What is tar-stuff on woofer cone?

[Rudy2]

Hi folks,

I took the good advice of you folks and ordered some new foam surrounds for my old KLH 12" woofers. They should be here next week.

Now I am wondering what the black tar-like stuff is that is painted on the cone of one of my woofers but not the other? I am sure it is intended to dampen unwanted harmonics in the cone itself and I would like both speakers to match acoustically as well as visually. You can actually hear about 1/2 tonal pitch difference between the two woofers just by tapping on each with a finger. Is this black goop available to paint on? I was thinking that roof patch asphalt emulsion diluted with paint thinner might work as well as anything.... I dunno though.

Randy

[manek]

that goop is what you call driver dope.

you are right in saying they control harmonics in some way. Dont know what doping compound they have used so it would be foolist to paint the other one too :-)