was actually shocked at how shiny the speaker output posts are. inside, also good.
this thread was about an old 15" jensen i use for a guitar box. i ended up just pulling off the dustcap with pliers and leaving it. i'll probably attempt a cover this fall; it isn't the rocket science (like all this other amp stuff) that i originally thought it might be.
i put the a25s away for a long time, but now that i have the grillcloth, and caps, and can venture outside the house due to weather, i'm going to launch into them soon. i routed off the edges with a 1/4" router bit wayy back(or was it 3/8"?), then i quit. thats what i do when the going gets tough.
but more soon, i swear