Classic speaker repair

[Doug K]

Just finished off a box full of foam surrounds that I purchased back in '97.

Thought, as I was cleaning the basket with my wifes fingernail polish remover, whew... nearly caught a buzz, this might save some bucks for those of you with older but efficient speakers.

Many of these paid for friends, end up on the heap because of "blown speakers". While some may indeed be electrically toasted, I'm talking about the repair of the mechanical process.

Inside the cabinet are generally several sizes of transducers. The ones with cone diameters greater that 3" are suceptable to a condition aptly named "foam rot". This foam is actually the mechanical connection from the "basket" and the "cone". When this foam takes a dive, your sound will be best described as "rattlely". When you hear it it is umistakable. It will not repair itself if you turn it down, it just won't rattle as loudly.

The really good news is that you can purchase from several speaker repair organizations, or just check with your speakers manufacturer, the replacement foam surrounds.

The first one is the hardest because you'll be worried about breaking something. Remember that it is already broken and you are going to save the replacement cost with a ten dollar fix, and the speaker will be offline for the day.

Tools: Sharp knife, screwdriver (phillips most likely) some denatured alcohol and elmers glue. (you might also want some of the afforemetioned nail polish remover, just be careful with it)

Remove the speaker from the cabinet. If the wire connections are tight, just snip 'em close to the pin. Remove the twist and strip back 3/4in the leads. they will be colored and they need to be reattached to the same pin as original.

Gently pry the gasket from the basket. Since most speakers are mounted from the front, the gasket only serves to help with the adhesion of the surround foam. Be nice to it, but it has to go.

Remove the foam from the basket with a sharp knife and a dab of alcohol/remover. Clean to a nice smooth finish. That was the hard part.

Now remove the old foam surround from the cone. I've found that by simply rubbing the old foam along the cone edge with yoru fingertips, removes 99% of it. Clean it as best you can, but a little old foam left on is a good thing. It helps the glue to adhere to the new foam and cone.

And its time to do that. Check that the new surround fits then put a lighhhhhtttt strip of glue on both contact surfaces. Smear with a swab or your fingers until tacky. Place surround on the cone and squeeze the connection area with your fingertips until a firm seal is confirmed. Press carefully on the cone with your fingertips spread. Release the pressure on the cone quickly and the cone will center itself perfectly.

Apply glue the same way to the basket and then the foam at their contact areas. Let it get tacky then press together the contact points lightly. Once lightly sealed, press the cone inward and release quickly again. Now firmly press the foam to the basket. Reapply the gasket aligning the screw holes. Use the weight of the speaker to seal the gasket and foam in place by resting the speaker face down. Walk away for two hours- threes better.

You can reinstall the speaker in the cabinet after this time. Pay attention to the speaker wire polarity. I just reattach the wireby twisting the lead around the pin with my leathermans pliers, but you could solder them too.

Really try not to turn it on for a day. Its just like a new speaker and a bit of break in time will pay dividends. After a day, its ready to rock. Like I said, ten bucks and a day offline.

I've repaired some classic, really fine sounding loudspeakers in this fashion. The repair lasts as long if not longer that the original.

Hope some of this works for you guys.

Doug k