I just got an inquiry about what happens to the box tuning and low-end behavior when port plugs are installed on the TC212. The cabinet has three 3" diameter flared ports in a vertical line on the back of the cab, with the top and bottom port right behind the woofers and the middle port centered between them.
No plugs = 48 Hz tuning frequency, -3 dB @ 56 Hz, "flat" upper bass region (sounds "big").
One plug (middle one to maintain symmetry) = 40 Hz tuning frequency, -3 dB @ 60 Hz, a little bit less upper bass energy (medium bigness, a little tighter).
Two plugs (top and bottom) = 29 Hz tuning frequency, -3 dB @ 70 Hz, even less upper bass energy (starting to get lean, and tighter).
Three plugs = sealed box (Qtc = .54 ballpark), -3 dB in the lower 90's (definitely on the lean side of the spectrum).
I may not have included three plugs with all of the TC212s that went out, so if anyone with a TC212 needs more plugs, shoot me an e-mail or private message and I'll take care of it.