JBL L100 century - woofer surround with goo on them?

[special_20]

So I managed to find 2 pairs of rather minty JBL100 Centruries at a local estate sale and they stuck around for 50% off day Got them home and everything is working. however, upon close inspection, there is some sort of oil on the surrounds of all 4 woofers. It's still wet/tacky and enough was applied that it's pooled on the bottom and has dripped down the front of the speaker and there is some minor staining of the woofer cones.

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Are these cloth surrounds that need to be doped or sealed? Any clue what this stuff might be? Should I be worried or am I just being paranoid and should listen to my new toys while I decide what to do with them long term

 

[ra.ra]

My thought is that your suspicion is probably correct about a coating of surround "dope" pooling at the bottom due to gravity. Whether this is desirable or harmful is one thing, but the application does appear to have been done with care. The red color made me think it might be the Permatex gasket sealant sold in auto parts stores that some people used to use (unwisely) on cloth surrounds. Maybe you can determine its original solvent and carefully mop up some of the goop.

https://www.permatex.com/products/gasketing/gasket-sealants/permatex-high-tack-gasket-sealant/

 

[dc270]

If it has not created an out of balance causing the slim voice coil to rub, just flip it 180 degrees and let the "goo" drift back down the other way for several years.......
DC

 

[bobins08]

I recall people treating surrounds with automotive power steering fluid or brake fluid or some such thing. ?

Could something like that have been wiped on sometime in the past?

 

[jim249]

All the cloth surrounds I have seen over the years have had a sticky feel to them. It preserves the cloth surround so it won't disintegrate.

 

[dc270]

It is common for any treated accordion surround to drip sag over the years.
DC

 

[bowtie427ss]

It preserves the cloth surround so it won't disintegrate.

Has nothing to do with preservation. Cloth surrounds MUST be sealed so that no air can pass thru them.

It is common for any treated accordion surround to drip sag over the years.
DC

I strongly disagree. Migrating surround dope has only two causes. A) Too much was applied initially. B) The speaker has been in an INAPPROPRIATE environment(read too hot) for an extended length of time.

What is common are speakers exposed to environmental conditions outside of the manufacturers recommendations.

 

[dc270]

Has nothing to do with preservation. Cloth surrounds MUST be sealed so that no air can pass thru them.

I strongly disagree. Migrating surround dope has only two causes. A) Too much was applied initially. B) The speaker has been in an INAPPROPRIATE environment(read too hot) for an extended length of time.

What is common are speakers exposed to environmental conditions outside of the manufacturers recommendations.

and how often do people actually know or even read those recommendations?

FWIW- I agree with you, but having seen a LOT of dope surround in "drip" mode it is far more common to see them sagging that not I am afraid to say!
DC