[morzh]

Well,

The speaker came back Wednesday.
I used the 90 chassis to test it.

Dee could not save the cone; according to him as soon as he tried to take it off, it started to crumble.
Anyway, he replaced the cone for a modern one with "propeller" spider. For free.

Now first the seaker sounded the same as the other 90 speaker I have.
Then during commercial when a man with deep low voice spoke, I heard buzz, "bzzzzzzzz" type. I plugged in the other speaker, and it was OK.

Then I started touching the membrane and the spider, and when I pressed upon the spider the buzz stopped.
Then I saw something surrounding the spider under it, which it touched.
I thought first it was the metal, but then realized there is no metal there.

Eventually I think it is the lower part of the cone's funnel, as the spider is kind of wide and could not be glued to that part. The spider, I think, resonated on low and was buzing against that part of the cone.

I had the thin leftovers of felt padding for furniture legs.
I cut thin segments and glued them under the spider using fabric glue.

Seems like the buzzing has stopped.

The ultimate test will be when they resume musical programming, as so far it has been mostly sports. But so far during commercials deep voices and low-pitched music sound fine. No buzz.