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Old 9th November 2003, 06:38 AM   #11
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JOE DIRT®'s Avatar
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Location: Brantford, ON
baby powder....avoid Armour All
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Old 11th March 2012, 04:22 AM   #12
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Originally Posted by phase_accurate View Post
A good friend of mine once used silicone rubber to repair a foam surround.
He dissoleved it slightly and applied it with a small paintbrush. Maybe one can apply a thin protective coating that way (Vas will decrease slightly and fs increase). I will see him today or tomorrow so I can ask him what solvent he used. But I think it was alcohol as fa as I remember.
Hi Charles. I know that this is a *very* old thread but I can't see where you ever got back with the info on what your friend used to dilute the silicone rubber. I'm hoping you're still a member.
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Old 27th July 2012, 07:01 PM   #13
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Simply Speakers (Simply Speakers - Official Speaker Repair Page - Speaker Parts and Repair Service) offers a water based emulsion in a bottle for about $8.00US that claims to preserve new foam surrounds upto 50% longer. I don't know if it will help once the deterioration starts though? It is probably time to change your surrounds anyway. Those damn microbes! My opinion is that it is all in the chemistry of the foam surrounds during manufacture which Simply Speakers also claims has been addressed for more longer lasting reults using their new foam surrounds? This stuff goes on looking like Elmers Wood Glue but dries clear and flexible. I'll get back to you guys in 12 years or so when I know the results. I am now on my 3rd set of surrounds for my AR9 towers and any help in this area is welcome. I hear some big manufacturers (excpet Cerwin Vega it seems - they start to rot tin the box before you get the speaker) use a similar formula on spider cloth, foam surrounds and or paper cones. Simply Speakers claims; "Our special formula Foam Guard PVA vinyl emulsion sealer is designed to extend the life of new foam edges by preventing moisture absorption, microbial attack, and UV damage. Dries clear and flexible. One bottle will treat 6 to 8 speaker surrounds. It is also used on professional speakers to seal and treat fabric or cloth cone edge suspensions, and to seal and dampen paper edge cones." Part Number MI-1291FG
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Old 27th July 2012, 08:57 PM   #14
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Location: New England
white, PVA sealants are commonly used to seal the fabric edge on pro-audio drivers like JBL, Eminence, etc. While effective for those non-critical applications, those sealants DO harden a bit as they age and WILL affect the resonant frequency of acoustic suspension speakers.
Many tests have been done using these PVA sealants on vintage AR, KLH and Advent fabric surround woofers to 're-seal' them. Unfortunately after about a month re-testing the resonant freq. shows it has increased a significant 5 to 10 hz.

Trying to preserve aging foam surrounds is a loosing battle. Evidently, those to fight it fear having to face DIY refoaming having never done it. However, once you get one done successfully, you wonder what all the fuss was about.

It's my understanding from my foam supplier that modern foam are polyether based and will last much longer than old ones.

It's been my experience with refoaming vintage woofers that there are two types I deal with. The dry, crumbly foam and the soft, tar-like foam that's a mess to clean up. Infinity is famous for having the latter foams.

Last edited by speakerdoctor; 27th July 2012 at 09:02 PM.
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Old 28th July 2012, 03:41 AM   #15
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Originally Posted by JOE DIRT® View Post
(snip)....avoid Armour All

Silicones whether diluted or not will alter the excursion of the cones and are a #itch to remove should one ever decide to properly install new surrounds.

I would suggest the use of liquid latex rubber which manages to penetrate the foam and is easily removed anytime down the road.

