Peavey 80's 4x12 Speaker Cab?

[soundguruman]

I don't think it has anything to *pressure*...there has been bazillions of speakers made without vented construction. Its more to vent heat from the VC assembly. That way the reliability tends to be somewhat better if not deliberately abused.

It has to do with 2 things, pressure, and venting the voice coil heat. Considering how easily these speakers blow, (frequently) I think you need that vent.

[Gtr_tech]

Well if you wanna get right down to it, the spider is porous and will breathe some with a "solid" dustcap. A ton of PA speakers are made with solid dustcaps and no polepiece vent. But the higher power speakers will use a vent at the back of the magnet to increase airflow for safety margin.

Either way....the foam is a *bad* idea as it *will* rot with age. I yank out those bastards without thinking about it. A piece of fine screen glued in place of it works just the same.

[soundguruman]

Pretty much any foam, used in any pro-sound application, rots. And when it does, it turns into sticky goo balls, liquified acidic poop. If this rotted foam sticks to a circuit board, it will eat through the copper circuit tracks, in time destroying a circuit board.
I don't know why PV puts the foam there, cause they KNOW it will rot, and it will be sucked into the speaker voice coil. It makes a #!!(*) mess.
So without a doubt, remove the foam.
If you have an old MXR pedal, take the foam out of that too, before it destroys the circuit board. No, I am not making this up, be informed and do it now.

[Danelectron]

Those speakers have a substantial vent in the back of the magnet structure with a porous foam plug.

Is that similar to the Black Widows? If I remember back to the late 70s, they had a vent with a pretty heavy metal screen covering it. That screen was probably quadruple the guage of steel window screen.