06-30-2011, 07:59 AM
I have several of the 70/90 cathedral speakers here and the field coil insulators look to be just plain cardboard to me. I have had a few radios here that had an asbestos heat shield in them, so I am familiar with it. It is usually a white colored material made of a kind of coarse woven cloth-like material. I usually don't worry too much about it, unless it has been damaged in some way.
Ed
Ed