Quoted from Boslaw:I've never seen one on a speaker before either, but this was definitely supposed to be there on the old speaker. There were terminals specifically for the cap. I just don't know if it's needed on the new (or what it's even for)
It's not necessary, remove it, is your replacement a 4ohm or an 8ohm?
Ive been replacing old tattered speakers in my pins lately, originals had 4ohm, I replaced with 8ohm