Goop Alert!

[mah]

This could be getting a bit tacky. :lol:

[bfish]

The goop is thermoplastic...

Only true in some cases. Different products were used over the multi-decade span. Recone sheets even show that different drivers used different products in the same era. The Airflex 520 from the 80s used on 515s and pro drivers wasn't thermoplastic, nor is the current dope used by GPA. I've heated that stuff in a steam bath trying to ease the application, but it made no difference at all.

The difference is pretty visual, the plastic dope(s) look "wetter".

The fact that they used products application-specifically (ie 416/515) strongly suggests there was a performance variable in play. The practice ended with the homogenization of several variations, resulting in the one-dope-fits-all practice of late.

[Steve Schell]

Thanks bfish. My experience is limited to four 414Z drivers in a pair of Malibus and several 416-8A woofers; all accordian cloth surround drivers. With these the goop was a honey color and yielded to the treatment I described, learned from an audio buyer/exporter who fixed up Altec drivers on a regular basis for resale.

[voice of the theater]

Thanks everyone--I learned a lot on this thread. If I ever buy a woofer with a goop mess like this one, I may put what I learned to good use (or if I move down to Colombia or Ecaudor, and don't run the A.C.).....