Originally Posted by Mfusick
How much max depth do you have to work with? (JPA)
If you build 4 Gjallerhorns you might not end up needing smoothing subs. You certainly would NOT need more bass
One Ghorn alone already has more output than 4 sealed UXL18's at 16hz. Multiple subs in different locations have a way of smoothing themselves too.
If you could fit them the infinity 1260 would make a really nice smoothing sub. $60 each. Good quality with harman technologies. They are almost a proper bass solution unto themselves. You don't need much low or ULF output for smoothing subs, most of the trouble is between 30hz-90hz. You have a big room too.
I could probably swing 16" for the column depth if I had to. I'm actually considering some mid-build changes that may give me a little more flexibility in column depth.
WIth regard to the subs, my issue is going to be room modes. It looks like both rows of seating fall in a null at 38 Hz and 76 Hz. No amount of extra output will fix that. So I'm looking at adding smoothing subs to help eliminate modes, not increase output. The question I have is, if my horn subs are giving me 115 dB at the LP, but I have a 9 db null at 38 Hz, does the smoothing sub have to be able to output 115 dB to smooth out the response. I'm guessing it does not, but I can't think of why the physics would support that.
Another option I have, recommended by Toole, is a single sub at the front wall midpoint and another at the rear wall midpoint. This is supposedly an optimal configuration for a rectangular room with the seats within a 6' square at the middle of the room.