TLAH closed to open size ratio

[y2kindyz]

Hello all,

I am in the planning stages to build a set of TLAH that will be floor standing. The closed end on the floor and open on top.

I will be lengthening the enclosure to about 10-12 inches to accommodate 8-9 5 1/4" mids . My question is with regards to the closed and open ends. When lengthening the enclosure can I keep the open and closed ends the same as original? Or do I need to make them bigger, or keep the open end the same and make the bottom larger?

thanks in advance,

Oscar