This should be a fairly short post about a recent first time experience re-foaming the woofers in a set of speakers I picked up from the local flea market for 5 bucks. The speakers are a set of ADS L300Cs that, except for the rotted foam and a few scuffs on the grill, seemed physically perfect, tweeter domes included, and worth a small gamble especially given the surprising heft for their small size. The sticker above the wire terminals listing a specification of 4 Ohms and 75W didn't hurt either. Taking them home and hooking them up to an amp at low volume proved there was still life in the set so I looked into how to replace the foam surrounds. The only tools required to clear up the old foam were an exacto knife, some acetone, and plenty cotton swaps. I ended up having to buy 2 sets of foam surrounds due to not correctly centering one of the speakers in the end for reasons that will be explained. The first set came with instructions for replacing the foam without having to cut out the middle cap and a bottle of glue that worked well enough.
The exacto knife was used to cut away the larger peices of the old foam surround including a thick plastic gasket that was around the outer edge of the speaker. Originally I didn't notice this gasket wasn't part of the speaker base due to the way the original glue cleaned up until after attaching the center portion of the first replacement foam surrounds which contributed to problems hand centering it later.
The first step after clean up was to glue the center edge to the speaker. This part was relatively easy since the foam is angled slightly downward and sit nicely on the cone. One step I did not know about until I re-did the first woofer was to play a 50Hz sine wave from a phone app with the amp wired directly to the woofer. I don't think I would have needed this step if I hadn't bent the first replacement foam surround removing the last of the old one as the replacement foam on the second woofer sat very flush with rim and thus was easy to hand center without a signal generator app. Due to the first one being off center you could hear the center of the speaker scraping during use so I had to remove the first attempt at replacing the foam and looked around for another replacement set at a cheaper price since I didn't need another bottle of glue. The new set still ended up being a bitter harder to glue down on the outer edge than the first set, obviously not counting the one I bent, so the phone signal app still helped a lot when it came to making sure the glued dryed with it centered. One last thing I needed to do was fix the scuffed paint on the front grills. Since I had some matte black spray paint left over from another project so I opted to used that to replace the marred gloss black it came with after taping over the ADS logo badges with painters tape. A couple coats later and the front grills looked better than they did out of the box in my opinion.
The sound these little guys produce is pretty great for their small size and in the end it was well worth the couple hours and $35-ish investment.