I've refoamed a pair of EV woofers that have a vented pole piece. The
original dust cap was made of a non-porous paper. I removed most of it to be
able to shim the 2 inch diameter voice coil.
I have some very porous screen type dust caps I can use to replace the
originals but hesitate to use them for fear of reducing the bass a bit due
the loss of air moving area of the total cone assembly. The dust cap is 3
inches in Dia. so it's not a trivial amount of total cone area that would
become porous if I use the screen type.
Has anyone ever compared the effect of using a porous dust cap with a
non-porous one?

"CARL RICHARD" wrote in message
...
I've refoamed a pair of EV woofers that have a vented pole piece. The
original dust cap was made of a non-porous paper. I removed most of it to
be
able to shim the 2 inch diameter voice coil.
I have some very porous screen type dust caps I can use to replace the
originals but hesitate to use them for fear of reducing the bass a bit due
the loss of air moving area of the total cone assembly. The dust cap is 3
inches in Dia. so it's not a trivial amount of total cone area that would
become porous if I use the screen type.
Has anyone ever compared the effect of using a porous dust cap with a
non-porous one?

The main problem is that it changes the compliance of the woofer.
If the speaker is a bass reflex design, this will cause severe
irregularities in response.
If the speaker is a sealed box design, it will cause moderate
irregularities.