It wouldn't be the first time I overanalysed something
Seems the final outcome will most likely be getting an unshielded sub and keeping it at the rear of the room... but first I would like to make an effort to find a suitable shielded one, for a couple of reasons:
Obviously there's the convenience of being able to place it wherever in the room it sounds best, regardless of where the CRT is. Also, even if the chance of damaging the CRT with subwoofer magnets is low, it would be a big expense/effort to repair the damage in the event that it did happen (I only know one guy who can repair CRTs). And also, I've already gone to the effort of tracking down a magnetically shielded front pair (Ascend Acoustics CBM-170SE Bookshelf Monitor Pair
) and centre speaker (Ascend Acoustics CMT-340SE2 Signature Series
), so it would be great to have cohesion between the subwoofer and the existing speakers. (My AVR is a Yamaha Aventage RX-A2040
I think I've confirmed six relatively new subwoofers with magnetic shielding - @lovinthehd
mentioned the Genelec 5040A and the Sony SA-WMSP85, and there's a bunch of Velodyne models (about 10-15 years old) that would also be magnetically shielded. What I'm unsure about is how well any of these would pair up with the Ascend Acoustics front left/right and centre in the room.
I definitely don't pretend to understand the specsheets of subwoofers when it comes to stuff like frequency response, SPL or nominal impedance etc etc, but this Audioholics article
seems to suggest that there's no need to match your subwoofer to the rest of your speakers based on these specs anyway? With that in mind, maybe my best approach would be to get any affordable 12-inch* vented shielded subwoofer I can find, and try it out?
(*12-inch because the room is 8ft x 12 ft x 12 ft=1152 cubic feet, vented because it would be mainly used for movies and games)