I am slowly building one of these sub cabinets with an eye to finishing and ordering the electronics in a month or so. For the outer walls I am using 2 pieces of 3/4" MDF to get a 1 1/2" wall. I am using 6 1/2 " as the depth of each woofer well as per the plans but want to make the outer of the 2 MDF pieces 1 " wider to give a 1/2" overhang on each end to frame a grill cloth. Will extending the depth of each woofer well by 1/2" seriously change the sound? I can give up the 1/2" extension - I just think a frame around the grill cloth would look nice. Or should I adjust the size of each wall piece so that the final depth is still only 6 1/2" with a grill attached"?
I had the exact same idea for my W-frames, and extended the outer 3/4" MDF layer 1" past the inner layer at the front, to allow for an inset 3/4" thick grill frame. It gives the cabinet the look of the 50's-60's (and even 70's) speakers, like Klipsch, AR, Dynaco, Advent, etc. speakers had (Klipsch STILL has that look in it's classic series). That style cabinet (with the grill inset into the front of the cabinet) went out of favor when research discovered the problem of diffraction caused by the sound from the drivers reflecting off of the front edges of the cabinet, solved by having the front baffle not inset into the cab. At subwoofer frequencies, however, diffraction is not a concern. That 6-1/2" depth is a compromise between supporting the lowest possible frequency while not creating too much of a cavity resonance. The depth of the driver cavity doesn't have to be exactly 6-1/2"---You can make it an inch shallower or deeper without incurring a serious penalty in sound quality or quantity.
