On December 17, 2017 at 13:01, tomciara said...
I would start simple. Cut some 2 x 4 or 2 x 6 at 14–1/2 inches and just frame in the cavity to get the proper cubic volume. Caulk all the seams to prevent leakage. You should get a pretty good approximation of whether it is going to be worth your trouble to start building back boxes.
I would agree with other posters that most rooms are background listening and not critical listening rooms, so you will be putting in a lot of effort, without a lot of return.
For those rooms where are more critical listening is desired, it will be a big jump upwards in trouble and in the budget as well.
Keep it simple. I would use the existing joist cavity, and just block it in, if you have attic access.
And, I wouldn't even try to come close to KEF's provided 'optimal' back box volume. Whatever is good, for background music.
