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Repairing Speaker Foam Surrounds?
bigmush asks: "I have an old pair of speakers, and they had been working fine until recently. I took off the covers, and saw that the foam surround had started to wear out on both of the woofers. After 15 years of service, this was a sad discovery (though also an opportunity to justify an upgrade!). I found a few foam surround repair kits available online. How well do these work? What experiences have you had with them?"
It seemed to work well enough at first, but after only a few months of my listening habits, they were shot again. But as usual, YMMV.
This depends. If you get a high quality repair kit, one with good adhesive and high quality foam, you might have better results. It's tedious, difficult work, and requires a steady hand. You have to get everything just so, or else it will lose it's seal after a while and the thing will disintegrate again.
I've had to do this before. Not just wanted to, but had to. On a 2K Watt Yamaha S215IV Full range. One of the woofers had gone out, and replacements weren't exactly in my budget (I actually didn't have one).
I won't debate the performance of a Yamaha speaker in a Sound Reinforcement environment (I'm not a fan of Yamaha, especially their mixers), but these weren't too bad. However, it wasn't my choice to buy them, and if I'd had my way, I'd have just bought new ones as well.
For a professional environment, when a brand new replacement driver can be >$400 (and that's just a driver, not a full box), sometimes repairing the cone can be the way to go.
But, on the other hand, you have something to be thankful for. You think cone repair is tedious and annoying? Just be thankful you don't have to repair a voice coil. It's actually not too difficult to wrap the coil (some kits out there have pre-wrapped and even special tools for wrapping coils easily and quickly), but trying to scrape melted copper off of a heavily overdriven and not very well cooled driver will make you wonder why you ever went into technical audio.
Next project, resurrecting the old main sanctuary mixer, a Yamaha MC1604( current one is an Allen & Heath GL3300 :-)that spent a year in the youth annex with ants wandering around inside enjoying all the spilled sodas.
I see even classic Slashdot is now pretty much unusable on dial up anymore.
Even today Accoustic Research 3a's are used as reference speakers. Yamaha NS1000's are used for critical monitoring. Who would stick a substandard consumer driver into a pro cabinet? The driver is matched for the crossover. Using a substitute of differing coupling, suspension, and/or weight can mess up the system response and create resonances that didn't exist before. A sub is probably OK for your home theatre, but for studio critical monitoring, accept no substitutes. Your quality product depends on it.
Here is what Stereo Review has to say about both of them. See items 97 and 91. They are the ones I have.
http://www.stereophile.com/features/709/
Compare the graphs with anything BOSE. I'll tell you which one can create a better image of the original environment.
For my old 3a's, I do have the foam edge problem. I bought them used in 1978. Because they are acoustic suspension (very loose long throw) they are worth the money to find a shop that can do a good job re-coneing them. It's hard to replace the foam because of the damage removing it and the added weight of old + new glue. A good shop can re-cone them for about $40 each. I found a shop in Portland OR that does a great job.
The NS1000's are now going on 24 years old (bought in 1980) without any problems of any kind. There isn't much stuff out there that reliable to run problem free for 20+ years without a glitch. When they have a problem, I'll probably have them repaired instead of replaced as there isn't much on the market that has that quality, relibility and longevity. I've has other speakers fall apart in less than 1/3rd the time. Don't think they lasted this long just because I baby them. I don't.
It's sad when cheap speakers fall apart after only 10-15 years or less.
The truth shall set you free!
This summer I came into possession of a big old pair of 15" Scotts whose foam had substantially rotted away. While I had seen refoam kits on the internet, I always though to myself, "could that really work?", and kind of doubted it. Since I was unemployed and brokish at the time, I didn't want to blow cash on an unproven technology (internet refoam kits) and had entirely too much free time. So I decided I would spend an afternoon performing a "ghetto refoam" with silicon sealant and dryer sheets(!) to see if this home refoaming thing was actually feasible before plunking down for an actual kit.
The ghetto refoam was easy. Dryer sheets (brand unknown) were selected due to their strength, flexibility and lack of sound/noise when flexed. Cut into rounded strips matching the contour of the original foam, but a little wider; slather the strips with silicone-rubber sealant that maintains flexibility when cured; layer to suit taste (2 layers seemed like a good enough guess of the original foam's rigidity), and form around whatever's handy to match the diameter of the speaker (bucket top, coiled hose, etc.)
Once the silicone rubber had cured, it was an easy matter to arrange the pieces in place of the original foam and sort of splice them together, at this point following the normal procedures for refoaming (e.g. shimming the voice coil with whatever works, e.g. strips of Dixie cup, gluing on the new "foam", etc.).
Much to my surprise, this actually worked! It worked so well, in fact, that I just left the ghetto-foam on as a semi-permanent repair. The Scotts shake the entire neighborhood without any noticable distortion. I am amazed.
Caveat Emptor is not a business model.