Anyone aware of a site of such tips for renovation. About 50 years old. Looks as though the card of the cone hase weakened with age, probably like the paper of books goes brown and crumbly over time. Looks as though the central cone area probably has failed to resist the returning force of the periphery and the spider and has buckled torsionally but not split in that inner zone ,one or so inches, from the voice coil join and radially out.
Recone the thing.
-- You can't have a sense of humor, if you have no sense.
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If you attempt to splint or reinforce that area, perhaps with a collar of paper, you will change the mass and thus lower the output. If the speaker is meant to reproduce a wide frequency range, it will no longer go up as high in frequency.
Acoustic design of speaker cones relies on the shape of the cone and the material from which it's made. Speakers meant to be woofers only are the least demanding -- you merely have to get the mass right. Midrange and full range speaker performance depends largely on the diaphragm material.
Does it play? I would have to see it.
Greg
I missed the original post, but, if it's of any value take it to Paul at Wembley Loudspeakers.
Ron(UK)
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If it actually works, and just the paper is going bad, try spraying the cone with an aeresol(sp) spray varnish, a little at a time until you get the stiffness that you think it should be. If the flexible portion around the perimeter is going, a very thin layer of spray adhesive may hold things together.
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If it actually works, and just the paper is going bad, try spraying the cone with an aeresol(sp) spray varnish, a little at a time until you get the stiffness that you think it should be. If the flexible portion around the perimeter is going, a very thin layer of spray adhesive may hold things together.
+++++This is a 12 inch Jensen speaker of about 1960. I suspect the periphery corrugations that should flex, had hardened up over the decades. Owner not overdrive abusing , I removed the central dome to check how much rubbing there was, no obvious scoring but did brush in some silicone oil. The VC showed through the gap in the former , as the original unusual green enamelling (not copper carbonate), looked fine. I covered this central area with a silicone bakeware cupcake mould and blasted the worst cockled areas with hot air on a low setting and pushed back wirth a spoon. In the end perhaps 50 percent of the original cockling. Then some spray adhesive in that cockled area Next time I may try hotter temp or try chemical to soften the card , water? diluted paint stripper? a small test patch initially whatever chosen. I think next time it would be a hotter temp of hot air and a matching cone of wood as a former , pushed in place, while cooling. There was some small cracks in the cone near the outer edge, 1mm hotmelt string "soldered" in those. After all that, here was still some very slight rubbing at the core, flexing the cone in by hand, perhaps the VC former needs remoulding as well, but it seems to work well enough to reduced power levels without distortion. Do the electromagnetic forces , form the former into more of a circle during powering?
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Are you aware that there are recone kits for these classic speakers, along with reconing companies?
Why spend so much time trying to half-ass a solution? I'm assuming the owner wants to use this half-century old unit, and not keep it as a curiosity.
If you buy a recone kit, you will need to make a centering jig for the voice coil. We used a short, thickwalled aluminum tube the diameter of the steel slug, with a plastic tube that slipped over the Al tube. The plastic tube's outer diameter was the inner diameter of the voice coil. Glue down the spider and the surround (an Elmer's-type glue will suffice. When dried, remove the jig and glue on the dust cap. Then take the voice coil braid and solder to the lugs, being careful to provide sufficient slack for the full excursion of the cone, without allowing the braid to slap the cone or the housing.
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