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 Post subject: Cloth speaker surrounds
PostPosted: May Sat 04, 2019 2:39 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Warner Robins, GA
I have a pair of Automatic Radio two way speakers where the 5" woofers have cloth surrounds that were doped with stuff that turns hard after many years such that the cone cannot properly move.

Several years ago I tried break fluid which softened up the dope, but I want a permanent solution.

How do I safely remove the dope and what can I use as a replacement?

I've got 91% isopropyl alcohol, full strength acetone and q-dope thinner at work that I can use


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 Post subject: Re: Cloth speaker surrounds
PostPosted: May Fri 17, 2019 6:49 am 
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The only permanent solution I have found is to replace the surrounds. Hopefully new cloth surrounds are available in the size you need.


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 Post subject: Re: Cloth speaker surrounds
PostPosted: May Fri 17, 2019 2:28 pm 
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Location: Warner Robins, GA
I had a pair of KLH 22A speakers where the dope had deteriorated and I was able to redo the dope.

Am hoping there's something that can remove the old dope.

I am going to check though and see if the cones still move relatively freely first. If they do then I'll leave them alone.


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 Post subject: Re: Cloth speaker surrounds
PostPosted: May Fri 17, 2019 5:09 pm 
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Location: Dos Rios, CA.
Dabble some Coca cola on the hard areas of the surround? Works better than anything on hardened mouse droppings on chassis's in my experience


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 Post subject: Re: Cloth speaker surrounds
PostPosted: May Fri 17, 2019 5:55 pm 
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Location: S. Dartmouth MA 02748-1225 USA
A solvent (petroleum) that won't: Dissolve the fabric of the cone, the existing surround to cone bond, the surround to landing zone bond and the cone itself.

Good Luck...

http://www.substech.com/dokuwiki/doku.p ... n_solvents

Be aware the the base elastomer embedded in the fabric could be destroyed by the solvent, fabric could be ruined too.

IMHO bite the bullet, hard, re-cone or at least replace the surrounds. The labor is going to be just as much and the result marginal re-moving and re-coating.

Chas

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Smith's Ale Gives Strength, Smith Bros. Brewers, New Bedford MA


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 Post subject: Re: Cloth speaker surrounds
PostPosted: May Fri 17, 2019 6:34 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Warner Robins, GA
I brought the 4 ohm version of that same driver from home thinking to try stuff on that, but it had no dope whatsoever or very little.

So I looked at one of the drivers in the speakers. It had dope, but was still fairly flexible perhaps a little stiff. I tried Acetone and it seemed to make the surround a little more flexible.

The other driver didn't look to have the same amount of dope at least it wasn't shiny like the other driver. It was stiff so I tried the acetone and it seemed to work to free up the surround and is about as free as the other driver based on feel.

Whether each stays as free is anybody's guess.

I cross these over at 80Hz with a 6 dB/octave passive crossover in series with the woofers as I run a powered sub with them so I doubt the ultimate flexibility of the surrounds really matters that much if at all.


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