Using Latex Cement for KLH Cloth Surround Doping
- Thread starter KingBubba
- Start date
Larry didn't experiment with anything. He is using the compound I/we (um, DIY guy(s)!) came up with over at the CSP forum based on some solid research. Larry happens to be an astute businessman, and latched onto it after extensive testing and measurements were conducted. Who knew...? This stuff is only popular in our little world of speaker-geekdom. Nobody is getting rich.
Roy
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KingBubba,
Permatex seemed close to our goal based on what we were learning about the original compound, which is why we mentioned it in the AR-3a restoration guide. Later measurements by me and another CSP member confirmed it was not working as well as we had hoped, though it was still "better" than the vast majority of concoctions being discussed (when not heavily applied). This motivated further research.
The truth be known, AR woofers seldom require much in the way of "re-sealing". KLH woofers benefit much more.
It can't hurt to apply the sealant to KLH dust caps at this point, but I don't believe it is necessary...especially if the high cost of the sealant is of concern. In fact, since the dust cap is not a moving part, Permatex, or the various other sealants discussed here and elsewhere could easily be used.
Roy
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I recently redoped my KLH22 speakers using the AR product. I ruined my first pair of KLH sixes using an interweb recipe. This stuff works perfectly. In fact, with a recap, it restored my speakers to a level that I did not realize possible. Those old KLH's were supremely musical and imaged great.
Sounds like a recipe (formula, whatever) to me even if "solid research" and "extensive testing and measurements were conducted" is involved. You must feel the connotation of recipe implies guesswork being done by simple minds.
Of course it is a formula/recipe, but Vintage AR had nothing to do with developing it. It was the product of a DIY endeavor....which was my only point. Reading the whole thread often provides insight.
Roy
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I use Premium PL S20 polyurethane masonry sealant to make and/or repair surrounds. IT MUST be of the SELF LEVELING type of sealant. Polyurethane is tough, flexible, weather proof and sticks well to anything except waxed polypropylene that I make my fixtures from. Just brush it onto your surround(speaker horizontal, cone facing UP or it probably run) I've repaired four, 12" Cerwin Vega speakers a year ago and they still look like the day I started using them. They get played almost every day. Excellant cone movement and Bass reproduction.
I assume that you are referring to foam or butyl surrounds? This thread is about cloth surrounds.
Retrovert
Addicted Member
As I've written elsewhere, based upon my research and reading and as confirmed by Roy, the original sealant for cloth surrounds used at the time of AR, KLH, and Advent was a simple mix of butyl (aka butylene) rubber dissolved in a low-molecular weight solvent carrier such as a mix of toluene and xylene. A mix of solvents slows the evaporation rate so your sealant doesn't harden while you're applying it. The latter versions of the mix added carbon black to make the surround opaque.
Butyl rubber is seriously sticky as everyone has experienced: chewing gum is a food-grade butyl rubber, and does it stick to everything in sight. If you know how sticky chewing gum remains over time, even when on sidewalks in sunlight and air, you can appreciate that butyl rubber is likely the right material for surrounds which are to remain flexible and tacky over time. (Chewing gum has glycerin or vegetable oil added to keep it soft.) The stickyness and flexibility is why rubber has to be crosslinked (aka vulcanized) with sulphur to harden it and make it useful. That was Charles Goodyear's great, and hard won, contribution to making rubber useful. ( www.goodyear.com/corporate/history/history_story.html )
I don't know that the concentration of toluene is great enough to soften the existing butyl surround. I think it is more that the new butyl is so sticky it will adhere to just about anything—this includes clothing and skin so wear old clothes and gloves—so the existing rubber, fabric, and paper are very happy to bond (one might even say positively promiscuous) when it comes to adhesives.
Roy is nearly entirely correct about caulking, but not all caulking dries hard or stiff. Some of the permanently sticky grey stuff is very useful for sealing around speakers, since one can still remove the speaker years later with the caulk being pliable. Frost King Mortite Caulking Cord ( www.frostking.com/mortite-caulking-cord ) comes to mind as one of the brands that doesn't harden and remains very sticky for years and years. Its formulation, no surprise here, is about two-thirds butylene with a filler (calcium carbonate or titanium dioxide for color), some surfactants to increase adhesion (mostly to metals, as wood is pretty easy to bind to), and some antioxidants to slow the oxidative cross-linking and keep it flexible over time.
I suspect a similar caulk formulation was used in AR, KLH, and Advent line to seal the drivers to the cabinet, but this is speculation. While I have read of its use as a replacement sealant, I haven't seen any confirmation from someone with knowledge of the production line. I know some of drivers were epoxied in place so it wasn't always caulking.
