One speaker company, Northcreek, offered tunable ports: essentially straws inserted in the port and pulled in or out to change the sound (always thought of a trombone when considering this concept). This doesn't stuff the port, since obviously there are holes in straws but modifies its volume and length. Maybe try those mini-straws that are used to stir/sip drinks???
I never tried this, but it SHOULD have an effect.
Google offered this link--
http://www.northcreekmusic.com/Borealis/SBReview.htmThe relevant section is
"A second area that requires more discussion is our method of port tuning, or "the straws".
It would be nice to say that it was invented here, but it was actually discussed first in writing by Dr. Neville Thiele himself, in an ASA journal in the late 1950's. The purpose of the straws in the port tube is to force laminar air flow through the port at high volume levels. Dr. Theile found this to be more effective than flaring the port's egress, a method used by many manufacturers at the time and recently reinvented. The method we developed of tuning the port - by keeping the port tube length constant while changing the length of the straws in the port - allows the builder to control both the tuning frequency and port Q. This in turn allows the Borealis' low frequency response to be precisely tuned to the builder's listening room and electronics.
Adding straws to the port will not work with most woofers because the additional flow resistance lowers Ql and can cause the woofer to go into over-excursion, as Dr. D'Appolito points out. It works with the Borealis because the Scan Speak 18W/8545 motor is constructed in such a way that over-excursion is not an issue. The benefit of forcing laminar flow through the port is the elimination of port noise, particularly at high volume levels, which Mr. Florian confirmed.
