Had a question for those of you who have built columns in your theaters to hide your rear surrounds.

How did you determine in cavity size for the speaker? If you looked at the size of the speakers you where planning on using and then added a couple of extra inches, are you concerned when you upgrade your speakers that the new ones might not fit? Did you use a ported speaker?

Please post your column dimensions (W and D) as well. Thanks in advance! :)