Rubber cement is neoprene rubber, which is not sticky and much harder, in a solvent carrier like toluene. So it will dry hard and be far less compliant.
Other caulks are often latex rubber which is less hard and can remain slightly sticky, but nowhere near as much as butylene. (I have a bit of experience with latex prosthetics for special FX and Halloween costumes need to be dusted with talk to keep them from sticking to everything, and state they remain sticky for months, even years, until the latex surface oxidizes and hardens.)
Silicone caulks, or blends with latex or acrylics, harden and would be disastrous for surrounds as has been reported here on numerous occasions.
The "Restoring the AR-3a" document over at ClassicSpeakerPages has a lot of information on sealants.
To expand on this, most of these glues are PVA (poly vinyl acetate) which is white glue, although clear formulations do exist. As an artist I've used the clear ones extensively and can tell you they dry hard, but not completely inflexible. I would not suggest using them for anything in a speaker other than gluing cabinets back together or gluing veneer down. Carpenter's glue is often a PVA adhesive with some ammonia to reduce the surface tension of water and thus wet the surface better and bond even if the surface isn't perfectly clean. Putting hard adhesives into a driver cone is obviously a bad thing as it reduces compliance and raises the lowest frequency response.
Speaker refoaming kits commonly include a PVA adhesive because water-based adhesives are (a) safer since the solvents are hepatotoxic and neurotoxic with routine exposure, and safe-handling rules require ventilation and product-label warnings, and (b) easy for novices to apply. The fact that they don't work, and alter the speaker response, doesn't matter when one is dealing with safety. Me, I'll use solvents outdoors or in well-ventilated areas and not breathe the stuff, but I'm doing one-offs, not a product line or running a repair facility.
One more thing: when Roy says something about speaker sealants it is an excellent idea to follow his advice. To do otherwise will damage your speakers, likely irreparably so.
Hanleyster
ambitious but rubbish
You and just about everyone else on this forum.
That's probably true! I guess I should have been more clear that I do it the work primarily for others, as a business. I think the majority of DIY AKer's are doing work primarily for themselves (to keep or flip).
Brian
An Old Geezer
Not weighing into the diy or other discussions but found it almost amusing that some say the $15 price tag for what appears to be the best solution to date is expensive while I read throughout threads recommendations about spending massively more amounts of money on capacitors that very likely make minimal improvements over far less costly caps or wiring, etc. We are a strange lot, indeed.
I am not related to vintage-ar but am a happy customer who has used the sealer. I found after doing the Fives woofer surrounds, dust cover and mids, I still had about half a bottle left over. So, about $3.25 per speaker exclusive of shipping costs. Can not think of a less expensive investment for a real sonic improvement that is substantial with not element of subjectivity attached.
I am not related to vintage-ar but am a happy customer who has used the sealer. I found after doing the Fives woofer surrounds, dust cover and mids, I still had about half a bottle left over. So, about $3.25 per speaker exclusive of shipping costs. Can not think of a less expensive investment for a real sonic improvement that is substantial with not element of subjectivity attached.
Retrovert
Addicted Member
You're welcome.
Retrovert
Addicted Member
Many times making something isn't about the money, it's about the craft, in that one buys all the components and builds something that one can point to saying, not only did I rewire the crossover, not only did I refinished the cabinet, but I even went so far as to make my own surround dope.
In this case whipping up a batch of one's own sealant delivers a level of pride and satisfaction that using something purchased does not. It's the same reason I have, on occasion, grown my own tomatoes which ended up costing me more than the greenmarket purchases would have. (Although I maintain that tomatoes picked at the peak of ripeness—the point of greatest fragility—and immediately eaten taste vastly superior to anything picked a day before when it wasn't perfect for consumption but could be transported to the market without damage.)
Then there's the issue of cost as a matter of principle. I would rather make my own deoxit where I can mix up a gallon of the stuff for the same price as a few ounces and clean all of the contacts in the surrounding three counties at no extra cost.
Retrovert
Addicted Member
Well, this is the same forum where somebody complained that $15 for new foam surrounds was too expensive, and a lot of people agreed.
Strange lot, indeed. Cheap lot, too.
Maybe, except a foam surround is a thin piece of urethane which has minimal raw ingredients and virtually no labor component because it is made by slaves, and thus costs next to nothing to make. What one is paying for is the labor to keep it stocked and put it in a box.
So it is kind of offensive to pay $15 for a piece of plastic with those characteristics. That's not cheapness, it's just practicality. Particularly when one can buy an entire speaker with a surround for only a few dollars more.