What's Best for Recoating EVM-12L Cloth Surround?

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tictac
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What's Best for Recoating EVM-12L Cloth Surround?

Post by tictac »

I have a EVM-12L speaker I picked up used a few years back that exhibits some cone cry around D on the 10th fret of the high E string....

I've been trying to find all info I can on cone cry and how to deal with it.

Doping the surround of the speaker is one option I see alot and as I examine my speaker more it looks like someone may have tried to un-dope the cloth surround; it looks kind of dry compared to other EVM-12L's I've had.

Does anyone have any recommendations as to what could be used to re-coat the cloth surround? I've read comments about using white glue, contact cement, rubber cement, etc....

One recommendation was for Loctite 410 adhesive which seems to be a rubber impregnated super-glue. This stuff is hard to find and expensive plus it's described as "high-viscosity" and I'm thinking something with a lower viscosity would give you better control in allowing you to apply multiple coats until the cone cry is gone...

Does anyone have experience using contact cement with success? This seems to be the best thing that is available in my mind but I'd appreciate hearing from those who have some experience or knowledge about speaker doping...

Thank you for any insight you cam provide....

TT
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JMFahey
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Re: What's Best for Recoating EVM-12L Cloth Surround?

Post by JMFahey »

No, NONE of them, no matter what some forum might say, those are all adhesives, will dry stiff.

Original edge doping compound is a close (thicker) cousin of that milky "white latex" material which is often used to seal roofs against leaks so in a pinch you may use the same, just let dry and apply a couple extra coats.

First clean speaker edge which is probably caked in dust and lint with a rag soaked in acetone (what is often used to remove dope) and then recoat with a brush.

It will look white-bluish at first but later it will dry shiny sticky "black".
It´s actually transparent and black is, of course, old cone paper or cloth.
Design/Make/Service Musical stuff in Buenos Aires, Argentina, since 1969
potatofarmer
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Re: What's Best for Recoating EVM-12L Cloth Surround?

Post by potatofarmer »

Bit of a necro-bump, but I've used EVA-based glue for surround coating, specifically Helmar Super-Tac thinned with water. It's white, but dries clear after the water fully evaporates. I dried a puddle of some and it forms a silicone-like rubber. I've been thinning it in hopes that it'll penetrate the paper surround but it doesn't seem to soak in at all. The thinner coats make it easier to dial in, at least.

EVA is short for Ethylene Vinyl Acetate; it's often used in book binding. I doubt this is what is used professionally, but it's effective at damping the surround and safe to evaporate indoors.

I've been trying to find a butyl rubber solution for the black tacky surround dope that Celestion uses (and maybe Altec used) but the promising products (automotive window glass adhesive) seem to all be adulterated with silica. I'm sure it'd have to be thinned anyway, most likely with toluene, and maybe that would cause the silica to fall out of solution. I've also considered just trying to dissolve a bike tire inner tube in some toluene, but I suspect that'll require heat, and I've got the know-how to reflux organic solvents but not the equipment and I'd really rather not do that at home.

But for DIY reconing, EVA-based glue will get the job done.

Oop, just realized I've only tried it on cloth surrounds, only paper, so I can't comment on how well it'll seal against air flow, but it's good at adding mass.

I've also tried liquid latex, which didn't work.
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martin manning
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Re: What's Best for Recoating EVM-12L Cloth Surround?

Post by martin manning »

tictac
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Re: What's Best for Recoating EVM-12L Cloth Surround?

Post by tictac »

Thanks but I ended up buying a recone kit and reconing. Speaker had a voice coil rub which caused the cone cry and now it sounds great.... :D

TT
MKB
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Re: What's Best for Recoating EVM-12L Cloth Surround?

Post by MKB »

I used the stuff JMFahey suggested, and it works great. That's my go-to stuff now. However another thing that looks promising is FlexSeal Clear spray, you can buy it for around $12 a can at your local WalMart. The paintable sealant can leave brush marks, and I'm hoping the FlexSeal spray will look better. Will be trying that on my next recone.

Whatever you do, don't use the Permatex red gasket sealant recommended by some reconers for sealing cloth surrounds. That stuff never quite dries and will smear off onto surfaces it touches. It's messy.
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