Lightweight, easy to work with, apply with a small paint brush and remove the latex lasts as long if not longer than foam surrounds without changing the character of the treated surround as noticably as silicone, rubberized sprays, speaker dope etc.
"A problem left to itself dries up or goes rotten. But fertilize a problem with a solution--you'll hatch out dozens." (N.F.Simpson)
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Old 28th July 2012, 05:54 PM   #16
sbrads is offline sbrads  United Kingdom
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I used silicone rubber neat, smeared on as thin as possible on my Castle Conway 2 woofers about 20+ yrs ago. Still working fine and never sounded better. This was after having the original perished foam surrounds replaced by Castle after about 7 or 8 yrs and me not wanting to have to go through the hassle again. Good job I did it as Castle are sadly gone now.
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Old 30th July 2012, 11:22 PM   #17
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This cake just came out of the oven today along the lines of speaker maintenance. A soon to be vintage pair of circa 1994 Acarian Systems Alon II needed a pit stop for re-foaming. The real fun in re-foaming for me is challenging my tweaked AR9s to a brawl.against all new-comers during testing (photos links follow);








Note: The last photo shows one of the 10" woofers from the rear view after completion. When gluing the inner edge to the cone it is also a good idea at that time to check that the start of the foam surround arch is not only concentric to the paper cone diameter all the way around the circumference but that the foam arch is also properly centered in between the opening of the outer basket side and the inner cone side of the arch and that an optional trim ring can fit to the outer edge without touching or squeezing the start of the outer arch - that would be a sin.. This tolerance can be tighter for some woofers than others given that inner cone diameters and outer basket diameters at the outer foam ledge can vary a bit and the foam kits are generic in size to fit many of the "same size" woofers. There is room for wiggle here. That is why you will always see, read, or hear that anything within 1/8" is OK from the installation instructions. In this case the start of the inner edge slant of the foam has almost a 1/16th inch ledge before the arch begins all the way around the cone side but the arch is exactly where I want it to be. To have tried to make that edge perfect would have possibly contorted the new foam edge a bit which could have led to unwanted stresses of the foam resulting in possible wrinkles on the outer edge when gluing down, etc. Also, a properly fitting foam kit insures the arch is very close to where it should be. Just be aware is all. We might as well try do it right..

Note2: I like to use a putty type caulk for all drivers mounted in sealed and ported boxes. It insures no air leaks and I feel I get a bit better bass response out of most cabinets when I do this. This is more audible/noticeable in larger volume and tower speakers in my opinion. I also know there are no air leaks from the mounting screw locations with this method and I am never sure of this when using the old used thin speaker foam gaskets or with weather strip tape. If you have whimpy woofer mounting screws the formed caulk gasket needs to be thinner. I used a healthy amount in this install since the screws and cabinet accommodated and rolled it very flat before mounting.. I let the woofer sit for over 20 minutes after the initial star pattern tightening of the mounting screws and come back later and then torque them down after the putty has squeezed out a bit by the woofer seating in. Never over-tighten screws since MDF board or wood can strip out easily. I have been using ACE Hardware Rope Caulk with great success and it comes in white and brown. I don't use plumber's putty any longer since some installs I performed over 10-20 years ago displayed drying and crumbling of the putty and that defeats the purpose of the anti-resonance gasket concept.. Never use silicone or glue since the SpeakerDoctor or the next guy will be pissed if he gets your speaker in for service! Some like to use 1/8 or 1/4 inch wide adhesive backed weather strip foam tape also available at most hardware stores. Black speaker caulk intended for this purpose is also sold at distributors and I have never used it but DIY at the local hardware store is usually cheaper. Alon used a real nice black goopy caulk that stays tacky forever. Other than rolling off and scraping the main bulk of the old goop I left the remnants on the speaker basket rear edge and cabinet and then applied the new caulk. No need to grind down onto the paint of the woofer basket rear to remove it all..
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Old 31st July 2012, 12:04 AM   #18
sreten is offline sreten  United Kingdom
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Foam surrounds that are going where the foam meets the cone can
fixed with a bead of PVA wood glue to fill the crack without really
affecting the driver parameters at all.

Rubber type contact adhesive can work well, coating the whole surround.
If you don't wan't this to become "dusty" to to fluff, talcum powder can
be used to prevent that.

Though note that some foam surrounds are simply unstable and will
disintegrate whatever you do, they are simply a chemical timebomb.

So many different types, its very hard to generalise.

rgds, sreten.

Last edited by sreten; 31st July 2012 at 12:07 AM.
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