The plate on the end of the port on the inside kills diode like chuffing/farting of the port. It tends to increase fidelity in ported systems by a very noticable amount. Sometimes this effect can be so severe it blows a woofer via this diode like issue of the port air mass. The plate equalizes the air mass loading on either side of the port : CRITICAL.
ThanksDiar, nice site, very stylish
I'm having a hard time understanding how it could be so easy. Collo referred to equivalent-models, but I'm not into electrics as much to grasp it.