High F# above the 12th fret of the B string? I've heard that. And it was cone cry. I've heard it in Celestion Vintage 30's. Well...just don't play that note!
Or: you could get some rubber cement and do a little extra layer of dope around the edge surround...that's what that shiny stuff around the edge of a Celestion is for. It dampens cone cry and edge yowl.
But to much will also dampen the highs a touch and make the speaker sound a little less lively. Don't overdo it!
It can be removed with Acetone tho.
My brother Bruce came up with a trick for making speakers livlier and deeper sounding that has been adopted by Ted Weber. But Bruce thought of it.
He hooks a new speaker up to a sound source and then takes a soldering brush and little bowl of ACETONE and keeps painting the edge surround of the speaker with acetone while the speaker has music or a tone from a signal generator playing through it.
The speaker doesn't have to be mounted...he just does it to new speakers sitting face up on his work bench.
The acetone removes the edge dope but also softens the paper and edge surround and the speaker opens up and the tone gets deeper.
It works! Works especially well on some of the new Jensen RI speakers like the C10Q which is kind of thin and bright right out of the box.
Lew