Speaker repair question

[Johnny C.]

Fixing a pair of Harmon Kardon HK-20's from 1972. These are 'sealed acoustic' - they have some type of putty covering the screws around the speakers to prevent any air from escaping.

Anyone know what this is? It almost looks like plumbers putty.

Thanks for any help!

John

[Sckott]

It doesn't seem like gasket material?

[Johnny C.]

Originally posted by Sckott
It doesn't seem like gasket material?

Nope, it's some kind of grey putty. The same color as plumbers putty but it's hard as a rock.

Weird.

[-=Rudy=-]

If you're going to replace it, silicone will work nicely. In fact, one tweak for Boston A40's was to silicone the driver in place. Can't say I like that idea 100%, but it's pliable and doesn't dry out. And easy enough to remove if need be.

What kind of repair do you need to do on the speakers?

[Johnny C.]

Originally posted by Rudy@A&MCorner
If you're going to replace it, silicone will work nicely. In fact, one tweak for Boston A40's was to silicone the driver in place. Can't say I like that idea 100%, but it's pliable and doesn't dry out. And easy enough to remove if need be.

What kind of repair do you need to do on the speakers?

The easiest kind - remove and replace a tweeter. Doing so means removing the putty seal around the tweeter - I think silicone should do nicely, thanks!

These HK-20's have very nice definition, and I've never heard a more perfect center image on anything in mono. The first real speakers I ever bought - in 1972, but they had to go in storage for the past decade - they were falling apart due to flood damage and I couldn't bear to part with them.

Now, a pair showed up at my door but one of the tweeters was shot, so I was able to prove to my wife, Tina, that keeping 'old junk' in the shed wasn't always a bad idea.

[Gerry]

It sounds like it may well be, in fact, plumber's putty. It stinks and it's messy, but does a great job. I've never used it to seal a box though, I use it when the router slips or to repair stripped screw holes.

[-=Rudy=-]

Originally posted by D-104

The easiest kind - remove and replace a tweeter. Doing so means removing the putty seal around the tweeter - I think silicone should do nicely, thanks!


Clear would probably work best, just so it's not visible. Tweeter swaps are a cinch, provided you can find genuine replacements like you had. :)

My main speakers for the past 20-25 years (two pairs) use a Philips tweeter. I keep wishing I'd bought a few spare tweeters when I was able to buy them. Philips went out of the aftermarket speaker component business, so I just have to make sure I never stress these out. These speakers, even my few pairs of Boston Acoustics speakers, use some kind of foam-like material for the gaskets.